<?php

function isIphone($user_agent=NULL) {
    if(!isset($user_agent)) {
        $user_agent = isset($_SERVER['HTTP_USER_AGENT']) ? $_SERVER['HTTP_USER_AGENT'] : '';
    }
    return (strpos($user_agent, 'iPhone') !== FALSE);
}

function download_file( $fullPath ){

    // Must be fresh start
    if( headers_sent() )
        die('Headers Sent');

    $fullPath = $_SERVER['DOCUMENT_ROOT'].$fullPath;


    // Required for some browsers
    if(ini_get('zlib.output_compression'))
        ini_set('zlib.output_compression', 'Off');

    // File Exists?
    if( file_exists($fullPath) ){

        // Parse Info / Get Extension
        $fsize = filesize($fullPath);
        $path_parts = pathinfo($fullPath);
        $ext = strtolower($path_parts["extension"]);

        // Determine Content Type
        if ($ext != "mp4")
            die('Allow only mp4 files!');


        if (isIphone()) {
            header("Pragma: public");
            header("Expires: 0");
            header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
            header("Cache-Control: private", false);
            header("Content-Type: video/mp4");
        }
        else {
            header("Pragma: public"); // required
            header("Expires: 0");
            header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
            header("Cache-Control: private",false); // required for certain browsers
            header("Content-Type: video/mp4");
            header("Content-Disposition: attachment; filename=\"".basename($fullPath)."\";" );
            header("Content-Transfer-Encoding: binary");
            header("Content-Length: ".$fsize);
        }


        ob_clean();
        flush();
        readfile( $fullPath );

    } else
        die('File Not Found');

}
?>