Xử lý đăng nhập bằng facebook đơn giản

facebook.php
<?php
include 'Facebook/autoload.php';

$fb = new \Facebook\Facebook([
  'app_id' => '156339800000000',
  'app_secret' => '29a083d80dsaf0dsdf0dfds0sa9safda',
  'default_graph_version' => 'v3.2',
  //'default_access_token' => '{access-token}', // optional
]);

$helper = $fb->getRedirectLoginHelper();
$permissions = ['email','user_likes']; // optional
$loginUrl = $helper->getLoginUrl('https://test.tronghao.site/facebook-callback.php', $permissions);

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

facebook-callback.php
<?php
//session_start();
include 'Facebook/autoload.php';

$fb = new \Facebook\Facebook([
  'app_id' => '156339800000000',
  'app_secret' => '29a083d80dsaf0dsdf0dfds0sa9safda',
  'default_graph_version' => 'v3.2',
  //'default_access_token' => '{access-token}', // optional
]);

$helper = $fb->getRedirectLoginHelper();
if(isset($_GET["state"]))
{
  $helper->getPersistentDataHandler()->set('state', $_GET["state"]);
}

try {
  $accessToken = $helper->getAccessToken();
} catch(Facebook\Exceptions\FacebookResponseException $e) {
  // When Graph returns an error
  echo 'Graph returned an error: ' . $e->getMessage();
  exit;
} catch(Facebook\Exceptions\FacebookSDKException $e) {
  // When validation fails or other local issues
  echo 'Facebook SDK returned an error: ' . $e->getMessage();
  exit;
}

if (! isset($accessToken)) {
  if ($helper->getError()) {
    header('HTTP/1.0 401 Unauthorized');
    echo "Error: " . $helper->getError() . "\n";
    echo "Error Code: " . $helper->getErrorCode() . "\n";
    echo "Error Reason: " . $helper->getErrorReason() . "\n";
    echo "Error Description: " . $helper->getErrorDescription() . "\n";
  } else {
    header('HTTP/1.0 400 Bad Request');
    echo 'Bad request';
  }
  exit;
}

try {
  $response = $fb->get('/me', $accessToken);
  $userNode = $response->getGraphUser();
} catch(Facebook\Exceptions\FacebookResponseException $e) {
  // When Graph returns an error
  echo 'Graph returned an error: ' . $e->getMessage();
  exit;
} catch(Facebook\Exceptions\FacebookSDKException $e) {
  // When validation fails or other local issues
  echo 'Facebook SDK returned an error: ' . $e->getMessage();
  exit;
}

echo 'Logged in as ' . $userNode->getName()." id: ".$userNode["id"];
?>