PHP Decode

<?php 
    $data = array( 
    'title'=>"Alia Bhatt", 
    'message'=>"Sweet Heart", 
    'color'=>"#0000ff", 
    'summary'=>"I like you sweet heart", 
    'bigText'=>"I really like you Alia bhat", 
    'notificationId'=>"139", 
    'bigAllowIcon'=>"1", 
    'bigIconUrl' => "https://img.timesnownews.com/story/1551004158-Untitled_design_14_3.jpg?d=400x400", 
    'url'=>"https://wikifamous.com/wp-content/uploads/2018/11/Alia-Bhatt-Wallpaper-1000x630.jpg?x50236", 
    'type'=>"1"); 
                             
                // transfer data to FCM SERVER 
                $target=["fD_f0xlKRwa8Y8zU6RCcnz:APA91bHIAMeKMN54U3Pl0Why0YmvN__5Yso4HLZNNHT2pdenc4tqrPJQYkeNhp5U296z2A8sKk_08HljFklpZtAIHhzexB9yr6GCKWHz1AC3wCoeXR22uzQY0_p0Wr9fyatkcuuCKdit"]; 
                $url = 'https://fcm.googleapis.com/fcm/send'; 
                //api_key available in Firebase Console -> Project Settings -> CLOUD 
                $server_key = 'AAAAVuUc9R4:APA91bFslSr-3NRFvcjqEAlfjHIarufADe5NxHL8W0_eWIfjrc4o3MEBJtxi0QIF7r0NPIuNnOueVCjxL5YafEipBBAXgF5Yk3NzPJDfm3kjoALcIKLFHfWBSY-hIv1sm7sFwSA9UXbJ'; 
                $fields = array(); 
                if(is_array($target)){ 
                $fields['registration_ids'] = $target; 
                }else{ 
                $fields['to'] = $target; 
                } 
             
                $fields['data'] = $data; 
                //header with content_type api key 
                $headers = array( 
                'Content-Type:application/json', 
                'Authorization:key='.$server_key 
                ); 
                $ch = curl_init(); 
                curl_setopt($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($ch, CURLOPT_POSTFIELDS, json_encode($fields)); 
                //echo json_encode($fields); 
                $result = curl_exec($ch); 
                curl_close($ch); 
                if ($result === FALSE) 
                { 
                     
                        $fail["status"]=false; 
                        $fail["message"]="no data found operation"; 
                        echo $result; 
                         
                } 
                else 
                { 
                        echo $result; 
                        $success["status"]=true; 
                        $success["message"]="response attached to data"; 
                        $success["data"]=json_decode($result); 
                     
                         
                } 
?>