first commit

application/libraries/Accounts.php

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+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.5.0
+ * ---------------------------------------------------------------------------- */
+
+/**
+ * Accounts library.
+ *
+ * Handles account related functionality.
+ *
+ * @package Libraries
+ */
+class Accounts
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Accounts constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('users_model');
+        $this->CI->load->model('roles_model');
+
+        $this->CI->load->library('timezones');
+    }
+
+    /**
+     * Authenticate the provided credentials.
+     *
+     * @param string $username Username.
+     * @param string $password Password (non-hashed).
+     *
+     * @return array|null Returns an associative array with the PHP session data or NULL on failure.
+     * @throws Exception
+     */
+    public function check_login(string $username, string $password): ?array
+    {
+        $salt = $this->get_salt_by_username($username);
+
+        $password = hash_password($salt, $password);
+
+        $user_settings = $this->CI->db
+            ->get_where('user_settings', [
+                'username' => $username,
+                'password' => $password,
+            ])
+            ->row_array();
+
+        if (empty($user_settings)) {
+            return null;
+        }
+
+        $user = $this->CI->users_model->find($user_settings['id_users']);
+
+        $role = $this->CI->roles_model->find($user['id_roles']);
+
+        $default_timezone = $this->CI->timezones->get_default_timezone();
+
+        return [
+            'user_id' => $user['id'],
+            'user_email' => $user['email'],
+            'username' => $username,
+            'timezone' => !empty($user['timezone']) ? $user['timezone'] : $default_timezone,
+            'language' => !empty($user['language']) ? $user['language'] : Config::LANGUAGE,
+            'role_slug' => $role['slug'],
+        ];
+    }
+
+    /**
+     * Get the user's salt value.
+     *
+     * @param string $username Username.
+     *
+     * @return string Returns the salt value.
+     */
+    public function get_salt_by_username(string $username): string
+    {
+        $user_settings = $this->CI->db->get_where('user_settings', ['username' => $username])->row_array();
+
+        return $user_settings['salt'] ?? '';
+    }
+
+    /**
+     * Get the user full name.
+     *
+     * @param int $user_id User ID.
+     *
+     * @return string Returns the user full name.
+     */
+    public function get_user_display_name(int $user_id): string
+    {
+        $user = $this->CI->users_model->find($user_id);
+
+        return $user['first_name'] . ' ' . $user['last_name'];
+    }
+
+    /**
+     * Regenerate the password of the user that matches the provided username and email.
+     *
+     * @param string $username Username.
+     * @param string $email Email.
+     *
+     * @return string Returns the new password on success or FALSE on failure.
+     *
+     * @throws Exception
+     */
+    public function regenerate_password(string $username, string $email): string
+    {
+        $query = $this->CI->db
+            ->select('users.id')
+            ->from('users')
+            ->join('user_settings', 'user_settings.id_users = users.id', 'inner')
+            ->where('users.email', $email)
+            ->where('user_settings.username', $username)
+            ->get();
+
+        if (!$query->num_rows()) {
+            throw new RuntimeException('The user was not found in the database with the provided info.');
+        }
+
+        $user = $query->row_array();
+
+        // Generate a new password for the user.
+        $new_password = random_string('alnum', 12);
+
+        $salt = $this->get_salt_by_username($username);
+
+        $hash_password = hash_password($salt, $new_password);
+
+        $this->CI->users_model->set_setting($user['id'], 'password', $hash_password);
+
+        return $new_password;
+    }
+
+    /**
+     * Check if a user account exists or not.
+     *
+     * @param int $user_id
+     *
+     * @return bool
+     */
+    public function does_account_exist(int $user_id): bool
+    {
+        return $this->CI->users_model
+            ->query()
+            ->where(['id' => $user_id])
+            ->get()
+            ->num_rows() > 0;
+    }
+
+    /**
+     * Get a user record based on the provided username value
+     *
+     * @param string $username
+     *
+     * @return array|null
+     */
+    public function get_user_by_username(string $username): ?array
+    {
+        $user_settings = $this->CI->db->get_where('user_settings', ['username' => $username])->row_array();
+
+        if (!$user_settings) {
+            return null;
+        }
+
+        $user_id = $user_settings['id_users'];
+
+        return $this->CI->users_model->find($user_id);
+    }
+}

application/libraries/Api.php

@@ -0,0 +1,261 @@
+<?php use JetBrains\PhpStorm\NoReturn;
+
+defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.5.0
+ * ---------------------------------------------------------------------------- */
+
+/**
+ * Api library.
+ *
+ * Handles API related functionality.
+ *
+ * @package Libraries
+ */
+class Api
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * @var int
+     */
+    protected int $default_length = 20;
+
+    /**
+     * @var EA_Model
+     */
+    protected EA_Model $model;
+
+    /**
+     * Api constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->library('accounts');
+    }
+
+    /**
+     * Load and use the provided model class.
+     *
+     * @param string $model
+     */
+    public function model(string $model): void
+    {
+        $this->CI->load->model($model);
+
+        $this->model = $this->CI->{$model};
+    }
+
+    /**
+     * Authorize the API request (Basic Auth or Bearer Token supported).
+     */
+    public function auth(): void
+    {
+        try {
+            // Bearer token.
+            $api_token = setting('api_token');
+
+            if (!empty($api_token) && $api_token === $this->get_bearer_token()) {
+                return;
+            }
+
+            // Basic auth.
+            $username = $_SERVER['PHP_AUTH_USER'] ?? null;
+
+            $password = $_SERVER['PHP_AUTH_PW'] ?? null;
+
+            $user_data = $this->CI->accounts->check_login($username, $password);
+
+            if (empty($user_data['role_slug']) || $user_data['role_slug'] !== DB_SLUG_ADMIN) {
+                throw new RuntimeException(
+                    'The provided credentials do not match any admin user!',
+                    401,
+                    'Unauthorized',
+                );
+            }
+        } catch (Throwable) {
+            $this->request_authentication();
+        }
+    }
+
+    /**
+     * Returns the bearer token value.
+     *
+     * @return string|null
+     */
+    protected function get_bearer_token(): ?string
+    {
+        $headers = $this->get_authorization_header();
+
+        // HEADER: Get the access token from the header
+
+        if (!empty($headers)) {
+            if (preg_match('/Bearer\s(\S+)/', $headers, $matches)) {
+                return $matches[1];
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Returns the authorization header.
+     *
+     * @return string|null
+     */
+    protected function get_authorization_header(): ?string
+    {
+        $headers = null;
+
+        if (isset($_SERVER['Authorization'])) {
+            $headers = trim($_SERVER['Authorization']);
+        } else {
+            if (isset($_SERVER['HTTP_AUTHORIZATION'])) {
+                // Nginx or fast CGI
+                $headers = trim($_SERVER['HTTP_AUTHORIZATION']);
+            } elseif (function_exists('apache_request_headers')) {
+                $requestHeaders = apache_request_headers();
+
+                // Server-side fix for bug in old Android versions (a nice side effect of this fix means we don't care
+                // about capitalization for Authorization).
+                $requestHeaders = array_combine(
+                    array_map('ucwords', array_keys($requestHeaders)),
+                    array_values($requestHeaders),
+                );
+
+                if (isset($requestHeaders['Authorization'])) {
+                    $headers = trim($requestHeaders['Authorization']);
+                }
+            }
+        }
+
+        return $headers;
+    }
+
+    /**
+     * Sets request authentication headers.
+     */
+    #[NoReturn]
+    public function request_authentication(): void
+    {
+        header('WWW-Authenticate: Basic realm="Easy!Appointments"');
+        header('HTTP/1.0 401 Unauthorized');
+        exit('You are not authorized to use the API.');
+    }
+
+    /**
+     * Get the search keyword value of the current request.
+     *
+     * @return string|null
+     */
+    public function request_keyword(): ?string
+    {
+        return request('q');
+    }
+
+    /**
+     * Get the limit value of the current request.
+     *
+     * @return int|null
+     */
+    public function request_limit(): ?int
+    {
+        return request('length', $this->default_length);
+    }
+
+    /**
+     * Get the limit value of the current request.
+     *
+     * @return int|null
+     */
+    public function request_offset(): ?int
+    {
+        $page = request('page', 1);
+
+        $length = request('length', $this->default_length);
+
+        return ($page - 1) * $length;
+    }
+
+    /**
+     * Get the order by value of the current request.
+     *
+     * @return string|null
+     */
+    public function request_order_by(): ?string
+    {
+        $sort = request('sort');
+
+        if (!$sort) {
+            return null;
+        }
+
+        $sort_tokens = array_map('trim', explode(',', $sort));
+
+        $order_by = [];
+
+        foreach ($sort_tokens as $sort_token) {
+            $api_field = substr($sort_token, 1);
+
+            $direction_operator = substr($sort_token, 0, 1);
+
+            if (!in_array($direction_operator, ['-', '+'])) {
+                $direction_operator = '+';
+                $api_field = $sort_token;
+            }
+
+            $db_field = $this->model->db_field($api_field);
+
+            $direction = $direction_operator === '-' ? 'DESC' : 'ASC';
+
+            $order_by[] = $db_field . ' ' . $direction;
+        }
+
+        return implode(', ', $order_by);
+    }
+
+    /**
+     * Get the chosen "fields" array of the current request.
+     *
+     * @return array|null
+     */
+    public function request_fields(): ?array
+    {
+        $fields = request('fields');
+
+        if (!$fields) {
+            return null;
+        }
+
+        return array_map('trim', explode(',', $fields));
+    }
+
+    /**
+     * Get the provided "with" array of the current request.
+     *
+     * @return array|null
+     */
+    public function request_with(): ?array
+    {
+        $with = request('with');
+
+        if (!$with) {
+            return null;
+        }
+
+        return array_map('trim', explode(',', $with));
+    }
+}

application/libraries/Availability.php

@@ -0,0 +1,642 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.4.0
+ * ---------------------------------------------------------------------------- */
+
+/**
+ * Availability library.
+ *
+ * Handles availability related functionality.
+ *
+ * @package Libraries
+ */
+class Availability
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Availability constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('admins_model');
+        $this->CI->load->model('appointments_model');
+        $this->CI->load->model('providers_model');
+        $this->CI->load->model('secretaries_model');
+        $this->CI->load->model('secretaries_model');
+        $this->CI->load->model('settings_model');
+        $this->CI->load->model('unavailabilities_model');
+        $this->CI->load->model('blocked_periods_model');
+
+        $this->CI->load->library('ics_file');
+    }
+
+    /**
+     * Get the available hours of a provider.
+     *
+     * @param string $date Selected date (Y-m-d).
+     * @param array $service Service data.
+     * @param array $provider Provider data.
+     * @param int|null $exclude_appointment_id Exclude an appointment from the availability generation.
+     *
+     * @return array
+     *
+     * @throws Exception
+     */
+    public function get_available_hours(
+        string $date,
+        array $service,
+        array $provider,
+        ?int $exclude_appointment_id = null,
+    ): array {
+        if ($this->CI->blocked_periods_model->is_entire_date_blocked($date)) {
+            return [];
+        }
+
+        if ($service['attendants_number'] > 1) {
+            $available_hours = $this->consider_multiple_attendants($date, $service, $provider, $exclude_appointment_id);
+        } else {
+            $available_periods = $this->get_available_periods($date, $provider, $exclude_appointment_id);
+
+            $available_hours = $this->generate_available_hours($date, $service, $available_periods);
+        }
+
+        $available_hours = $this->consider_book_advance_timeout($date, $available_hours, $provider);
+
+        return $this->consider_future_booking_limit($date, $available_hours, $provider);
+    }
+
+    /**
+     * Get multiple attendants hours.
+     *
+     * This method will add the additional appointment hours whenever a service accepts multiple attendants.
+     *
+     * @param string $date Selected date (Y-m-d).
+     * @param array $service Service data.
+     * @param array $provider Provider data.
+     * @param int|null $exclude_appointment_id Exclude an appointment from the availability generation.
+     *
+     * @return array Returns the available hours array.
+     *
+     * @throws Exception
+     */
+    protected function consider_multiple_attendants(
+        string $date,
+        array $service,
+        array $provider,
+        ?int $exclude_appointment_id = null,
+    ): array {
+        $unavailability_events = $this->CI->unavailabilities_model->get([
+            'is_unavailability' => true,
+            'DATE(start_datetime) <=' => $date,
+            'DATE(end_datetime) >=' => $date,
+            'id_users_provider' => $provider['id'],
+        ]);
+
+        $working_plan = json_decode($provider['settings']['working_plan'], true);
+
+        $working_plan_exceptions = json_decode($provider['settings']['working_plan_exceptions'], true);
+
+        $working_day = strtolower(date('l', strtotime($date)));
+
+        $date_working_plan = $working_plan[$working_day] ?? null;
+
+        // Search if the $date is a custom availability period added outside the normal working plan.
+        if (array_key_exists($date, $working_plan_exceptions)) {
+            $date_working_plan = $working_plan_exceptions[$date];
+        }
+
+        if (!$date_working_plan) {
+            return [];
+        }
+
+        $periods = [
+            [
+                'start' => new DateTime($date . ' ' . $date_working_plan['start']),
+                'end' => new DateTime($date . ' ' . $date_working_plan['end']),
+            ],
+        ];
+
+        $blocked_periods = $this->CI->blocked_periods_model->get_for_period($date, $date);
+
+        $periods = $this->remove_breaks($date, $periods, $date_working_plan['breaks']);
+        $periods = $this->remove_unavailability_events($periods, $unavailability_events);
+        $periods = $this->remove_unavailability_events($periods, $blocked_periods);
+
+        $hours = [];
+
+        $interval_value = $service['availabilities_type'] == AVAILABILITIES_TYPE_FIXED ? $service['duration'] : '15';
+        $interval = new DateInterval('PT' . (int) $interval_value . 'M');
+        $duration = new DateInterval('PT' . (int) $service['duration'] . 'M');
+
+        foreach ($periods as $period) {
+            $slot_start = clone $period['start'];
+            $slot_end = clone $slot_start;
+            $slot_end->add($duration);
+
+            while ($slot_end <= $period['end']) {
+                // Make sure there is no other service appointment for this time slot.
+                $other_service_attendants_number = $this->CI->appointments_model->get_other_service_attendants_number(
+                    $slot_start,
+                    $slot_end,
+                    $service['id'],
+                    $provider['id'],
+                    $exclude_appointment_id,
+                );
+
+                if ($other_service_attendants_number > 0) {
+                    $slot_start->add($interval);
+                    $slot_end->add($interval);
+                    continue;
+                }
+
+                // Check reserved attendants for this time slot and see if current attendants fit.
+                $appointment_attendants_number = $this->CI->appointments_model->get_attendants_number_for_period(
+                    $slot_start,
+                    $slot_end,
+                    $service['id'],
+                    $provider['id'],
+                    $exclude_appointment_id,
+                );
+
+                if ($appointment_attendants_number < $service['attendants_number']) {
+                    $hours[] = $slot_start->format('H:i');
+                }
+
+                $slot_start->add($interval);
+                $slot_end->add($interval);
+            }
+        }
+
+        return $hours;
+    }
+
+    /**
+     * Remove breaks from available time periods.
+     *
+     * @param string $date Selected date (Y-m-d).
+     * @param array $periods Empty periods.
+     * @param array $breaks Array of breaks.
+     *
+     * @return array Returns the available time periods without the breaks.
+     *
+     * @throws Exception
+     */
+    public function remove_breaks(string $date, array $periods, array $breaks): array
+    {
+        if (!$breaks) {
+            return $periods;
+        }
+
+        foreach ($breaks as $break) {
+            $break_start = new DateTime($date . ' ' . $break['start']);
+
+            $break_end = new DateTime($date . ' ' . $break['end']);
+
+            foreach ($periods as &$period) {
+                $period_start = $period['start'];
+
+                $period_end = $period['end'];
+
+                if ($break_start <= $period_start && $break_end >= $period_start && $break_end <= $period_end) {
+                    // left
+                    $period['start'] = $break_end;
+                    continue;
+                }
+
+                if (
+                    $break_start >= $period_start &&
+                    $break_start <= $period_end &&
+                    $break_end >= $period_start &&
+                    $break_end <= $period_end
+                ) {
+                    // middle
+                    $period['end'] = $break_start;
+                    $periods[] = [
+                        'start' => $break_end,
+                        'end' => $period_end,
+                    ];
+                    continue;
+                }
+
+                if ($break_start >= $period_start && $break_start <= $period_end && $break_end >= $period_end) {
+                    // right
+                    $period['end'] = $break_start;
+                    continue;
+                }
+
+                if ($break_start <= $period_start && $break_end >= $period_end) {
+                    // break contains period
+                    $period['start'] = $break_end;
+                }
+            }
+        }
+
+        return $periods;
+    }
+
+    /**
+     * Remove the unavailability entries from the available time periods of the selected date.
+     *
+     * @param array $periods Available time periods.
+     * @param array $unavailability_events Unavailability events of the current date.
+     *
+     * @return array Returns the available time periods without the unavailability events.
+     *
+     * @throws Exception
+     */
+    public function remove_unavailability_events(array $periods, array $unavailability_events): array
+    {
+        foreach ($unavailability_events as $unavailability_event) {
+            $unavailability_start = new DateTime($unavailability_event['start_datetime']);
+
+            $unavailability_end = new DateTime($unavailability_event['end_datetime']);
+
+            foreach ($periods as &$period) {
+                $period_start = $period['start'];
+
+                $period_end = $period['end'];
+
+                if (
+                    $unavailability_start <= $period_start &&
+                    $unavailability_end >= $period_start &&
+                    $unavailability_end <= $period_end
+                ) {
+                    // Left
+                    $period['start'] = $unavailability_end;
+                    continue;
+                }
+
+                if (
+                    $unavailability_start >= $period_start &&
+                    $unavailability_start <= $period_end &&
+                    $unavailability_end >= $period_start &&
+                    $unavailability_end <= $period_end
+                ) {
+                    // Middle
+                    $period['end'] = $unavailability_start;
+                    $periods[] = [
+                        'start' => $unavailability_end,
+                        'end' => $period_end,
+                    ];
+                    continue;
+                }
+
+                if (
+                    $unavailability_start >= $period_start &&
+                    $unavailability_start <= $period_end &&
+                    $unavailability_end >= $period_end
+                ) {
+                    // Right
+                    $period['end'] = $unavailability_start;
+                    continue;
+                }
+
+                if ($unavailability_start <= $period_start && $unavailability_end >= $period_end) {
+                    // Unavailability contains period
+                    $period['start'] = $unavailability_end;
+                }
+            }
+        }
+
+        return $periods;
+    }
+
+    /**
+     * Get an array containing the free time periods (start - end) of a selected date.
+     *
+     * This method is very important because there are many cases where the system needs to know when a provider is
+     * available for an appointment. It will return an array that belongs to the selected date and contains values that
+     * have the start and the end time of an available time period.
+     *
+     * @param string $date Selected date (Y-m-d).
+     * @param array $provider Provider data.
+     * @param int|null $exclude_appointment_id Exclude an appointment from the availability generation.
+     *
+     * @return array Returns an array with the available time periods of the provider.
+     *
+     * @throws Exception
+     */
+    public function get_available_periods(string $date, array $provider, ?int $exclude_appointment_id = null): array
+    {
+        // Get the service, provider's working plan and provider appointments.
+        $working_plan = json_decode($provider['settings']['working_plan'], true);
+
+        // Get the provider's working plan exceptions.
+        $working_plan_exceptions_json = $provider['settings']['working_plan_exceptions'];
+
+        $working_plan_exceptions = $working_plan_exceptions_json
+            ? json_decode($provider['settings']['working_plan_exceptions'], true)
+            : [];
+
+        $escaped_provider_id = $this->CI->db->escape($provider['id']);
+
+        $escaped_date = $this->CI->db->escape($date);
+
+        $where =
+            'id_users_provider = ' .
+            $escaped_provider_id .
+            ' AND DATE(start_datetime) <= ' .
+            $escaped_date .
+            ' AND DATE(end_datetime) >= ' .
+            $escaped_date;
+
+        // Sometimes it might be necessary to exclude an appointment from the calculation (e.g. when editing an
+        // existing appointment).
+        if ($exclude_appointment_id) {
+            $escaped_exclude_appointment_id = $this->CI->db->escape($exclude_appointment_id);
+            $where .= ' AND id != ' . $escaped_exclude_appointment_id;
+        }
+
+        $appointments = array_values(
+            array_merge(
+                $this->CI->appointments_model->get($where),
+                $this->CI->unavailabilities_model->get($where),
+                $this->CI->blocked_periods_model->get_for_period($date, $date),
+            ),
+        );
+
+        // Find the empty spaces on the plan. The first split between the plan is due to a break (if any). After that
+        // every reserved appointment is considered to be a taken space in the plan.
+        $working_day = strtolower(date('l', strtotime($date)));
+
+        $date_working_plan = $working_plan[$working_day] ?? null;
+
+        // Search if the $date is a custom availability period added outside the normal working plan.
+        if (array_key_exists($date, $working_plan_exceptions)) {
+            $date_working_plan = $working_plan_exceptions[$date];
+        }
+
+        if (!$date_working_plan) {
+            return [];
+        }
+
+        $periods = [];
+
+        if (isset($date_working_plan['breaks'])) {
+            $periods[] = [
+                'start' => $date_working_plan['start'],
+                'end' => $date_working_plan['end'],
+            ];
+
+            $day_start = new DateTime($date_working_plan['start']);
+            $day_end = new DateTime($date_working_plan['end']);
+
+            // Split the working plan to available time periods that do not contain the breaks in them.
+            foreach ($date_working_plan['breaks'] as $break) {
+                $break_start = new DateTime($break['start']);
+                $break_end = new DateTime($break['end']);
+
+                if ($break_start < $day_start) {
+                    $break_start = $day_start;
+                }
+
+                if ($break_end > $day_end) {
+                    $break_end = $day_end;
+                }
+
+                if ($break_start >= $break_end) {
+                    continue;
+                }
+
+                foreach ($periods as $key => $period) {
+                    $period_start = new DateTime($period['start']);
+                    $period_end = new DateTime($period['end']);
+
+                    $remove_current_period = false;
+
+                    if ($break_start > $period_start && $break_start < $period_end && $break_end > $period_start) {
+                        $periods[] = [
+                            'start' => $period_start->format('H:i'),
+                            'end' => $break_start->format('H:i'),
+                        ];
+
+                        $remove_current_period = true;
+                    }
+
+                    if ($break_start < $period_end && $break_end > $period_start && $break_end < $period_end) {
+                        $periods[] = [
+                            'start' => $break_end->format('H:i'),
+                            'end' => $period_end->format('H:i'),
+                        ];
+
+                        $remove_current_period = true;
+                    }
+
+                    if ($break_start == $period_start && $break_end == $period_end) {
+                        $remove_current_period = true;
+                    }
+
+                    if ($remove_current_period) {
+                        unset($periods[$key]);
+                    }
+                }
+            }
+        }
+
+        // Break the empty periods with the reserved appointments.
+        foreach ($appointments as $appointment) {
+            foreach ($periods as $index => &$period) {
+                $appointment_start = new DateTime($appointment['start_datetime']);
+                $appointment_end = new DateTime($appointment['end_datetime']);
+
+                if ($appointment_start >= $appointment_end) {
+                    continue;
+                }
+
+                $period_start = new DateTime($date . ' ' . $period['start']);
+                $period_end = new DateTime($date . ' ' . $period['end']);
+
+                if (
+                    $appointment_start <= $period_start &&
+                    $appointment_end <= $period_end &&
+                    $appointment_end <= $period_start
+                ) {
+                    // The appointment does not belong in this time period, so we  will not change anything.
+                    continue;
+                } else {
+                    if (
+                        $appointment_start <= $period_start &&
+                        $appointment_end <= $period_end &&
+                        $appointment_end >= $period_start
+                    ) {
+                        // The appointment starts before the period and finishes somewhere inside. We will need to break
+                        // this period and leave the available part.
+                        $period['start'] = $appointment_end->format('H:i');
+                    } else {
+                        if ($appointment_start >= $period_start && $appointment_end < $period_end) {
+                            // The appointment is inside the time period, so we will split the period into two new
+                            // others.
+                            unset($periods[$index]);
+
+                            $periods[] = [
+                                'start' => $period_start->format('H:i'),
+                                'end' => $appointment_start->format('H:i'),
+                            ];
+
+                            $periods[] = [
+                                'start' => $appointment_end->format('H:i'),
+                                'end' => $period_end->format('H:i'),
+                            ];
+                        } elseif ($appointment_start == $period_start && $appointment_end == $period_end) {
+                            unset($periods[$index]); // The whole period is blocked so remove it from the available periods array.
+                        } else {
+                            if (
+                                $appointment_start >= $period_start &&
+                                $appointment_end >= $period_start &&
+                                $appointment_start <= $period_end
+                            ) {
+                                // The appointment starts in the period and finishes out of it. We will need to remove
+                                // the time that is taken from the appointment.
+                                $period['end'] = $appointment_start->format('H:i');
+                            } else {
+                                if (
+                                    $appointment_start >= $period_start &&
+                                    $appointment_end >= $period_end &&
+                                    $appointment_start >= $period_end
+                                ) {
+                                    // The appointment does not belong in the period so do not change anything.
+                                    continue;
+                                } else {
+                                    if (
+                                        $appointment_start <= $period_start &&
+                                        $appointment_end >= $period_end &&
+                                        $appointment_start <= $period_end
+                                    ) {
+                                        // The appointment is bigger than the period, so this period needs to be removed.
+                                        unset($periods[$index]);
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        return array_values($periods);
+    }
+
+    /**
+     * Calculate the available appointment hours.
+     *
+     * Calculate the available appointment hours for the given date. The empty spaces are broken down to 15 min and if
+     * the service fit in each quarter then a new available hour is added to the "$available_hours" array.
+     *
+     * @param string $date Selected date (Y-m-d).
+     * @param array $service Service data.
+     * @param array $empty_periods Empty periods array.
+     *
+     * @return array Returns an array with the available hours for the appointment.
+     *
+     * @throws Exception
+     */
+    protected function generate_available_hours(string $date, array $service, array $empty_periods): array
+    {
+        $available_hours = [];
+
+        foreach ($empty_periods as $period) {
+            $start_hour = new DateTime($date . ' ' . $period['start']);
+
+            $end_hour = new DateTime($date . ' ' . $period['end']);
+
+            $interval = $service['availabilities_type'] === AVAILABILITIES_TYPE_FIXED ? (int) $service['duration'] : 15;
+
+            $current_hour = $start_hour;
+
+            $diff = $current_hour->diff($end_hour);
+
+            while ($diff->h * 60 + $diff->i >= (int) $service['duration'] && $diff->invert === 0) {
+                $available_hours[] = $current_hour->format('H:i');
+
+                $current_hour->add(new DateInterval('PT' . $interval . 'M'));
+
+                $diff = $current_hour->diff($end_hour);
+            }
+        }
+
+        return $available_hours;
+    }
+
+    /**
+     * Consider the book advance timeout and remove available hours that have passed the threshold.
+     *
+     * If the selected date is today, remove past hours. It is important  include the timeout before booking
+     * that is set in the back-office the system. Normally we might want the customer to book an appointment
+     * that is at least half or one hour from now. The setting is stored in minutes.
+     *
+     * @param string $date The selected date.
+     * @param array $available_hours Already generated available hours.
+     * @param array $provider Provider information.
+     *
+     * @return array Returns the updated available hours.
+     *
+     * @throws Exception
+     */
+    protected function consider_book_advance_timeout(string $date, array $available_hours, array $provider): array
+    {
+        $provider_timezone = new DateTimeZone($provider['timezone']);
+
+        $book_advance_timeout = setting('book_advance_timeout');
+
+        $threshold = new DateTime('+' . $book_advance_timeout . ' minutes', $provider_timezone);
+
+        foreach ($available_hours as $index => $value) {
+            $available_hour = new DateTime($date . ' ' . $value, $provider_timezone);
+
+            if ($available_hour->getTimestamp() <= $threshold->getTimestamp()) {
+                unset($available_hours[$index]);
+            }
+        }
+
+        $available_hours = array_values($available_hours);
+
+        sort($available_hours, SORT_STRING);
+
+        return array_values($available_hours);
+    }
+
+    /**
+     * Remove times if succeed the future booking limit.
+     *
+     * @param string $selected_date
+     * @param array $available_hours
+     * @param array $provider
+     *
+     * @return array
+     *
+     * @throws Exception
+     */
+    protected function consider_future_booking_limit(
+        string $selected_date,
+        array $available_hours,
+        array $provider,
+    ): array {
+        $provider_timezone = new DateTimeZone($provider['timezone']);
+
+        $future_booking_limit = setting('future_booking_limit'); // in days
+
+        $threshold = new DateTime('+' . $future_booking_limit . ' days', $provider_timezone);
+
+        $selected_date_time = new DateTime($selected_date);
+
+        if ($threshold < $selected_date_time) {
+            return [];
+        }
+
+        return $threshold > $selected_date_time ? $available_hours : [];
+    }
+}

application/libraries/Caldav_sync.php

@@ -0,0 +1,585 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.5.0
+ * ---------------------------------------------------------------------------- */
+
+use GuzzleHttp\Client;
+use GuzzleHttp\Exception\GuzzleException;
+use GuzzleHttp\Exception\RequestException;
+use Jsvrcek\ICS\Exception\CalendarEventException;
+use Psr\Http\Message\ResponseInterface;
+use Sabre\VObject\Component\VEvent;
+use Sabre\VObject\Reader;
+
+/**
+ * Caldav sync library.
+ *
+ * Handles CalDAV related operations using Guzzle.
+ *
+ * @package Libraries
+ */
+class Caldav_sync
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Caldav_sync constructor.
+     *
+     * This method initializes the Caldav client class and the Calendar service class so that they can be used by the
+     * other methods.
+     *
+     * @throws Exception If there is an issue with the initialization.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('appointments_model');
+        $this->CI->load->model('customers_model');
+        $this->CI->load->model('providers_model');
+        $this->CI->load->model('services_model');
+
+        $this->CI->load->library('ics_file');
+    }
+
+    /**
+     * Add an appointment record to the connected CalDAV calendar.
+     *
+     * @param array $appointment Appointment record.
+     * @param array $service Service record.
+     * @param array $provider Provider record.
+     * @param array $customer Customer record.
+     *
+     * @return string|null Returns the event ID
+     *
+     * @throws CalendarEventException If there's an issue generating the ICS file.
+     */
+    public function save_appointment(array $appointment, array $service, array $provider, array $customer): ?string
+    {
+        try {
+            $ics_file = $this->get_appointment_ics_file($appointment, $service, $provider, $customer);
+
+            $client = $this->get_http_client_by_provider_id($provider['id']);
+
+            $caldav_event_id =
+                $appointment['id_caldav_calendar'] ?: $this->CI->ics_file->generate_uid($appointment['id']);
+
+            $uri = $this->get_caldav_event_uri($provider['settings']['caldav_url'], $caldav_event_id);
+
+            $client->request('PUT', $uri, [
+                'headers' => [
+                    'Content-Type' => 'text/calendar',
+                ],
+                'body' => $ics_file,
+            ]);
+
+            return $caldav_event_id;
+        } catch (GuzzleException $e) {
+            $this->handle_guzzle_exception($e, 'Failed to save CalDAV appointment event');
+            return null;
+        }
+    }
+
+    /**
+     * Add an unavailability record to the connected CalDAV calendar.
+     *
+     * @param array $unavailability Appointment record.
+     * @param array $provider Provider record.
+     *
+     * @return string|null Returns the event ID
+     *
+     * @throws CalendarEventException If there's an issue generating the ICS file.
+     */
+    public function save_unavailability(array $unavailability, array $provider): ?string
+    {
+        try {
+            if (str_contains((string) $unavailability['id_caldav_calendar'], 'RECURRENCE')) {
+                return $unavailability['id_caldav_calendar'] ?? null; // Do not sync recurring unavailabilities
+            }
+
+            $ics_file = $this->get_unavailability_ics_file($unavailability, $provider);
+
+            $client = $this->get_http_client_by_provider_id($provider['id']);
+
+            $caldav_event_id =
+                $unavailability['id_caldav_calendar'] ?: $this->CI->ics_file->generate_uid($unavailability['id']);
+
+            $uri = $this->get_caldav_event_uri($provider['settings']['caldav_url'], $caldav_event_id);
+
+            $client->request('PUT', $uri, [
+                'headers' => [
+                    'Content-Type' => 'text/calendar',
+                ],
+                'body' => $ics_file,
+            ]);
+
+            return $caldav_event_id;
+        } catch (GuzzleException $e) {
+            $this->handle_guzzle_exception($e, 'Failed to save CalDAV unavailability event');
+            return null;
+        }
+    }
+
+    /**
+     * Delete an existing appointment from Caldav Calendar.
+     *
+     * @param array $provider Provider data.
+     * @param string $caldav_event_id The Caldav Calendar event ID to be removed.
+     */
+    public function delete_event(array $provider, string $caldav_event_id): void
+    {
+        try {
+            $client = $this->get_http_client_by_provider_id($provider['id']);
+
+            $uri = $this->get_caldav_event_uri($provider['settings']['caldav_url'], $caldav_event_id);
+
+            $client->request('DELETE', $uri);
+        } catch (GuzzleException $e) {
+            $this->handle_guzzle_exception($e, 'Failed to delete CalDAV event');
+        }
+    }
+
+    /**
+     * Get a Caldav Calendar event.
+     *
+     * @param array $provider Provider Data.
+     * @param string $caldav_event_id CalDAV calendar event ID.
+     *
+     * @return array|null
+     * @throws Exception If there’s an issue parsing the ICS data.
+     */
+    public function get_event(array $provider, string $caldav_event_id): ?array
+    {
+        try {
+            $client = $this->get_http_client_by_provider_id($provider['id']);
+
+            $provider_timezone_object = new DateTimeZone($provider['timezone']);
+
+            $uri = $this->get_caldav_event_uri($provider['settings']['caldav_url'], $caldav_event_id);
+
+            $response = $client->request('GET', $uri);
+
+            $ics_file = $response->getBody()->getContents();
+
+            $vcalendar = Reader::read($ics_file);
+
+            return $this->convert_caldav_event_to_array_event($vcalendar->VEVENT, $provider_timezone_object);
+        } catch (GuzzleException $e) {
+            $this->handle_guzzle_exception($e, 'Failed to get CalDAV event');
+            return null;
+        }
+    }
+
+    /**
+     * Get all the events between the sync period.
+     *
+     * @param array $provider Provider data.
+     * @param string $start_date_time The start date of sync period.
+     * @param string $end_date_time The end date of sync period.
+     *
+     * @return array
+     * @throws Exception If there's an issue with event fetching or parsing.
+     */
+    public function get_sync_events(array $provider, string $start_date_time, string $end_date_time): array
+    {
+        try {
+            $client = $this->get_http_client_by_provider_id($provider['id']);
+            $provider_timezone_object = new DateTimeZone($provider['timezone']);
+
+            $response = $this->fetch_events($client, $start_date_time, $end_date_time);
+
+            if (!$response->getBody()) {
+                log_message('error', 'No response body from fetch_events' . PHP_EOL);
+                return [];
+            }
+
+            $xml = new SimpleXMLElement($response->getBody(), 0, false, 'd', true);
+
+            if ($xml->children('d', true)) {
+                return $this->parse_xml_events($xml, $start_date_time, $end_date_time, $provider_timezone_object);
+            }
+
+            $ics_file_urls = $this->extract_ics_file_urls($response->getBody());
+            return $this->fetch_and_parse_ics_files(
+                $client,
+                $ics_file_urls,
+                $start_date_time,
+                $end_date_time,
+                $provider_timezone_object,
+            );
+        } catch (GuzzleException $e) {
+            $this->handle_guzzle_exception($e, 'Failed to get CalDAV sync events');
+            return [];
+        }
+    }
+
+    private function parse_xml_events(
+        SimpleXMLElement $xml,
+        string $start_date_time,
+        string $end_date_time,
+        DateTimeZone $timezone,
+    ): array {
+        $events = [];
+
+        foreach ($xml->children('d', true) as $response) {
+            $ics_contents = (string) $response->propstat->prop->children('cal', true);
+
+            $events = array_merge(
+                $events,
+                $this->expand_ics_content($ics_contents, $start_date_time, $end_date_time, $timezone),
+            );
+        }
+
+        return $events;
+    }
+
+    private function extract_ics_file_urls(string $body): array
+    {
+        $ics_files = [];
+        $lines = explode("\n", $body);
+        foreach ($lines as $line) {
+            if (preg_match('/\/calendars\/.*?\.ics/', $line, $matches)) {
+                $ics_files[] = $matches[0];
+            }
+        }
+        return $ics_files;
+    }
+
+    /**
+     * Fetch and parse the ICS files from the remote server
+     *
+     * @param Client $client
+     * @param array $ics_file_urls
+     * @param string $start_date_time
+     * @param string $end_date_time
+     * @param DateTimeZone $timezone_OBJECT
+     *
+     * @return array
+     */
+    private function fetch_and_parse_ics_files(
+        Client $client,
+        array $ics_file_urls,
+        string $start_date_time,
+        string $end_date_time,
+        DateTimeZone $timezone_OBJECT,
+    ): array {
+        $events = [];
+
+        foreach ($ics_file_urls as $ics_file_url) {
+            try {
+                $ics_response = $client->request('GET', $ics_file_url);
+
+                $ics_contents = $ics_response->getBody()->getContents();
+
+                if (empty($ics_contents)) {
+                    log_message('error', 'ICS file data is empty for URL: ' . $ics_file_url . PHP_EOL);
+                    continue;
+                }
+
+                $events = array_merge(
+                    $events,
+                    $this->expand_ics_content($ics_contents, $start_date_time, $end_date_time, $timezone_OBJECT),
+                );
+            } catch (GuzzleException $e) {
+                log_message(
+                    'error',
+                    'Failed to fetch ICS content from ' . $ics_file_url . ': ' . $e->getMessage() . PHP_EOL,
+                );
+            }
+        }
+
+        return $events;
+    }
+
+    private function expand_ics_content(
+        string $ics_contents,
+        string $start_date_time,
+        string $end_date_time,
+        DateTimeZone $timezone_object,
+    ): array {
+        $events = [];
+
+        try {
+            $vcalendar = Reader::read($ics_contents);
+
+            $expanded_vcalendar = $vcalendar->expand(new DateTime($start_date_time), new DateTime($end_date_time));
+
+            foreach ($expanded_vcalendar->VEVENT as $event) {
+                $events[] = $this->convert_caldav_event_to_array_event($event, $timezone_object);
+            }
+        } catch (Throwable $e) {
+            log_message('error', 'Failed to parse or expand calendar data: ' . $e->getMessage() . PHP_EOL);
+        }
+
+        return $events;
+    }
+
+    /**
+     * Common error handling for the CalDAV requests.
+     *
+     * @param GuzzleException $e
+     * @param string $message
+     *
+     * @return void
+     */
+    private function handle_guzzle_exception(GuzzleException $e, string $message): void
+    {
+        // Guzzle throws a RequestException for HTTP errors
+
+        if ($e instanceof RequestException && $e->hasResponse()) {
+            // Handle HTTP error response
+
+            $response = $e->getResponse();
+
+            $status_code = $response->getStatusCode();
+
+            $guzzle_info = '(Status Code: ' . $status_code . '): ' . $response->getBody()->getContents() . PHP_EOL;
+        } else {
+            // Handle other request errors
+
+            $guzzle_info = $e->getMessage();
+        }
+
+        log_message('error', $message . ' ' . $guzzle_info);
+    }
+
+    /**
+     * @throws Exception If there is an invalid CalDAV URL or credentials.
+     * @throws GuzzleException If there’s an issue with the HTTP request.
+     */
+    private function get_http_client(string $caldav_url, string $caldav_username, string $caldav_password): Client
+    {
+        if (!filter_var($caldav_url, FILTER_VALIDATE_URL)) {
+            throw new InvalidArgumentException('Invalid CalDAV URL provided: ' . $caldav_url);
+        }
+
+        if (!$caldav_username) {
+            throw new InvalidArgumentException('Missing CalDAV username');
+        }
+
+        if (!$caldav_password) {
+            throw new InvalidArgumentException('Missing CalDAV password');
+        }
+
+        return new Client([
+            'base_uri' => rtrim($caldav_url, '/') . '/',
+            'connect_timeout' => 15,
+            'headers' => [
+                'Content-Type' => 'text/xml',
+            ],
+            'auth' => [$caldav_username, $caldav_password],
+        ]);
+    }
+
+    /**
+     * @throws Exception
+     * @throws GuzzleException
+     */
+    public function test_connection(string $caldav_url, string $caldav_username, string $caldav_password): void
+    {
+        try {
+            // Fetch some events to see if the connection is valid
+            $client = $this->get_http_client($caldav_url, $caldav_username, $caldav_password);
+
+            $start_date_time = date('Y-m-d 00:00:00');
+            $end_date_time = date('Y-m-d 23:59:59');
+
+            $this->fetch_events($client, $start_date_time, $end_date_time);
+        } catch (GuzzleException $e) {
+            $this->handle_guzzle_exception($e, 'Failed to test CalDAV connection');
+            throw $e;
+        }
+    }
+
+    /**
+     * @throws GuzzleException
+     */
+    private function get_http_client_by_provider_id(int $provider_id): Client
+    {
+        $provider = $this->CI->providers_model->find($provider_id);
+
+        if (!$provider['settings']['caldav_sync']) {
+            throw new RuntimeException('The selected provider does not have the CalDAV sync enabled: ' . $provider_id);
+        }
+
+        $caldav_url = $provider['settings']['caldav_url'];
+        $caldav_username = $provider['settings']['caldav_username'];
+        $caldav_password = $provider['settings']['caldav_password'];
+
+        return $this->get_http_client($caldav_url, $caldav_username, $caldav_password);
+    }
+
+    /**
+     * Generate the event URI, used in various requests.
+     *
+     * @param string $caldav_calendar
+     * @param string|null $caldav_event_id
+     *
+     * @return string
+     */
+    private function get_caldav_event_uri(string $caldav_calendar, ?string $caldav_event_id = null): string
+    {
+        return $caldav_event_id ? rtrim($caldav_calendar, '/') . '/' . $caldav_event_id . '.ics' : '';
+    }
+
+    /**
+     * @throws CalendarEventException
+     */
+    private function get_appointment_ics_file(
+        array $appointment,
+        array $service,
+        array $provider,
+        array $customer,
+    ): string {
+        $ics_file = $this->CI->ics_file->get_stream($appointment, $service, $provider, $customer);
+
+        return str_replace('METHOD:PUBLISH', '', $ics_file);
+    }
+
+    /**
+     * @throws CalendarEventException
+     */
+    private function get_unavailability_ics_file(array $unavailability, array $provider): string
+    {
+        $ics_file = $this->CI->ics_file->get_unavailability_stream($unavailability, $provider);
+
+        return str_replace('METHOD:PUBLISH', '', $ics_file);
+    }
+
+    /**
+     * Try to parse the CalDAV event date-time value with the right timezone.
+     *
+     * @throws DateMalformedStringException
+     * @throws DateInvalidTimeZoneException
+     */
+    private function parse_date_time_object(string $caldav_date_time, DateTimeZone $default_timezone_object): DateTime
+    {
+        try {
+            if (str_contains($caldav_date_time, 'TZID=')) {
+                // Extract the TZID and use it
+                preg_match('/TZID=([^:]+):/', $caldav_date_time, $matches);
+                $parsed_timezone = $matches[1];
+                $parsed_timezone_object = new DateTimeZone($parsed_timezone);
+                $date_time = preg_replace('/TZID=[^:]+:/', '', $caldav_date_time);
+                $date_time_object = new DateTime($date_time, $parsed_timezone_object);
+            } elseif (str_ends_with($caldav_date_time, 'Z')) {
+                // Handle UTC timestamps
+                $date_time_object = new DateTime($caldav_date_time, new DateTimeZone('UTC'));
+            } else {
+                // Default to the provided timezone
+                $date_time_object = new DateTime($caldav_date_time, $default_timezone_object);
+            }
+
+            return $date_time_object;
+        } catch (Throwable $e) {
+            error_log('Error parsing date-time value (' . $caldav_date_time . ') with timezone: ' . $e->getMessage());
+            throw $e;
+        }
+    }
+
+    /**
+     * Convert the VEvent object to an associative array
+     *
+     * @link https://sabre.io/vobject/icalendar
+     *
+     * @param VEvent $vevent Holds the VEVENT information
+     * @param DateTimeZone $timezone_object The date timezone values
+     *
+     * @return array
+     *
+     * @throws Throwable
+     */
+    private function convert_caldav_event_to_array_event(VEvent $vevent, DateTimeZone $timezone_object): array
+    {
+        try {
+            $caldav_start_date_time = (string) $vevent->DTSTART;
+            $start_date_time_object = $this->parse_date_time_object($caldav_start_date_time, $timezone_object);
+            $start_date_time_object->setTimezone($timezone_object); // Convert to the provider timezone
+
+            $caldav_end_date_time = (string) $vevent->DTEND;
+            $end_date_time_object = $this->parse_date_time_object($caldav_end_date_time, $timezone_object);
+            $end_date_time_object->setTimezone($timezone_object); // Convert to the provider timezone
+
+            // Check if the event is recurring
+
+            $is_recurring_event =
+                isset($vevent->RRULE) ||
+                isset($vevent->RDATE) ||
+                isset($vevent->{'RECURRENCE-ID'}) ||
+                isset($vevent->EXDATE);
+
+            // Generate ID based on recurrence status
+
+            $event_id = (string) $vevent->UID;
+
+            if ($is_recurring_event) {
+                $event_id .= '-RECURRENCE-' . random_string();
+            }
+
+            // Return the converted event
+
+            return [
+                'id' => $event_id,
+                'summary' => (string) $vevent->SUMMARY ?? null ?: '',
+                'start_datetime' => $start_date_time_object->format('Y-m-d H:i:s'),
+                'end_datetime' => $end_date_time_object->format('Y-m-d H:i:s'),
+                'description' => (string) $vevent->DESCRIPTION ?? null ?: '',
+                'status' => (string) $vevent->STATUS ?? null ?: 'CONFIRMED',
+                'location' => (string) $vevent->LOCATION ?? null ?: '',
+            ];
+        } catch (Throwable $e) {
+            error_log('Error parsing CalDAV event object (' . var_export($vevent, true) . '): ' . $e->getMessage());
+            throw $e;
+        }
+    }
+
+    /**
+     * @throws GuzzleException
+     * @throws Exception
+     */
+    private function fetch_events(Client $client, string $start_date_time, string $end_date_time): ResponseInterface
+    {
+        $start_date_time_object = new DateTime($start_date_time);
+        $formatted_start_date_time = $start_date_time_object->format('Ymd\THis\Z');
+        $end_date_time_object = new DateTime($end_date_time);
+        $formatted_end_date_time = $end_date_time_object->format('Ymd\THis\Z');
+
+        return $client->request('REPORT', '', [
+            'headers' => [
+                'Content-Type' => 'application/xml',
+                'Depth' => '1',
+            ],
+            'body' =>
+                '
+                <c:calendar-query xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">
+                    <d:prop>
+                        <d:getetag />
+                        <c:calendar-data />
+                    </d:prop>
+                    <c:filter>
+                        <c:comp-filter name="VCALENDAR">
+                            <c:comp-filter name="VEVENT">
+                                <c:time-range start="' .
+                $formatted_start_date_time .
+                '" end="' .
+                $formatted_end_date_time .
+                '"/>	
+                            </c:comp-filter>
+                        </c:comp-filter>
+                    </c:filter>
+                </c:calendar-query>
+            ',
+        ]);
+    }
+}

application/libraries/Captcha_builder.php

@@ -0,0 +1,741 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Open Source Web Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) 2013 - 2020, Alex Tselegidis
+ * @license     http://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        http://easyappointments.org
+ * @since       v1.4.3
+ * ---------------------------------------------------------------------------- */
+
+use Gregwar\Captcha\PhraseBuilder;
+use Gregwar\Captcha\PhraseBuilderInterface;
+
+/**
+ * Class Captcha_builder
+ *
+ * This class replaces the Gregwar\Captcha\CaptchaBuilder so that it becomes PHP 8.1 compatible.
+ */
+class Captcha_builder
+{
+    /**
+     * Temporary dir, for OCR check
+     */
+    public $tempDir = 'temp/';
+    /**
+     * @var array
+     */
+    protected $fingerprint = [];
+    /**
+     * @var bool
+     */
+    protected $useFingerprint = false;
+    /**
+     * @var array
+     */
+    protected $textColor = [];
+    /**
+     * @var array
+     */
+    protected $lineColor = null;
+    /**
+     * @var array
+     */
+    protected $background = null;
+    /**
+     * @var array
+     */
+    protected $backgroundColor = null;
+    /**
+     * @var array
+     */
+    protected $backgroundImages = [];
+    /**
+     * @var resource
+     */
+    protected $contents = null;
+    /**
+     * @var string
+     */
+    protected $phrase = null;
+    /**
+     * @var PhraseBuilderInterface
+     */
+    protected $builder;
+    /**
+     * @var bool
+     */
+    protected $distortion = true;
+    /**
+     * The maximum number of lines to draw in front of
+     * the image. null - use default algorithm
+     */
+    protected $maxFrontLines = null;
+    /**
+     * The maximum number of lines to draw behind
+     * the image. null - use default algorithm
+     */
+    protected $maxBehindLines = null;
+    /**
+     * The maximum angle of char
+     */
+    protected $maxAngle = 8;
+    /**
+     * The maximum offset of char
+     */
+    protected $maxOffset = 5;
+    /**
+     * Is the interpolation enabled ?
+     *
+     * @var bool
+     */
+    protected $interpolation = true;
+    /**
+     * Ignore all effects
+     *
+     * @var bool
+     */
+    protected $ignoreAllEffects = false;
+    /**
+     * Allowed image types for the background images
+     *
+     * @var array
+     */
+    protected $allowedBackgroundImageTypes = ['image/png', 'image/jpeg', 'image/gif'];
+
+    public function __construct($phrase = null, ?PhraseBuilderInterface $builder = null)
+    {
+        if ($builder === null) {
+            $this->builder = new PhraseBuilder();
+        } else {
+            $this->builder = $builder;
+        }
+
+        $this->phrase = is_string($phrase) ? $phrase : $this->builder->build($phrase);
+    }
+
+    /**
+     * Generate the image
+     * @throws Exception
+     */
+    public function build($width = 150, $height = 40, $font = null, $fingerprint = null)
+    {
+        if (null !== $fingerprint) {
+            $this->fingerprint = $fingerprint;
+            $this->useFingerprint = true;
+        } else {
+            $this->fingerprint = [];
+            $this->useFingerprint = false;
+        }
+
+        if ($font === null) {
+            $font =
+                __DIR__ . '/../../vendor/gregwar/captcha/src/Gregwar/Captcha/Font/captcha' . $this->rand(0, 5) . '.ttf';
+        }
+
+        $bg = null;
+
+        if (empty($this->backgroundImages)) {
+            // if background images list is not set, use a color fill as a background
+            $image = imagecreatetruecolor($width, $height);
+            if ($this->backgroundColor == null) {
+                $bg = imagecolorallocate($image, $this->rand(200, 255), $this->rand(200, 255), $this->rand(200, 255));
+            } else {
+                $color = $this->backgroundColor;
+                $bg = imagecolorallocate($image, $color[0], $color[1], $color[2]);
+            }
+            $this->background = $bg;
+            imagefill($image, 0, 0, $bg);
+        } else {
+            // use a random background image
+            $randomBackgroundImage = $this->backgroundImages[rand(0, count($this->backgroundImages) - 1)];
+
+            $imageType = $this->validateBackgroundImage($randomBackgroundImage);
+
+            $image = $this->createBackgroundImageFromType($randomBackgroundImage, $imageType);
+        }
+
+        // Apply effects
+        if (!$this->ignoreAllEffects) {
+            $square = $width * $height;
+            $effects = $this->rand($square / 3000, $square / 2000);
+
+            // set the maximum number of lines to draw in front of the text
+            if ($this->maxBehindLines != null && $this->maxBehindLines > 0) {
+                $effects = min($this->maxBehindLines, $effects);
+            }
+
+            if ($this->maxBehindLines !== 0) {
+                for ($e = 0; $e < $effects; $e++) {
+                    $this->drawLine($image, $width, $height);
+                }
+            }
+        }
+
+        // Write CAPTCHA text
+        $color = $this->writePhrase($image, $this->phrase, $font, $width, $height);
+
+        // Apply effects
+        if (!$this->ignoreAllEffects) {
+            $square = $width * $height;
+            $effects = $this->rand($square / 3000, $square / 2000);
+
+            // set the maximum number of lines to draw in front of the text
+            if ($this->maxFrontLines != null && $this->maxFrontLines > 0) {
+                $effects = min($this->maxFrontLines, $effects);
+            }
+
+            if ($this->maxFrontLines !== 0) {
+                for ($e = 0; $e < $effects; $e++) {
+                    $this->drawLine($image, $width, $height, $color);
+                }
+            }
+        }
+
+        // Distort the image
+        if ($this->distortion && !$this->ignoreAllEffects) {
+            $image = $this->distort($image, $width, $height, $bg);
+        }
+
+        // Post effects
+        if (!$this->ignoreAllEffects) {
+            $this->postEffect($image);
+        }
+
+        $this->contents = $image;
+
+        return $this;
+    }
+
+    /**
+     * Returns a random number or the next number in the
+     * fingerprint
+     */
+    protected function rand($min, $max)
+    {
+        if (!is_array($this->fingerprint)) {
+            $this->fingerprint = [];
+        }
+
+        if ($this->useFingerprint) {
+            $value = current($this->fingerprint);
+            next($this->fingerprint);
+        } else {
+            $value = mt_rand((int) $min, (int) $max);
+            $this->fingerprint[] = $value;
+        }
+
+        return $value;
+    }
+
+    /**
+     * Validate the background image path. Return the image type if valid
+     *
+     * @param string $backgroundImage
+     * @return string
+     * @throws Exception
+     */
+    protected function validateBackgroundImage($backgroundImage)
+    {
+        // check if file exists
+        if (!file_exists($backgroundImage)) {
+            $backgroundImageExploded = explode('/', $backgroundImage);
+            $imageFileName =
+                count($backgroundImageExploded) > 1
+                    ? $backgroundImageExploded[count($backgroundImageExploded) - 1]
+                    : $backgroundImage;
+
+            throw new Exception('Invalid background image: ' . $imageFileName);
+        }
+
+        // check image type
+        $finfo = finfo_open(FILEINFO_MIME_TYPE); // return mime type ala mimetype extension
+        $imageType = finfo_file($finfo, $backgroundImage);
+        finfo_close($finfo);
+
+        if (!in_array($imageType, $this->allowedBackgroundImageTypes)) {
+            throw new Exception(
+                'Invalid background image type! Allowed types are: ' . join(', ', $this->allowedBackgroundImageTypes),
+            );
+        }
+
+        return $imageType;
+    }
+
+    /**
+     * Create background image from type
+     *
+     * @param string $backgroundImage
+     * @param string $imageType
+     * @return resource
+     * @throws Exception
+     */
+    protected function createBackgroundImageFromType($backgroundImage, $imageType)
+    {
+        switch ($imageType) {
+            case 'image/jpeg':
+                $image = imagecreatefromjpeg($backgroundImage);
+                break;
+            case 'image/png':
+                $image = imagecreatefrompng($backgroundImage);
+                break;
+            case 'image/gif':
+                $image = imagecreatefromgif($backgroundImage);
+                break;
+
+            default:
+                throw new Exception('Not supported file type for background image!');
+                break;
+        }
+
+        return $image;
+    }
+
+    /**
+     * Draw lines over the image
+     */
+    protected function drawLine($image, $width, $height, $tcol = null)
+    {
+        if ($this->lineColor === null) {
+            $red = $this->rand(100, 255);
+            $green = $this->rand(100, 255);
+            $blue = $this->rand(100, 255);
+        } else {
+            $red = $this->lineColor[0];
+            $green = $this->lineColor[1];
+            $blue = $this->lineColor[2];
+        }
+
+        if ($tcol === null) {
+            $tcol = imagecolorallocate($image, $red, $green, $blue);
+        }
+
+        if ($this->rand(0, 1)) {
+            // Horizontal
+            $Xa = $this->rand(0, $width / 2);
+            $Ya = $this->rand(0, $height);
+            $Xb = $this->rand($width / 2, $width);
+            $Yb = $this->rand(0, $height);
+        } else {
+            // Vertical
+            $Xa = $this->rand(0, $width);
+            $Ya = $this->rand(0, $height / 2);
+            $Xb = $this->rand(0, $width);
+            $Yb = $this->rand($height / 2, $height);
+        }
+        imagesetthickness($image, $this->rand(1, 3));
+        imageline($image, $Xa, $Ya, $Xb, $Yb, $tcol);
+    }
+
+    /**
+     * Writes the phrase on the image
+     */
+    protected function writePhrase($image, $phrase, $font, $width, $height)
+    {
+        $length = mb_strlen($phrase);
+        if ($length === 0) {
+            return imagecolorallocate($image, 0, 0, 0);
+        }
+
+        // Gets the text size and start position
+        $size = (int) round($width / $length) - $this->rand(0, 3) - 1;
+        $box = imagettfbbox($size, 0, $font, $phrase);
+        $textWidth = $box[2] - $box[0];
+        $textHeight = $box[1] - $box[7];
+        $x = (int) round(($width - $textWidth) / 2);
+        $y = (int) round(($height - $textHeight) / 2) + $size;
+
+        if (!$this->textColor) {
+            $textColor = [$this->rand(0, 150), $this->rand(0, 150), $this->rand(0, 150)];
+        } else {
+            $textColor = $this->textColor;
+        }
+        $col = imagecolorallocate($image, $textColor[0], $textColor[1], $textColor[2]);
+
+        // Write the letters one by one, with random angle
+        for ($i = 0; $i < $length; $i++) {
+            $symbol = mb_substr($phrase, $i, 1);
+            $box = imagettfbbox($size, 0, $font, $symbol);
+            $w = $box[2] - $box[0];
+            $angle = $this->rand(-$this->maxAngle, $this->maxAngle);
+            $offset = $this->rand(-$this->maxOffset, $this->maxOffset);
+            imagettftext($image, $size, $angle, $x, $y + $offset, $col, $font, $symbol);
+            $x += $w;
+        }
+
+        return $col;
+    }
+
+    /**
+     * Distorts the image
+     */
+    public function distort($image, $width, $height, $bg)
+    {
+        $contents = imagecreatetruecolor($width, $height);
+        $X = $this->rand(0, $width);
+        $Y = $this->rand(0, $height);
+        $phase = $this->rand(0, 10);
+        $scale = 1.1 + $this->rand(0, 10000) / 30000;
+        for ($x = 0; $x < $width; $x++) {
+            for ($y = 0; $y < $height; $y++) {
+                $Vx = $x - $X;
+                $Vy = $y - $Y;
+                $Vn = sqrt($Vx * $Vx + $Vy * $Vy);
+
+                if ($Vn != 0) {
+                    $Vn2 = $Vn + 4 * sin($Vn / 30);
+                    $nX = $X + ($Vx * $Vn2) / $Vn;
+                    $nY = $Y + ($Vy * $Vn2) / $Vn;
+                } else {
+                    $nX = $X;
+                    $nY = $Y;
+                }
+                $nY = $nY + $scale * sin($phase + $nX * 0.2);
+
+                if ($this->interpolation) {
+                    $p = $this->interpolate(
+                        $nX - floor($nX),
+                        $nY - floor($nY),
+                        $this->getCol($image, floor($nX), floor($nY), $bg),
+                        $this->getCol($image, ceil($nX), floor($nY), $bg),
+                        $this->getCol($image, floor($nX), ceil($nY), $bg),
+                        $this->getCol($image, ceil($nX), ceil($nY), $bg),
+                    );
+                } else {
+                    $p = $this->getCol($image, round($nX), round($nY), $bg);
+                }
+
+                if ($p == 0) {
+                    $p = $bg;
+                }
+
+                imagesetpixel($contents, $x, $y, $p);
+            }
+        }
+
+        return $contents;
+    }
+
+    /**
+     * @param $x
+     * @param $y
+     * @param $nw
+     * @param $ne
+     * @param $sw
+     * @param $se
+     *
+     * @return int
+     */
+    protected function interpolate($x, $y, $nw, $ne, $sw, $se)
+    {
+        [$r0, $g0, $b0] = $this->getRGB($nw);
+        [$r1, $g1, $b1] = $this->getRGB($ne);
+        [$r2, $g2, $b2] = $this->getRGB($sw);
+        [$r3, $g3, $b3] = $this->getRGB($se);
+
+        $cx = 1.0 - $x;
+        $cy = 1.0 - $y;
+
+        $m0 = $cx * $r0 + $x * $r1;
+        $m1 = $cx * $r2 + $x * $r3;
+        $r = (int) ($cy * $m0 + $y * $m1);
+
+        $m0 = $cx * $g0 + $x * $g1;
+        $m1 = $cx * $g2 + $x * $g3;
+        $g = (int) ($cy * $m0 + $y * $m1);
+
+        $m0 = $cx * $b0 + $x * $b1;
+        $m1 = $cx * $b2 + $x * $b3;
+        $b = (int) ($cy * $m0 + $y * $m1);
+
+        return ($r << 16) | ($g << 8) | $b;
+    }
+
+    /**
+     * @param $col
+     *
+     * @return array
+     */
+    protected function getRGB($col)
+    {
+        return [(int) ($col >> 16) & 0xff, (int) ($col >> 8) & 0xff, (int) $col & 0xff];
+    }
+
+    /**
+     * @param $image
+     * @param $x
+     * @param $y
+     *
+     * @return int
+     */
+    protected function getCol($image, $x, $y, $background)
+    {
+        $L = imagesx($image);
+        $H = imagesy($image);
+        if ($x < 0 || $x >= $L || $y < 0 || $y >= $H) {
+            return $background;
+        }
+
+        return imagecolorat($image, $x, $y);
+    }
+
+    /**
+     * Apply some post effects
+     */
+    protected function postEffect($image)
+    {
+        if (!function_exists('imagefilter')) {
+            return;
+        }
+
+        if ($this->backgroundColor != null || $this->textColor != null) {
+            return;
+        }
+
+        // Negate ?
+        if ($this->rand(0, 1) == 0) {
+            imagefilter($image, IMG_FILTER_NEGATE);
+        }
+
+        // Edge ?
+        if ($this->rand(0, 10) == 0) {
+            imagefilter($image, IMG_FILTER_EDGEDETECT);
+        }
+
+        // Contrast
+        imagefilter($image, IMG_FILTER_CONTRAST, $this->rand(-50, 10));
+
+        // Colorize
+        if ($this->rand(0, 5) == 0) {
+            imagefilter($image, IMG_FILTER_COLORIZE, $this->rand(-80, 50), $this->rand(-80, 50), $this->rand(-80, 50));
+        }
+    }
+
+    /**
+     * Instantiation
+     */
+    public static function create($phrase = null)
+    {
+        return new self($phrase);
+    }
+
+    /**
+     * The image contents
+     */
+    public function getContents()
+    {
+        return $this->contents;
+    }
+
+    /**
+     * Enable/Disables the interpolation
+     *
+     * @param $interpolate bool  True to enable, false to disable
+     *
+     * @return Captcha_builder
+     */
+    public function setInterpolation($interpolate = true)
+    {
+        $this->interpolation = $interpolate;
+
+        return $this;
+    }
+
+    /**
+     * Enables/disable distortion
+     */
+    public function setDistortion($distortion)
+    {
+        $this->distortion = (bool) $distortion;
+
+        return $this;
+    }
+
+    public function setMaxBehindLines($maxBehindLines)
+    {
+        $this->maxBehindLines = $maxBehindLines;
+
+        return $this;
+    }
+
+    public function setMaxFrontLines($maxFrontLines)
+    {
+        $this->maxFrontLines = $maxFrontLines;
+
+        return $this;
+    }
+
+    public function setMaxAngle($maxAngle)
+    {
+        $this->maxAngle = $maxAngle;
+
+        return $this;
+    }
+
+    public function setMaxOffset($maxOffset)
+    {
+        $this->maxOffset = $maxOffset;
+
+        return $this;
+    }
+
+    /**
+     * Sets the text color to use
+     */
+    public function setTextColor($r, $g, $b)
+    {
+        $this->textColor = [$r, $g, $b];
+
+        return $this;
+    }
+
+    /**
+     * Sets the background color to use
+     */
+    public function setBackgroundColor($r, $g, $b)
+    {
+        $this->backgroundColor = [$r, $g, $b];
+
+        return $this;
+    }
+
+    public function setLineColor($r, $g, $b)
+    {
+        $this->lineColor = [$r, $g, $b];
+
+        return $this;
+    }
+
+    /**
+     * Sets the ignoreAllEffects value
+     *
+     * @param bool $ignoreAllEffects
+     * @return Captcha_builder
+     */
+    public function setIgnoreAllEffects($ignoreAllEffects)
+    {
+        $this->ignoreAllEffects = $ignoreAllEffects;
+
+        return $this;
+    }
+
+    /**
+     * Sets the list of background images to use (one image is randomly selected)
+     */
+    public function setBackgroundImages(array $backgroundImages)
+    {
+        $this->backgroundImages = $backgroundImages;
+
+        return $this;
+    }
+
+    /**
+     * Builds while the code is readable against an OCR
+     */
+    public function buildAgainstOCR($width = 150, $height = 40, $font = null, $fingerprint = null)
+    {
+        do {
+            $this->build($width, $height, $font, $fingerprint);
+        } while ($this->isOCRReadable());
+    }
+
+    /**
+     * Try to read the code against an OCR
+     */
+    public function isOCRReadable()
+    {
+        if (!is_dir($this->tempDir)) {
+            @mkdir($this->tempDir, 0755, true);
+        }
+
+        $tempj = $this->tempDir . uniqid('captcha', true) . '.jpg';
+        $tempp = $this->tempDir . uniqid('captcha', true) . '.pgm';
+
+        $this->save($tempj);
+        shell_exec("convert $tempj $tempp");
+        $value = trim(strtolower(shell_exec("ocrad $tempp")));
+
+        @unlink($tempj);
+        @unlink($tempp);
+
+        return $this->testPhrase($value);
+    }
+
+    /**
+     * Saves the Captcha to a jpeg file
+     */
+    public function save($filename, $quality = 90)
+    {
+        imagejpeg($this->contents, $filename, $quality);
+    }
+
+    /**
+     * Returns true if the given phrase is good
+     */
+    public function testPhrase($phrase)
+    {
+        return $this->builder->niceize($phrase) == $this->builder->niceize($this->getPhrase());
+    }
+
+    /**
+     * Gets the captcha phrase
+     */
+    public function getPhrase()
+    {
+        return $this->phrase;
+    }
+
+    /**
+     * Setting the phrase
+     */
+    public function setPhrase($phrase)
+    {
+        $this->phrase = (string) $phrase;
+    }
+
+    /**
+     * Gets the image GD
+     */
+    public function getGd()
+    {
+        return $this->contents;
+    }
+
+    /**
+     * Gets the HTML inline base64
+     */
+    public function inline($quality = 90)
+    {
+        return 'data:image/jpeg;base64,' . base64_encode($this->get($quality));
+    }
+
+    /**
+     * Gets the image contents
+     */
+    public function get($quality = 90)
+    {
+        ob_start();
+        $this->output($quality);
+
+        return ob_get_clean();
+    }
+
+    /**
+     * Outputs the image
+     */
+    public function output($quality = 90)
+    {
+        imagejpeg($this->contents, null, $quality);
+    }
+
+    /**
+     * @return array
+     */
+    public function getFingerprint()
+    {
+        return $this->fingerprint;
+    }
+}

application/libraries/Email_messages.php

@@ -0,0 +1,267 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.4.0
+ * ---------------------------------------------------------------------------- */
+
+use PHPMailer\PHPMailer\PHPMailer;
+use PHPMailer\PHPMailer\SMTP;
+use PHPMailer\PHPMailer\Exception;
+
+/**
+ * Email messages library.
+ *
+ * Handles the email messaging related functionality.
+ *
+ * @package Libraries
+ */
+class Email_messages
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Email_messages constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('admins_model');
+        $this->CI->load->model('appointments_model');
+        $this->CI->load->model('providers_model');
+        $this->CI->load->model('secretaries_model');
+        $this->CI->load->model('secretaries_model');
+        $this->CI->load->model('settings_model');
+
+        $this->CI->load->library('email');
+        $this->CI->load->library('ics_file');
+        $this->CI->load->library('timezones');
+    }
+
+    /**
+     * Send an email with the appointment details.
+     *
+     * @param array $appointment Appointment data.
+     * @param array $provider Provider data.
+     * @param array $service Service data.
+     * @param array $customer Customer data.
+     * @param array $settings App settings.
+     * @param string $subject Email subject.
+     * @param string $message Email message.
+     * @param string $appointment_link Appointment unique URL.
+     * @param string $recipient_email Recipient email address.
+     * @param string $ics_stream ICS file contents.
+     * @param string|null $timezone Custom timezone.
+     *
+     * @throws DateInvalidTimeZoneException
+     * @throws DateMalformedStringException
+     * @throws Exception
+     */
+    public function send_appointment_saved(
+        array $appointment,
+        array $provider,
+        array $service,
+        array $customer,
+        array $settings,
+        string $subject,
+        string $message,
+        string $appointment_link,
+        string $recipient_email,
+        string $ics_stream,
+        ?string $timezone = null,
+    ): void {
+        $appointment_timezone = new DateTimeZone($provider['timezone']);
+
+        $appointment_start = new DateTime($appointment['start_datetime'], $appointment_timezone);
+
+        $appointment_end = new DateTime($appointment['end_datetime'], $appointment_timezone);
+
+        if ($timezone && $timezone !== $provider['timezone']) {
+            $custom_timezone = new DateTimeZone($timezone);
+
+            $appointment_start->setTimezone($custom_timezone);
+            $appointment['start_datetime'] = $appointment_start->format('Y-m-d H:i:s');
+
+            $appointment_end->setTimezone($custom_timezone);
+            $appointment['end_datetime'] = $appointment_end->format('Y-m-d H:i:s');
+        }
+
+        $html = $this->CI->load->view(
+            'emails/appointment_saved_email',
+            [
+                'subject' => $subject,
+                'message' => $message,
+                'appointment' => $appointment,
+                'service' => $service,
+                'provider' => $provider,
+                'customer' => $customer,
+                'settings' => $settings,
+                'timezone' => $timezone,
+                'appointment_link' => $appointment_link,
+            ],
+            true,
+        );
+
+        $php_mailer = $this->get_php_mailer($recipient_email, $subject, $html);
+
+        $php_mailer->addStringAttachment($ics_stream, 'invitation.ics', PHPMailer::ENCODING_BASE64, 'text/calendar');
+
+        $php_mailer->send();
+    }
+
+    /**
+     * Send an email with the appointment removal details.
+     *
+     * @param array $appointment Appointment data.
+     * @param array $provider Provider data.
+     * @param array $service Service data.
+     * @param array $customer Customer data.
+     * @param array $settings App settings.
+     * @param string $recipient_email Recipient email address.
+     * @param string|null $reason Removal reason.
+     * @param string|null $timezone Custom timezone.
+     *
+     * @throws DateInvalidTimeZoneException
+     * @throws DateMalformedStringException
+     * @throws Exception
+     */
+    public function send_appointment_deleted(
+        array $appointment,
+        array $provider,
+        array $service,
+        array $customer,
+        array $settings,
+        string $recipient_email,
+        ?string $reason = null,
+        ?string $timezone = null,
+    ): void {
+        $appointment_timezone = new DateTimeZone($provider['timezone']);
+
+        $appointment_start = new DateTime($appointment['start_datetime'], $appointment_timezone);
+
+        $appointment_end = new DateTime($appointment['end_datetime'], $appointment_timezone);
+
+        if ($timezone && $timezone !== $provider['timezone']) {
+            $custom_timezone = new DateTimeZone($timezone);
+
+            $appointment_start->setTimezone($custom_timezone);
+            $appointment['start_datetime'] = $appointment_start->format('Y-m-d H:i:s');
+
+            $appointment_end->setTimezone($custom_timezone);
+            $appointment['end_datetime'] = $appointment_end->format('Y-m-d H:i:s');
+        }
+
+        $html = $this->CI->load->view(
+            'emails/appointment_deleted_email',
+            [
+                'appointment' => $appointment,
+                'service' => $service,
+                'provider' => $provider,
+                'customer' => $customer,
+                'settings' => $settings,
+                'timezone' => $timezone,
+                'reason' => $reason,
+            ],
+            true,
+        );
+
+        $subject = lang('appointment_cancelled_title');
+
+        $php_mailer = $this->get_php_mailer($recipient_email, $subject, $html);
+
+        $php_mailer->send();
+    }
+
+    /**
+     * Send the account recovery details.
+     *
+     * @param string $password New password.
+     * @param string $recipient_email Recipient email address.
+     * @param array $settings App settings.
+     *
+     * @throws Exception
+     */
+    public function send_password(string $password, string $recipient_email, array $settings): void
+    {
+        $html = $this->CI->load->view(
+            'emails/account_recovery_email',
+            [
+                'subject' => lang('new_account_password'),
+                'message' => str_replace('$password', '<strong>' . $password . '</strong>', lang('new_password_is')),
+                'settings' => $settings,
+            ],
+            true,
+        );
+
+        $subject = lang('new_account_password');
+
+        $php_mailer = $this->get_php_mailer($recipient_email, $subject, $html);
+
+        $php_mailer->send();
+    }
+
+    /**
+     * Create PHP Mailer instance based on the email configuration.
+     *
+     * @param string|null $recipient_email
+     * @param string|null $subject
+     * @param string|null $html
+     *
+     * @return PHPMailer
+     *
+     * @throws Exception
+     */
+    private function get_php_mailer(
+        ?string $recipient_email = null,
+        ?string $subject = null,
+        ?string $html = null,
+    ): PHPMailer {
+        $php_mailer = new PHPMailer(true);
+
+        $php_mailer->isHTML();
+        $php_mailer->CharSet = 'UTF-8';
+        $php_mailer->SMTPDebug = config('smtp_debug') ? SMTP::DEBUG_SERVER : null;
+
+        if (config('protocol') === 'smtp') {
+            $php_mailer->isSMTP();
+            $php_mailer->Host = config('smtp_host');
+            $php_mailer->SMTPAuth = config('smtp_auth');
+            $php_mailer->Username = config('smtp_user');
+            $php_mailer->Password = config('smtp_pass');
+            $php_mailer->SMTPSecure = config('smtp_crypto');
+            $php_mailer->Port = config('smtp_port');
+        }
+
+        $from_name = config('from_name') ?: setting('company_name');
+        $from_address = config('from_address') ?: setting('company_email');
+        $reply_to_address = config('reply_to') ?: setting('company_email');
+
+        $php_mailer->setFrom($from_address, $from_name);
+        $php_mailer->addReplyTo($reply_to_address);
+
+        if ($recipient_email) {
+            $php_mailer->addAddress($recipient_email);
+        }
+
+        if ($subject) {
+            $php_mailer->Subject = $subject;
+        }
+
+        if ($html) {
+            $php_mailer->Body = $html;
+            $php_mailer->AltBody = $html;
+        }
+
+        return $php_mailer;
+    }
+}

application/libraries/Google_sync.php

@@ -0,0 +1,471 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.0.0
+ * ---------------------------------------------------------------------------- */
+
+use Google\Service\Calendar\Event;
+use Google\Service\Calendar\Events;
+
+/**
+ * Google sync library.
+ *
+ * Handles Google Calendar API related functionality.
+ *
+ * @package Libraries
+ */
+class Google_sync
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * @var Google_Client
+     */
+    protected Google_Client $client;
+
+    /**
+     * @var Google_Service_Calendar
+     */
+    protected Google_Service_Calendar $service;
+
+    /**
+     * Google_sync constructor.
+     *
+     * This method initializes the Google client class and the Calendar service class so that they can be used by the
+     * other methods.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('appointments_model');
+        $this->CI->load->model('customers_model');
+        $this->CI->load->model('providers_model');
+        $this->CI->load->model('services_model');
+
+        $this->initialize_clients();
+    }
+
+    /**
+     * Initialize the client, so that existing execution errors are not passed from one provider to another.
+     */
+    public function initialize_clients(): void
+    {
+        $http = new GuzzleHttp\Client([
+            'verify' => false,
+        ]);
+
+        $this->client = new Google_Client();
+        $this->client->setHttpClient($http);
+        $this->client->setApplicationName('Easy!Appointments');
+        $this->client->setClientId(config('google_client_id'));
+        $this->client->setClientSecret(config('google_client_secret'));
+        $this->client->setRedirectUri(site_url('google/oauth_callback'));
+        $this->client->setPrompt('consent');
+        $this->client->setAccessType('offline');
+        $this->client->addScope([Google_Service_Calendar::CALENDAR]);
+
+        $this->service = new Google_Service_Calendar($this->client);
+    }
+
+    /**
+     * Get Google OAuth authorization url.
+     *
+     * This url must be used to redirect the user to the Google user consent page,
+     * where the user grants access to his data for the Easy!Appointments app.
+     */
+    public function get_auth_url(): string
+    {
+        // The "max_auth_age" is needed because the user needs to always log in and not use an existing session.
+        return $this->client->createAuthUrl() . '&max_auth_age=0';
+    }
+
+    /**
+     * Authenticate the Google API usage.
+     *
+     * When the user grants consent for his data usage, Google is going to redirect the browser back to the given
+     * redirect URL. There an authentication code is provided. Using this code, we can authenticate the API usage and
+     * store the token information to the database.
+     *
+     * @param string $code
+     *
+     * @return array
+     *
+     * @throws Exception
+     */
+    public function authenticate(string $code): array
+    {
+        $response = $this->client->fetchAccessTokenWithAuthCode($code);
+
+        if (isset($response['error'])) {
+            throw new RuntimeException(
+                'Google Authentication Error (' . $response['error'] . '): ' . $response['error_description'],
+            );
+        }
+
+        return $response;
+    }
+
+    /**
+     * Refresh the Google Client access token.
+     *
+     * This method must be executed every time we need to make actions on a provider's Google Calendar account. A new
+     * token is necessary and the only way to get it is to use the stored refresh token that was provided when the
+     * provider granted consent to Easy!Appointments for use his Google Calendar account.
+     *
+     * @param string $refresh_token The provider's refresh token. This value is stored in the database and used every
+     * time we need to make actions to his Google Calendar account.
+     */
+    public function refresh_token(string $refresh_token): void
+    {
+        $this->initialize_clients();
+
+        $this->client->refreshToken($refresh_token);
+    }
+
+    /**
+     * Add an appointment record to its providers Google Calendar account.
+     *
+     * This method checks whether the appointment's provider has enabled the Google Sync utility of Easy!Appointments
+     * and the stored access token is still valid. If yes, the selected appointment record is going to be added to the
+     * Google Calendar account.
+     *
+     * @param array $appointment Appointment data.
+     * @param array $provider Provider data.
+     * @param array $service Service data.
+     * @param array $customer Customer data.
+     * @param array $settings Required settings.
+     *
+     * @return Event Returns the Google_Event class object.
+     *
+     * @throws Exception
+     */
+    public function add_appointment(
+        array $appointment,
+        array $provider,
+        array $service,
+        array $customer,
+        array $settings,
+    ): Event {
+        $event = new Google_Service_Calendar_Event();
+        $event->setSummary(!empty($service) ? $service['name'] : 'Unavailable');
+        $event->setDescription($appointment['notes']);
+        $event->setLocation($appointment['location'] ?? $settings['company_name']);
+
+        $timezone = new DateTimeZone($provider['timezone']);
+
+        $start = new Google_Service_Calendar_EventDateTime();
+        $start->setDateTime(
+            (new DateTime($appointment['start_datetime'], $timezone))->format(DateTimeInterface::RFC3339),
+        );
+        $event->setStart($start);
+
+        $end = new Google_Service_Calendar_EventDateTime();
+        $end->setDateTime((new DateTime($appointment['end_datetime'], $timezone))->format(DateTimeInterface::RFC3339));
+        $event->setEnd($end);
+
+        $event->attendees = [];
+
+        $event_provider = new Google_Service_Calendar_EventAttendee();
+        $event_provider->setDisplayName($provider['first_name'] . ' ' . $provider['last_name']);
+        $event_provider->setEmail($provider['email']);
+        $event->attendees[] = $event_provider;
+
+        if (!empty($customer['first_name']) && !empty($customer['last_name']) && !empty($customer['email'])) {
+            $event_customer = new Google_Service_Calendar_EventAttendee();
+            $event_customer->setDisplayName($customer['first_name'] . ' ' . $customer['last_name']);
+            $event_customer->setEmail($customer['email']);
+            $event->attendees[] = $event_customer;
+        }
+
+        // Add the new event to the Google Calendar.
+        return $this->service->events->insert($provider['settings']['google_calendar'], $event);
+    }
+
+    /**
+     * Update an existing appointment that is already synced with Google Calendar.
+     *
+     * This method updates the Google Calendar event item that is connected with the provided appointment record of
+     * Easy!Appointments.
+     *
+     * @param array $appointment Appointment data.
+     * @param array $provider Provider data.
+     * @param array $service Service data.
+     * @param array $customer Customer data.
+     * @parma array $settings Required settings.
+     *
+     * @return Event Returns the Google_Service_Calendar_Event class object.
+     *
+     * @throws Exception
+     */
+    public function update_appointment(
+        array $appointment,
+        array $provider,
+        array $service,
+        array $customer,
+        array $settings,
+    ): Event {
+        $event = $this->service->events->get(
+            $provider['settings']['google_calendar'],
+            $appointment['id_google_calendar'],
+        );
+
+        $event->setSummary($service['name']);
+        $event->setDescription($appointment['notes']);
+        $event->setLocation($appointment['location'] ?? $settings['company_name']);
+
+        $timezone = new DateTimeZone($provider['timezone']);
+
+        $start = new Google_Service_Calendar_EventDateTime();
+        $start->setDateTime(
+            (new DateTime($appointment['start_datetime'], $timezone))->format(DateTimeInterface::RFC3339),
+        );
+        $event->setStart($start);
+
+        $end = new Google_Service_Calendar_EventDateTime();
+        $end->setDateTime((new DateTime($appointment['end_datetime'], $timezone))->format(DateTimeInterface::RFC3339));
+        $event->setEnd($end);
+
+        $event->attendees = [];
+
+        $event_provider = new Google_Service_Calendar_EventAttendee();
+        $event_provider->setDisplayName($provider['first_name'] . ' ' . $provider['last_name']);
+        $event_provider->setEmail($provider['email']);
+        $event->attendees[] = $event_provider;
+
+        if (!empty($customer['first_name']) && !empty($customer['last_name']) && !empty($customer['email'])) {
+            $event_customer = new Google_Service_Calendar_EventAttendee();
+            $event_customer->setDisplayName($customer['first_name'] . ' ' . $customer['last_name']);
+            $event_customer->setEmail($customer['email']);
+            $event->attendees[] = $event_customer;
+        }
+
+        return $this->service->events->update($provider['settings']['google_calendar'], $event->getId(), $event);
+    }
+
+    /**
+     * Delete an existing appointment from Google Calendar.
+     *
+     * @param array $provider Provider data.
+     * @param string $google_event_id The Google Calendar event ID to be removed.
+     *
+     * @throws \Google\Service\Exception
+     */
+    public function delete_appointment(array $provider, string $google_event_id): void
+    {
+        $this->service->events->delete($provider['settings']['google_calendar'], $google_event_id);
+    }
+
+    /**
+     * Add unavailability period event to Google Calendar.
+     *
+     * @param array $provider Provider data.
+     * @param array $unavailability Unavailable data.
+     *
+     * @return Google_Service_Calendar_Event Returns the Google event.
+     *
+     * @throws Exception
+     */
+    public function add_unavailability(array $provider, array $unavailability): Google_Service_Calendar_Event
+    {
+        $event = new Google_Service_Calendar_Event();
+        $event->setSummary('Unavailable');
+        $event->setDescription($unavailability['notes']);
+
+        $timezone = new DateTimeZone($provider['timezone']);
+
+        $start = new Google_Service_Calendar_EventDateTime();
+        $start->setDateTime(
+            (new DateTime($unavailability['start_datetime'], $timezone))->format(DateTimeInterface::RFC3339),
+        );
+        $event->setStart($start);
+
+        $end = new Google_Service_Calendar_EventDateTime();
+        $end->setDateTime(
+            (new DateTime($unavailability['end_datetime'], $timezone))->format(DateTimeInterface::RFC3339),
+        );
+        $event->setEnd($end);
+
+        // Add the new event to the Google Calendar.
+        return $this->service->events->insert($provider['settings']['google_calendar'], $event);
+    }
+
+    /**
+     * Update Google Calendar unavailability period event.
+     *
+     * @param array $provider Provider data.
+     * @param array $unavailability Unavailability data.
+     *
+     * @return Google_Service_Calendar_Event Returns the Google_Service_Calendar_Event object.
+     *
+     * @throws Exception
+     */
+    public function update_unavailability(array $provider, array $unavailability): Google_Service_Calendar_Event
+    {
+        $event = $this->service->events->get(
+            $provider['settings']['google_calendar'],
+            $unavailability['id_google_calendar'],
+        );
+
+        $event->setSummary('Unavailable');
+        $event->setDescription($unavailability['notes']);
+
+        $timezone = new DateTimeZone($provider['timezone']);
+
+        $start = new Google_Service_Calendar_EventDateTime();
+        $start->setDateTime(
+            (new DateTime($unavailability['start_datetime'], $timezone))->format(DateTimeInterface::RFC3339),
+        );
+        $event->setStart($start);
+
+        $end = new Google_Service_Calendar_EventDateTime();
+        $end->setDateTime(
+            (new DateTime($unavailability['end_datetime'], $timezone))->format(DateTimeInterface::RFC3339),
+        );
+        $event->setEnd($end);
+
+        return $this->service->events->update($provider['settings']['google_calendar'], $event->getId(), $event);
+    }
+
+    /**
+     * Delete unavailability period event from Google Calendar.
+     *
+     * @param array $provider Provider data.
+     * @param string $google_event_id Google Calendar event ID to be removed.
+     *
+     * @throws \Google\Service\Exception
+     */
+    public function delete_unavailability(array $provider, string $google_event_id): void
+    {
+        $this->service->events->delete($provider['settings']['google_calendar'], $google_event_id);
+    }
+
+    /**
+     * Get a Google Calendar event.
+     *
+     * @param array $provider Provider data.
+     * @param string $google_event_id Google Calendar event ID.
+     *
+     * @return Event Returns the Google Calendar event.
+     *
+     * @throws \Google\Service\Exception
+     */
+    public function get_event(array $provider, string $google_event_id): Event
+    {
+        return $this->service->events->get($provider['settings']['google_calendar'], $google_event_id);
+    }
+
+    /**
+     * Get all the events between the sync period.
+     *
+     * @param string $google_calendar The name of the Google Calendar to be used.
+     * @param string $start The start date of sync period.
+     * @param string $end The end date of sync period.
+     *
+     * @return Events Returns a collection of events.
+     *
+     * @throws \Google\Service\Exception
+     */
+    public function get_sync_events(string $google_calendar, string $start, string $end): Events
+    {
+        $params = [
+            'timeMin' => date(DateTimeInterface::RFC3339, $start),
+            'timeMax' => date(DateTimeInterface::RFC3339, $end),
+            'singleEvents' => true,
+        ];
+
+        return $this->service->events->listEvents($google_calendar, $params);
+    }
+
+    /**
+     * Return available Google Calendars for specific user.
+     *
+     * The given user's token must already exist in db in order to get access to his
+     * Google Calendar account.
+     *
+     * @return array Returns an array with the available calendars.
+     *
+     * @throws \Google\Service\Exception
+     */
+    public function get_google_calendars(): array
+    {
+        $calendar_list = $this->service->calendarList->listCalendarList();
+
+        $calendars = [];
+
+        foreach ($calendar_list->getItems() as $google_calendar) {
+            if ($google_calendar->getAccessRole() === 'reader') {
+                continue;
+            }
+
+            $calendars[] = [
+                'id' => $google_calendar->getId(),
+                'summary' => $google_calendar->getSummary(),
+            ];
+        }
+
+        return $calendars;
+    }
+
+    /**
+     * Get the Add-To-Google-URL, that can be used by anyone to quickly add the event to Google Calendar (no API needed).
+     *
+     * @param int $appointment_id
+     *
+     * @return string
+     *
+     * @throws Exception
+     */
+    public function get_add_to_google_url(int $appointment_id): string
+    {
+        $appointment = $this->CI->appointments_model->find($appointment_id);
+
+        $service = $this->CI->services_model->find($appointment['id_services']);
+
+        $provider = $this->CI->providers_model->find($appointment['id_users_provider']);
+
+        $customer = $this->CI->customers_model->find($appointment['id_users_customer']);
+
+        $provider_timezone_instance = new DateTimeZone($provider['timezone']);
+
+        $utc_timezone_instance = new DateTimeZone('UTC');
+
+        $appointment_start_instance = new DateTime($appointment['start_datetime'], $provider_timezone_instance);
+
+        $appointment_start_instance->setTimezone($utc_timezone_instance);
+
+        $appointment_end_instance = new DateTime($appointment['end_datetime'], $provider_timezone_instance);
+
+        $appointment_end_instance->setTimezone($utc_timezone_instance);
+
+        $add = [$provider['email']];
+
+        if (!empty($customer['email'])) {
+            $add[] = $customer['email'];
+        }
+
+        $add_to_google_url_params = [
+            'action' => 'TEMPLATE',
+            'text' => $service['name'],
+            'dates' =>
+                $appointment_start_instance->format('Ymd\THis\Z') .
+                '/' .
+                $appointment_end_instance->format('Ymd\THis\Z'),
+            'location' => setting('company_name'),
+            'details' => 'View/Change Appointment: ' . site_url('booking/reschedule/' . $appointment['hash']),
+            'add' => implode(', ', $add),
+        ];
+
+        return 'https://calendar.google.com/calendar/render?' . http_build_query($add_to_google_url_params);
+    }
+}

application/libraries/Ics_calendar.php

@@ -0,0 +1,415 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Open Source Web Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) 2013 - 2020, Alex Tselegidis
+ * @license     http://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        http://easyappointments.org
+ * @since       v1.4.3
+ * ---------------------------------------------------------------------------- */
+
+use Jsvrcek\ICS\Model\Calendar;
+use Jsvrcek\ICS\Model\CalendarEvent;
+use Jsvrcek\ICS\Model\CalendarFreeBusy;
+use Jsvrcek\ICS\Model\CalendarTodo;
+use Jsvrcek\ICS\Utility\Provider;
+
+/**
+ * Class Ics_calendar
+ *
+ * This class replaces the Jsvrcek\ICS\Model\Calendar so that it uses the new Ics_provider instances, which is
+ * compatible to PHP 8.1.
+ *
+ * There is no other change to the original file.
+ */
+class Ics_calendar extends Calendar
+{
+    /**
+     * @var string
+     */
+    private $version = '2.0';
+
+    /**
+     * @var string
+     */
+    private $prodId = '';
+
+    /**
+     * @var string
+     */
+    private $name = '';
+
+    /**
+     * @var string
+     */
+    private $calendarScale = 'GREGORIAN';
+
+    /**
+     * @var string
+     */
+    private $method = 'PUBLISH';
+
+    /**
+     * @var array
+     */
+    private $image = [];
+
+    /**
+     * @var array
+     */
+    private $customHeaders = [];
+
+    /**
+     * @var DateTimeZone
+     */
+    private $timezone;
+
+    /**
+     * @var Provider
+     */
+    private $events;
+
+    /**
+     * @var Provider
+     */
+    private $todos;
+
+    /**
+     * @var Provider
+     */
+    private $freeBusy;
+
+    /**
+     * @var string
+     */
+    private $color;
+
+    /**
+     * Calendar constructor.
+     */
+    public function __construct()
+    {
+        $this->timezone = new DateTimeZone('America/New_York');
+        $this->events = new Ics_provider();
+        $this->todos = new Ics_provider();
+        $this->freeBusy = new Ics_provider();
+    }
+
+    /**
+     * For use if you want CalendarExport::getStream to get events in batches from a database during
+     * the output of the ics feed, instead of adding all events to the Calendar object before outputting
+     * the ics feed.
+     * - CalendarExport::getStream iterates through the Calendar::$events internal data array. The $eventsProvider
+     *     closure will be called every time this data array reaches its end during iteration, and the closure should
+     *     return the next batch of events
+     * - A $startKey argument with the current key of the data array will be passed to the $eventsProvider closure
+     * - The $eventsProvider must return an array of CalendarEvent objects
+     *
+     *  Example: Calendar::setEventsProvider(function($startKey){
+     *      //get database rows starting with $startKey
+     *      //return an array of CalendarEvent objects
+     *  })
+     *
+     * @param Closure $eventsProvider
+     * @return Calendar
+     */
+    public function setEventsProvider(Closure $eventsProvider)
+    {
+        $this->events = new Ics_provider($eventsProvider);
+        return $this;
+    }
+
+    /**
+     * @return string
+     */
+    public function getVersion()
+    {
+        return $this->version;
+    }
+
+    /**
+     * @param string $version
+     * @return Calendar
+     */
+    public function setVersion($version)
+    {
+        $this->version = $version;
+        return $this;
+    }
+
+    /**
+     * @return string
+     */
+    public function getProdId()
+    {
+        return $this->prodId;
+    }
+
+    /**
+     * @param string $prodId
+     * @return Calendar
+     */
+    public function setProdId($prodId)
+    {
+        $this->prodId = $prodId;
+        return $this;
+    }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->name;
+    }
+
+    /**
+     * Sets the RFC-7986 "Name" field for the calendar
+     *
+     * @param string $name
+     */
+    public function setName($name)
+    {
+        $this->name = $name;
+    }
+
+    /**
+     * @return string
+     */
+    public function getCalendarScale()
+    {
+        return $this->calendarScale;
+    }
+
+    /**
+     * @param string $calendarScale
+     * @return Calendar
+     */
+    public function setCalendarScale($calendarScale)
+    {
+        $this->calendarScale = $calendarScale;
+        return $this;
+    }
+
+    /**
+     * @return string
+     */
+    public function getMethod()
+    {
+        return $this->method;
+    }
+
+    /**
+     * @param string $method
+     * @return Calendar
+     */
+    public function setMethod($method)
+    {
+        $this->method = $method;
+        return $this;
+    }
+
+    /**
+     * @return array
+     */
+    public function getImage()
+    {
+        return $this->image;
+    }
+
+    /**
+     * Images can come in one of two formats:
+     *    1: URI - where a URI to the relevant image is provided
+     *    2: BINARY - Where a Binary representation of the image is provided, normally Base64 Encoded.
+     *
+     * If sending a URI for the image, set the "VALUE" key to be "URI" and provide a URI key with the relevant URI.
+     * IE:
+     *     $calendar->setImage(
+     *         'VALUE' => 'URL',
+     *         'URI' => 'https://some.domain.com/path/to/image.jpg'
+     *     );
+     * It is optional to add a FMTTYPE key as well in the array, to indicate relevant mime type.
+     * IE: 'FMTTYPE' => 'image/jpg'
+     *
+     * When sending Binary version, you must provide the encoding type of the image, as well as the encoded string.
+     * IE:
+     *    $calendar->setImage(
+     *        'VALUE' => 'BINARY',
+     *        'ENCODING' => 'BASE64',
+     *        'BINARY' => $base64_encoded_string
+     *    );
+     * For Binary, it is RECOMMENDED to add the FMTTYPE as well, but still not REQUIRED
+     *
+     * @param array $image
+     */
+    public function setImage($image)
+    {
+        // Do some validation on provided data.
+        if (array_key_exists('VALUE', $image) && in_array($image['VALUE'], ['URI', 'BINARY'])) {
+            if ($image['VALUE'] == 'URI' && $image['URI']) {
+                $new_image = [
+                    'VALUE' => 'URI',
+                    'URI' => $image['URI'],
+                ];
+            } elseif ($image['VALUE'] == 'BINARY' && $image['ENCODING'] && $image['BINARY']) {
+                $new_image = [
+                    'VALUE' => 'BINARY',
+                    'ENCODING' => $image['ENCODING'],
+                    'BINARY' => $image['BINARY'],
+                ];
+            } else {
+                return;
+            }
+            $new_image['DISPLAY'] = isset($image['DISPLAY']) ? $image['DISPLAY'] : '';
+            $new_image['FMTTYPE'] = isset($image['FMTTYPE']) ? $image['FMTTYPE'] : '';
+            $this->image = $new_image;
+        }
+    }
+
+    /**
+     * @return array
+     */
+    public function getCustomHeaders()
+    {
+        return $this->customHeaders;
+    }
+
+    /**
+     * use to add custom headers as array key-value pairs<br>
+     * <strong>Example:</strong> $customHeaders = array('X-WR-TIMEZONE' => 'America/New_York')
+     *
+     * @param array $customHeaders
+     * @return Calendar
+     */
+    public function setCustomHeaders(array $customHeaders)
+    {
+        $this->customHeaders = $customHeaders;
+        return $this;
+    }
+
+    /**
+     * @param string $key
+     * @param string $value
+     * @return Calendar
+     */
+    public function addCustomHeader($key, $value)
+    {
+        $this->customHeaders[$key] = $value;
+        return $this;
+    }
+
+    /**
+     * @return DateTimeZone
+     */
+    public function getTimezone()
+    {
+        return $this->timezone;
+    }
+
+    /**
+     * @param DateTimeZone $timezone
+     * @return Calendar
+     */
+    public function setTimezone(DateTimeZone $timezone)
+    {
+        $this->timezone = $timezone;
+        return $this;
+    }
+
+    /**
+     * @return Provider
+     */
+    public function getEvents()
+    {
+        return $this->events;
+    }
+
+    /**
+     * @param CalendarEvent $event
+     * @return Calendar
+     */
+    public function addEvent(CalendarEvent $event)
+    {
+        $this->events->add($event);
+        return $this;
+    }
+
+    /**
+     * @return Provider returs array of CalendarTodo objects
+     */
+    public function getTodos()
+    {
+        return $this->todos;
+    }
+
+    /**
+     * @param array $todos
+     * @return Calendar
+     */
+    public function setTodos(array $todos)
+    {
+        $this->todos = $todos;
+        return $this;
+    }
+
+    /**
+     * @param CalendarTodo $todo
+     * @return Calendar
+     */
+    public function addTodo(CalendarTodo $todo)
+    {
+        $this->todos[] = $todo;
+        return $this;
+    }
+
+    /**
+     * @return Provider returs array of CalendarFreeBusy objects
+     */
+    public function getFreeBusy()
+    {
+        return $this->freeBusy;
+    }
+
+    /**
+     * @param array $freeBusy
+     * @return Calendar
+     */
+    public function setFreeBusy(array $freeBusy)
+    {
+        $this->freeBusy = $freeBusy;
+        return $this;
+    }
+
+    /**
+     * @param CalendarFreeBusy $todo
+     * @return Calendar
+     */
+    public function addFreeBusy(CalendarFreeBusy $todo)
+    {
+        $this->freeBusy[] = $todo;
+        return $this;
+    }
+
+    /**
+     * @return string
+     */
+    public function getColor()
+    {
+        return $this->color;
+    }
+
+    /**
+     * Set color as CSS3 string
+     *
+     * @param string $color
+     * @return Calendar
+     */
+    public function setColor($color)
+    {
+        $this->color = $color;
+        return $this;
+    }
+}

application/libraries/Ics_file.php

@@ -0,0 +1,231 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.3.0
+ * ---------------------------------------------------------------------------- */
+
+use Jsvrcek\ICS\CalendarExport;
+use Jsvrcek\ICS\CalendarStream;
+use Jsvrcek\ICS\Exception\CalendarEventException;
+use Jsvrcek\ICS\Model\CalendarAlarm;
+use Jsvrcek\ICS\Model\CalendarEvent;
+use Jsvrcek\ICS\Model\Description\Location;
+use Jsvrcek\ICS\Model\Relationship\Attendee;
+use Jsvrcek\ICS\Model\Relationship\Organizer;
+use Jsvrcek\ICS\Utility\Formatter;
+
+/**
+ * Ics file library.
+ *
+ * Handle ICS related functionality.
+ *
+ * An ICS file is a calendar file saved in a universal calendar format used by many email and calendar programs,
+ * including Microsoft Outlook, Google Calendar, and Apple Calendar.
+ *
+ * @package Libraries
+ */
+class Ics_file
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Availability constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->library('ics_provider');
+        $this->CI->load->library('ics_calendar');
+    }
+
+    /**
+     * Get the ICS file contents for the provided arguments.
+     *
+     * @param array $appointment Appointment data.
+     * @param array $service Service data.
+     * @param array $provider Provider data.
+     * @param array $customer Customer data.
+     *
+     * @return string Returns the contents of the ICS file.
+     *
+     * @throws CalendarEventException
+     * @throws Exception
+     */
+    public function get_stream(array $appointment, array $service, array $provider, array $customer): string
+    {
+        $appointment_timezone = new DateTimeZone($provider['timezone']);
+
+        $appointment_start = new DateTime($appointment['start_datetime'], $appointment_timezone);
+
+        $appointment_end = new DateTime($appointment['end_datetime'], $appointment_timezone);
+
+        // Set up the event.
+        $event = new CalendarEvent();
+
+        $event
+            ->setStart($appointment_start)
+            ->setEnd($appointment_end)
+            ->setStatus('CONFIRMED')
+            ->setSummary($service['name'])
+            ->setUid($appointment['id_caldav_calendar'] ?: $this->generate_uid($appointment['id']));
+
+        if (!empty($service['location'])) {
+            $location = new Location();
+            $location->setName((string) $service['location']);
+            $event->addLocation($location);
+        }
+
+        $description = [
+            '',
+            lang('provider'),
+            '',
+            lang('name') . ': ' . $provider['first_name'] . ' ' . $provider['last_name'],
+            lang('email') . ': ' . $provider['email'],
+            lang('phone_number') . ': ' . $provider['phone_number'],
+            lang('address') . ': ' . $provider['address'],
+            lang('city') . ': ' . $provider['city'],
+            lang('zip_code') . ': ' . $provider['zip_code'],
+            '',
+            lang('customer'),
+            '',
+            lang('name') . ': ' . $customer['first_name'] . ' ' . $customer['last_name'],
+            lang('email') . ': ' . $customer['email'],
+            lang('phone_number') . ': ' . ($customer['phone_number'] ?? '-'),
+            lang('address') . ': ' . $customer['address'],
+            lang('city') . ': ' . $customer['city'],
+            lang('zip_code') . ': ' . $customer['zip_code'],
+            '',
+            lang('notes'),
+            '',
+            $appointment['notes'],
+        ];
+
+        $event->setDescription(implode("\\n", $description));
+
+        $attendee = new Attendee(new Formatter());
+
+        if (isset($customer['email']) && !empty($customer['email'])) {
+            $attendee->setValue($customer['email']);
+        }
+
+        // Add the event attendees.
+        $attendee->setName($customer['first_name'] . ' ' . $customer['last_name']);
+        $attendee
+            ->setCalendarUserType('INDIVIDUAL')
+            ->setRole('REQ-PARTICIPANT')
+            ->setParticipationStatus('NEEDS-ACTION')
+            ->setRsvp('TRUE');
+        $event->addAttendee($attendee);
+
+        $alarm = new CalendarAlarm();
+        $alarm_datetime = clone $appointment_start;
+        $alarm->setTrigger($alarm_datetime->modify('-15 minutes'));
+        $alarm->setSummary('Alarm notification');
+        $alarm->setDescription('This is an event reminder');
+        $alarm->setAction('EMAIL');
+        $alarm->addAttendee($attendee);
+        $event->addAlarm($alarm);
+
+        $alarm = new CalendarAlarm();
+        $alarm_datetime = clone $appointment_start;
+        $alarm->setTrigger($alarm_datetime->modify('-60 minutes'));
+        $alarm->setSummary('Alarm notification');
+        $alarm->setDescription('This is an event reminder');
+        $alarm->setAction('EMAIL');
+        $alarm->addAttendee($attendee);
+        $event->addAlarm($alarm);
+
+        $attendee = new Attendee(new Formatter());
+
+        if (isset($provider['email']) && !empty($provider['email'])) {
+            $attendee->setValue($provider['email']);
+        }
+
+        $attendee->setName($provider['first_name'] . ' ' . $provider['last_name']);
+        $attendee
+            ->setCalendarUserType('INDIVIDUAL')
+            ->setRole('REQ-PARTICIPANT')
+            ->setParticipationStatus('ACCEPTED')
+            ->setRsvp('FALSE');
+        $event->addAttendee($attendee);
+
+        // Set the organizer.
+        $organizer = new Organizer(new Formatter());
+
+        $organizer->setValue($provider['email'])->setName($provider['first_name'] . ' ' . $provider['last_name']);
+
+        $event->setOrganizer($organizer);
+
+        // Setup calendar.
+        $calendar = new Ics_calendar();
+
+        $calendar
+            ->setProdId('-//EasyAppointments//Open Source Web Scheduler//EN')
+            ->setTimezone(new DateTimeZone($provider['timezone']))
+            ->addEvent($event);
+
+        // Setup exporter.
+        $calendarExport = new CalendarExport(new CalendarStream(), new Formatter());
+        $calendarExport->addCalendar($calendar);
+
+        return $calendarExport->getStream();
+    }
+
+    public function get_unavailability_stream(array $unavailability, array $provider): string
+    {
+        $unavailability_timezone = new DateTimeZone($provider['timezone']);
+
+        $unavailability_start = new DateTime($unavailability['start_datetime'], $unavailability_timezone);
+
+        $unavailability_end = new DateTime($unavailability['end_datetime'], $unavailability_timezone);
+
+        // Set up the event.
+        $event = new CalendarEvent();
+
+        $event
+            ->setStart($unavailability_start)
+            ->setEnd($unavailability_end)
+            ->setStatus('CONFIRMED')
+            ->setSummary('Unavailability')
+            ->setUid($unavailability['id_caldav_calendar'] ?: $this->generate_uid($unavailability['id']));
+
+        $event->setDescription(str_replace("\n", "\\n", (string) $unavailability['notes']));
+
+        // Set the organizer.
+        $organizer = new Organizer(new Formatter());
+
+        $organizer->setValue($provider['email'])->setName($provider['first_name'] . ' ' . $provider['last_name']);
+
+        $event->setOrganizer($organizer);
+
+        // Setup calendar.
+        $calendar = new Ics_calendar();
+
+        $calendar
+            ->setProdId('-//EasyAppointments//Open Source Web Scheduler//EN')
+            ->setTimezone(new DateTimeZone($provider['timezone']))
+            ->addEvent($event);
+
+        // Setup exporter.
+        $calendarExport = new CalendarExport(new CalendarStream(), new Formatter());
+        $calendarExport->addCalendar($calendar);
+
+        return $calendarExport->getStream();
+    }
+
+    public function generate_uid(int $db_record_id): string
+    {
+        return 'ea-' . md5($db_record_id);
+    }
+}

application/libraries/Ics_provider.php

@@ -0,0 +1,162 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Open Source Web Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) 2013 - 2020, Alex Tselegidis
+ * @license     http://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        http://easyappointments.org
+ * @since       v1.4.3
+ * ---------------------------------------------------------------------------- */
+
+/**
+ * Class Ics_calendar
+ *
+ * This class replaces the Jsvrcek\ICS\Utility\Provider so that it becomes a PHP 8.1 compatible Iterator class.
+ *
+ * Since the method signatures changed in PHP 8.1, the ReturnTypeWillChange attribute allows us to keep compatibility
+ * between different PHP versions.
+ */
+class Ics_provider implements Iterator
+{
+    /**
+     * @var array
+     */
+    public $data = [];
+    /**
+     * @var array
+     */
+    public $manuallyAddedData = [];
+    /**
+     * @var Closure
+     */
+    private $provider;
+    /**
+     * @var integer
+     */
+    private $key;
+
+    /**
+     * @var mixed
+     */
+    private $first;
+
+    /**
+     * @param Closure $provider An optional closure for adding items in batches during iteration. The closure will be
+     *     called each time the end of the internal data array is reached during iteration, and the current data
+     *     array key value will be passed as an argument. The closure should return an array containing the next
+     *     batch of items.
+     */
+    public function __construct(?Closure $provider = null)
+    {
+        $this->provider = $provider;
+    }
+
+    /**
+     * for manually adding items, rather than using a provider closure to add items in batches during iteration
+     * Cannot be used in conjunction with a provider closure!
+     *
+     * @param mixed $item
+     * @return void
+     */
+    #[ReturnTypeWillChange]
+    public function add($item)
+    {
+        $this->manuallyAddedData[] = $item;
+    }
+
+    /**
+     * @return false|mixed
+     * @see Iterator::current()
+     */
+    #[ReturnTypeWillChange]
+    public function current()
+    {
+        return current($this->data);
+    }
+
+    /**
+     * @return float|int|null
+     * @see Iterator::key()
+     */
+    #[ReturnTypeWillChange]
+    public function key()
+    {
+        return $this->key;
+    }
+
+    /**
+     * @return void
+     * @see Iterator::next()
+     */
+    #[ReturnTypeWillChange]
+    public function next()
+    {
+        array_shift($this->data);
+        $this->key++;
+    }
+
+    /**
+     * @return void
+     * @see Iterator::rewind()
+     */
+    #[ReturnTypeWillChange]
+    public function rewind()
+    {
+        $this->data = [];
+        $this->key = 0;
+    }
+
+    /**
+     * Returns first event
+     *
+     * @return false|mixed
+     */
+    #[ReturnTypeWillChange]
+    public function first()
+    {
+        if (isset($this->first)) {
+            return $this->first;
+        }
+
+        if ($this->provider instanceof Closure) {
+            if ($this->valid()) {
+                return $this->first;
+            } else {
+                return false;
+            }
+        }
+
+        if (!isset($this->manuallyAddedData[0])) {
+            return false;
+        }
+
+        return $this->manuallyAddedData[0];
+    }
+
+    /**
+     * get next batch from provider if data array is at the end
+     *
+     * @return bool
+     * @see Iterator::valid()
+     */
+    #[ReturnTypeWillChange]
+    public function valid()
+    {
+        if (count($this->data) < 1) {
+            if ($this->provider instanceof Closure) {
+                $this->data = $this->provider->__invoke($this->key);
+                if (isset($this->data[0])) {
+                    $this->first = $this->data[0];
+                }
+            } else {
+                $this->data = $this->manuallyAddedData;
+                $this->manuallyAddedData = [];
+            }
+        }
+
+        return count($this->data) > 0;
+    }
+}

application/libraries/Instance.php

@@ -0,0 +1,183 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.4.0
+ * ---------------------------------------------------------------------------- */
+
+require_once __DIR__ . '/../core/EA_Migration.php';
+
+/**
+ * Instance library.
+ *
+ * Handles all Easy!Appointments instance related functionality.
+ *
+ * @package Libraries
+ */
+class Instance
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Installation constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('admins_model');
+        $this->CI->load->model('services_model');
+        $this->CI->load->model('providers_model');
+        $this->CI->load->model('customers_model');
+
+        $this->CI->load->library('timezones');
+        $this->CI->load->library('migration');
+    }
+
+    /**
+     * Migrate the database to the latest state.
+     *
+     * @param string $type Provide "fresh" to revert previous migrations and start from the beginning or "up"/"down" to step.
+     */
+    public function migrate(string $type = ''): void
+    {
+        $current_version = $this->CI->migration->current_version();
+
+        if ($type === 'up') {
+            if (!$this->CI->migration->version($current_version + 1)) {
+                show_error($this->CI->migration->error_string());
+            }
+
+            return;
+        }
+
+        if ($type === 'down') {
+            if (!$this->CI->migration->version($current_version - 1)) {
+                show_error($this->CI->migration->error_string());
+            }
+
+            return;
+        }
+
+        if ($type === 'fresh' && !$this->CI->migration->version(0)) {
+            show_error($this->CI->migration->error_string());
+        }
+
+        if ($this->CI->migration->latest() === false) {
+            show_error($this->CI->migration->error_string());
+        }
+    }
+
+    /**
+     * Seed the database with test data.
+     *
+     * @return string Return's the administrator user password.
+     *
+     * @throws Exception
+     */
+    public function seed(): string
+    {
+        // Settings
+
+        setting([
+            'company_name' => 'Company Name',
+            'company_email' => 'info@example.org',
+            'company_link' => 'https://example.org',
+        ]);
+
+        // Admin
+
+        $password = 'administrator';
+
+        $this->CI->admins_model->save([
+            'first_name' => 'John',
+            'last_name' => 'Doe',
+            'email' => 'john@example.org',
+            'phone_number' => '+10000000000',
+            'settings' => [
+                'username' => 'administrator',
+                'password' => $password,
+                'notifications' => true,
+                'calendar_view' => CALENDAR_VIEW_DEFAULT,
+            ],
+        ]);
+
+        // Service
+
+        $service_id = $this->CI->services_model->save([
+            'name' => 'Service',
+            'duration' => '30',
+            'price' => '0',
+            'currency' => '',
+            'availabilities_type' => 'flexible',
+            'attendants_number' => '1',
+        ]);
+
+        // Provider
+
+        $this->CI->providers_model->save([
+            'first_name' => 'Jane',
+            'last_name' => 'Doe',
+            'email' => 'jane@example.org',
+            'phone_number' => '+10000000000',
+            'services' => [$service_id],
+            'settings' => [
+                'username' => 'janedoe',
+                'password' => random_string(),
+                'working_plan' => setting('company_working_plan'),
+                'working_plan_exceptions' => '{}',
+                'notifications' => true,
+                'google_sync' => false,
+                'sync_past_days' => 30,
+                'sync_future_days' => 90,
+                'calendar_view' => CALENDAR_VIEW_DEFAULT,
+            ],
+        ]);
+
+        // Customer
+
+        $this->CI->customers_model->save([
+            'first_name' => 'James',
+            'last_name' => 'Doe',
+            'email' => 'james@example.org',
+            'phone_number' => '+10000000000',
+        ]);
+
+        return $password;
+    }
+
+    /**
+     * Create a database backup file.
+     *
+     * @param string|null $path Override the default backup path (storage/backups/*).
+     *
+     * @throws Exception
+     */
+    public function backup(string $path = null): void
+    {
+        $path = $path ?? APPPATH . '/../storage/backups';
+
+        if (!file_exists($path)) {
+            throw new InvalidArgumentException('The backup path does not exist: ' . $path);
+        }
+
+        if (!is_writable($path)) {
+            throw new RuntimeException('The backup path is not writable: ' . $path);
+        }
+
+        $contents = $this->CI->dbutil->backup();
+
+        $filename = 'easyappointments-backup-' . date('Y-m-d-His') . '.gz';
+
+        write_file(rtrim($path, '/') . '/' . $filename, $contents);
+    }
+}

application/libraries/Ldap_client.php

@@ -0,0 +1,187 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.5.0
+ * ---------------------------------------------------------------------------- */
+
+/**
+ * Ldap_client library.
+ *
+ * Handles LDAP  related functionality.
+ *
+ * @package Libraries
+ */
+class Ldap_client
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Ldap_client constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('roles_model');
+
+        $this->CI->load->library('timezones');
+        $this->CI->load->library('accounts');
+    }
+
+    /**
+     * Try authenticating the user with LDAP
+     *
+     * @param string $username
+     * @param string $password
+     *
+     * @return array|null
+     *
+     * @throws Exception
+     */
+    public function check_login(string $username, string $password): ?array
+    {
+        if (!extension_loaded('ldap')) {
+            return null;
+        }
+
+        if (empty($username)) {
+            throw new InvalidArgumentException('No username value provided.');
+        }
+
+        $ldap_is_active = setting('ldap_is_active');
+
+        if (!$ldap_is_active) {
+            return null;
+        }
+
+        // Match user by username
+
+        $user = $this->CI->accounts->get_user_by_username($username);
+
+        if (empty($user['ldap_dn'])) {
+            return null; // User does not exist in Easy!Appointments
+        }
+
+        // Connect to LDAP server
+
+        $ldap_host = setting('ldap_host');
+        $ldap_port = (int) setting('ldap_port');
+
+        $connection = @ldap_connect($ldap_host, $ldap_port);
+        @ldap_set_option($connection, LDAP_OPT_PROTOCOL_VERSION, 3);
+        $user_bind = @ldap_bind($connection, $user['ldap_dn'], $password);
+
+        if ($user_bind) {
+            $role = $this->CI->roles_model->find($user['id_roles']);
+
+            $default_timezone = $this->CI->timezones->get_default_timezone();
+
+            return [
+                'user_id' => $user['id'],
+                'user_email' => $user['email'],
+                'username' => $username,
+                'timezone' => !empty($user['timezone']) ? $user['timezone'] : $default_timezone,
+                'language' => !empty($user['language']) ? $user['language'] : Config::LANGUAGE,
+                'role_slug' => $role['slug'],
+            ];
+        }
+
+        return null;
+    }
+
+    /**
+     * Search the LDAP server based on the provided keyword and configuration.
+     *
+     * @param string $keyword
+     *
+     * @return array
+     *
+     * @throws Exception
+     */
+    public function search(string $keyword): array
+    {
+        $this->check_environment();
+
+        $host = setting('ldap_host');
+        $port = (int) setting('ldap_port');
+        $user_dn = setting('ldap_user_dn');
+        $password = setting('ldap_password');
+        $base_dn = setting('ldap_base_dn');
+        $filter = setting('ldap_filter');
+
+        $connection = @ldap_connect($host, $port);
+
+        if (!$connection) {
+            throw new Exception('Could not connect to LDAP server: ' . @ldap_error($connection));
+        }
+
+        @ldap_set_option($connection, LDAP_OPT_PROTOCOL_VERSION, 3);
+        @ldap_set_option($connection, LDAP_OPT_REFERRALS, 0); // We need this for doing an LDAP search.
+
+        $bind = @ldap_bind($connection, $user_dn, $password);
+
+        if (!$bind) {
+            throw new Exception('LDAP bind failed: ' . @ldap_error($connection));
+        }
+
+        $wildcard_keyword = !empty($keyword) ? '*' . $keyword . '*' : '*';
+
+        $interpolated_filter = str_replace('{{KEYWORD}}', $wildcard_keyword, $filter);
+
+        $result = @ldap_search($connection, $base_dn, $interpolated_filter);
+
+        if (!$result) {
+            throw new Exception('Search failed: ' . @ldap_error($connection));
+        }
+
+        $ldap_entries = @ldap_get_entries($connection, $result);
+
+        // Flatten the LDAP entries so that they become easier to import
+
+        $entries = [];
+
+        foreach ($ldap_entries as $ldap_entry) {
+            if (!is_array($ldap_entry)) {
+                continue;
+            }
+
+            $entry = [
+                'dn' => $ldap_entry['dn'],
+            ];
+
+            foreach ($ldap_entry as $key => $value) {
+                if (!is_array($value) || !in_array($key, LDAP_WHITELISTED_ATTRIBUTES)) {
+                    continue;
+                }
+
+                $entry[$key] = $value[0] ?? null;
+            }
+
+            $entries[] = $entry;
+        }
+
+        return $entries;
+    }
+
+    /**
+     * Check if the ldap extension is installed
+     *
+     * @return void
+     */
+    private function check_environment(): void
+    {
+        if (!extension_loaded('ldap')) {
+            throw new RuntimeException('The LDAP extension is not loaded.');
+        }
+    }
+}

application/libraries/Notifications.php

@@ -0,0 +1,324 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.4.0
+ * ---------------------------------------------------------------------------- */
+
+/**
+ * Notifications library.
+ *
+ * Handles the notifications related functionality.
+ *
+ * @package Libraries
+ */
+class Notifications
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Notifications constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('admins_model');
+        $this->CI->load->model('appointments_model');
+        $this->CI->load->model('providers_model');
+        $this->CI->load->model('secretaries_model');
+        $this->CI->load->model('settings_model');
+
+        $this->CI->load->library('email_messages');
+        $this->CI->load->library('ics_file');
+        $this->CI->load->library('timezones');
+    }
+
+    /**
+     * Send the required notifications, related to an appointment creation/modification.
+     *
+     * @param array $appointment Appointment data.
+     * @param array $service Service data.
+     * @param array $provider Provider data.
+     * @param array $customer Customer data.
+     * @param array $settings Required settings.
+     * @param bool|false $manage_mode Manage mode.
+     */
+    public function notify_appointment_saved(
+        array $appointment,
+        array $service,
+        array $provider,
+        array $customer,
+        array $settings,
+        bool $manage_mode = false,
+    ): void {
+        try {
+            $current_language = config('language');
+
+            $customer_link = site_url('booking/reschedule/' . $appointment['hash']);
+
+            $provider_link = site_url('calendar/reschedule/' . $appointment['hash']);
+
+            $ics_stream = $this->CI->ics_file->get_stream($appointment, $service, $provider, $customer);
+
+            // Notify customer.
+            $send_customer =
+                !empty($customer['email']) && filter_var(setting('customer_notifications'), FILTER_VALIDATE_BOOLEAN);
+
+            if ($send_customer === true) {
+                config(['language' => $customer['language']]);
+                $this->CI->lang->load('translations');
+                $subject = $manage_mode ? lang('appointment_details_changed') : lang('appointment_booked');
+                $message = $manage_mode ? '' : lang('thank_you_for_appointment');
+
+                $this->CI->email_messages->send_appointment_saved(
+                    $appointment,
+                    $provider,
+                    $service,
+                    $customer,
+                    $settings,
+                    $subject,
+                    $message,
+                    $customer_link,
+                    $customer['email'],
+                    $ics_stream,
+                    $customer['timezone'],
+                );
+            }
+
+            // Notify provider.
+            $send_provider = filter_var(
+                $this->CI->providers_model->get_setting($provider['id'], 'notifications'),
+                FILTER_VALIDATE_BOOLEAN,
+            );
+
+            if ($send_provider === true) {
+                config(['language' => $provider['language']]);
+                $this->CI->lang->load('translations');
+                $subject = $manage_mode ? lang('appointment_details_changed') : lang('appointment_added_to_your_plan');
+                $message = $manage_mode ? '' : lang('appointment_link_description');
+
+                $this->CI->email_messages->send_appointment_saved(
+                    $appointment,
+                    $provider,
+                    $service,
+                    $customer,
+                    $settings,
+                    $subject,
+                    $message,
+                    $provider_link,
+                    $provider['email'],
+                    $ics_stream,
+                    $provider['timezone'],
+                );
+            }
+
+            // Notify admins.
+            $admins = $this->CI->admins_model->get();
+
+            foreach ($admins as $admin) {
+                if ($admin['settings']['notifications'] === '0') {
+                    continue;
+                }
+
+                config(['language' => $admin['language']]);
+                $this->CI->lang->load('translations');
+                $subject = $manage_mode ? lang('appointment_details_changed') : lang('appointment_added_to_your_plan');
+                $message = $manage_mode ? '' : lang('appointment_link_description');
+
+                $this->CI->email_messages->send_appointment_saved(
+                    $appointment,
+                    $provider,
+                    $service,
+                    $customer,
+                    $settings,
+                    $subject,
+                    $message,
+                    $provider_link,
+                    $admin['email'],
+                    $ics_stream,
+                    $admin['timezone'],
+                );
+            }
+
+            // Notify secretaries.
+            $secretaries = $this->CI->secretaries_model->get();
+
+            foreach ($secretaries as $secretary) {
+                if ($secretary['settings']['notifications'] === '0') {
+                    continue;
+                }
+
+                if (!in_array($provider['id'], $secretary['providers'])) {
+                    continue;
+                }
+
+                config(['language' => $secretary['language']]);
+                $this->CI->lang->load('translations');
+                $subject = $manage_mode ? lang('appointment_details_changed') : lang('appointment_added_to_your_plan');
+                $message = $manage_mode ? '' : lang('appointment_link_description');
+
+                $this->CI->email_messages->send_appointment_saved(
+                    $appointment,
+                    $provider,
+                    $service,
+                    $customer,
+                    $settings,
+                    $subject,
+                    $message,
+                    $provider_link,
+                    $secretary['email'],
+                    $ics_stream,
+                    $secretary['timezone'],
+                );
+            }
+        } catch (Throwable $e) {
+            log_message(
+                'error',
+                'Notifications - Could not email confirmation details of appointment (' .
+                    ($appointment['id'] ?? '-') .
+                    ') : ' .
+                    $e->getMessage(),
+            );
+            log_message('error', $e->getTraceAsString());
+        } finally {
+            config(['language' => $current_language ?? 'english']);
+            $this->CI->lang->load('translations');
+        }
+    }
+
+    /**
+     * Send the required notifications, related to an appointment removal.
+     *
+     * @param array $appointment Appointment data.
+     * @param array $service Service data.
+     * @param array $provider Provider data.
+     * @param array $customer Customer data.
+     * @param array $settings Required settings.
+     */
+    public function notify_appointment_deleted(
+        array $appointment,
+        array $service,
+        array $provider,
+        array $customer,
+        array $settings,
+        string $cancellation_reason = '',
+    ): void {
+        try {
+            $current_language = config('language');
+
+            // Notify provider.
+            $send_provider = filter_var(
+                $this->CI->providers_model->get_setting($provider['id'], 'notifications'),
+                FILTER_VALIDATE_BOOLEAN,
+            );
+
+            if ($send_provider === true) {
+                config(['language' => $provider['language']]);
+                $this->CI->lang->load('translations');
+
+                $this->CI->email_messages->send_appointment_deleted(
+                    $appointment,
+                    $provider,
+                    $service,
+                    $customer,
+                    $settings,
+                    $provider['email'],
+                    $cancellation_reason,
+                    $provider['timezone'],
+                );
+            }
+
+            // Notify customer.
+            $send_customer =
+                !empty($customer['email']) && filter_var(setting('customer_notifications'), FILTER_VALIDATE_BOOLEAN);
+
+            if ($send_customer === true) {
+                config(['language' => $customer['language']]);
+                $this->CI->lang->load('translations');
+
+                $this->CI->email_messages->send_appointment_deleted(
+                    $appointment,
+                    $provider,
+                    $service,
+                    $customer,
+                    $settings,
+                    $customer['email'],
+                    $cancellation_reason,
+                    $customer['timezone'],
+                );
+            }
+
+            // Notify admins.
+            $admins = $this->CI->admins_model->get();
+
+            foreach ($admins as $admin) {
+                if ($admin['settings']['notifications'] === '0') {
+                    continue;
+                }
+
+                config(['language' => $admin['language']]);
+                $this->CI->lang->load('translations');
+
+                $this->CI->email_messages->send_appointment_deleted(
+                    $appointment,
+                    $provider,
+                    $service,
+                    $customer,
+                    $settings,
+                    $admin['email'],
+                    $cancellation_reason,
+                    $admin['timezone'],
+                );
+            }
+
+            // Notify secretaries.
+            $secretaries = $this->CI->secretaries_model->get();
+
+            foreach ($secretaries as $secretary) {
+                if ($secretary['settings']['notifications'] === '0') {
+                    continue;
+                }
+
+                if (!in_array($provider['id'], $secretary['providers'])) {
+                    continue;
+                }
+
+                config(['language' => $secretary['language']]);
+                $this->CI->lang->load('translations');
+
+                $this->CI->email_messages->send_appointment_deleted(
+                    $appointment,
+                    $provider,
+                    $service,
+                    $customer,
+                    $settings,
+                    $secretary['email'],
+                    $cancellation_reason,
+                    $secretary['timezone'],
+                );
+            }
+        } catch (Throwable $e) {
+            log_message(
+                'error',
+                'Notifications - Could not email cancellation details of appointment (' .
+                    ($appointment['id'] ?? '-') .
+                    ') : ' .
+                    $e->getMessage(),
+            );
+            log_message('error', $e->getTraceAsString());
+        } finally {
+            config(['language' => $current_language ?? 'english']);
+            $this->CI->lang->load('translations');
+        }
+    }
+}

application/libraries/Permissions.php

@@ -0,0 +1,96 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.5.0
+ * ---------------------------------------------------------------------------- */
+
+/**
+ * Permissions library.
+ *
+ * Handles permission related functionality.
+ *
+ * @package Libraries
+ */
+class Permissions
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Permissions constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('appointments_model');
+        $this->CI->load->model('roles_model');
+        $this->CI->load->model('secretaries_model');
+        $this->CI->load->model('users_model');
+
+        $this->CI->load->library('timezones');
+    }
+
+    /**
+     * Check if a user is allowed to manage the provided customer.
+     *
+     * The "limit_customer_access" setting changes the access permissions to customer entries. In order for a provider
+     * or a secretary to be able to make changes to a customer, they will first need to at least have a single
+     * appointment with them.
+     *
+     * @param int $user_id
+     * @param int $customer_id
+     *
+     * @return bool
+     */
+    public function has_customer_access(int $user_id, int $customer_id): bool
+    {
+        $role_id = $this->CI->users_model->value($user_id, 'id_roles');
+
+        $role_slug = $this->CI->roles_model->value($role_id, 'slug');
+
+        $limit_customer_access = setting('limit_customer_access');
+
+        if ($role_slug === DB_SLUG_ADMIN || !$limit_customer_access) {
+            return true;
+        }
+
+        if ($role_slug === DB_SLUG_PROVIDER) {
+            return $this->CI->appointments_model
+                ->query()
+                ->where(['id_users_provider' => $user_id, 'id_users_customer' => $customer_id])
+                ->get()
+                ->num_rows() > 0;
+        }
+
+        if ($role_slug === DB_SLUG_SECRETARY) {
+            $secretary = $this->CI->secretaries_model->find($user_id);
+
+            foreach ($secretary['providers'] as $secretary_provider_id) {
+                $has_appointments_with_customer =
+                    $this->CI->appointments_model
+                        ->query()
+                        ->where(['id_users_provider' => $secretary_provider_id, 'id_users_customer' => $customer_id])
+                        ->get()
+                        ->num_rows() > 0;
+
+                if ($has_appointments_with_customer) {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        return false;
+    }
+}

application/libraries/Synchronization.php

@@ -0,0 +1,270 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.4.0
+ * ---------------------------------------------------------------------------- */
+
+/**
+ * Synchronization library.
+ *
+ * Handles external calendar synchronization functionality.
+ *
+ * @package Libraries
+ */
+class Synchronization
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Synchronization constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('providers_model');
+        $this->CI->load->model('appointments_model');
+
+        $this->CI->load->library('google_sync');
+        $this->CI->load->library('caldav_sync');
+    }
+
+    /**
+     * Synchronize changes made to the appointment with external calendars.
+     *
+     * @param array $appointment Appointment record.
+     * @param array $service Service record.
+     * @param array $provider Provider record.
+     * @param array $customer Customer record.
+     * @param array $settings Required settings for the notification content.
+     */
+    public function sync_appointment_saved(
+        array $appointment,
+        array $service,
+        array $provider,
+        array $customer,
+        array $settings,
+    ): void {
+        try {
+            // Google
+
+            if ($provider['settings']['google_sync']) {
+                if (empty($provider['settings']['google_token'])) {
+                    throw new RuntimeException('No google token available for the provider: ' . $provider['id']);
+                }
+
+                $google_token = json_decode($provider['settings']['google_token'], true);
+
+                $this->CI->google_sync->refresh_token($google_token['refresh_token']);
+
+                if (empty($appointment['id_google_calendar'])) {
+                    $google_event = $this->CI->google_sync->add_appointment(
+                        $appointment,
+                        $provider,
+                        $service,
+                        $customer,
+                        $settings,
+                    );
+
+                    $appointment['id_google_calendar'] = $google_event->getId();
+
+                    $this->CI->appointments_model->save($appointment);
+                } else {
+                    $this->CI->google_sync->update_appointment($appointment, $provider, $service, $customer, $settings);
+                }
+            }
+
+            // CalDAV
+
+            if ($provider['settings']['caldav_sync']) {
+                $appointment['id_caldav_calendar'] = $this->CI->caldav_sync->save_appointment(
+                    $appointment,
+                    $service,
+                    $provider,
+                    $customer,
+                );
+
+                $this->CI->appointments_model->save($appointment);
+            }
+        } catch (Throwable $e) {
+            log_message(
+                'error',
+                'Synchronization - Could not sync confirmation details of appointment (' .
+                    ($appointment['id'] ?? '-') .
+                    ') : ' .
+                    $e->getMessage(),
+            );
+
+            log_message('error', $e->getTraceAsString());
+        }
+    }
+
+    /**
+     * Synchronize removal of an appointment with external calendars.
+     *
+     * @param array $appointment Appointment record.
+     * @param array $provider Provider record.
+     */
+    public function sync_appointment_deleted(array $appointment, array $provider): void
+    {
+        try {
+            // Google
+
+            if ($provider['settings']['google_sync'] && !empty($appointment['id_google_calendar'])) {
+                if (empty($provider['settings']['google_token'])) {
+                    throw new RuntimeException('No google token available for the provider: ' . $provider['id']);
+                }
+
+                $google_token = json_decode($provider['settings']['google_token'], true);
+
+                $this->CI->google_sync->refresh_token($google_token['refresh_token']);
+
+                $this->CI->google_sync->delete_appointment($provider, $appointment['id_google_calendar']);
+            }
+
+            // CalDAV
+
+            if ($provider['settings']['caldav_sync'] && !empty($appointment['id_caldav_calendar'])) {
+                $this->CI->caldav_sync->delete_event($provider, $appointment['id_caldav_calendar']);
+            }
+        } catch (Throwable $e) {
+            log_message(
+                'error',
+                'Synchronization - Could not sync cancellation details of appointment (' .
+                    ($appointment['id'] ?? '-') .
+                    ') : ' .
+                    $e->getMessage(),
+            );
+            log_message('error', $e->getTraceAsString());
+        }
+    }
+
+    /**
+     * Synchronize changes made to the unavailability with external calendars.
+     *
+     * @param array $unavailability Unavailability record.
+     * @param array $provider Provider record.
+     */
+    public function sync_unavailability_saved(array $unavailability, array $provider): void
+    {
+        try {
+            // Google
+
+            if ($provider['settings']['google_sync']) {
+                if (empty($provider['settings']['google_token'])) {
+                    throw new RuntimeException('No google token available for the provider: ' . $provider['id']);
+                }
+
+                $google_token = json_decode($provider['settings']['google_token'], true);
+
+                $this->CI->google_sync->refresh_token($google_token['refresh_token']);
+
+                if (empty($unavailability['id_google_calendar'])) {
+                    $google_event = $this->CI->google_sync->add_unavailability($provider, $unavailability);
+
+                    $unavailability['id_google_calendar'] = $google_event->getId();
+
+                    $this->CI->unavailabilities_model->save($unavailability);
+                } else {
+                    $this->CI->google_sync->update_unavailability($provider, $unavailability);
+                }
+            }
+
+            // CalDAV
+
+            if ($provider['settings']['caldav_sync']) {
+                $unavailability['id_caldav_calendar'] = $this->CI->caldav_sync->save_unavailability(
+                    $unavailability,
+                    $provider,
+                );
+
+                $this->CI->unavailabilities_model->save($unavailability);
+            }
+        } catch (Throwable $e) {
+            log_message(
+                'error',
+                'Synchronization - Could not sync cancellation details of unavailability (' .
+                    ($appointment['id'] ?? '-') .
+                    ') : ' .
+                    $e->getMessage(),
+            );
+            log_message('error', $e->getTraceAsString());
+        }
+    }
+
+    /**
+     * Synchronize removal of an unavailability with external calendars.
+     *
+     * @param array $unavailability Unavailability record.
+     * @param array $provider Provider record.
+     */
+    public function sync_unavailability_deleted(array $unavailability, array $provider): void
+    {
+        try {
+            // Google
+
+            if ($provider['settings']['google_sync'] && !empty($unavailability['id_google_calendar'])) {
+                if (empty($provider['settings']['google_token'])) {
+                    throw new RuntimeException('No google token available for the provider: ' . $provider['id']);
+                }
+
+                $google_token = json_decode($provider['settings']['google_token'], true);
+
+                $this->CI->google_sync->refresh_token($google_token['refresh_token']);
+
+                $this->CI->google_sync->delete_unavailability($provider, $unavailability['id_google_calendar']);
+            }
+
+            // CalDAV
+
+            if ($provider['settings']['caldav_sync'] && !empty($unavailability['id_caldav_calendar'])) {
+                $this->CI->caldav_sync->delete_event($provider, $unavailability['id_caldav_calendar']);
+            }
+        } catch (Throwable $e) {
+            log_message(
+                'error',
+                'Synchronization - Could not sync cancellation details of unavailability (' .
+                    ($appointment['id'] ?? '-') .
+                    ') : ' .
+                    $e->getMessage(),
+            );
+            log_message('error', $e->getTraceAsString());
+        }
+    }
+
+    /**
+     * Make sure a synced appointment is removed from Google/CalDAV Calendar, if its provider is changed.
+     *
+     * @throws Exception
+     */
+    public function remove_appointment_on_provider_change($appointment_id): void
+    {
+        $existing_appointment = $this->CI->appointments_model->find($appointment_id);
+
+        $existing_google_id = $existing_appointment['id_google_calendar'];
+        $existing_caldav_id = $existing_appointment['id_caldav_calendar'];
+
+        $existing_provider_id = $existing_appointment['id_users_provider'];
+
+        if (
+            (!empty($existing_google_id) || !empty($existing_caldav_id)) &&
+            (int) $existing_provider_id !== (int) $existing_appointment['id_users_provider']
+        ) {
+            $existing_provider = $this->CI->providers_model->find($existing_provider_id);
+
+            if ($existing_provider['settings']['google_sync'] || $existing_provider['settings']['caldav_sync']) {
+                $this->sync_appointment_deleted($existing_appointment, $existing_provider);
+            }
+        }
+    }
+}

application/libraries/Timezones.php

@@ -0,0 +1,587 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Online Appointment Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) Alex Tselegidis
+ * @license     https://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        https://easyappointments.org
+ * @since       v1.4.0
+ * ---------------------------------------------------------------------------- */
+
+/**
+ * Timezones library.
+ *
+ * Handles timezone related functionality.
+ *
+ * @package Libraries
+ */
+class Timezones
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * @var string
+     */
+    protected string $default = 'UTC';
+
+    /**
+     * @var array
+     */
+    protected array $timezones = [
+        'UTC' => [
+            'UTC' => 'UTC',
+        ],
+        'America' => [
+            'America/Adak' => 'Adak (-10:00)',
+            'America/Atka' => 'Atka (-10:00)',
+            'America/Anchorage' => 'Anchorage (-9:00)',
+            'America/Juneau' => 'Juneau (-9:00)',
+            'America/Nome' => 'Nome (-9:00)',
+            'America/Yakutat' => 'Yakutat (-9:00)',
+            'America/Dawson' => 'Dawson (-8:00)',
+            'America/Ensenada' => 'Ensenada (-8:00)',
+            'America/Los_Angeles' => 'Los_Angeles (-8:00)',
+            'America/Tijuana' => 'Tijuana (-8:00)',
+            'America/Vancouver' => 'Vancouver (-8:00)',
+            'America/Whitehorse' => 'Whitehorse (-8:00)',
+            'America/Boise' => 'Boise (-7:00)',
+            'America/Cambridge_Bay' => 'Cambridge_Bay (-7:00)',
+            'America/Chihuahua' => 'Chihuahua (-7:00)',
+            'America/Dawson_Creek' => 'Dawson_Creek (-7:00)',
+            'America/Denver' => 'Denver (-7:00)',
+            'America/Edmonton' => 'Edmonton (-7:00)',
+            'America/Hermosillo' => 'Hermosillo (-7:00)',
+            'America/Inuvik' => 'Inuvik (-7:00)',
+            'America/Mazatlan' => 'Mazatlan (-7:00)',
+            'America/Phoenix' => 'Phoenix (-7:00)',
+            'America/Shiprock' => 'Shiprock (-7:00)',
+            'America/Yellowknife' => 'Yellowknife (-7:00)',
+            'America/Belize' => 'Belize (-6:00)',
+            'America/Cancun' => 'Cancun (-6:00)',
+            'America/Chicago' => 'Chicago (-6:00)',
+            'America/Costa_Rica' => 'Costa_Rica (-6:00)',
+            'America/El_Salvador' => 'El_Salvador (-6:00)',
+            'America/Guatemala' => 'Guatemala (-6:00)',
+            'America/Knox_IN' => 'Knox_IN (-6:00)',
+            'America/Managua' => 'Managua (-6:00)',
+            'America/Menominee' => 'Menominee (-6:00)',
+            'America/Merida' => 'Merida (-6:00)',
+            'America/Mexico_City' => 'Mexico_City (-6:00)',
+            'America/Monterrey' => 'Monterrey (-6:00)',
+            'America/Rainy_River' => 'Rainy_River (-6:00)',
+            'America/Rankin_Inlet' => 'Rankin_Inlet (-6:00)',
+            'America/Regina' => 'Regina (-6:00)',
+            'America/Swift_Current' => 'Swift_Current (-6:00)',
+            'America/Tegucigalpa' => 'Tegucigalpa (-6:00)',
+            'America/Winnipeg' => 'Winnipeg (-6:00)',
+            'America/Atikokan' => 'Atikokan (-5:00)',
+            'America/Bogota' => 'Bogota (-5:00)',
+            'America/Cayman' => 'Cayman (-5:00)',
+            'America/Coral_Harbour' => 'Coral_Harbour (-5:00)',
+            'America/Detroit' => 'Detroit (-5:00)',
+            'America/Fort_Wayne' => 'Fort_Wayne (-5:00)',
+            'America/Grand_Turk' => 'Grand_Turk (-5:00)',
+            'America/Guayaquil' => 'Guayaquil (-5:00)',
+            'America/Havana' => 'Havana (-5:00)',
+            'America/Indianapolis' => 'Indianapolis (-5:00)',
+            'America/Iqaluit' => 'Iqaluit (-5:00)',
+            'America/Jamaica' => 'Jamaica (-5:00)',
+            'America/Lima' => 'Lima (-5:00)',
+            'America/Louisville' => 'Louisville (-5:00)',
+            'America/Montreal' => 'Montreal (-5:00)',
+            'America/Nassau' => 'Nassau (-5:00)',
+            'America/New_York' => 'New_York (-5:00)',
+            'America/Nipigon' => 'Nipigon (-5:00)',
+            'America/Panama' => 'Panama (-5:00)',
+            'America/Pangnirtung' => 'Pangnirtung (-5:00)',
+            'America/Port-au-Prince' => 'Port-au-Prince (-5:00)',
+            'America/Resolute' => 'Resolute (-5:00)',
+            'America/Thunder_Bay' => 'Thunder_Bay (-5:00)',
+            'America/Toronto' => 'Toronto (-5:00)',
+            'America/Caracas' => 'Caracas (-4:-30)',
+            'America/Anguilla' => 'Anguilla (-4:00)',
+            'America/Antigua' => 'Antigua (-4:00)',
+            'America/Aruba' => 'Aruba (-4:00)',
+            'America/Asuncion' => 'Asuncion (-4:00)',
+            'America/Barbados' => 'Barbados (-4:00)',
+            'America/Blanc-Sablon' => 'Blanc-Sablon (-4:00)',
+            'America/Boa_Vista' => 'Boa_Vista (-4:00)',
+            'America/Campo_Grande' => 'Campo_Grande (-4:00)',
+            'America/Cuiaba' => 'Cuiaba (-4:00)',
+            'America/Curacao' => 'Curacao (-4:00)',
+            'America/Dominica' => 'Dominica (-4:00)',
+            'America/Eirunepe' => 'Eirunepe (-4:00)',
+            'America/Glace_Bay' => 'Glace_Bay (-4:00)',
+            'America/Goose_Bay' => 'Goose_Bay (-4:00)',
+            'America/Grenada' => 'Grenada (-4:00)',
+            'America/Guadeloupe' => 'Guadeloupe (-4:00)',
+            'America/Guyana' => 'Guyana (-4:00)',
+            'America/Halifax' => 'Halifax (-4:00)',
+            'America/La_Paz' => 'La_Paz (-4:00)',
+            'America/Manaus' => 'Manaus (-4:00)',
+            'America/Marigot' => 'Marigot (-4:00)',
+            'America/Martinique' => 'Martinique (-4:00)',
+            'America/Moncton' => 'Moncton (-4:00)',
+            'America/Montserrat' => 'Montserrat (-4:00)',
+            'America/Port_of_Spain' => 'Port_of_Spain (-4:00)',
+            'America/Porto_Acre' => 'Porto_Acre (-4:00)',
+            'America/Porto_Velho' => 'Porto_Velho (-4:00)',
+            'America/Puerto_Rico' => 'Puerto_Rico (-4:00)',
+            'America/Rio_Branco' => 'Rio_Branco (-4:00)',
+            'America/Santiago' => 'Santiago (-4:00)',
+            'America/Santo_Domingo' => 'Santo_Domingo (-4:00)',
+            'America/St_Barthelemy' => 'St_Barthelemy (-4:00)',
+            'America/St_Kitts' => 'St_Kitts (-4:00)',
+            'America/St_Lucia' => 'St_Lucia (-4:00)',
+            'America/St_Thomas' => 'St_Thomas (-4:00)',
+            'America/St_Vincent' => 'St_Vincent (-4:00)',
+            'America/Thule' => 'Thule (-4:00)',
+            'America/Tortola' => 'Tortola (-4:00)',
+            'America/Virgin' => 'Virgin (-4:00)',
+            'America/St_Johns' => 'St_Johns (-3:-30)',
+            'America/Araguaina' => 'Araguaina (-3:00)',
+            'America/Bahia' => 'Bahia (-3:00)',
+            'America/Belem' => 'Belem (-3:00)',
+            'America/Buenos_Aires' => 'Buenos_Aires (-3:00)',
+            'America/Catamarca' => 'Catamarca (-3:00)',
+            'America/Cayenne' => 'Cayenne (-3:00)',
+            'America/Cordoba' => 'Cordoba (-3:00)',
+            'America/Fortaleza' => 'Fortaleza (-3:00)',
+            'America/Godthab' => 'Godthab (-3:00)',
+            'America/Jujuy' => 'Jujuy (-3:00)',
+            'America/Maceio' => 'Maceio (-3:00)',
+            'America/Mendoza' => 'Mendoza (-3:00)',
+            'America/Miquelon' => 'Miquelon (-3:00)',
+            'America/Montevideo' => 'Montevideo (-3:00)',
+            'America/Paramaribo' => 'Paramaribo (-3:00)',
+            'America/Recife' => 'Recife (-3:00)',
+            'America/Rosario' => 'Rosario (-3:00)',
+            'America/Santarem' => 'Santarem (-3:00)',
+            'America/Sao_Paulo' => 'Sao_Paulo (-3:00)',
+            'America/Noronha' => 'Noronha (-2:00)',
+            'America/Scoresbysund' => 'Scoresbysund (-1:00)',
+            'America/Danmarkshavn' => 'Danmarkshavn (+0:00)',
+        ],
+        'Canada' => [
+            'Canada/Pacific' => 'Pacific (-8:00)',
+            'Canada/Yukon' => 'Yukon (-8:00)',
+            'Canada/Mountain' => 'Mountain (-7:00)',
+            'Canada/Central' => 'Central (-6:00)',
+            'Canada/East-Saskatchewan' => 'East-Saskatchewan (-6:00)',
+            'Canada/Saskatchewan' => 'Saskatchewan (-6:00)',
+            'Canada/Eastern' => 'Eastern (-5:00)',
+            'Canada/Atlantic' => 'Atlantic (-4:00)',
+            'Canada/Newfoundland' => 'Newfoundland (-3:-30)',
+        ],
+        'Mexico' => [
+            'Mexico/BajaNorte' => 'BajaNorte (-8:00)',
+            'Mexico/BajaSur' => 'BajaSur (-7:00)',
+            'Mexico/General' => 'General (-6:00)',
+        ],
+        'Chile' => [
+            'Chile/EasterIsland' => 'EasterIsland (-6:00)',
+            'Chile/Continental' => 'Continental (-4:00)',
+        ],
+        'Antarctica' => [
+            'Antarctica/Palmer' => 'Palmer (-4:00)',
+            'Antarctica/Rothera' => 'Rothera (-3:00)',
+            'Antarctica/Syowa' => 'Syowa (+3:00)',
+            'Antarctica/Mawson' => 'Mawson (+6:00)',
+            'Antarctica/Vostok' => 'Vostok (+6:00)',
+            'Antarctica/Davis' => 'Davis (+7:00)',
+            'Antarctica/Casey' => 'Casey (+8:00)',
+            'Antarctica/DumontDUrville' => 'DumontDUrville (+10:00)',
+            'Antarctica/McMurdo' => 'McMurdo (+12:00)',
+            'Antarctica/South_Pole' => 'South_Pole (+12:00)',
+        ],
+        'Atlantic' => [
+            'Atlantic/Bermuda' => 'Bermuda (-4:00)',
+            'Atlantic/Stanley' => 'Stanley (-4:00)',
+            'Atlantic/South_Georgia' => 'South_Georgia (-2:00)',
+            'Atlantic/Azores' => 'Azores (-1:00)',
+            'Atlantic/Cape_Verde' => 'Cape_Verde (-1:00)',
+            'Atlantic/Canary' => 'Canary (+0:00)',
+            'Atlantic/Faeroe' => 'Faeroe (+0:00)',
+            'Atlantic/Faroe' => 'Faroe (+0:00)',
+            'Atlantic/Madeira' => 'Madeira (+0:00)',
+            'Atlantic/Reykjavik' => 'Reykjavik (+0:00)',
+            'Atlantic/St_Helena' => 'St_Helena (+0:00)',
+            'Atlantic/Jan_Mayen' => 'Jan_Mayen (+1:00)',
+        ],
+        'Brazil' => [
+            'Brazil/Acre' => 'Acre (-4:00)',
+            'Brazil/West' => 'West (-4:00)',
+            'Brazil/East' => 'East (-3:00)',
+            'Brazil/DeNoronha' => 'DeNoronha (-2:00)',
+        ],
+        'Africa' => [
+            'Africa/Abidjan' => 'Abidjan (+0:00)',
+            'Africa/Accra' => 'Accra (+0:00)',
+            'Africa/Bamako' => 'Bamako (+0:00)',
+            'Africa/Banjul' => 'Banjul (+0:00)',
+            'Africa/Bissau' => 'Bissau (+0:00)',
+            'Africa/Casablanca' => 'Casablanca (+0:00)',
+            'Africa/Conakry' => 'Conakry (+0:00)',
+            'Africa/Dakar' => 'Dakar (+0:00)',
+            'Africa/El_Aaiun' => 'El_Aaiun (+0:00)',
+            'Africa/Freetown' => 'Freetown (+0:00)',
+            'Africa/Lome' => 'Lome (+0:00)',
+            'Africa/Monrovia' => 'Monrovia (+0:00)',
+            'Africa/Nouakchott' => 'Nouakchott (+0:00)',
+            'Africa/Ouagadougou' => 'Ouagadougou (+0:00)',
+            'Africa/Sao_Tome' => 'Sao_Tome (+0:00)',
+            'Africa/Timbuktu' => 'Timbuktu (+0:00)',
+            'Africa/Algiers' => 'Algiers (+1:00)',
+            'Africa/Bangui' => 'Bangui (+1:00)',
+            'Africa/Brazzaville' => 'Brazzaville (+1:00)',
+            'Africa/Ceuta' => 'Ceuta (+1:00)',
+            'Africa/Douala' => 'Douala (+1:00)',
+            'Africa/Kinshasa' => 'Kinshasa (+1:00)',
+            'Africa/Lagos' => 'Lagos (+1:00)',
+            'Africa/Libreville' => 'Libreville (+1:00)',
+            'Africa/Luanda' => 'Luanda (+1:00)',
+            'Africa/Malabo' => 'Malabo (+1:00)',
+            'Africa/Ndjamena' => 'Ndjamena (+1:00)',
+            'Africa/Niamey' => 'Niamey (+1:00)',
+            'Africa/Porto-Novo' => 'Porto-Novo (+1:00)',
+            'Africa/Tunis' => 'Tunis (+1:00)',
+            'Africa/Windhoek' => 'Windhoek (+1:00)',
+            'Africa/Blantyre' => 'Blantyre (+2:00)',
+            'Africa/Bujumbura' => 'Bujumbura (+2:00)',
+            'Africa/Cairo' => 'Cairo (+2:00)',
+            'Africa/Gaborone' => 'Gaborone (+2:00)',
+            'Africa/Harare' => 'Harare (+2:00)',
+            'Africa/Johannesburg' => 'Johannesburg (+2:00)',
+            'Africa/Kigali' => 'Kigali (+2:00)',
+            'Africa/Lubumbashi' => 'Lubumbashi (+2:00)',
+            'Africa/Lusaka' => 'Lusaka (+2:00)',
+            'Africa/Maputo' => 'Maputo (+2:00)',
+            'Africa/Maseru' => 'Maseru (+2:00)',
+            'Africa/Mbabane' => 'Mbabane (+2:00)',
+            'Africa/Tripoli' => 'Tripoli (+2:00)',
+            'Africa/Addis_Ababa' => 'Addis_Ababa (+3:00)',
+            'Africa/Asmara' => 'Asmara (+3:00)',
+            'Africa/Asmera' => 'Asmera (+3:00)',
+            'Africa/Dar_es_Salaam' => 'Dar_es_Salaam (+3:00)',
+            'Africa/Djibouti' => 'Djibouti (+3:00)',
+            'Africa/Kampala' => 'Kampala (+3:00)',
+            'Africa/Khartoum' => 'Khartoum (+3:00)',
+            'Africa/Mogadishu' => 'Mogadishu (+3:00)',
+            'Africa/Nairobi' => 'Nairobi (+3:00)',
+        ],
+        'Europe' => [
+            'Europe/Belfast' => 'Belfast (+0:00)',
+            'Europe/Dublin' => 'Dublin (+0:00)',
+            'Europe/Guernsey' => 'Guernsey (+0:00)',
+            'Europe/Isle_of_Man' => 'Isle_of_Man (+0:00)',
+            'Europe/Jersey' => 'Jersey (+0:00)',
+            'Europe/Lisbon' => 'Lisbon (+0:00)',
+            'Europe/London' => 'London (+0:00)',
+            'Europe/Amsterdam' => 'Amsterdam (+1:00)',
+            'Europe/Andorra' => 'Andorra (+1:00)',
+            'Europe/Belgrade' => 'Belgrade (+1:00)',
+            'Europe/Berlin' => 'Berlin (+1:00)',
+            'Europe/Bratislava' => 'Bratislava (+1:00)',
+            'Europe/Brussels' => 'Brussels (+1:00)',
+            'Europe/Budapest' => 'Budapest (+1:00)',
+            'Europe/Copenhagen' => 'Copenhagen (+1:00)',
+            'Europe/Gibraltar' => 'Gibraltar (+1:00)',
+            'Europe/Ljubljana' => 'Ljubljana (+1:00)',
+            'Europe/Luxembourg' => 'Luxembourg (+1:00)',
+            'Europe/Madrid' => 'Madrid (+1:00)',
+            'Europe/Malta' => 'Malta (+1:00)',
+            'Europe/Monaco' => 'Monaco (+1:00)',
+            'Europe/Oslo' => 'Oslo (+1:00)',
+            'Europe/Paris' => 'Paris (+1:00)',
+            'Europe/Podgorica' => 'Podgorica (+1:00)',
+            'Europe/Prague' => 'Prague (+1:00)',
+            'Europe/Rome' => 'Rome (+1:00)',
+            'Europe/San_Marino' => 'San_Marino (+1:00)',
+            'Europe/Sarajevo' => 'Sarajevo (+1:00)',
+            'Europe/Skopje' => 'Skopje (+1:00)',
+            'Europe/Stockholm' => 'Stockholm (+1:00)',
+            'Europe/Tirane' => 'Tirane (+1:00)',
+            'Europe/Vaduz' => 'Vaduz (+1:00)',
+            'Europe/Vatican' => 'Vatican (+1:00)',
+            'Europe/Vienna' => 'Vienna (+1:00)',
+            'Europe/Warsaw' => 'Warsaw (+1:00)',
+            'Europe/Zagreb' => 'Zagreb (+1:00)',
+            'Europe/Zurich' => 'Zurich (+1:00)',
+            'Europe/Athens' => 'Athens (+2:00)',
+            'Europe/Bucharest' => 'Bucharest (+2:00)',
+            'Europe/Chisinau' => 'Chisinau (+2:00)',
+            'Europe/Helsinki' => 'Helsinki (+2:00)',
+            'Europe/Kaliningrad' => 'Kaliningrad (+2:00)',
+            'Europe/Kiev' => 'Kiev (+2:00)',
+            'Europe/Mariehamn' => 'Mariehamn (+2:00)',
+            'Europe/Minsk' => 'Minsk (+2:00)',
+            'Europe/Nicosia' => 'Nicosia (+2:00)',
+            'Europe/Riga' => 'Riga (+2:00)',
+            'Europe/Simferopol' => 'Simferopol (+2:00)',
+            'Europe/Sofia' => 'Sofia (+2:00)',
+            'Europe/Tallinn' => 'Tallinn (+2:00)',
+            'Europe/Tiraspol' => 'Tiraspol (+2:00)',
+            'Europe/Uzhgorod' => 'Uzhgorod (+2:00)',
+            'Europe/Vilnius' => 'Vilnius (+2:00)',
+            'Europe/Zaporozhye' => 'Zaporozhye (+2:00)',
+            'Europe/Istanbul' => 'Istanbul (+3:00)',
+            'Europe/Moscow' => 'Moscow (+3:00)',
+            'Europe/Volgograd' => 'Volgograd (+3:00)',
+            'Europe/Samara' => 'Samara (+4:00)',
+        ],
+        'Arctic' => [
+            'Arctic/Longyearbyen' => 'Longyearbyen (+1:00)',
+        ],
+        'Asia' => [
+            'Asia/Amman' => 'Amman (+2:00)',
+            'Asia/Beirut' => 'Beirut (+2:00)',
+            'Asia/Damascus' => 'Damascus (+2:00)',
+            'Asia/Gaza' => 'Gaza (+2:00)',
+            'Asia/Jerusalem' => 'Jerusalem (+2:00)',
+            'Asia/Nicosia' => 'Nicosia (+2:00)',
+            'Asia/Tel_Aviv' => 'Tel_Aviv (+2:00)',
+            'Asia/Aden' => 'Aden (+3:00)',
+            'Asia/Baghdad' => 'Baghdad (+3:00)',
+            'Asia/Bahrain' => 'Bahrain (+3:00)',
+            'Asia/Istanbul' => 'Istanbul (+3:00)',
+            'Asia/Kuwait' => 'Kuwait (+3:00)',
+            'Asia/Qatar' => 'Qatar (+3:00)',
+            'Asia/Tehran' => 'Tehran (+3:30)',
+            'Asia/Baku' => 'Baku (+4:00)',
+            'Asia/Dubai' => 'Dubai (+4:00)',
+            'Asia/Muscat' => 'Muscat (+4:00)',
+            'Asia/Tbilisi' => 'Tbilisi (+4:00)',
+            'Asia/Yerevan' => 'Yerevan (+4:00)',
+            'Asia/Kabul' => 'Kabul (+4:30)',
+            'Asia/Aqtau' => 'Aqtau (+5:00)',
+            'Asia/Aqtobe' => 'Aqtobe (+5:00)',
+            'Asia/Ashgabat' => 'Ashgabat (+5:00)',
+            'Asia/Ashkhabad' => 'Ashkhabad (+5:00)',
+            'Asia/Dushanbe' => 'Dushanbe (+5:00)',
+            'Asia/Karachi' => 'Karachi (+5:00)',
+            'Asia/Oral' => 'Oral (+5:00)',
+            'Asia/Samarkand' => 'Samarkand (+5:00)',
+            'Asia/Tashkent' => 'Tashkent (+5:00)',
+            'Asia/Yekaterinburg' => 'Yekaterinburg (+5:00)',
+            'Asia/Calcutta' => 'Calcutta (+5:30)',
+            'Asia/Colombo' => 'Colombo (+5:30)',
+            'Asia/Kolkata' => 'Kolkata (+5:30)',
+            'Asia/Katmandu' => 'Katmandu (+5:45)',
+            'Asia/Almaty' => 'Almaty (+6:00)',
+            'Asia/Bishkek' => 'Bishkek (+6:00)',
+            'Asia/Dacca' => 'Dacca (+6:00)',
+            'Asia/Dhaka' => 'Dhaka (+6:00)',
+            'Asia/Novosibirsk' => 'Novosibirsk (+6:00)',
+            'Asia/Omsk' => 'Omsk (+6:00)',
+            'Asia/Qyzylorda' => 'Qyzylorda (+6:00)',
+            'Asia/Thimbu' => 'Thimbu (+6:00)',
+            'Asia/Thimphu' => 'Thimphu (+6:00)',
+            'Asia/Rangoon' => 'Rangoon (+6:30)',
+            'Asia/Bangkok' => 'Bangkok (+7:00)',
+            'Asia/Ho_Chi_Minh' => 'Ho_Chi_Minh (+7:00)',
+            'Asia/Hovd' => 'Hovd (+7:00)',
+            'Asia/Jakarta' => 'Jakarta (+7:00)',
+            'Asia/Krasnoyarsk' => 'Krasnoyarsk (+7:00)',
+            'Asia/Phnom_Penh' => 'Phnom_Penh (+7:00)',
+            'Asia/Pontianak' => 'Pontianak (+7:00)',
+            'Asia/Saigon' => 'Saigon (+7:00)',
+            'Asia/Vientiane' => 'Vientiane (+7:00)',
+            'Asia/Brunei' => 'Brunei (+8:00)',
+            'Asia/Choibalsan' => 'Choibalsan (+8:00)',
+            'Asia/Chongqing' => 'Chongqing (+8:00)',
+            'Asia/Chungking' => 'Chungking (+8:00)',
+            'Asia/Harbin' => 'Harbin (+8:00)',
+            'Asia/Hong_Kong' => 'Hong_Kong (+8:00)',
+            'Asia/Irkutsk' => 'Irkutsk (+8:00)',
+            'Asia/Kashgar' => 'Kashgar (+8:00)',
+            'Asia/Kuala_Lumpur' => 'Kuala_Lumpur (+8:00)',
+            'Asia/Kuching' => 'Kuching (+8:00)',
+            'Asia/Macao' => 'Macao (+8:00)',
+            'Asia/Macau' => 'Macau (+8:00)',
+            'Asia/Makassar' => 'Makassar (+8:00)',
+            'Asia/Manila' => 'Manila (+8:00)',
+            'Asia/Shanghai' => 'Shanghai (+8:00)',
+            'Asia/Singapore' => 'Singapore (+8:00)',
+            'Asia/Taipei' => 'Taipei (+8:00)',
+            'Asia/Ujung_Pandang' => 'Ujung_Pandang (+8:00)',
+            'Asia/Ulaanbaatar' => 'Ulaanbaatar (+8:00)',
+            'Asia/Ulan_Bator' => 'Ulan_Bator (+8:00)',
+            'Asia/Urumqi' => 'Urumqi (+8:00)',
+            'Asia/Dili' => 'Dili (+9:00)',
+            'Asia/Jayapura' => 'Jayapura (+9:00)',
+            'Asia/Pyongyang' => 'Pyongyang (+9:00)',
+            'Asia/Seoul' => 'Seoul (+9:00)',
+            'Asia/Tokyo' => 'Tokyo (+9:00)',
+            'Asia/Yakutsk' => 'Yakutsk (+9:00)',
+            'Asia/Sakhalin' => 'Sakhalin (+10:00)',
+            'Asia/Vladivostok' => 'Vladivostok (+10:00)',
+            'Asia/Magadan' => 'Magadan (+11:00)',
+            'Asia/Anadyr' => 'Anadyr (+12:00)',
+            'Asia/Kamchatka' => 'Kamchatka (+12:00)',
+        ],
+        'Indian' => [
+            'Indian/Antananarivo' => 'Antananarivo (+3:00)',
+            'Indian/Comoro' => 'Comoro (+3:00)',
+            'Indian/Mayotte' => 'Mayotte (+3:00)',
+            'Indian/Mahe' => 'Mahe (+4:00)',
+            'Indian/Mauritius' => 'Mauritius (+4:00)',
+            'Indian/Reunion' => 'Reunion (+4:00)',
+            'Indian/Kerguelen' => 'Kerguelen (+5:00)',
+            'Indian/Maldives' => 'Maldives (+5:00)',
+            'Indian/Chagos' => 'Chagos (+6:00)',
+            'Indian/Cocos' => 'Cocos (+6:30)',
+            'Indian/Christmas' => 'Christmas (+7:00)',
+        ],
+        'Australia' => [
+            'Australia/Perth' => 'Perth (+8:00)',
+            'Australia/West' => 'West (+8:00)',
+            'Australia/Eucla' => 'Eucla (+8:45)',
+            'Australia/Adelaide' => 'Adelaide (+9:30)',
+            'Australia/Broken_Hill' => 'Broken_Hill (+9:30)',
+            'Australia/Darwin' => 'Darwin (+9:30)',
+            'Australia/North' => 'North (+9:30)',
+            'Australia/South' => 'South (+9:30)',
+            'Australia/Yancowinna' => 'Yancowinna (+9:30)',
+            'Australia/ACT' => 'ACT (+10:00)',
+            'Australia/Brisbane' => 'Brisbane (+10:00)',
+            'Australia/Canberra' => 'Canberra (+10:00)',
+            'Australia/Currie' => 'Currie (+10:00)',
+            'Australia/Hobart' => 'Hobart (+10:00)',
+            'Australia/Lindeman' => 'Lindeman (+10:00)',
+            'Australia/Melbourne' => 'Melbourne (+10:00)',
+            'Australia/NSW' => 'NSW (+10:00)',
+            'Australia/Queensland' => 'Queensland (+10:00)',
+            'Australia/Sydney' => 'Sydney (+10:00)',
+            'Australia/Tasmania' => 'Tasmania (+10:00)',
+            'Australia/Victoria' => 'Victoria (+10:00)',
+            'Australia/LHI' => 'LHI (+10:30)',
+            'Australia/Lord_Howe' => 'Lord_Howe (+10:30)',
+        ],
+        'Pacific' => [
+            'Pacific/Apia' => 'Apia (+13:00)',
+            'Pacific/Auckland' => 'Auckland (+12:00)',
+            'Pacific/Bougainville' => 'Bougainville (+11:00)',
+            'Pacific/Chatham' => 'Chatham (+12:45)',
+            'Pacific/Chuuk' => 'Chuuk (+10:00)',
+            'Pacific/Easter' => 'Easter (−06:00)',
+            'Pacific/Efate' => 'Efate (+11:00)',
+            'Pacific/Enderbury' => 'Enderbury (+13:00)',
+            'Pacific/Fakaofo' => 'Fakaofo (+13:00)',
+            'Pacific/Fiji' => 'Fiji (+12:00)',
+            'Pacific/Funafuti' => 'Funafuti (+12:00)',
+            'Pacific/Galapagos' => 'Galapagos (−06:00)',
+            'Pacific/Gambier' => 'Gambier (−09:00)',
+            'Pacific/Guadalcanal' => 'Guadalcanal (+11:00)',
+            'Pacific/Guam' => 'Guam (+10:00)',
+            'Pacific/Honolulu' => 'Honolulu (−10:00)',
+            'Pacific/Kiritimati' => 'Kiritimati (+14:00)',
+            'Pacific/Kosrae' => 'Kosrae (+11:00)',
+            'Pacific/Kwajalein' => 'Kwajalein (+12:00)',
+            'Pacific/Majuro' => 'Majuro (+12:00)',
+            'Pacific/Marquesas' => 'Marquesas (−09:30)',
+            'Pacific/Nauru' => 'Nauru (+12:00)',
+            'Pacific/Niue' => 'Niue (−11:00)',
+            'Pacific/Norfolk' => 'Norfolk (+11:00)',
+            'Pacific/Noumea' => 'Noumea (+11:00)',
+            'Pacific/Pago_Pago' => 'Pago_Pago (−11:00)',
+            'Pacific/Palau' => 'Palau (+09:00)',
+            'Pacific/Pitcairn' => 'Pitcairn (−08:00)',
+            'Pacific/Pohnpei' => 'Pohnpei (+11:00)',
+            'Pacific/Port_Moresby' => 'Port_Moresby (+10:00)',
+            'Pacific/Rarotonga' => 'Rarotonga (−10:00)',
+            'Pacific/Tahiti' => 'Tahiti (−10:00)',
+            'Pacific/Tarawa' => 'Tarawa (+12:00)',
+            'Pacific/Tongatapu' => 'Tongatapu (+13:00)',
+            'Pacific/Wake' => 'Wake (+12:00)',
+            'Pacific/Wallis' => 'Wallis (+12:00)',
+        ],
+    ];
+
+    /**
+     * Timezones constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('users_model');
+    }
+
+    /**
+     * Get all timezones to a grouped array (by continent).
+     *
+     * @return array
+     */
+    public function to_grouped_array(): array
+    {
+        return $this->timezones;
+    }
+
+    /**
+     * Get the default timezone value of the current system.
+     *
+     * @return string
+     */
+    public function get_default_timezone(): string
+    {
+        return date_default_timezone_get();
+    }
+
+    /**
+     * Convert a date time value to a new timezone.
+     *
+     * @param string $value Provide a date time value as a string (format Y-m-d H:i:s).
+     * @param string $from_timezone From timezone value.
+     * @param string $to_timezone To timezone value.
+     *
+     * @return string
+     *
+     * @throws Exception
+     */
+    public function convert(string $value, string $from_timezone, string $to_timezone): string
+    {
+        if (!$to_timezone || $from_timezone === $to_timezone) {
+            return $value;
+        }
+
+        $from = new DateTimeZone($from_timezone);
+
+        $to = new DateTimeZone($to_timezone);
+
+        $result = new DateTime($value, $from);
+
+        $result->setTimezone($to);
+
+        return $result->format('Y-m-d H:i:s');
+    }
+
+    /**
+     * Get the timezone name for the provided value.
+     *
+     * @param string $value
+     *
+     * @return string|null
+     */
+    public function get_timezone_name(string $value): ?string
+    {
+        $timezones = $this->to_array();
+
+        return $timezones[$value] ?? null;
+    }
+
+    /**
+     * Get all timezones to a flat array.
+     *
+     * @return array
+     */
+    public function to_array(): array
+    {
+        return array_merge(...array_values($this->timezones));
+    }
+}

application/libraries/Webhooks_client.php

@@ -0,0 +1,104 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Open Source Web Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) 2013 - 2020, Alex Tselegidis
+ * @license     http://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        http://easyappointments.org
+ * @since       v1.4.0
+ * ---------------------------------------------------------------------------- */
+
+use GuzzleHttp\Client;
+
+/**
+ * Webhooks client library.
+ *
+ * Handles the webhook HTTP related functionality.
+ *
+ * @package Libraries
+ */
+class Webhooks_client
+{
+    /**
+     * @var EA_Controller|CI_Controller
+     */
+    protected EA_Controller|CI_Controller $CI;
+
+    /**
+     * Webhook client constructor.
+     */
+    public function __construct()
+    {
+        $this->CI = &get_instance();
+
+        $this->CI->load->model('providers_model');
+        $this->CI->load->model('secretaries_model');
+        $this->CI->load->model('secretaries_model');
+        $this->CI->load->model('admins_model');
+        $this->CI->load->model('appointments_model');
+        $this->CI->load->model('settings_model');
+        $this->CI->load->model('webhooks_model');
+    }
+
+    /**
+     * Trigger the registered webhooks for the provided action.
+     *
+     * @param string $action Webhook action.
+     * @param array $payload Payload data.
+     *
+     * @return void|null
+     */
+    public function trigger(string $action, array $payload)
+    {
+        $webhooks = $this->CI->webhooks_model->get();
+
+        foreach ($webhooks as $webhook) {
+            if (str_contains($webhook['actions'], $action)) {
+                $this->call($webhook, $action, $payload);
+            }
+        }
+    }
+
+    /**
+     * Call the provided webhook.
+     *
+     * @param array $webhook
+     * @param string $action
+     * @param array $payload
+     */
+    private function call(array $webhook, string $action, array $payload): void
+    {
+        try {
+            $client = new Client();
+
+            $headers = [];
+
+            if (!empty($webhook['secret_header']) && !empty($webhook['secret_token'])) {
+                $headers[$webhook['secret_header']] = $webhook['secret_token'];
+            }
+
+            $response = $client->post($webhook['url'], [
+                'verify' => $webhook['is_ssl_verified'],
+                'headers' => $headers,
+                'json' => [
+                    'action' => $action,
+                    'payload' => $payload,
+                ],
+            ]);
+
+            echo $response->getBody()->getContents(); // Use this for quick debugging
+        } catch (Throwable $e) {
+            log_message(
+                'error',
+                'Webhooks Client - The webhook (' .
+                    ($webhook['id'] ?? null) .
+                    ') request received an unexpected exception: ' .
+                    $e->getMessage(),
+            );
+            log_message('error', $e->getTraceAsString());
+        }
+    }
+}

application/libraries/index.html

@@ -0,0 +1,10 @@
+<html>
+<head>
+    <title>403 Forbidden</title>
+</head>
+<body>
+
+<p>Directory access is forbidden.</p>
+
+</body>
+</html>