<?php

$json_data = array(
    'to' => 'dRbCRkw774Y:APA91bEXSfFnm-1bJzgECCGEK9ImhS40ZjG7wzyTA2e4pUKxtCx_lW5B2oriTCwqQfB1-TJaGWs3lN-OpCuAErrUW3szyFLgasCZfAvGCJ_y_BEWDWcw4PfvRLv9sHdk8qPk2Oa3Mht8',
    'notification' => array(
        'body' => 'something',
        'title' => 'something',
    ),
    'data' => null,
);

// print(json_encode($json_data));

$data = json_encode($json_data);
//FCM API end-point
$url = 'https://fcm.googleapis.com/fcm/send';

//api_key in Firebase Console -> Project Settings -> CLOUD MESSAGING -> Server key
$server_key = 'AAAAQGz59Vw:APA91bE-arA2TUKPFw3Lsk2_PaesNhoWAZfpmFxVfijUrpS3d6OmuBKBZZfV-JhGDFQNEjN2_4VxG8qbgQXBBD8HviFEqyh4FUTWp-0EiqI3uhh7unk4jISYMSSq77ndG8uB3bAPxO0c';
//header with content_type api key
$headers = array(
    'Content-Type:application/json',
    'Authorization:key=' . $server_key
);
//CURL request to route notification to FCM connection server (provided by Google)
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
$result = curl_exec($ch);
if ($result === FALSE) {
    die('Oops! FCM Send Error: ' . curl_error($ch));
}
curl_close($ch);