Fix Some Noob's code

index.php

<?php
error_reporting(E_ALL);
ini_set('display_errors', 1);
require_once('facebook/src/Facebook/autoload.php');
 
// some settings you might want to change
$params = array(
    "app_id"  => "xxxxxxxxxxxxxxxxxxxxx",
    "app_secret" => "xxxxxxxxxxxxxxxxxxx",
    "page_id" => "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
    "access_token" => "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
);
$post = array(
    "message" => "Here is a blog post about auto posting on Facebook using PHP #php #facebook",
    "link" => "http://www.gadgetrolley.com/Store/",
    "picture" => "http://www.gadgetrolley.com/Store/image/data/gt.png",
    "name" => "Online Mobile and Electronic Store",
    "caption" => "www.gadgetrolley.com",
    "description" => "Automatically post on Facebook with PHP using Facebook PHP SDK. How to create a Facebook app. Obtain and extend Facebook access tokens. Cron automation."
);
     
// Create a facebook instance
$fb = new Facebook\Facebook ([
    'app_id'  => $params['app_id'],
    'app_secret' => $params['app_secret'],
    'default_graph_version' => 'v2.2',
]);
 
// Trying to get our own user name and id
try {
    $response = $fb->get('/' . $params['page_id'] . '?fields=id,name', $params['access_token']);
}
catch(Facebook\Exceptions\FacebookResponseException $e) {
    echo 'Graph returned an error: ' . $e->getMessage();
    exit;
}
catch(Facebook\Exceptions\FacebookSDKException $e) {
  echo 'Facebook SDK returned an error: ' . $e->getMessage();
  exit;
}
$user = $response->getGraphUser();
 
// Debug output
//print_r($user);
//exit;
 
if ($user) {
    try {
        $post_id = $fb->post('/' . $params['page_id'] . '/feed', $params, $params['access_token']);
    }
  catch (Exception $e) {
    error_log($e);
    $user = null;
  }
}
 
// Login or logout url will be needed depending on current user state.
if ($user) {
  $logoutUrl = $fb->getLogoutUrl();
} else {
  $helper = $fb->getRedirectLoginHelper();
	$permissions = ['email']; // Optional permissions
	$loginUrl = $helper->getLoginUrl('http://example.com/', $permissions);

	echo '<a href="' . htmlspecialchars($loginUrl) . '">Log in with Facebook!</a>';
}
?>