Login_facebook.php

<?php
session_start(); // Sessao do php deve estar ativa

ini_set('display_errors',1);
ini_set('display_startup_erros',1);
error_reporting(E_ALL);

require_once __DIR__ . '/facebook/autoload.php';
  
// configurar APP_ID e SECRET
define('APP_ID', '586659104822158');
define('APP_SECRET', '21464332800b1d145ee2c55b511943e6');
 
// instancia
$fb = new Facebook\Facebook([
    'app_id'     => APP_ID,
    'app_secret' => APP_SECRET,
    'default_graph_version' => 'v2.5'
]);

if(isset($_SESSION['fb_access_token'])) {
    $accessToken = $_SESSION['fb_access_token'];
 
    // verifica validade e expiracao do token
    $oAuth2Client = $fb->getOAuth2Client();
    $tokenMetadata = $oAuth2Client->debugToken($accessToken);
 
    // valida token
    try {
        $tokenMetadata->validateAppId(APP_ID);
        $tokenMetadata->validateExpiration();
 
    } catch(Facebook\Exceptions\FacebookSDKException $e) {
        unset($accessToken);
        unset($_SESSION['fb_access_token']);
    }
} else {
 
    $helper = $fb->getRedirectLoginHelper();
    try {
        $accessToken = $helper->getAccessToken();
    } 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;
    }
}
 
if(isset($accessToken)) {
    // Logged in!
    $_SESSION['fb_access_token'] = (string) $accessToken;
 
    try {
        $response = $fb->get('/me?fields=id,name,email,gender,birthday,last_name,locale,hometown', $accessToken);
        $resposta = $response->getDecodedBody();
?>
        
<form id="my_form" name="sendin" method="post" action="http://teste.wifiaqui.com.br/teste/?login=login_face">
  <input type="hidden" name="face_nome" id="face_nome" value="<?php echo $resposta['name']; ?>">
  <input type="hidden" name="face_email" id="face_email" value="<?php echo $resposta['email'];?>">
  <input type="hidden" name="face_sexo" id="face_sexo" value="<?php echo $resposta['gender'];?>">
  <input type="hidden" name="face_ano_nascimento" id="face_ano_nascimento" value="<?php echo $resposta['birthday'];?>">
  <input type="hidden" name="face_sobre_nome" id="face_sobre_nome" value="<?php echo $resposta['last_name']; ?>">
</form>

<script>
    document.sendin.submit();
</script>

<?php
    } 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;
    } 
} else {
    $helper = $fb->getRedirectLoginHelper();
 
    $redirect_url = 'http://teste.wifiaqui.com.br/mediador_facebook/login_facebook.php?belavista'; 
    $loginUrl = $helper->getLoginUrl($redirect_url);
    echo '<a href="' . $loginUrl . '">Log in with Facebook!</a>';
}