<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class GoogleCalendar {

    private $service = null;

    public function __construct() {
        require_once FCPATH . 'vendor/autoload.php';

        $CI =& get_instance();
        $CI->config->load('google_calendar');
        $serviceAccountPath = $CI->config->item('gcal_service_account_path');

        if (!file_exists($serviceAccountPath)) {
            return;
        }

        try {
            $client = new Google_Client();
            $client->setAuthConfig($serviceAccountPath);
            $client->setScopes([Google_Service_Calendar::CALENDAR]);
            $this->service = new Google_Service_Calendar($client);
        } catch (Exception $e) {
            // Silently fail — calendar errors must never break the booking flow
        }
    }

    /**
     * Create a calendar event and notify the attendee.
     * @param  string      $calendarId     Calendar to insert into
     * @param  string      $title
     * @param  string      $description
     * @param  string      $startDatetime  ISO 8601 (e.g. 2026-03-10T10:00:00)
     * @param  string      $endDatetime
     * @param  string|null $attendeeEmail  If set, added as attendee — triggers push notification + invite email
     * @return string|null  The new event ID, or null on failure.
     */
    public function createEvent($calendarId, $title, $description, $startDatetime, $endDatetime, $attendeeEmail = null) {
        if (!$this->service || empty($calendarId)) return null;
        try {
            $eventData = [
                'summary'     => $title,
                'description' => $description,
                'start'       => ['dateTime' => $startDatetime, 'timeZone' => 'Europe/Oslo'],
                'end'         => ['dateTime' => $endDatetime,   'timeZone' => 'Europe/Oslo'],
            ];
            if (!empty($attendeeEmail)) {
                $eventData['attendees'] = [['email' => $attendeeEmail]];
            }
            $event = new Google_Service_Calendar_Event($eventData);
            $params = !empty($attendeeEmail) ? ['sendUpdates' => 'all'] : [];
            $result = $this->service->events->insert($calendarId, $event, $params);
            return $result->getId();
        } catch (Exception $e) {
            return null;
        }
    }

    /**
     * Update an existing calendar event and notify the attendee.
     * @param  string|null $attendeeEmail  If set, added as attendee — triggers update notification
     * @return string|null  The event ID, or null on failure.
     */
    public function updateEvent($calendarId, $eventId, $title, $description, $startDatetime, $endDatetime, $attendeeEmail = null) {
        if (!$this->service || empty($calendarId) || empty($eventId)) return null;
        try {
            $event = $this->service->events->get($calendarId, $eventId);
            $event->setSummary($title);
            $event->setDescription($description);
            $event->setStart(new Google_Service_Calendar_EventDateTime([
                'dateTime' => $startDatetime,
                'timeZone' => 'Europe/Oslo',
            ]));
            $event->setEnd(new Google_Service_Calendar_EventDateTime([
                'dateTime' => $endDatetime,
                'timeZone' => 'Europe/Oslo',
            ]));
            if (!empty($attendeeEmail)) {
                $event->setAttendees([new Google_Service_Calendar_EventAttendee(['email' => $attendeeEmail])]);
            }
            $params = !empty($attendeeEmail) ? ['sendUpdates' => 'all'] : [];
            $result = $this->service->events->update($calendarId, $eventId, $event, $params);
            return $result->getId();
        } catch (Exception $e) {
            return null;
        }
    }

    /**
     * Delete a calendar event. Silently skips if not found.
     */
    public function deleteEvent($calendarId, $eventId) {
        if (!$this->service || empty($calendarId) || empty($eventId)) return;
        try {
            $this->service->events->delete($calendarId, $eventId);
        } catch (Exception $e) {
            // Silently skip — event may already be gone
        }
    }
}