login-with-facebook-php

create login with facebook in core php First of all create a new facebook app and get the APP_ID and APP_SECRET_KEY.

Now time to install facebook sdk directly or by composer

By composer create a file in your directory composer.json

{
  "require" : {
    "facebook/php-sdk-v4" : "~5.0"
  }
}

and run command composer install and facebook phpsdk will download in your directory. Now create a file index.php and configure facebook sdk.

session_start();
require_once __DIR__ . '/vendor/autoload.php';
$fb = new Facebook\Facebook([
    'app_id' => 'APP_ID',
    'app_secret' => 'APP_SECRET_KEY',
    'default_graph_version' => 'v2.5',
]);

Generate login url -

   $helper = $fb->getRedirectLoginHelper();
    $permissions = ['email']; // optional
    $loginUrl = $helper->getLoginUrl($baseUrl.'login-callback.php', $permissions);
     <a href="<?php echo $loginUrl ; ?>" class="form-facebook-button">Facebook</a>

See Demo here