#!/usr/bin/php
<?
function filter($l, $arr) {
  $v = array();
  foreach($arr as $k => $o) if ($l($o)) $v[$k] = $o;
  return $v;
}

function map($l, $arr) {
  $v = array();
  foreach($arr as $k => $o) $v[$k] = $l($o);
  return $v;
}

function combine($v1, $v2, $l) {
  $vc = array();
  while(!empty($v1) && !empty($v2))
    $vc[] = $l(array_pop($v1), array_pop($v2));

  return $vc;
}

function file_ext($fname)
  { return substr($fname, 1+strrpos($fname, ".")); }

function get_files($dir) {
  $dp = opendir($dir); $v = array();
  while(false !== ($fname = readdir($dp))) $v[] = $fname;
  return $v;
}

function get_cue_file($dir) {
  $l = create_function('$f', 'return (file_ext($f) == "cue");');
  return array_pop(filter($l, get_files($dir)));
}

function get_lines_array($file)
  { return explode("\n", file_get_contents($file)); }

function is_title($line)
  { return (false !== strpos($line, "TITLE")); }
function filter_titles2($line)
  { return substr($line, 1+strpos($line, '"')); }
function filter_titles($line)
  { return substr(filter_titles2($line), 0, -2); }

function is_track($line)
  { return (false !== strpos($line, "TRACK")); }
function filter_tracks2($line)
  { return substr($line, strlen("TRACK") + strpos($line, "TRACK")); }
function filter_tracks($line)
  { return substr(filter_tracks2($line), 1, 2); }

function get_track_fnames_from($cue_fname) {
  $cue = get_lines_array($cue_fname);
  $titles = map('filter_titles', filter('is_title', $cue));
  $tracks = map('filter_tracks', filter('is_track', $cue));
  return combine($tracks, $titles, create_function('$a, $b', 'return $a." - ".$b;'));
}

function create_search_match_for($new_name) {
  $num = substr($new_name, 0, 2);
  return create_function('$a', "return (false !== strpos(\$a, '$num'));");
}

function pair_cue_files_in($dir) {
  $files = get_files($dir); $v = array();
  foreach(get_track_fnames_from(get_cue_file($dir)) as $k => $nfn)
    $v[array_pop(filter(create_search_match_for($nfn), $files))] = $nfn;

  return $v;
}

function invalid_rename_rules($list) {
  foreach($list as $old => $new) {
    if ($old == "") return "Can't match $new";
    if ($new == "") return "Can't match $old";
    if (file_exists($new)) return "File $new already exists";
  }
  return NULL;
}

function prnt($old, $new){ echo "$old => $new\n"; }
function do_rename($list, $preview=true) {
  $l = ($preview)? 'prnt' : 'rename';
  foreach($list as $old => $new)
    $l($old, $new.".".file_ext($old));
}

$list = pair_cue_files_in(".");
if (($msg = invalid_rename_rules($list))) die($msg);
do_rename($list, false);
?>