<?php
/**
 * Firebase Cloud Messaging (FCM) Integration
 *
 * Handles push notifications to mobile devices via FCM
 */
class TWP_FCM {

    private $server_key;
    private $fcm_url = 'https://fcm.googleapis.com/fcm/send';

    /**
     * Constructor
     */
    public function __construct() {
        $this->server_key = get_option('twp_fcm_server_key', '');
    }

    /**
     * Send push notification to user's devices
     */
    public function send_notification($user_id, $title, $body, $data = array()) {
        if (empty($this->server_key)) {
            error_log('TWP FCM: Server key not configured');
            return false;
        }

        // Get user's FCM tokens
        $tokens = $this->get_user_tokens($user_id);

        if (empty($tokens)) {
            error_log("TWP FCM: No tokens found for user $user_id");
            return false;
        }

        $success_count = 0;
        $failed_tokens = array();

        foreach ($tokens as $token) {
            $result = $this->send_to_token($token, $title, $body, $data);

            if ($result['success']) {
                $success_count++;
            } else {
                $failed_tokens[] = $token;

                // If token is invalid, remove it from database
                if ($result['error'] === 'invalid_token') {
                    $this->remove_invalid_token($token);
                }
            }
        }

        error_log("TWP FCM: Sent notification to $success_count/" . count($tokens) . " devices for user $user_id");

        return $success_count > 0;
    }

    /**
     * Send notification to specific token
     */
    private function send_to_token($token, $title, $body, $data = array()) {
        $notification = array(
            'title' => $title,
            'body' => $body,
            'sound' => 'default',
            'priority' => 'high',
            'click_action' => 'FLUTTER_NOTIFICATION_CLICK'
        );

        $payload = array(
            'to' => $token,
            'notification' => $notification,
            'data' => array_merge($data, array(
                'title' => $title,
                'body' => $body,
                'timestamp' => time()
            )),
            'priority' => 'high'
        );

        $headers = array(
            'Authorization: key=' . $this->server_key,
            'Content-Type: application/json'
        );

        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $this->fcm_url);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload));

        $response = curl_exec($ch);
        $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);

        if ($http_code !== 200) {
            error_log("TWP FCM: Failed to send notification. HTTP $http_code: $response");

            // Check if token is invalid
            $response_data = json_decode($response, true);
            if (isset($response_data['results'][0]['error']) &&
                in_array($response_data['results'][0]['error'], array('InvalidRegistration', 'NotRegistered'))) {
                return array('success' => false, 'error' => 'invalid_token');
            }

            return array('success' => false, 'error' => 'http_error');
        }

        return array('success' => true);
    }

    /**
     * Get all active FCM tokens for a user
     */
    private function get_user_tokens($user_id) {
        global $wpdb;
        $table = $wpdb->prefix . 'twp_mobile_sessions';

        return $wpdb->get_col($wpdb->prepare(
            "SELECT fcm_token FROM $table
             WHERE user_id = %d
             AND is_active = 1
             AND fcm_token IS NOT NULL
             AND fcm_token != ''
             AND expires_at > NOW()",
            $user_id
        ));
    }

    /**
     * Remove invalid FCM token from database
     */
    private function remove_invalid_token($token) {
        global $wpdb;
        $table = $wpdb->prefix . 'twp_mobile_sessions';

        $wpdb->update(
            $table,
            array('fcm_token' => null),
            array('fcm_token' => $token),
            array('%s'),
            array('%s')
        );

        error_log("TWP FCM: Removed invalid token from database");
    }

    /**
     * Send incoming call notification
     */
    public function notify_incoming_call($user_id, $from_number, $queue_name, $call_sid) {
        $title = 'Incoming Call';
        $body = "Call from $from_number in $queue_name queue";

        $data = array(
            'type' => 'incoming_call',
            'call_sid' => $call_sid,
            'from_number' => $from_number,
            'queue_name' => $queue_name
        );

        return $this->send_notification($user_id, $title, $body, $data);
    }

    /**
     * Send queue timeout notification
     */
    public function notify_queue_timeout($user_id, $queue_name, $waiting_count) {
        $title = 'Queue Alert';
        $body = "$queue_name has $waiting_count waiting call" . ($waiting_count > 1 ? 's' : '');

        $data = array(
            'type' => 'queue_timeout',
            'queue_name' => $queue_name,
            'waiting_count' => $waiting_count
        );

        return $this->send_notification($user_id, $title, $body, $data);
    }

    /**
     * Send agent status change notification
     */
    public function notify_status_change($user_id, $old_status, $new_status) {
        $title = 'Status Changed';
        $body = "Your status changed from $old_status to $new_status";

        $data = array(
            'type' => 'status_change',
            'old_status' => $old_status,
            'new_status' => $new_status
        );

        return $this->send_notification($user_id, $title, $body, $data);
    }

    /**
     * Test notification (for settings page)
     */
    public function send_test_notification($user_id) {
        $title = 'Test Notification';
        $body = 'This is a test notification from Twilio WordPress Plugin';

        $data = array(
            'type' => 'test',
            'test' => true
        );

        return $this->send_notification($user_id, $title, $body, $data);
    }
}