What is issue in my code Sandbox paypal future payment

I made a Paypal Module, hope this code would help you.

$result_json = json_decode($result);/* Check if authentication is valid */if (isset($result_json->access_token)){    $enc_data = json_encode($data);    $ch = curl_init();    curl_setopt($ch, CURLOPT_URL, 'https://api.sandbox.paypal.com/v1/payments/payment');    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, !in_array($_SERVER['REMOTE_ADDR'], array('127.0.0.1', '::1')));    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);    curl_setopt($ch, CURLOPT_VERBOSE, true);    curl_setopt($ch, CURLOPT_POST, true);    curl_setopt($ch, CURLOPT_POSTFIELDS, $enc_data);    curl_setopt($ch, CURLOPT_HTTPHEADER, array(        'Content-Type: application/json',        'Authorization: Bearer '.$result_json->access_token,        'PayPal-Client-Metadata-Id: ************'    ));    $result = curl_exec($ch);    $json_result = json_decode($result);    curl_close($ch);}

json_encode($data) there are additional information that may not be useful for the transaction you might trying to do but it is an example.

{    "intent": "sale",    "payer": {        "payment_method": "credit_card",        "payer_info": {            "email": "...",            "shipping_address": {                [...]            }        },        "funding_instruments": [            {                "credit_card": {                    [...]                    }                }            }        ]    },    "transactions": [        {            "amount": {                "total": 32.91,                "currency": "USD"            },            "item_list": {                "items": [                    {                        "quantity": 1,                        "name": "Product Name",                        "price": 16.51,                        "currency": "USD"                    },                    {                        "quantity": 1,                        "name": "Product Name 2",                        "price": "16.40",                        "currency": "USD"                    },                    {                        "quantity": 1,                        "name": "Shipping",                        "price": 0,                        "currency": "USD"                    }                ],                "shipping_address": {                    [...]                }            }        }    ]}

As I didn't get any solution from anybody so I dug into my code step by step and found solution.

function paypalFuturePayment($userID,$amount){    $amount=number_format($amount,2);    /* paypal App truxx dev client and secret key*/    if($userID && $amount){    $userData = selectById('tbl_users','*',"id='".$userID."'");    $refresh_token = $userData['paypal_refresh_tokens'];    $Metadata_id = $userData['paypal_metadata_id'];    if($refresh_token && $Metadata_id){        if ($_SERVER['SERVER_NAME'] == 'syonserver.com') {            $clientId = "xxxxx";            $secret = "xxx";            $url1="https://api.sandbox.paypal.com/v1/oauth2/token";            $url2="https://api.sandbox.paypal.com/v1/payments/payment";        }else{            $account = 0; // 0 for sandbox ,1 for live            if ($account == 1) {                //client live                $clientId = "xxx";                $secret = xxx";                $url1 = "https://api.paypal.com/v1/oauth2/token";                $url2 = "https://api.paypal.com/v1/payments/payment";            } else {                //client sandbox                $clientId = "xxx";                $secret = "xxx";                $url1 = "https://api.sandbox.paypal.com/v1/oauth2/token";                $url2 = "https://api.sandbox.paypal.com/v1/payments/payment";        }    }//print_r($refresh_token);die;        $ch = curl_init();        curl_setopt($ch, CURLOPT_URL, $url1);        curl_setopt($ch, CURLOPT_HEADER, "Content-Type: application/x-www-form-urlencoded");        curl_setopt($ch, CURLOPT_USERPWD, $clientId . ":" . $secret);        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);        curl_setopt($ch, CURLOPT_POSTFIELDS, "grant_type=refresh_token&refresh_token=" . $refresh_token);        $result = curl_exec($ch);        curl_close($ch);        $result=json_decode($result);       //11111111   for payment Authorize: For example, to first authorize the payment, use a request similar to this:        $access_token =  $result->access_token;        $data = array(            "intent" => "authorize",            "payer" => array(                "payment_method" => "paypal"            ),            "transactions" => array(                array("amount" => array(                    "currency" => "USD",                    "total" => $amount                ),                    "description" => "future of sauces")            ));        $data_string = json_encode($data);        $ch1 = curl_init();        curl_setopt($ch1, CURLOPT_URL, $url2);        $headers = array(            'Content-Type: application/json',            'PayPal-Client-Metadata-Id: '.$Metadata_id,            'Authorization: Bearer '.$access_token,            'Content-Length: ' . strlen($data_string)        );        curl_setopt($ch1, CURLOPT_HTTPHEADER, $headers);        curl_setopt($ch1, CURLOPT_POST, true);        curl_setopt($ch1, CURLOPT_RETURNTRANSFER, 1);        curl_setopt($ch1, CURLOPT_POSTFIELDS, $data_string);        $result1 = curl_exec($ch1);        curl_close($ch1);        $result1=json_decode($result1);        $message  = $result1->message;       if($result1->state=='approved'){           $access_id=  $result1->transactions[0]->related_resources[0]->authorization->id;       }else{           if(empty($message)){               $message ='Authorization error, Please try again.';           }           return array('response' => '', 'success' => '0','message'=>$message);       }       // print_r($result1);die;      //2222222   capture the payment:        $data =  array("amount" => array(            "currency" => "USD",            "total" => $amount        ),            "is_final_capture" => "true"        );        $data_string = json_encode($data);        $ch2 = curl_init();        if ($_SERVER['SERVER_NAME'] == 'syonserver.com') {            curl_setopt($ch2, CURLOPT_URL, "https://api.sandbox.paypal.com/v1/payments/authorization/$access_id/capture");        }else {            $account = 0; // 0 for sandbox ,1 for live            if ($account == 1) {                //client live             curl_setopt($ch2, CURLOPT_URL, "https://api.paypal.com/v1/payments/authorization/$access_id/capture");        }else{                curl_setopt($ch2, CURLOPT_URL, "https://api.sandbox.paypal.com/v1/payments/authorization/$access_id/capture");            }        }        $headers = array(            'Content-Type: application/json',            'Authorization: Bearer '.$access_token,            'Content-Length: ' . strlen($data_string)        );        curl_setopt($ch2, CURLOPT_HTTPHEADER, $headers);        curl_setopt($ch2, CURLOPT_POST, true);        curl_setopt($ch2, CURLOPT_RETURNTRANSFER, 1);        curl_setopt($ch2, CURLOPT_POSTFIELDS, $data_string);        $response = curl_exec($ch2);        curl_close($ch2);        $response_a = json_decode($response, true);        $state = $response_a['state'];        $message = $response_a['message'];        if(!empty($response_a)){            if($state=='completed') {                return array('response' => $response_a, 'success' => '1','message'=>'Data received');            }else{                if(empty($message)){                    $message ='Payment authorization error, Please try again.';                }                return array('response' => '', 'success' => '0','message'=>$message);             }        }       else{           return array('response' => '','success'=>'0','message'=>'Response nil');           }        }      else        {            return array('response' => '', 'success' => '0','message'=>'Authorization code not available.');        }}else{        return array('response' => '', 'success' => '0','message'=>'Unauthorize request.');    }}