<?php

/**
 * @file
 * Module file for favicon module.
 */

/**
 * Implements hook_menu().
 */
function favicon_menu() {
  $items['favicon.ico'] = array(
    'page callback' => 'favicon_get_favicon_file',
    'delivery callback' => 'favicon_deliver_favicon_file',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['admin/config/system/favicon'] = array(
    'title' => 'Favicon',
    'description' => 'Manage favicon settings.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('favicon_settings_form'),
    'access arguments' => array('administer site configuration'),
    'file' => 'favicon.admin.inc',
  );

  return $items;
}

/**
 * Implements hook_html_head_alter().
 */
function favicon_html_head_alter(&$elements) {
  $file = favicon_get_favicon_file();
  if (empty($file) || $file->uri === DrupalFavicon::DEFAULT_URI) {
    return;
  }

  // Replace the existing shortcut icon link with the actual URL.
  $file->url = file_create_url($file->uri);
  if (!isset($elements['drupal_add_html_head_link:shortcut icon:' . $file->url])) {
    foreach ($elements as $key => $element) {
      if (strpos($key, 'drupal_add_html_head_link:shortcut icon:') === 0) {
        $new_key = 'drupal_add_html_head_link:shortcut icon:' . $file->url;
        $elements[$new_key] = $elements[$key];
        $elements[$new_key]['#attributes']['href'] = $file->url;
        $elements[$new_key]['#attributes']['type'] = $file->filemime;
        unset($elements[$key]);
      }
    }
  }
}

/**
 * Fetches the favicon URI.
 *
 * This will attempt to retrieve the calculated favicon based on the current
 * theme and base URL.
 *
 * @return object|bool
 *   A favicon file object if one was found, or FALSE if there was a failure.
 */
function favicon_get_favicon_file() {
  $file = &drupal_static(__FUNCTION__);

  if (!isset($file)) {
    try {
      $file = DrupalFavicon::fetchFile();
    }
    catch (Exception $e) {
      watchdog_exception('favicon', $e);
      $file = FALSE;
    }
  }

  return $file;
}

/**
 * Delivery callback; send the favicon file through configured delivery method.
 *
 * @param object $file
 *   The favicon file object.
 */
function favicon_deliver_favicon_file($file) {
  // Drupal doesn't support static class methods as delivery callbacks, so
  // we just need to use a wrapper here.
  $callback = variable_get('favicon_delivery_callback', 'DrupalFavicon::deliverFileTransfer');
  call_user_func($callback, $file);
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function favicon_form_system_theme_settings_alter(&$form, &$form_state) {
  $form['#validate'][] = 'favicon_form_system_theme_settings_validate';
  $form['#submit'][] = 'favicon_cache_clear';
}

/**
 * Form validate handler for the system_theme_settings form.
 */
function favicon_form_system_theme_settings_validate($form, $form_state) {
  if (!empty($form_state['values']['favicon_path'])) {
    if ($uri = _system_theme_settings_validate_path($form_state['values']['favicon_path'])) {
      try {
        DrupalFavicon::getFileFromUri($uri);
      }
      catch (DrupalFaviconValidationException $e) {
        form_set_error('favicon_path', filter_xss($e->getMessage()));
      }
    }
  }
}

/**
 * Clears all favicon caches.
 */
function favicon_cache_clear() {
  drupal_static_reset('favicon_get_favicon_file');
  // Clear the favicon cache.
  cache_clear_all('favicon', 'cache', TRUE);
  // Clear the page cache.
  cache_clear_all(NULL, 'cache_page');
}