#php: #CodeIgniter import Facebook SDK

//libraries/Facebook.php

<?php

define('FACEBOOK_SDK_DIR', 'facebook-php-sdk/src/Facebook/');

class Facebook{
    function __construct(){
        require __DIR__ . '/facebook-php-sdk/autoload.php';
    }
}

//controllers/Welcome.php

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

use Facebook\FacebookSession;
use Facebook\FacebookRequest;
use Facebook\GraphUser;
use Facebook\FacebookRequestException;
use Facebook\FacebookRedirectLoginHelper;

class Welcome extends CI_Controller {
    public $user = "";

    public function __construct() {
        parent::__construct();
        session_start();
        $this->load->library('facebook');
        FacebookSession::setDefaultApplication('___', '_______________');
    }

    public function oauth_login() {
        try {
            $session = $this->_get_session(base_url('welcome/oauth_login'));
            if($session){
                $me = (new FacebookRequest($session, 'GET', '/me'))->execute()->getGraphObject(GraphUser::className());
                echo $me->getName();
            }
        }
        catch(FacebookRequestException $e) {
            echo $e->getMessage();
        }
        catch(\Exception $e) {
            echo $e->getMessage();
        }
    }

    private function _get_session($url) {
        $helper = new FacebookRedirectLoginHelper($url);
        try {
            $session = $helper->getSessionFromRedirect();
        }
        catch(FacebookRequestException $e) {
            echo $e->getMessage();
        }
        catch(\Exception $e) {
            echo $e->getMessage();
        }

        if(isset($session)){
            return $session;
        } else{
            echo '<a href="', $helper->getLoginUrl(), '">Login Facebook</a>';
            return false;
        }
    }
}