<?php
namespace App\Http\Controllers;
use App\Providers\NotificationProvider;
use App\Http\Requests\NotificationRequest;
class NotificationController extends Controller
{
    public function send(NotificationRequest $request)
    {
        $validated = $request->validated();
        if ('production' !== config('app.env')) {
            $validated['to'] = 'test';
        }
        // Get $data from $request
        // For postman verification of valid type for data parameter
        if (isset($request->data)) {
            $data = $request->data;
            if ('string' === gettype($request->data)) {
                $data = json_decode($data, true);
            }
        } else {
            $data = [];
        }
        $response = '';
        // Send to a group of devices by 'investor_id_#' flutter topic
        if (isset($validated['all_users_for_this_model'])) {
            $all_users_for_this_model = $validated['all_users_for_this_model'];
            if ($validated['to'] = 'new_content') {
                $user = User::find($all_users_for_this_model);
                $androidChannel = 'new_content';
            } else {
                return response()->json("Parameter 'to' is not valid for all_users_for_this_model");
            }
            $response = [];
            foreach ($users->toArray() as $key => $investor) {
                $validated['to'] = "user_id_{$investor['id']}";
                $data['screen_data'] = $user->id;
                $responseByNotificationProvider = NotificationProvider::sendPushNotification($validated, $data, true, $androidChannel);
                array_push($response, $responseByNotificationProvider);
            }
            // Send to all devices
        } else {
            $response = NotificationProvider::sendPushNotification($validated, $data);
        }
        return response()->json($response);
    }
}

<?php
namespace App\Providers;
use Illuminate\Http\JsonResponse;
use Illuminate\Contracts\Container\BindingResolutionException;
class NotificationProvider
{
    /**
     * Send push notification to com.group.project.flutter with FCM.
     *
     * @throws BindingResolutionException
     *
     * @return JsonResponse
     */
    public static function sendPushNotification(array $validated, array $data = [], bool $toTopic = true, string $androidChannel = 'Misc')
    {
        $title = $validated['title'];
        $body = $validated['body'];
        $to = $validated['to'];
        if (isset($validated['toTopic'])) {
            $toTopic = $validated['toTopic'];
        }
        if (null === $androidChannel) {
            $androidChannel = $to;
        }
        $url = 'https://fcm.googleapis.com/fcm/send';
        $serverKey = config('firebase.cm_server_key');
        $notification = [
            'body'               => $body,
            'title'              => $title,
            'android_channel_id' => $androidChannel,
            'click_action'       => 'FLUTTER_NOTIFICATION_CLICK',
        ];
        $priority = 'high';
        if ($toTopic) {
            $to = "/topics/$to";
        }
        $arrayToSend = [
            'notification'             => $notification,
            'priority'                 => $priority,
            'data'                     => $data,
            'to'                       => $to,
        ];
        $json = json_encode($arrayToSend);
        $headers = [];
        $headers[] = 'Content-Type: application/json';
        $headers[] = 'Authorization: key='.$serverKey;
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
        curl_setopt($ch, CURLOPT_POSTFIELDS, $json);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        //Send the request
        $response = curl_exec($ch);
        //Close request
        if (false === $response) {
            exit('FCM Send Error: '.curl_error($ch));
        }
        curl_close($ch);
        $response = json_decode($response);
        $response = (array) $response;
        return [
            'response'     => $response,
            'notification' => $arrayToSend,
        ];
    }
    /**
     * [DEPRECATED]
     * Create notification from https://documentation.onesignal.com/reference/create-notification.
     * Push notification for Flutter application by OneSignal.
     *
     * @return string|bool
     */
    public static function sendNotificationOneSignal($title, $message, string $appId = 'app-id', string $authorization = 'auth_key')
    {
        $content = [
            'en' => $message,
        ];
        $headings = [
            'en' => $title,
        ];
        $subtitle = [
            'en' => 'Subtitle',
        ];
        $hashes_array = [];
        $fields = [
            'app_id'            => $appId,
            'included_segments' => [
                'All',
            ],
            'data' => [
                'foo' => 'bar',
            ],
            'contents'                          => $content,
            'headings'                          => $headings,
            // 'subtitle'                          => $subtitle,
            'android_background_layout'         => 'https://domain.com/images/bg.jpg',
            'message_icon'                      => 'ic_stat_onesignal_default',
            'android_accent_color'              => 'ffce6442',
            'android_channel_id'                => 'android_channel_id',
            'buttons'                           => $hashes_array,
        ];
        $fields = json_encode($fields);
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, 'https://onesignal.com/api/v1/notifications');
        curl_setopt($ch, CURLOPT_HTTPHEADER, [
            'Content-Type: application/json; charset=utf-8',
            'Authorization: Basic '.$authorization,
        ]);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_HEADER, false);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $fields);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        $response = curl_exec($ch);
        curl_close($ch);
        return [
            'response' => json_decode($response),
            'fields'   => json_decode($fields),
        ];
    }
}