<?php
/**
 * CAPTCHA antispam plugin - sound generator
 *
 * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
 * @author     Andreas Gohr <gohr@cosmocode.de>
 */

if(!defined('DOKU_INC')) define('DOKU_INC', dirname(__FILE__).'/../../../');
define('NOSESSION', true);
define('DOKU_DISABLE_GZIP_OUTPUT', 1);
require_once(DOKU_INC.'inc/init.php');
require_once(DOKU_INC.'inc/auth.php');

$ID = $_REQUEST['id'];
/** @var $plugin helper_plugin_captcha */
$plugin = plugin_load('helper', 'captcha');

if($plugin->getConf('mode') != 'audio' && $plugin->getConf('mode') != 'svgaudio') {
    http_status(404);
    exit;
}

$rand = $plugin->decrypt($_REQUEST['secret']);
$code = strtolower($plugin->_generateCAPTCHA($plugin->_fixedIdent(), $rand));

// prepare an array of wavfiles
$lc   = dirname(__FILE__).'/lang/'.$conf['lang'].'/audio/';
$en   = dirname(__FILE__).'/lang/en/audio/';
$wavs = array();
$lettercount = $plugin->getConf('lettercount');
if($lettercount > strlen($code)) $lettercount = strlen($code);
for($i = 0; $i < $lettercount; $i++) {
    $file = $lc.$code{$i}.'.wav';
    if(!@file_exists($file)) $file = $en.$code{$i}.'.wav';
    $wavs[] = $file;
}

header('Content-type: audio/x-wav');
header('Content-Disposition: attachment;filename=captcha.wav');

echo joinwavs($wavs);

/**
 * Join multiple wav files
 *
 * All wave files need to have the same format and need to be uncompressed.
 * The headers of the last file will be used (with recalculated datasize
 * of course)
 *
 * @link http://ccrma.stanford.edu/CCRMA/Courses/422/projects/WaveFormat/
 * @link http://www.thescripts.com/forum/thread3770.html
 */
function joinwavs($wavs) {
    $fields = join(
        '/', array(
                  'H8ChunkID', 'VChunkSize', 'H8Format',
                  'H8Subchunk1ID', 'VSubchunk1Size',
                  'vAudioFormat', 'vNumChannels', 'VSampleRate',
                  'VByteRate', 'vBlockAlign', 'vBitsPerSample'
             )
    );

    $data = '';
    foreach($wavs as $wav) {
        $fp     = fopen($wav, 'rb');
        $header = fread($fp, 36);
        $info   = unpack($fields, $header);

        // read optional extra stuff
        if($info['Subchunk1Size'] > 16) {
            $header .= fread($fp, ($info['Subchunk1Size'] - 16));
        }

        // read SubChunk2ID
        $header .= fread($fp, 4);

        // read Subchunk2Size
        $size = unpack('vsize', fread($fp, 4));
        $size = $size['size'];

        // read data
        $data .= fread($fp, $size);
    }

    return $header.pack('V', strlen($data)).$data;
}