Can't get the renew access token in FACEBOOK APP - php

Question

I'm working in Facebook bot that replies to some comments (so far so good), yet at some point I need to renew the user authentification token (access_token), yet I still can't get it right. This is my webhook so far...yet I can't get the access token. I used 3 methods yet still nothing. How can I get the renew access token or how to get it with logic that I'm using? No FB SDK implemented so I rather would like to know a solution based on this code.
<?php
if(isset($_GET['hub_mode']) && isset($_GET['hub_challenge']) && isset($_GET['hub_verify_token'])){
if($_GET['hub_verify_token'] == '1234567890')echo $_GET['hub_challenge'];
}else{
$feedData = file_get_contents('php://input');
$data = json_decode($feedData);
$code = NULL;
//$code = $_REQUEST["code"]; //I Tried $_REQUEST yet I can't get the code value.
if (isset($_GET['code'])) { //I tried $_GET yet still no luck.
$code = $_GET['code'];
$app_id = 4444444444444444;
$my_url = 'https://example.com/robots/jotabot-comment-replier/fbwebhook.php';
$app_secret = 'ee....8';
$token_url="https://graph.facebook.com/oauth/access_token?client_id="
. $app_id . "&redirect_uri=" . urlencode($my_url)
. "&client_secret=" . $app_secret
. "&code=" . $code . "&display=popup";
$response = file_get_contents($token_url);
$params = null;
parse_str($response, $params);
$access_token = $params['access_token'];
//KEEP GOING FROM HERE WITH TOKEN.
http_response_code(200);
return;
}
if($data->object == "page"){
$userMsg = $data->entry[0]->changes[0]->value->message;
$commentID = $data->entry[0]->changes[0]->value->comment_id;
$accessToken = "EAAKGo...AZDZD";
$url = 'https://graph.facebook.com/v15.0/me/messages?access_token='.$accessToken;
$reply = "Thanks for your comment";
$btn1 = array("type"=>"postback","title"=>"OPTION 1","payload"=>"BUDGET_10_PAYLOAD");
$btn2 = array("type"=>"postback","title"=>"OPTION 2","payload"=>"BUDGET_20_PAYLOAD");
$data = array("recipient"=>array("comment_id"=>$commentID),"message"=>array("attachment"=>array("type"=>"template","payload"=>array("template_type"=>"button","text"=>$reply,"buttons"=>[$btn1,$btn2]))));
$postdata = json_encode($data);
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postdata);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));
$response = curl_exec($ch);
curl_close($ch);
$data = json_decode($response);
$errorCode = $data->error->code;
// If we had an error code that means that there is an authentification error.
if ($errorCode) {
$my_url = 'https://example.com/robots/jotabot-comment-replier/fbwebhook.php';
$token_url="https://graph.facebook.com/oauth/authorize?client_id=88884888&redirect_uri=".urlencode($my_url);
//If I put this URL with this parameters manually in my browser I successfully got the redirection with the code that I need:
//https://example.com/robots/jotabot-comment-replier/fbwebhook.php?code=AQS...Puw#_=_
//I tried 3 methods, JS (1st is how documentation suggests), file_get_contents and cURL.
//echo("<script> top.location.href='" . $token_url . "'</script>"); //I tried the way the documentation suggests, yet still no luck.
//$response = file_get_contents($token_url);
//$params = null;
//parse_str($response, $params);
//$access_token = $params['access_token']; //There's no $access_token
$url = $token_url;
$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_URL, $url);
$result = curl_exec($ch); //I tried to catch the code after the redirection yet I can't.
curl_close($ch);
}
}
}
http_response_code(200);

Answer 1

You can't renew your User's access_token without going through Facebook Login flow.
That's why for your application it's better to use Page access_token which has no expiration date. You can read here how to obtain one