<?php
// $Id: media_metadata.module,v 1.1.2.1 2009-07-11 02:54:50 aaron Exp $

/**
 * @file
 * This module provides metadata integration with the Media module.
 */

/**
 *  Returns the metadata keys associated with a file stream mimetype.
 *
 *  The hook_media_metadata_keys of all implementing modules will be invoked
 *  with the mimetype to build a list of keys to be collected and saved for
 *  file resources of that mimetype.
 *
 *  @param string $mimetype
 *    The file mimetype to return the keys. If '*' is passed, then only the
 *    keys stored for all mimetypes will be returned.
 *  @param boolean $exclusive
 *    If TRUE, then only the keys exclusive to that metadata will be returned.
 *    Otherwise, also include all metadata for the wildcard '*' mimetype.
 *  @param boolean $reset
 *    If TRUE, then rebuild the static cache of keys.
 *  @return array
 *    An array of unique metadata keys that will be saved for that mimetype.
 */
function media_metadata_keys($mimetype = '*', $exclusive = FALSE, $reset = FALSE) {
  static $keys;

  // Build our static cache.
  if (is_null($keys)) {
    $keys = array();
    // Collect all metadata keys for the wildcard/all '*' mimetype.
    $keys['*'] = module_invoke_all('media_metadata_keys', '*');
  }

  // If NULL is passed, assume it's the wildcard.
  if (is_null($mimetype)) {
    $mimetype = '*';
  }

  // Don't call module_invoke_all more than necessary; use the static variable.
  if (isset($mimetype) && ($mimetype != '*') && ($reset || is_null($keys[$mimetype]))) {
    // Build a unique array from all modules implementing hook_metadata_keys.
    $keys[$mimetype] = array_unique(module_invoke_all('media_metadata_keys', $mimetype));
  }

  // Return either the keys for that mimetype, or the merged array of keys for
  // the mimetype and for all '*' mimetypes, depending on $exclusive.
  return ($exclusive || ($mimetype == '*')) ? $keys[$mimetype] : array_unique(array_merge($keys['*'], $keys[$mimetype]));
}

// @TODO: Add the file info here as well.
function media_metadata_form($form_state, $mimetype = '*') {
  $form = module_invoke_all('media_metadata_form', $form_state, $mimetype);
  $form['mimetype'] = array(
    '#type' => 'value',
    '#value' => $mimetype,
  );
  $form['#submit'] = array('media_metadata_form_submit');
}

function media_metadata_form_submit($form, &$form_state) {
  $mimetype = $form_state['values']['mimetype'];
  $keys = media_metadata_keys($mimetype);
  $values = array();
  foreach ($keys as $key) {
    $values[$key] = $form_state['values'][$key];
  }
  // @TODO: Grab the file info and save the record.
}