Help to Bug Push Notification

push.simple.php

<?php 

function push_notification($index){
		
	$url = 'https://fcm.googleapis.com/fcm/send';

	$fields = array (
			"to" => "",
			"priority" => "normal",
			"collapse_key" => "Campaing News",
			"content_available"=> true,
			"content-available" => 1,
			"restricted_package_name" => "",
			'data' => array (
					"code" => 1
			),
			"notification" => array(
				"title"	=> "Vitrine",
				"body" => "great match! 1" . $index,
				"sound" => "default",
				"image" => "www/assets/icon/icon.png",
				"actions" => array(
					array(
					 "icon" =>  "emailGuests",
					 "title" =>  "EMAIL GUESTS",
					 "callback" =>  "app.emailGuests",
					 "foreground" =>  true
					),
					array(
					 "icon" =>  "snooze",
					 "title" =>  "SNOOZE",
					 "callback" =>  "app.snooze", 
					 "foreground" =>  false
					)
				)
    		
				
			)
	);
	$fields = json_encode ( $fields );

	$headers = array (
			'Authorization: key=' . "", //firebase server key
			'Content-Type: application/json'
	);

	$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_POSTFIELDS, $fields );

	$result = curl_exec ( $ch );
	var_dump($result);
	curl_close ( $ch );

	
}

for ($i=0; $i < 5; $i++) { 
	push_notification($i);
}

?>