<?php
// $Id$

/**
 * @file
 * Defines a "managed_file" Form API field and a "file" field for Field module.
 */

// Load all Field module hooks for File.
require_once DRUPAL_ROOT . '/modules/file/file.field.inc';

/**
 * Implements hook_help().
 */
function file_help($path, $arg) {
  switch ($path) {
    case 'admin/help#file':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The File module defines a <em>File</em> field type for the Field module, which lets you manage and validate uploaded files attached to content on your site (see the <a href="@field-help">Field module help page</a> for more information about fields). For more information, see the online handbook entry for <a href="@file">File module</a>.', array('@field-help' => url('admin/help/field'), '@file' => 'http://drupal.org/handbook/modules/file')) . '</p>';
      $output .= '<h3>' . t('Uses') . '</h3>';
      $output .= '<dl>';
      $output .= '<dt>' . t('Attaching files to content') . '</dt>';
      $output .= '<dd>' . t('The File module allows users to attach files to content (e.g., PDF files, spreadsheets, etc.), when a <em>File</em> field is added to a given content type using the <a href="@fieldui-help">Field UI module</a>. You can add validation options to your File field, such as specifying a maximum file size and allowed file extensions.', array('@fieldui-help' => url('admin/help/field_ui'))) . '</dd>';
      $output .= '<dt>' . t('Managing attachment display') . '</dt>';
      $output .= '<dd>' . t('When you attach a file to content, you can specify whether it is <em>listed</em> or not. Listed files are displayed automatically in a section at the bottom of your content; non-listed files are available for embedding in your content, but are not included in the list at the bottom.') . '</dd>';
      $output .= '<dt>' . t('Managing file locations') . '</dt>';
      $output .= '<dd>' . t("When you create a File field, you can specify a directory where the files will be stored, which can be within either the <em>public</em> or <em>private</em> files directory. Files in the public directory can be accessed directly through the web server; when public files are listed, direct links to the files are used, and anyone who knows a file's URL can download the file. Files in the private directory are not accessible directly through the web server; when private files are listed, the links are Drupal path requests. This adds to server load and download time, since Drupal must start up and resolve the path for each file download request, but allows for access restrictions.") . '</dd>';
      $output .= '</dl>';
      return $output;
  }
}

/**
 * Implements hook_menu().
 */
function file_menu() {
  $items = array();

  $items['file/ajax'] = array(
    'page callback' => 'file_ajax_upload',
    'delivery callback' => 'ajax_deliver',
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK,
  );
  $items['file/progress'] = array(
    'page callback' => 'file_ajax_progress',
    'delivery callback' => 'ajax_deliver',
    'access arguments' => array('access content'),
    'type' => MENU_CALLBACK,
  );

  return $items;
}

/**
 * Implements hook_element_info().
 *
 * The managed file element may be used independently anywhere in Drupal.
 */
function file_element_info() {
  $file_path = drupal_get_path('module', 'file');
  $types['managed_file'] = array(
    '#input' => TRUE,
    '#process' => array('file_managed_file_process'),
    '#value_callback' => 'file_managed_file_value',
    '#element_validate' => array('file_managed_file_validate'),
    '#pre_render' => array('file_managed_file_pre_render'),
    '#theme' => 'file_managed_file',
    '#theme_wrappers' => array('form_element'),
    '#progress_indicator' => 'throbber',
    '#progress_message' => NULL,
    '#upload_validators' => array(),
    '#upload_location' => NULL,
    '#extended' => FALSE,
    '#attached' => array(
      'css' => array($file_path . '/file.css'),
      'js' => array($file_path . '/file.js'),
    ),
  );
  return $types;
}

/**
 * Implements hook_theme().
 */
function file_theme() {
  return array(
    // file.module.
    'file_link' => array(
      'variables' => array('file' => NULL),
    ),
    'file_icon' => array(
      'variables' => array('file' => NULL),
    ),
    'file_managed_file' => array(
      'render element' => 'element',
    ),

    // file.field.inc.
    'file_widget' => array(
      'render element' => 'element',
    ),
    'file_widget_multiple' => array(
      'render element' => 'element',
    ),
    'file_formatter_table' => array(
      'variables' => array('items' => NULL),
    ),
    'file_upload_help' => array(
      'variables' => array('description' => NULL, 'upload_validators' => NULL),
    ),
  );
}

/**
 * Implements hook_file_download().
 *
 * This function takes an extra parameter $field_type so that it may
 * be re-used by other File-like modules, such as Image.
 */
function file_file_download($uri, $field_type = 'file') {
  global $user;

  // Get the file record based on the URI. If not in the database just return.
  $files = file_load_multiple(array(), array('uri' => $uri));
  if (count($files)) {
    $file = reset($files);
  }
  else {
    return;
  }

  // Find out which (if any) file fields contain this file.
  $references = file_get_file_references($file, NULL, FIELD_LOAD_REVISION, $field_type);

  // TODO: Check field-level access if available here.

  $denied = $file->status ? NULL : FALSE;
  // Check access to content containing the file fields. If access is allowed
  // to any of this content, allow the download.
  foreach ($references as $field_name => $field_references) {
    foreach ($field_references as $entity_type => $type_references) {
      foreach ($type_references as $reference) {
        // If access is allowed to any object, immediately stop and grant
        // access. If access is denied, continue through in case another object
        // grants access.
        // TODO: Switch this to a universal access check mechanism if available.
        if ($entity_type == 'node' && ($node = node_load($reference->nid))) {
          if (node_access('view', $node)) {
            $denied = FALSE;
            break 3;
          }
          else {
            $denied = TRUE;
          }
        }
        if ($entity_type == 'user') {
          if (user_access('access user profiles') || $user->uid == $reference->uid) {
            $denied = FALSE;
            break 3;
          }
          else {
            $denied = TRUE;
          }
        }
      }
    }
  }

  // No access was denied or granted.
  if (!isset($denied)) {
    return;
  }
  // Access specifically denied and not granted elsewhere.
  elseif ($denied == TRUE) {
    return -1;
  }

  // Access is granted.
  $name = mime_header_encode($file->filename);
  $type = mime_header_encode($file->filemime);
  // Serve images, text, and flash content for display rather than download.
  $inline_types = variable_get('file_inline_types', array('^text/', '^image/', 'flash$'));
  $disposition = 'attachment';
  foreach ($inline_types as $inline_type) {
    // Exclamation marks are used as delimiters to avoid escaping slashes.
    if (preg_match('!' . $inline_type . '!', $file->filemime)) {
      $disposition = 'inline';
    }
  }

  return array(
    'Content-Type' => $type . '; name="' . $name . '"',
    'Content-Length' => $file->filesize,
    'Content-Disposition' => $disposition . '; filename="' . $name . '"',
    'Cache-Control' => 'private',
  );
}

/**
 * Menu callback; Shared AJAX callback for file uploads and deletions.
 *
 * This rebuilds the form element for a particular field item. As long as the
 * form processing is properly encapsulated in the widget element the form
 * should rebuild correctly using FAPI without the need for additional callbacks
 * or processing.
 */
function file_ajax_upload() {
  $form_parents = func_get_args();
  $form_build_id = (string) array_pop($form_parents);

  if (empty($_POST['form_build_id']) || $form_build_id != $_POST['form_build_id']) {
    // Invalid request.
    drupal_set_message(t('An unrecoverable error occurred. The uploaded file likely exceeded the maximum file size (@size) that this server supports.', array('@size' => format_size(file_upload_max_size()))), 'error');
    $commands = array();
    $commands[] = ajax_command_replace(NULL, theme('status_messages'));
    return array('#type' => 'ajax', '#commands' => $commands, '#header' => FALSE);
  }

  list($form, $form_state, $form_id, $form_build_id) = ajax_get_form();

  if (!$form) {
    // Invalid form_build_id.
    drupal_set_message(t('An unrecoverable error occurred. Use of this form has expired. Try reloading the page and submitting again.'), 'error');
    $commands = array();
    $commands[] = ajax_command_replace(NULL, theme('status_messages'));
    return array('#type' => 'ajax', '#commands' => $commands, '#header' => FALSE);
  }

  // Get the current element and count the number of files.
  $current_element = $form;
  foreach ($form_parents as $parent) {
    $current_element = $current_element[$parent];
  }
  $current_file_count = isset($current_element['#file_upload_delta']) ? $current_element['#file_upload_delta'] : 0;

  // Build, validate and if possible, submit the form.
  drupal_process_form($form_id, $form, $form_state);

  // This call recreates the form relying solely on the form_state that the
  // drupal_process_form() set up.
  $form = drupal_rebuild_form($form_id, $form_state, $form);

  // Retrieve the element to be rendered.
  foreach ($form_parents as $parent) {
    $form = $form[$parent];
  }

  // Add the special AJAX class if a new file was added.
  if (isset($form['#file_upload_delta']) && $current_file_count < $form['#file_upload_delta']) {
    $form[$current_file_count]['#attributes']['class'][] = 'ajax-new-content';
  }
  // Otherwise just add the new content class on a placeholder.
  else {
    $form['#suffix'] .= '<span class="ajax-new-content"></span>';
  }

  $output = theme('status_messages') . drupal_render($form);
  $js = drupal_add_js();
  $settings = call_user_func_array('array_merge_recursive', $js['settings']['data']);

  $commands = array();
  $commands[] = ajax_command_replace(NULL, $output, $settings);
  return array('#type' => 'ajax', '#commands' => $commands, '#header' => FALSE);
}

/**
 * Menu callback for upload progress.
 *
 * @param $key
 *   The unique key for this upload process.
 */
function file_ajax_progress($key) {
  $progress = array(
    'message' => t('Starting upload...'),
    'percentage' => -1,
  );

  $implementation = file_progress_implementation();
  if ($implementation == 'uploadprogress') {
    $status = uploadprogress_get_info($key);
    if (isset($status['bytes_uploaded']) && !empty($status['bytes_total'])) {
      $progress['message'] = t('Uploading... (@current of @total)', array('@current' => format_size($status['bytes_uploaded']), '@total' => format_size($status['bytes_total'])));
      $progress['percentage'] = round(100 * $status['bytes_uploaded'] / $status['bytes_total']);
    }
  }
  elseif ($implementation == 'apc') {
    $status = apc_fetch('upload_' . $key);
    if (isset($status['current']) && !empty($status['total'])) {
      $progress['message'] = t('Uploading... (@current of @total)', array('@current' => format_size($status['current']), '@total' => format_size($status['total'])));
      $progress['percentage'] = round(100 * $status['current'] / $status['total']);
    }
  }

  drupal_json_output($progress);
}

/**
 * Determine the preferred upload progress implementation.
 *
 * @return
 *   A string indicating which upload progress system is available. Either "apc"
 *   or "uploadprogress". If neither are available, returns FALSE.
 */
function file_progress_implementation() {
  static $implementation;
  if (!isset($implementation)) {
    $implementation = FALSE;

    // We prefer the PECL extension uploadprogress because it supports multiple
    // simultaneous uploads. APC only supports one at a time.
    if (extension_loaded('uploadprogress')) {
      $implementation = 'uploadprogress';
    }
    elseif (extension_loaded('apc') && ini_get('apc.rfc1867')) {
      $implementation = 'apc';
    }
  }
  return $implementation;
}

/**
 * Implements hook_file_references().
 */
function file_file_references($file) {
  $count = file_get_file_reference_count($file, NULL, 'file');
  return $count ? array('file' => $count) : NULL;
}

/**
 * Implements hook_file_delete().
 */
function file_file_delete($file) {
  // TODO: Remove references to a file that is in-use.
}

/**
 * Process function to expand the managed_file element type.
 *
 * Expands the file type to include Upload and Remove buttons, as well as
 * support for a default value.
 */
function file_managed_file_process($element, &$form_state, $form) {
  $fid = isset($element['#value']['fid']) ? $element['#value']['fid'] : 0;

  // Set some default element properties.
  $element['#progress_indicator'] = empty($element['#progress_indicator']) ? 'none' : $element['#progress_indicator'];
  $element['#file'] = $fid ? file_load($fid) : FALSE;
  $element['#tree'] = TRUE;

  $ajax_settings = array(
    'path' => 'file/ajax/' . implode('/', $element['#parents']) . '/' . $form['form_build_id']['#value'],
    'wrapper' => $element['#id'] . '-ajax-wrapper',
    'effect' => 'fade',
    'progress' => array(
      'type' => $element['#progress_indicator'],
      'message' => $element['#progress_message'],
    ),
  );

  // Set up the buttons first since we need to check if they were clicked.
  $element['upload_button'] = array(
    '#name' => implode('_', $element['#parents']) . '_upload_button',
    '#type' => 'submit',
    '#value' => t('Upload'),
    '#validate' => array(),
    '#submit' => array('file_managed_file_submit'),
    '#limit_validation_errors' => array($element['#parents']),
    '#ajax' => $ajax_settings,
    '#weight' => -5,
  );

  $ajax_settings['progress']['type'] ? $ajax_settings['progress']['type'] == 'bar' : 'throbber';
  $ajax_settings['progress']['message'] = NULL;
  $ajax_settings['effect'] = 'none';
  $element['remove_button'] = array(
    '#name' => implode('_', $element['#parents']) . '_remove_button',
    '#type' => 'submit',
    '#value' => t('Remove'),
    '#validate' => array(),
    '#submit' => array('file_managed_file_submit'),
    '#limit_validation_errors' => array($element['#parents']),
    '#ajax' => $ajax_settings,
    '#weight' => -5,
  );

  $element['fid'] = array(
    '#type' => 'hidden',
    '#value' => $fid,
  );

  // Add progress bar support to the upload if possible.
  if ($element['#progress_indicator'] == 'bar' && $implementation = file_progress_implementation()) {
    $upload_progress_key = mt_rand();

    if ($implementation == 'uploadprogress') {
      $element['UPLOAD_IDENTIFIER'] = array(
        '#type' => 'hidden',
        '#value' => $upload_progress_key,
        '#attributes' => array('class' => array('file-progress')),
      );
    }
    elseif ($implementation == 'apc') {
      $element['APC_UPLOAD_PROGRESS'] = array(
        '#type' => 'hidden',
        '#value' => $upload_progress_key,
        '#attributes' => array('class' => array('file-progress')),
      );
    }

    // Add the upload progress callback.
    $element['upload_button']['#ajax']['progress']['path'] = 'file/progress/' . $upload_progress_key;
  }

  // The file upload field itself.
  $element['upload'] = array(
    '#name' => 'files[' . implode('_', $element['#parents']) . ']',
    '#type' => 'file',
    '#size' => 22,
    '#theme_wrappers' => array(),
    '#weight' => -10,
  );

  if ($fid && $element['#file']) {
    $element['filename'] = array(
      '#type' => 'markup',
      '#markup' => theme('file_link', array('file' => $element['#file'])) . ' ',
      '#weight' => -10,
    );
  }

  // The "accept" attribute is valid XHTML, but not enforced in browsers.
  // We use it for our own purposes in our JavaScript validation.
  if (isset($element['#upload_validators']['file_validate_extensions'][0])) {
    $element['upload']['#attributes']['accept'] = implode(',', array_filter(explode(' ', $element['#upload_validators']['file_validate_extensions'][0])));
  }

  // Prefix and suffix used for AJAX replacement.
  $element['#prefix'] = '<div id="' . $element['#id'] . '-ajax-wrapper">';
  $element['#suffix'] = '</div>';

  return $element;
}

/**
 * The #value_callback for a managed_file type element.
 */
function file_managed_file_value(&$element, $input = FALSE, $form_state = NULL) {
  $fid = 0;

  // Find the current value of this field from the form state.
  $form_state_fid = $form_state['values'];
  foreach ($element['#parents'] as $parent) {
    $form_state_fid = isset($form_state_fid[$parent]) ? $form_state_fid[$parent] : 0;
  }

  if ($element['#extended'] && isset($form_state_fid['fid'])) {
    $fid = $form_state_fid['fid'];
  }
  elseif (is_numeric($form_state_fid)) {
    $fid = $form_state_fid;
  }

  // Process any input and save new uploads.
  if ($input !== FALSE) {
    $return = $input;

    // Uploads take priority over all other values.
    if ($file = file_managed_file_save_upload($element)) {
      $fid = $file->fid;
    }
    else {
      // Check for #filefield_value_callback values.
      // Because FAPI does not allow multiple #value_callback values like it
      // does for #element_validate and #process, this fills the missing
      // functionality to allow File fields to be extended through FAPI.
      if (isset($element['#file_value_callbacks'])) {
        foreach ($element['#file_value_callbacks'] as $callback) {
          $callback($element, $input);
        }
      }
      // Load file if the FID has changed to confirm it exists.
      if (isset($input['fid']) && $file = file_load($input['fid'])) {
        $fid = $file->fid;
      }
    }
  }

  // If there is no input, set the default value.
  else {
    if ($element['#extended']) {
      $default_fid = isset($element['#default_value']['fid']) ? $element['#default_value']['fid'] : 0;
      $return = isset($element['#default_value']) ? $element['#default_value'] : array('fid' => 0);
    }
    else {
      $default_fid = isset($element['#default_value']) ? $element['#default_value'] : 0;
      $return = array('fid' => 0);
    }

    // Confirm that the file exists when used as a default value.
    if ($default_fid && $file = file_load($default_fid)) {
      $fid = $file->fid;
    }
  }

  $return['fid'] = $fid;

  return $return;
}

/**
 * An #element_validate callback for the managed_file element.
 */
function file_managed_file_validate(&$element, &$form_state) {
  // If referencing an existing file, only allow if there are existing
  // references. This prevents unmanaged files from being deleted if this
  // item were to be deleted.
  $clicked_button = end($form_state['clicked_button']['#parents']);
  if ($clicked_button != 'remove_button' && !empty($element['fid']['#value'])) {
    if ($file = file_load($element['fid']['#value'])) {
      if ($file->status == FILE_STATUS_PERMANENT) {
        $reference_count = 0;
        foreach (module_invoke_all('file_references', $file) as $module => $references) {
          $reference_count += $references;
        }
        if ($reference_count == 0) {
          form_error($element, t('Referencing to the file used in the !name field is not allowed.', array('!name' => $element['#title'])));
        }
      }
    }
    else {
      form_error($element, t('The file referenced by the !name field does not exist.', array('!name' => $element['#title'])));
    }
  }

  // Check required property based on the FID.
  if ($element['#required'] && empty($element['fid']['#value']) && !in_array($clicked_button, array('upload_button', 'remove_button'))) {
    form_error($element['upload'], t('!name field is required.', array('!name' => $element['#title'])));
  }

  // Consolidate the array value of this field to a single FID.
  if (!$element['#extended']) {
    form_set_value($element, $element['fid']['#value'], $form_state);
  }
}

/**
 * Submit handler for upload and remove buttons of managed_file elements.
 */
function file_managed_file_submit($form, &$form_state) {
  // Determine whether it was the upload or the remove button that was clicked,
  // and set $element to the managed_file element that contains that button.
  $parents = $form_state['triggering_element']['#array_parents'];
  $button_key = array_pop($parents);
  $element = $form;
  foreach ($parents as $parent) {
    $element = $element[$parent];
  }

  // No action is needed here for the upload button, because all file uploads on
  // the form are processed by file_managed_file_value() regardless of which
  // button was clicked. Action is needed here for the remove button, because we
  // only remove a file in response to its remove button being clicked.
  if ($button_key == 'remove_button') {
    // If it's a temporary file we can safely remove it immediately, otherwise
    // it's up to the implementing module to clean up files that are in use.
    if ($element['#file'] && $element['#file']->status == 0) {
      file_delete($element['#file']);
    }
    // Update both $form_state['values'] and $form_state['input'] to reflect
    // that the file has been removed, so that the form is rebuilt correctly.
    // $form_state['values'] must be updated in case additional submit handlers
    // run, and for form building functions that run during the rebuild, such as
    // when the managed_file element is part of a field widget.
    // $form_state['input'] must be updated so that file_managed_file_value()
    // has correct information during the rebuild. The Form API provides no
    // equivalent of form_set_value() for updating $form_state['input'], so
    // inline that implementation with the same logic that form_set_value()
    // uses.
    $values_element = $element['#extended'] ? $element['fid'] : $element;
    form_set_value($values_element, NULL, $form_state);
    _form_set_value($form_state['input'], $values_element, $values_element['#parents'], NULL);
  }

  // Set the form to rebuild so that $form is correctly updated in response to
  // processing the file removal. Since this function did not change $form_state
  // if the upload button was clicked, a rebuild isn't necessary in that
  // situation and setting $form_state['redirect'] to FALSE would suffice.
  // However, we choose to always rebuild, to keep the form processing workflow
  // consistent between the two buttons.
  $form_state['rebuild'] = TRUE;
}

/**
 * Given a managed_file element, save any files that have been uploaded into it.
 *
 * @param $element
 *   The FAPI element whose values are being saved.
 * @return
 *   The file object representing the file that was saved, or FALSE if no file
 *   was saved.
 */
function file_managed_file_save_upload($element) {
  $upload_name = implode('_', $element['#parents']);
  if (empty($_FILES['files']['name'][$upload_name])) {
    return FALSE;
  }

  $destination = isset($element['#upload_location']) ? $element['#upload_location'] : NULL;
  if (isset($destination) && !file_prepare_directory($destination, FILE_CREATE_DIRECTORY)) {
    watchdog('file', 'The upload directory %directory for the file field !name could not be created or is not accessible. A newly uploaded file could not be saved in this directory as a consequence, and the upload was canceled.', array('%directory' => $destination, '!name' => $element['#field_name']));
    form_set_error($upload_name, t('The file could not be uploaded.'));
    return FALSE;
  }

  if (!$file = file_save_upload($upload_name, $element['#upload_validators'], $destination)) {
    watchdog('file', 'The file upload failed. %upload', array('%upload' => $upload_name));
    form_set_error($upload_name, t('The file in the !name field was unable to be uploaded.', array('!name' => $element['#title'])));
    return FALSE;
  }

  return $file;
}

/**
 * Returns HTML for a managed file element.
 *
 * @param $variables
 *   An associative array containing:
 *   - element: A render element representing the file.
 *
 * @ingroup themeable
 */
function theme_file_managed_file($variables) {
  $element = $variables['element'];

  // This wrapper is required to apply JS behaviors and CSS styling.
  $output = '';
  $output .= '<div class="form-managed-file">';
  $output .= drupal_render_children($element);
  $output .= '</div>';
  return $output;
}

/**
 * #pre_render callback to hide display of the upload or remove controls.
 *
 * Upload controls are hidden when a file is already uploaded. Remove controls
 * are hidden when there is no file attached. Controls are hidden here instead
 * of in file_managed_file_process(), because #access for these buttons depends
 * on the managed_file element's #value. See the documentation of form_builder()
 * for more detailed information about the relationship between #process,
 * #value, and #access.
 *
 * Because #access is set here, it affects display only and does not prevent
 * JavaScript or other untrusted code from submitting the form as though access
 * were enabled. The form processing functions for these elements should not
 * assume that the buttons can't be "clicked" just because they are not
 * displayed.
 *
 * @see file_managed_file_process()
 * @see form_builder()
 */
function file_managed_file_pre_render($element) {
  // If we already have a file, we don't want to show the upload controls.
  if (!empty($element['#value']['fid'])) {
    $element['upload']['#access'] = FALSE;
    $element['upload_button']['#access'] = FALSE;
  }
  // If we don't already have a file, there is nothing to remove.
  else {
    $element['remove_button']['#access'] = FALSE;
  }
  return $element;
}

/**
 * Returns HTML for a link to a file.
 *
 * @param $variables
 *   An associative array containing:
 *   - file: A file object to which the link will be created.
 *
 * @ingroup themeable
 */
function theme_file_link($variables) {
  $file = $variables['file'];

  $url = file_create_url($file->uri);
  $icon = theme('file_icon', array('file' => $file));

  // Set options as per anchor format described at
  // http://microformats.org/wiki/file-format-examples
  $options = array(
    'attributes' => array(
      'type' => $file->filemime . '; length=' . $file->filesize,
    ),
  );

  // Use the description as the link text if available.
  if (empty($file->description)) {
    $link_text = $file->filename;
  }
  else {
    $link_text = $file->description;
    $options['attributes']['title'] = check_plain($file->filename);
  }

  return '<span class="file">' . $icon . ' ' . l($link_text, $url, $options) . '</span>';
}

/**
 * Returns HTML for an image with an appropriate icon for the given file.
 *
 * @param $variables
 *   An associative array containing:
 *   - file: A file object for which to make an icon.
 *
 * @ingroup themeable
 */
function theme_file_icon($variables) {
  $file = $variables['file'];

  $mime = check_plain($file->filemime);
  $icon_url = file_icon_url($file);
  return '<img class="file-icon" alt="" title="' . $mime . '" src="' . $icon_url . '" />';
}

/**
 * Given a file object, create a URL to a matching icon.
 *
 * @param $file
 *   A file object.
 * @param $icon_directory
 *   (optional) A path to a directory of icons to be used for files. Defaults to
 *   the value of the "file_icon_directory" variable.
 * @return
 *   A URL string to the icon, or FALSE if an appropriate icon cannot be found.
 */
function file_icon_url($file, $icon_directory = NULL) {
  if ($icon_path = file_icon_path($file, $icon_directory)) {
    return base_path() . $icon_path;
  }
  return FALSE;
}

/**
 * Given a file object, create a path to a matching icon.
 *
 * @param $file
 *   A file object.
 * @param $icon_directory
 *   (optional) A path to a directory of icons to be used for files. Defaults to
 *   the value of the "file_icon_directory" variable.
 * @return
 *   A string to the icon as a local path, or FALSE if an appropriate icon could
 *   not be found.
 */
function file_icon_path($file, $icon_directory = NULL) {
  // Use the default set of icons if none specified.
  if (!isset($icon_directory)) {
    $icon_directory = variable_get('file_icon_directory', drupal_get_path('module', 'file') . '/icons');
  }

  // If there's an icon matching the exact mimetype, go for it.
  $dashed_mime = strtr($file->filemime, array('/' => '-'));
  $icon_path = $icon_directory . '/' . $dashed_mime . '.png';
  if (file_exists($icon_path)) {
    return $icon_path;
  }

  // For a few mimetypes, we can "manually" map to a generic icon.
  $generic_mime = (string) file_icon_map($file);
  $icon_path = $icon_directory . '/' . $generic_mime . '.png';
  if ($generic_mime && file_exists($icon_path)) {
    return $icon_path;
  }

  // Use generic icons for each category that provides such icons.
  foreach (array('audio', 'image', 'text', 'video') as $category) {
    if (strpos($file->filemime, $category . '/') === 0) {
      $icon_path = $icon_directory . '/' . $category . '-x-generic.png';
      if (file_exists($icon_path)) {
        return $icon_path;
      }
    }
  }

  // Try application-octet-stream as last fallback.
  $icon_path = $icon_directory . '/application-octet-stream.png';
  if (file_exists($icon_path)) {
    return $icon_path;
  }

  // No icon can be found.
  return FALSE;
}

/**
 * Determine the generic icon MIME package based on a file's MIME type.
 *
 * @param $file
 *   A file object.
 * @return
 *   The generic icon MIME package expected for this file.
 */
function file_icon_map($file) {
  switch ($file->filemime) {
    // Word document types.
    case 'application/msword':
    case 'application/vnd.ms-word.document.macroEnabled.12':
    case 'application/vnd.oasis.opendocument.text':
    case 'application/vnd.oasis.opendocument.text-template':
    case 'application/vnd.oasis.opendocument.text-master':
    case 'application/vnd.oasis.opendocument.text-web':
    case 'application/vnd.openxmlformats-officedocument.wordprocessingml.document':
    case 'application/vnd.stardivision.writer':
    case 'application/vnd.sun.xml.writer':
    case 'application/vnd.sun.xml.writer.template':
    case 'application/vnd.sun.xml.writer.global':
    case 'application/vnd.wordperfect':
    case 'application/x-abiword':
    case 'application/x-applix-word':
    case 'application/x-kword':
    case 'application/x-kword-crypt':
      return 'x-office-document';

    // Spreadsheet document types.
    case 'application/vnd.ms-excel':
    case 'application/vnd.ms-excel.sheet.macroEnabled.12':
    case 'application/vnd.oasis.opendocument.spreadsheet':
    case 'application/vnd.oasis.opendocument.spreadsheet-template':
    case 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet':
    case 'application/vnd.stardivision.calc':
    case 'application/vnd.sun.xml.calc':
    case 'application/vnd.sun.xml.calc.template':
    case 'application/vnd.lotus-1-2-3':
    case 'application/x-applix-spreadsheet':
    case 'application/x-gnumeric':
    case 'application/x-kspread':
    case 'application/x-kspread-crypt':
      return 'x-office-spreadsheet';

    // Presentation document types.
    case 'application/vnd.ms-powerpoint':
    case 'application/vnd.ms-powerpoint.presentation.macroEnabled.12':
    case 'application/vnd.oasis.opendocument.presentation':
    case 'application/vnd.oasis.opendocument.presentation-template':
    case 'application/vnd.openxmlformats-officedocument.presentationml.presentation':
    case 'application/vnd.stardivision.impress':
    case 'application/vnd.sun.xml.impress':
    case 'application/vnd.sun.xml.impress.template':
    case 'application/x-kpresenter':
      return 'x-office-presentation';

    // Compressed archive types.
    case 'application/zip':
    case 'application/x-zip':
    case 'application/stuffit':
    case 'application/x-stuffit':
    case 'application/x-7z-compressed':
    case 'application/x-ace':
    case 'application/x-arj':
    case 'application/x-bzip':
    case 'application/x-bzip-compressed-tar':
    case 'application/x-compress':
    case 'application/x-compressed-tar':
    case 'application/x-cpio-compressed':
    case 'application/x-deb':
    case 'application/x-gzip':
    case 'application/x-java-archive':
    case 'application/x-lha':
    case 'application/x-lhz':
    case 'application/x-lzop':
    case 'application/x-rar':
    case 'application/x-rpm':
    case 'application/x-tzo':
    case 'application/x-tar':
    case 'application/x-tarz':
    case 'application/x-tgz':
      return 'package-x-generic';

    // Script file types.
    case 'application/ecmascript':
    case 'application/javascript':
    case 'application/mathematica':
    case 'application/vnd.mozilla.xul+xml':
    case 'application/x-asp':
    case 'application/x-awk':
    case 'application/x-cgi':
    case 'application/x-csh':
    case 'application/x-m4':
    case 'application/x-perl':
    case 'application/x-php':
    case 'application/x-ruby':
    case 'application/x-shellscript':
    case 'text/vnd.wap.wmlscript':
    case 'text/x-emacs-lisp':
    case 'text/x-haskell':
    case 'text/x-literate-haskell':
    case 'text/x-lua':
    case 'text/x-makefile':
    case 'text/x-matlab':
    case 'text/x-python':
    case 'text/x-sql':
    case 'text/x-tcl':
      return 'text-x-script';

    // HTML aliases.
    case 'application/xhtml+xml':
      return 'text-html';

    // Executable types.
    case 'application/x-macbinary':
    case 'application/x-ms-dos-executable':
    case 'application/x-pef-executable':
      return 'application-x-executable';

    default:
      return FALSE;
  }
}

/**
 * @defgroup file-module-api File module public API functions
 * @{
 * These functions may be used to determine if and where a file is in use.
 */

/**
 * Count the number of times the file is referenced.
 *
 * @param $file
 *   A file object.
 * @param $field
 *   (optional) A CCK field array or field name as a string. If provided,
 *   limits the reference check to the given field.
 * @param $field_type
 *   (optional) The name of a field type. If provided, limits the reference
 *   check to fields of the given type.
 * @return
 *   An integer value.
 */
function file_get_file_reference_count($file, $field = NULL, $field_type = NULL) {
  // Determine the collection of fields to check.
  if (isset($field)) {
    // Support $field as 'field name'.
    if (is_string($field)) {
      $field = field_info_field($field);
    }
    $fields = array($field['field_name'] => $field);
  }
  else {
    $fields = field_info_fields();
  }

  $types = entity_get_info();
  $reference_count = 0;

  foreach ($fields as $field) {
    if (empty($field_type) || $field['type'] == $field_type) {
      // TODO: Use a more efficient mechanism rather than actually retrieving
      // all the references themselves, such as using a COUNT() query.
      $references = file_get_file_references($file, $field, FIELD_LOAD_REVISION, $field_type);
      foreach ($references as $entity_type => $type_references) {
        $reference_count += count($type_references);
      }

      // If a field_name is present in the file object, the file is being deleted
      // from this field.
      if (isset($file->file_field_name) && $field['field_name'] == $file->file_field_name) {
        // If deleting the entire piece of content, decrement references.
        if (isset($file->file_field_type) && isset($file->file_field_id)) {
          if ($file->file_field_type == $entity_type) {
            $info = entity_get_info($entity_type);
            $id = $types[$entity_type]['entity keys']['id'];
            foreach ($type_references as $reference) {
              if ($file->file_field_id == $reference->$id) {
                $reference_count--;
              }
            }
          }
        }
        // Otherwise we're just deleting a single reference in this field.
        else {
          $reference_count--;
        }
      }
    }
  }

  return $reference_count;
}


/**
 * Get a list of references to a file.
 *
 * @param $file
 *   A file object.
 * @param $field
 *   (optional) A field array to be used for this check. If given, limits the
 *   reference check to the given field.
 * @param $age
 *   (optional) A constant that specifies which references to count. Use
 *   FIELD_LOAD_REVISION to retrieve all references within all revisions or
 *   FIELD_LOAD_CURRENT to retrieve references only in the current revisions.
 * @param $field_type
 *   Optional. The name of a field type. If given, limits the reference check to
 *   fields of the given type.
 * @return
 *   An integer value.
 */
function file_get_file_references($file, $field = NULL, $age = FIELD_LOAD_REVISION, $field_type = 'file') {
  $references = drupal_static(__FUNCTION__, array());
  $fields = isset($field) ? array($field['field_name'] => $field) : field_info_fields();

  foreach ($fields as $field_name => $file_field) {
    if ((empty($field_type) || $file_field['type'] == $field_type) && !isset($references[$field_name])) {
      // Get each time this file is used within a field.
      $query = new EntityFieldQuery();
      $query
        ->fieldCondition($file_field, 'fid', $file->fid)
        ->age($age);
      $references[$field_name] = $query->execute();
    }
  }

  return isset($field) ? $references[$field['field_name']] : $references;
}

/**
 * @} End of "defgroup file-module-api".
 */
