Pony.fm/app/AlbumDownloader.php

<?php

class AlbumDownloader
{
    private $_album;
    private $_format;

    function __construct($album, $format)
    {
        $this->_album = $album;
        $this->_format = $format;
    }

    function download()
    {
        $zip = new ZipStream($this->_album->user->display_name . ' - ' . $this->_album->title . '.zip');
        $zip->setComment(
            'Album: ' . $this->_album->title . "\r\n" .
            'Artist: ' . $this->_album->user->display_name . "\r\n" .
            'URL: ' . $this->_album->url . "\r\n" . "\r\n" .
            'Downloaded on ' . date('l, F jS, Y, \a\t h:i:s A') . '.'
        );

        $directory = $this->_album->user->display_name . '/' . $this->_album->title . '/';

        $notes =
            'Album: ' . $this->_album->title . "\r\n" .
            'Artist: ' . $this->_album->user->display_name . "\r\n" .
            'URL: ' . $this->_album->url . "\r\n" .
            "\r\n" .
            $this->_album->description . "\r\n" .
            "\r\n" .
            "\r\n" .
            'Tracks' . "\r\n" .
            "\r\n";

        foreach ($this->_album->tracks as $track) {
            if (!$track->is_downloadable) {
                continue;
            }

            $zip->addLargeFile($track->getFileFor($this->_format),
                $directory . $track->getDownloadFilenameFor($this->_format));
            $notes .=
                $track->track_number . '. ' . $track->title . "\r\n" .
                $track->description . "\r\n" .
                "\r\n";
        }

        $zip->addFile($notes, $directory . 'Album Notes.txt');
        $zip->finalize();
    }
}