albums-download.php

<?php

/**
 * Downloads the file after user authentication. Otherwise redirects the user to the Home Page.
 * 
 * PHP Version 7
 * 
 * @category Functionality
 * @package  FBAlbumBrowser
 * @author   Shashwat Mittal <shashwat.mittal5@gmail.com>
 * @license  http://opensource.org/licenses/gpl-license.php GNU Public License
 * @version  1.0.0
 * @link     https://fb.shashwatmittal.com/albums-download.php
 */
session_start();

//Include Facebook PHP SDK
require_once __DIR__ . '/vendor/autoload.php';

//Include the App ID, App Secret and the Callback url. 
require_once 'config.php';
// Functions file stores all the functions required for the project.
require_once 'functions.php';

// Saving the accessToken from the Session into an Access Token variable for sending requests.
if (isset($_SESSION[ 'accessToken' ]) ) {
    $accessToken = $_SESSION[ 'accessToken' ];

    $userID = getUserData($fb, $accessToken);

    $file = '/var/www/albums-' . userHash($userID) . '.zip';
    if (file_exists($file) ) {
        header('Content-Description: File Transfer');
        header('Content-type: application/octet-stream');
        header('Content-Disposition: attachment; filename=' . basename($file));
        header('Content-Transfer-Encoding: binary');
        header('Expires: 0');
        header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
        header('Pragma: public');
        header('Content-Length: ' . filesize($file));
        ob_clean();
        flush();
        readfile($file);
        exit;
    } else {
        // Redirects Logged in users to the Home Page.
        header('Location: http://fb.shashwatmittal.com/index.php');
    }
} else {
    // Redirects unauthorized users to the Home Page.
    header('Location: http://fb.shashwatmittal.com/index.php');
}