<?php

/**
 * @file
 * Enhances the token API in core: adds a browseable UI, missing tokens, etc.
 */

/**
 * The maximum depth for token tree recursion.
 */
define('TOKEN_MAX_DEPTH', 9);

/**
 * Implements hook_help().
 */
function token_help($path, $arg) {
  if ($path == 'admin/help#token') {
    if (current_path() != 'admin/help/token') {
      // Because system_modules() executes hook_help() for each module to 'test'
      // if they will return anything, but not actually display it, we want to
      // return a TRUE value if this is not actually the help page.
      return TRUE;
    }
    $output = '<dl>';
    $output .= '<dt>' . t('List of the currently available tokens on this site') . '</dt>';
    $output .= '<dd>' . theme('token_tree', array('token_types' => 'all', 'click_insert' => FALSE, 'show_restricted' => TRUE)) . '</dd>';
    $output .= '</dl>';
    return $output;
  }
}

/**
 * Implements hook_system_info_alter().
 *
 * Prevent the token_actions module from being enabled since updates may have
 * left the old module files still in the directory.
 */
function token_system_info_alter(&$info, $file, $type) {
  if ($type == 'module' && $file->name == 'token_actions') {
    $info['hidden'] = TRUE;
  }
}

/**
 * Return an array of the core modules supported by token.module.
 */
function _token_core_supported_modules() {
  return array('book', 'field', 'menu', 'profile');
}

/**
 * Implements hook_menu().
 */
function token_menu() {
  /*$items['token/autocomplete/all/%menu_tail'] = array(
    'page callback' => 'token_autocomplete',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
    'file' => 'token.pages.inc',
  );*/
  $items['token/autocomplete/%token_type'] = array(
    'page callback' => 'token_autocomplete_token',
    'page arguments' => array(2),
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
    'file' => 'token.pages.inc',
  );
  /*$items['token/autocomplete/%token_type/%menu_tail'] = array(
    'page callback' => 'token_autocomplete_token',
    'page arguments' => array(2, 3),
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
    'file' => 'token.pages.inc',
  );*/

  $items['token/tree'] = array(
    'page callback' => 'token_page_output_tree',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
    'file' => 'token.pages.inc',
    'theme callback' => 'ajax_base_page_theme',
  );

  // Devel token pages.
  if (module_exists('devel')) {
    $items['node/%node/devel/token'] = array(
      'title' => 'Tokens',
      'page callback' => 'token_devel_token_object',
      'page arguments' => array('node', 1),
      'access arguments' => array('access devel information'),
      'type' => MENU_LOCAL_TASK,
      'file' => 'token.pages.inc',
      'weight' => 5,
    );
    $items['comment/%comment/devel/token'] = array(
      'title' => 'Tokens',
      'page callback' => 'token_devel_token_object',
      'page arguments' => array('comment', 1),
      'access arguments' => array('access devel information'),
      'type' => MENU_LOCAL_TASK,
      'file' => 'token.pages.inc',
      'weight' => 5,
    );
    $items['taxonomy/term/%taxonomy_term/devel/token'] = array(
      'title' => 'Tokens',
      'page callback' => 'token_devel_token_object',
      'page arguments' => array('taxonomy_term', 2),
      'access arguments' => array('access devel information'),
      'type' => MENU_LOCAL_TASK,
      'file' => 'token.pages.inc',
      'weight' => 5,
    );
    $items['user/%user/devel/token'] = array(
      'title' => 'Tokens',
      'page callback' => 'token_devel_token_object',
      'page arguments' => array('user', 1),
      'access arguments' => array('access devel information'),
      'type' => MENU_LOCAL_TASK,
      'file' => 'token.pages.inc',
      'weight' => 5,
    );
  }

  // Admin menu callback to clear token caches.
  $items['token/flush-cache'] = array(
    'page callback' => 'token_flush_cache_callback',
    'access arguments' => array('flush caches'),
    'type' => MENU_CALLBACK,
    'file' => 'token.pages.inc',
  );

  return $items;
}

/**
 * Implements hook_admin_menu_output_alter().
 */
function token_admin_menu_output_alter(&$content) {
  $content['icon']['icon']['flush-cache']['token'] = array(
    '#title' => t('Token registry'),
    '#href' => 'token/flush-cache',
    '#options' => array(
      'query' => drupal_get_destination() + array('token' => drupal_get_token('token/flush-cache')),
    ),
  );
}

function token_type_load($token_type) {
  $info = token_get_info();
  return isset($info['types'][$token_type]) ? $info['types'][$token_type] : FALSE;
}

/**
 * Implements hook_theme().
 */
function token_theme() {
  $info['tree_table'] = array(
    'variables' => array(
      'header' => array(),
      'rows' => array(),
      'attributes' => array(),
      'empty' => '',
      'caption' => '',
    ),
    'file' => 'token.pages.inc',
  );
  $info['token_tree'] = array(
    'variables' => array(
      'token_types' => array(),
      'global_types' => TRUE,
      'click_insert' => TRUE,
      'show_restricted' => FALSE,
      'recursion_limit' => 3,
      'dialog' => FALSE,
    ),
    'file' => 'token.pages.inc',
  );
  $info['token_tree_link'] = array(
    'variables' => array(
      'text' => NULL,
      'options' => array(),
      'dialog' => TRUE,
    ),
    'file' => 'token.pages.inc',
  );

  return $info;
}

/**
 * Implements hook_library().
 */
function token_library() {
  // jQuery treeTable plugin.
  $libraries['treeTable'] = array(
    'title' => 'jQuery treeTable',
    'website' => 'http://plugins.jquery.com/project/treetable',
    'version' => '2.3.0',
    'js' => array(
      drupal_get_path('module', 'token') . '/jquery.treeTable.js' => array(),
    ),
    'css' => array(
      drupal_get_path('module', 'token') . '/jquery.treeTable.css' => array(),
    ),
  );

  $libraries['dialog'] = array(
    'title' => 'Token dialog',
    'version' => '1.0',
    'js' => array(
      drupal_get_path('module', 'token') . '/token.js' => array(),
    ),
    'dependencies' => array(
      array('system', 'ui.dialog'),
    ),
  );

  return $libraries;
}

/**
 * Implements hook_form_alter().
 *
 * Adds a submit handler to forms which could affect the tokens available on
 * the site.
 */
function token_form_alter(&$form, $form_state, $form_id) {
  switch ($form_id) {
    // Profile field forms.
    case 'profile_field_form':
    case 'profile_field_delete':
    // User picture form.
    case 'user_admin_settings':
    // System date type form.
    // @todo Remove when http://drupal.org/node/1173706 is fixed.
    case 'system_add_date_format_type_form':
    case 'system_delete_date_format_type_form':
      $form += array('#submit' => array());
      array_unshift($form['#submit'], 'token_clear_cache');
      break;
  }
}

/**
 * Implements hook_block_view_alter().
 */
function token_block_view_alter(&$data, $block) {
  if (!empty($block->title) && $block->title != '<none>') {
    // Perform unsanitized token replacement since _block_render_blocks() will
    // call check_plain() on $block->title.
    $block->title = token_replace($block->title, array(), array('sanitize' => FALSE));
  }
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function token_form_block_add_block_form_alter(&$form, $form_state) {
  token_form_block_admin_configure_alter($form, $form_state);
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function token_form_block_admin_configure_alter(&$form, $form_state) {
  $form['settings']['title']['#description'] .= ' ' . t('This field supports tokens.');
  // @todo Figure out why this token validation does not seem to be working here.
  $form['settings']['title']['#element_validate'][] = 'token_element_validate';
  $form['settings']['title'] += array('#token_types' => array());
}

/**
 * Implements hook_widget_form_alter().
 */
function token_field_widget_form_alter(&$element, &$form_state, $context) {
  if (!empty($element['#description']) && is_string($element['#description'])) {
    $element['#description'] = filter_xss_admin(token_replace($element['#description']));
  }
}

/**
 * Implements hook_field_info_alter().
 */
function token_field_info_alter(&$info) {
  $defaults = array(
    'taxonomy_term_reference' => 'taxonomy_term_reference_plain',
    'number_integer' => 'number_unformatted',
    'number_decimal' => 'number_unformatted',
    'number_float' => 'number_unformatted',
    'file' => 'file_url_plain',
    'image' => 'file_url_plain',
    'text' => 'text_default',
    'text_long' => 'text_default',
    'text_with_summary' => 'text_default',
    'list_integer' => 'list_default',
    'list_float' => 'list_default',
    'list_text' => 'list_default',
    'list_boolean' => 'list_default',
  );
  foreach ($defaults as $field_type => $default_token_formatter) {
    if (isset($info[$field_type])) {
      $info[$field_type] += array('default_token_formatter' => $default_token_formatter);
    }
  }
}

/**
 * Implements hook_field_display_alter().
 */
function token_field_display_alter(&$display, $context) {
  if ($context['view_mode'] == 'token') {
    $view_mode_settings = field_view_mode_settings($context['instance']['entity_type'], $context['instance']['bundle']);
    // If the token view mode fell back to the 'default' view mode, then
    // use the default token formatter.
    if (empty($view_mode_settings[$context['view_mode']]['custom_settings'])) {
      $field_type_info = field_info_field_types($context['field']['type']);

      // If the field has specified a specific formatter to be used by default
      // with tokens, use that, otherwise use the default formatter.
      $formatter = !empty($field_type_info['default_token_formatter']) ? $field_type_info['default_token_formatter'] : $field_type_info['default_formatter'];

      // Now that we have a formatter, fill in all the settings.
      $display['type'] = $formatter;
      $formatter_info = field_info_formatter_types($formatter);
      $display['settings'] = isset($formatter_info['settings']) ? $formatter_info['settings'] : array();
      $display['settings']['label'] = 'hidden';
      $display['module'] = $formatter_info['module'];
    }
  }
}

/**
 * Implements hook_field_create_instance().
 */
function token_field_create_instance($instance) {
  token_clear_cache();
}

/**
 * Implements hook_field_update_instance().
 */
function token_field_update_instance($instance) {
  token_clear_cache();
}

/**
 * Implements hook_field_delete_instance().
 */
function token_field_delete_instance($instance) {
  token_clear_cache();
}

/**
 * Clear token caches and static variables.
 */
function token_clear_cache() {
  if (db_table_exists('cache_token')) {
    cache_clear_all('*', 'cache_token', TRUE);
  }
  drupal_static_reset('token_get_info');
  drupal_static_reset('token_get_global_token_types');
  drupal_static_reset('token_get_entity_mapping');
  drupal_static_reset('token_build_tree');
  drupal_static_reset('_token_profile_fields');
  drupal_static_reset('token_menu_link_load');
  drupal_static_reset('token_book_link_load');
  drupal_static_reset('token_node_menu_link_load');
  drupal_static_reset('_token_field_info');
}

/**
 * Return an array of entity type to token type mappings.
 *
 * Why do we need this? Because when the token API was moved to core we did not
 * re-use the entity type as the base name for taxonomy terms and vocabulary
 * tokens.
 *
 * @see token_entity_info_alter()
 * @see http://drupal.org/node/737726
 */
function token_get_entity_mapping($value_type = 'token', $value = NULL, $fallback = FALSE) {
  $mapping = &drupal_static(__FUNCTION__, array());

  if (empty($mapping)) {
    foreach (entity_get_info() as $entity_type => $info) {
      $mapping[$entity_type] = !empty($info['token type']) ? $info['token type'] : $entity_type;
    }
    // Allow modules to alter the mapping array.
    drupal_alter('token_entity_mapping', $mapping);
  }

  if (!isset($value)) {
    return $value_type == 'token' ? array_flip($mapping) : $mapping;
  }
  elseif ($value_type == 'token') {
    $return = array_search($value, $mapping);
    return $return !== FALSE ? $return : ($fallback ? $value : FALSE);
  }
  elseif ($value_type == 'entity') {
    return isset($mapping[$value]) ? $mapping[$value] : ($fallback ? $value : FALSE);
  }
}

/**
 * Implements hook_entity_info_alter().
 *
 * Because some token types to do not match their entity type names, we have to
 * map them to the proper type. This is purely for other modules' benefit.
 *
 * @see token_get_entity_mapping()
 * @see http://drupal.org/node/737726
 */
function token_entity_info_alter(&$info) {
  foreach (array_keys($info) as $entity_type) {
    // Add a token view mode if it does not already exist.
    if (!empty($info[$entity_type]['view modes']) && !isset($info[$entity_type]['view modes']['token'])) {
      $info[$entity_type]['view modes']['token'] = array(
        'label' => t('Tokens'),
        'custom settings' => FALSE,
      );
    }

    if (!empty($info[$entity_type]['token type'])) {
      // If the entity's token type is already defined, great!
      continue;
    }

    // Fill in default token types for entities.
    switch ($entity_type) {
      case 'taxonomy_term':
      case 'taxonomy_vocabulary':
        // Stupid taxonomy token types...
        $info[$entity_type]['token type'] = str_replace('taxonomy_', '', $entity_type);
        break;
      default:
        // By default the token type is the same as the entity type.
        $info[$entity_type]['token type'] = $entity_type;
        break;
    }
  }
}

/**
 * Implements hook_module_implements_alter().
 *
 * Adds missing token support for core modules.
 */
function token_module_implements_alter(&$implementations, $hook) {
  module_load_include('inc', 'token', 'token.tokens');

  if ($hook == 'tokens' || $hook == 'token_info' || $hook == 'token_info_alter' || $hook == 'tokens_alter') {
    foreach (_token_core_supported_modules() as $module) {
      if (module_exists($module) && function_exists($module . '_' . $hook)) {
        $implementations[$module] = FALSE;
      }
    }
    // Move token.module to get included first since it is responsible for
    // other modules.
    unset($implementations['token']);
    $implementations = array_merge(array('token' => 'tokens'), $implementations);
  }
}

/**
 * Implements hook_flush_caches().
 */
function token_flush_caches() {
  if (db_table_exists('cache_token')) {
    return array('cache_token');
  }
}

/**
 * Retrieve, sort, store token info from the cache.
 *
 * @param $token_type
 *   The optional token type that if specified will return
 *   $info['types'][$token_type].
 * @param $token
 *   The optional token name if specified will return
 *   $info['tokens'][$token_type][$token].
 *
 * @return
 *   An array of all token information from hook_token_info(), or the array
 *   of a token type or specific token.
 *
 * @see hook_token_info()
 * @see hook_token_info_alter()
 */
function token_get_info($token_type = NULL, $token = NULL) {
  global $language;

  // Use the advanced drupal_static() pattern, since this is called very often.
  static $drupal_static_fast;
  if (!isset($drupal_static_fast)) {
    $drupal_static_fast['token_info'] = &drupal_static(__FUNCTION__);
  }
  $token_info = &$drupal_static_fast['token_info'];

  if (empty($token_info)) {
    $cid = "info:{$language->language}";

    if ($cache = cache_get($cid, 'cache_token')) {
      $token_info = $cache->data;
    }
    else {
      $token_info = token_info();

      foreach (array_keys($token_info['types']) as $type_key) {
        if (isset($token_info['types'][$type_key]['type'])) {
          $base_type = $token_info['types'][$type_key]['type'];
          // If this token type extends another token type, then merge in
          // the base token type's tokens.
          if (isset($token_info['tokens'][$base_type])) {
            $token_info['tokens'] += array($type_key => array());
            $token_info['tokens'][$type_key] += $token_info['tokens'][$base_type];
          }
        }
        else {
          // Add a 'type' value to each token type so we can properly use
          // token_type_load().
          $token_info['types'][$type_key]['type'] = $type_key;
        }
      }

      // Pre-sort tokens.
      uasort($token_info['types'], 'token_asort_tokens');
      foreach (array_keys($token_info['tokens']) as $type) {
        uasort($token_info['tokens'][$type], 'token_asort_tokens');
      }

      // Store info in cache for future use.
      cache_set($cid, $token_info, 'cache_token');
    }
  }

  if (isset($token_type) && isset($token)) {
    return isset($token_info['tokens'][$token_type][$token]) ? $token_info['tokens'][$token_type][$token] : NULL;
  }
  elseif (isset($token_type)) {
    return isset($token_info['types'][$token_type]) ? $token_info['types'][$token_type] : NULL;
  }
  else {
    return $token_info;
  }
}

/**
 * Return the module responsible for a token.
 *
 * @param string $type
 *   The token type.
 * @param string $name
 *   The token name.
 *
 * @return mixed
 *   The value of $info['tokens'][$type][$name]['module'] from token_get_info(),
 *   or NULL if the value does not exist.
 */
function _token_module($type, $name) {
  $token_info = token_get_info($type, $name);
  return isset($token_info['module']) ? $token_info['module'] : NULL;
}

/**
 * uasort() callback to sort tokens by the 'name' property.
 */
function token_asort_tokens($token_a, $token_b) {
  return strnatcmp($token_a['name'], $token_b['name']);
}

/**
 * Get a list of token types that can be used without any context (global).
 *
 * @return
 *   An array of global token types.
 */
function token_get_global_token_types() {
  $global_types = &drupal_static(__FUNCTION__, array());

  if (empty($global_types)) {
    $token_info = token_get_info();
    foreach ($token_info['types'] as $type => $type_info) {
      // If the token types has not specified that 'needs-data' => TRUE, then
      // it is a global token type that will always be replaced in any context.
      if (empty($type_info['needs-data'])) {
        $global_types[] = $type;
      }
    }
  }

  return $global_types;
}

/**
 * Validate an tokens in raw text based on possible contexts.
 *
 * @param $value
 *   A string with the raw text containing the raw tokens, or an array of
 *   tokens from token_scan().
 * @param $tokens
 *   An array of token types that will be used when token replacement is
 *   performed.
 * @return
 *   An array with the invalid tokens in their original raw forms.
 */
function token_get_invalid_tokens_by_context($value, $valid_types = array()) {
  if (in_array('all', $valid_types)) {
    $info = token_get_info();
    $valid_types = array_keys($info['types']);
  }
  else {
    // Add the token types that are always valid in global context.
    $valid_types = array_merge($valid_types, token_get_global_token_types());
  }

  $invalid_tokens = array();
  $value_tokens = is_string($value) ? token_scan($value) : $value;

  foreach ($value_tokens as $type => $tokens) {
    if (!in_array($type, $valid_types)) {
      // If the token type is not a valid context, its tokens are invalid.
      $invalid_tokens = array_merge($invalid_tokens, array_values($tokens));
    }
    else {
      // Check each individual token for validity.
      $invalid_tokens = array_merge($invalid_tokens, token_get_invalid_tokens($type, $tokens));
    }
  }

  array_unique($invalid_tokens);
  return $invalid_tokens;
}

/**
 * Validate an array of tokens based on their token type.
 *
 * @param $type
 *   The type of tokens to validate (e.g. 'node', etc.)
 * @param $tokens
 *   A keyed array of tokens, and their original raw form in the source text.
 * @return
 *   An array with the invalid tokens in their original raw forms.
 */
function token_get_invalid_tokens($type, $tokens) {
  $token_info = token_get_info();
  $invalid_tokens = array();

  foreach ($tokens as $token => $full_token) {
    // Split token up if it has chains.
    $parts = explode(':', $token, 2);

    if (!isset($token_info['tokens'][$type][$parts[0]])) {
      // This is an invalid token (not defined).
      $invalid_tokens[] = $full_token;
    }
    elseif (count($parts) == 2) {
      $sub_token_info = $token_info['tokens'][$type][$parts[0]];
      if (!empty($sub_token_info['dynamic'])) {
        // If this token has been flagged as a dynamic token, skip it.
        continue;
      }
      elseif (empty($sub_token_info['type'])) {
        // If the token has chains, but does not support it, it is invalid.
        $invalid_tokens[] = $full_token;
      }
      else {
        // Resursively check the chained tokens.
        $sub_tokens = token_find_with_prefix(array($token => $full_token), $parts[0]);
        $invalid_tokens = array_merge($invalid_tokens, token_get_invalid_tokens($sub_token_info['type'], $sub_tokens));
      }
    }
  }

  return $invalid_tokens;
}

/**
 * Validate a form element that should have tokens in it.
 *
 * Form elements that want to add this validation should have the #token_types
 * parameter defined.
 *
 * For example:
 * @code
 * $form['my_node_text_element'] = array(
 *   '#type' => 'textfield',
 *   '#title' => t('Some text to token-ize that has a node context.'),
 *   '#default_value' => 'The title of this node is [node:title].',
 *   '#element_validate' => array('token_element_validate'),
 *   '#token_types' => array('node'),
 *   '#min_tokens' => 1,
 *   '#max_tokens' => 10,
 * );
 * @endcode
 */
function token_element_validate(&$element, &$form_state) {
  $value = isset($element['#value']) ? $element['#value'] : $element['#default_value'];

  if (!drupal_strlen($value)) {
    // Empty value needs no further validation since the element should depend
    // on using the '#required' FAPI property.
    return $element;
  }

  $tokens = token_scan($value);
  $title = empty($element['#title']) ? $element['#parents'][0] : $element['#title'];
  // @todo Find old Drupal 6 style tokens and add them to invalid tokens.

  // Validate if an element must have a minimum number of tokens.
  if (isset($element['#min_tokens']) && count($tokens) < $element['#min_tokens']) {
    // @todo Change this error message to include the minimum number.
    $error = format_plural($element['#min_tokens'], 'The %element-title cannot contain fewer than one token.', 'The %element-title must contain at least @count tokens.', array('%element-title' => $title));
    form_error($element, $error);
  }

  // Validate if an element must have a maximum number of tokens.
  if (isset($element['#max_tokens']) && count($tokens) > $element['#max_tokens']) {
    // @todo Change this error message to include the maximum number.
    $error = format_plural($element['#max_tokens'], 'The %element-title must contain as most one token.', 'The %element-title must contain at most @count tokens.', array('%element-title' => $title));
    form_error($element, $error);
  }

  // Check if the field defines specific token types.
  if (isset($element['#token_types'])) {
    $invalid_tokens = token_get_invalid_tokens_by_context($tokens, $element['#token_types']);
    if ($invalid_tokens) {
      form_error($element, t('The %element-title is using the following invalid tokens: @invalid-tokens.', array('%element-title' => $title, '@invalid-tokens' => implode(', ', $invalid_tokens))));
    }
  }

  return $element;
}

/**
 * Deprecated. Use token_element_validate() instead.
 */
function token_element_validate_token_context(&$element, &$form_state) {
  return token_element_validate($element, $form_state);
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function token_form_field_ui_field_edit_form_alter(&$form, $form_state) {
  if (!isset($form['instance']) || !empty($form['#field']['locked'])) {
    return;
  }

  if (($form['#field']['type'] == 'file' || $form['#field']['type'] == 'image') && isset($form['instance']['settings']['file_directory']) && !module_exists('filefield_paths')) {
    // GAH! We can only support global tokens in the upload file directory path.
    $form['instance']['settings']['file_directory']['#element_validate'][] = 'token_element_validate';
    $form['instance']['settings']['file_directory'] += array('#token_types' => array());
    $form['instance']['settings']['file_directory']['#description'] .= ' ' . t('This field supports tokens.');
  }

  // Note that the description is tokenized via token_field_widget_form_alter().
  $form['instance']['description']['#description'] .= '<br />' . t('This field supports tokens.');
  $form['instance']['description']['#element_validate'][] = 'token_element_validate';
  $form['instance']['description'] += array('#token_types' => array());

  $form['instance']['settings']['token_tree'] = array(
    '#theme' => 'token_tree',
    '#token_types' => array(),
    '#dialog' => TRUE,
    '#weight' => $form['instance']['description']['#weight'] + 0.5,
  );
}

/**
 * Implements hook_form_FORM_ID_alter().
 *
 * Alters the configure action form to add token context validation and
 * adds the token tree for a better token UI and selection.
 */
function token_form_system_actions_configure_alter(&$form, $form_state) {
  $action = actions_function_lookup($form['actions_action']['#value']);

  switch ($action) {
    case 'system_message_action':
    case 'system_send_email_action':
    case 'system_goto_action':
      $form['token_tree'] = array(
        '#theme' => 'token_tree',
        '#token_types' => 'all',
        '#dialog' => TRUE,
        '#weight' => 100,
      );
      // @todo Add token validation to the action fields that can use tokens.
      break;
  }
}

/**
 * Implements hook_form_FORM_ID_alter().
 *
 * Alters the user e-mail fields to add token context validation and
 * adds the token tree for a better token UI and selection.
 */
function token_form_user_admin_settings_alter(&$form, &$form_state) {
  $email_token_help = t('Available variables are: [site:name], [site:url], [user:name], [user:mail], [site:login-url], [site:url-brief], [user:edit-url], [user:one-time-login-url], [user:cancel-url].');

  foreach (element_children($form) as $key) {
    $element = &$form[$key];

    // Remove the crummy default token help text.
    if (!empty($element['#description'])) {
      $element['#description'] = trim(str_replace($email_token_help, t('The list of available tokens that can be used in e-mails is provided below.'), $element['#description']));
    }

    switch ($key) {
      case 'email_admin_created':
      case 'email_pending_approval':
      case 'email_no_approval_required':
      case 'email_password_reset':
      case 'email_cancel_confirm':
        // Do nothing, but allow execution to continue.
        break;
      case 'email_activated':
      case 'email_blocked':
      case 'email_canceled':
        // These fieldsets have their e-mail elements inside a 'settings'
        // sub-element, so switch to that element instead.
        $element = &$form[$key]['settings'];
        break;
      default:
        continue 2;
    }

    foreach (element_children($element) as $sub_key) {
      if (!isset($element[$sub_key]['#type'])) {
        continue;
      }
      elseif ($element[$sub_key]['#type'] == 'textfield' && substr($sub_key, -8) === '_subject') {
        // Add validation to subject textfields.
        $element[$sub_key]['#element_validate'][] = 'token_element_validate';
        $element[$sub_key] += array('#token_types' => array('user'));
      }
      elseif ($element[$sub_key]['#type'] == 'textarea' && substr($sub_key, -5) === '_body') {
        // Add validation to body textareas.
        $element[$sub_key]['#element_validate'][] = 'token_element_validate';
        $element[$sub_key] += array('#token_types' => array('user'));
      }
    }
  }

  // Add the token tree UI.
  $form['email']['token_tree'] = array(
    '#theme' => 'token_tree',
    '#token_types' => array('user'),
    '#show_restricted' => TRUE,
    '#dialog' => TRUE,
    '#weight' => 90,
  );
}

/**
 * Build a tree array of tokens used for themeing or information.
 *
 * @param $token_type
 *   The token type.
 * @param $flat_tree
 *   A boolean if TRUE will only make a flat array of tokens, otherwise
 *   child tokens will be inside the 'children' parameter of a token.
 * @param $show_restricted
 *   A boolean if TRUE will show restricted tokens. Otherwise they will be
 *   hidden. Default is FALSE.
 * @param $recursion_limit
 *   An integer with the maximum number of token levels to recurse.
 * @param $parents
 *   An optional array with the current parents of the tokens.
 */
function token_build_tree($token_type, array $options = array()) {
  global $language;

  // Static cache of already built token trees.
  $trees = &drupal_static(__FUNCTION__, array());

  $options += array(
    'restricted' => FALSE,
    'depth' => 4,
    'data' => array(),
    'values' => FALSE,
    'flat' => FALSE,
  );

  // Do not allow past the maximum token information depth.
  $options['depth'] = min($options['depth'], TOKEN_MAX_DEPTH);

  // If $token_type is an entity, make sure we are using the actual token type.
  if ($entity_token_type = token_get_entity_mapping('entity', $token_type)) {
    $token_type = $entity_token_type;
  }

  $tree_cid = "tree:{$token_type}:{$language->language}:{$options['depth']}";

  // If we do not have this base tree in the static cache, check {cache_token}
  // otherwise generate and store it in the cache.
  if (!isset($trees[$tree_cid])) {
    if ($cache = cache_get($tree_cid, 'cache_token')) {
      $trees[$tree_cid] = $cache->data;
    }
    else {
      $options['parents'] = array();
      $trees[$tree_cid] = _token_build_tree($token_type, $options);
      cache_set($tree_cid, $trees[$tree_cid], 'cache_token');
    }
  }

  $tree = $trees[$tree_cid];

  // If the user has requested a flat tree, convert it.
  if (!empty($options['flat'])) {
    $tree = token_flatten_tree($tree);
  }

  // Fill in token values.
  if (!empty($options['values'])) {
    $token_values = array();
    foreach ($tree as $token => $token_info) {
      if (!empty($token_info['dynamic']) || !empty($token_info['restricted'])) {
        continue;
      }
      elseif (!isset($token_info['value'])) {
        $token_values[$token_info['token']] = $token;
      }
    }
    if (!empty($token_values)) {
      $token_values = token_generate($token_type, $token_values, $options['data']);
      foreach ($token_values as $token => $replacement) {
        $tree[$token]['value'] = $replacement;
      }
    }
  }

  return $tree;
}

/**
 * Flatten a token tree.
 */
function token_flatten_tree($tree) {
  $result = array();
  foreach ($tree as $token => $token_info) {
    $result[$token] = $token_info;
    if (isset($token_info['children']) && is_array($token_info['children'])) {
      $result += token_flatten_tree($token_info['children']);
      // unset($result[$token]['children']);
    }
  }
  return $result;
}

/**
 * Generate a token tree.
 */
function _token_build_tree($token_type, array $options) {
  $options += array(
    'parents' => array(),
  );

  $info = token_get_info();
  if ($options['depth'] <= 0 || !isset($info['types'][$token_type]) || !isset($info['tokens'][$token_type])) {
    return array();
  }

  $tree = array();
  foreach ($info['tokens'][$token_type] as $token => $token_info) {
    // Build the raw token string.
    $token_parents = $options['parents'];
    if (empty($token_parents)) {
      // If the parents array is currently empty, assume the token type is its
      // parent.
      $token_parents[] = $token_type;
    }
    elseif (in_array($token, array_slice($token_parents, 1))) {
      // Prevent duplicate recursive tokens. For example, this will prevent
      // the tree from generating the following tokens or deeper:
      // [comment:parent:parent]
      // [comment:parent:root:parent]
      continue;
    }

    $token_parents[] = $token;
    if (!empty($token_info['dynamic'])) {
      $token_parents[] = '?';
    }
    $raw_token = '[' . implode(':', $token_parents) . ']';
    $tree[$raw_token] = $token_info;
    $tree[$raw_token]['raw token'] = $raw_token;

    // Add the token's real name (leave out the base token type).
    $tree[$raw_token]['token'] = implode(':', array_slice($token_parents, 1));

    // Add the token's parent as its raw token value.
    if (!empty($options['parents'])) {
      $tree[$raw_token]['parent'] = '[' . implode(':', $options['parents']) . ']';
    }

    // Fetch the child tokens.
    if (!empty($token_info['type'])) {
      $child_options = $options;
      $child_options['depth']--;
      $child_options['parents'] = $token_parents;
      $tree[$raw_token]['children'] = _token_build_tree($token_info['type'], $child_options);
    }
  }

  return $tree;
}

/**
 * Get a translated menu link by its mlid, without access checking.
 *
 * This function is a copy of menu_link_load() but with its own cache and a
 * simpler query to load the link. This also skips normal menu link access
 * checking by using _token_menu_link_translate().
 *
 * @param $mlid
 *   The mlid of the menu item.
 *
 * @return
 *   A menu link translated for rendering.
 *
 * @see menu_link_load()
 * @see _token_menu_link_translate()
 */
function token_menu_link_load($mlid) {
  $cache = &drupal_static(__FUNCTION__, array());

  if (!is_numeric($mlid)) {
    return FALSE;
  }

  if (!isset($cache[$mlid])) {
    $item = db_query("SELECT * FROM {menu_links} ml LEFT JOIN {menu_router} m ON m.path = ml.router_path WHERE ml.mlid = :mlid", array(':mlid' => $mlid))->fetchAssoc();
    if (!empty($item)) {
      _token_menu_link_translate($item);
    }
    $cache[$mlid] = $item;
  }

  return $cache[$mlid];
}

/**
 * Get a translated book menu link by its mlid, without access checking.
 *
 * This function is a copy of book_link_load() but with its own cache and a
 * simpler query to load the link. This also skips normal menu link access
 * checking by using _token_menu_link_translate().
 *
 * @param $mlid
 *   The mlid of the book menu item.
 *
 * @return
 *   A book menu link translated for rendering.
 *
 * @see book_link_load()
 * @see _token_menu_link_translate()
 */
function token_book_link_load($mlid) {
  $cache = &drupal_static(__FUNCTION__, array());

  if (!is_numeric($mlid)) {
    return FALSE;
  }

  if (!isset($cache[$mlid])) {
    $item = db_query("SELECT * FROM {menu_links} ml INNER JOIN {book} b ON b.mlid = ml.mlid LEFT JOIN {menu_router} m ON m.path = ml.router_path WHERE ml.mlid = :mlid", array(':mlid' => $mlid))->fetchAssoc();
    if (!empty($item)) {
      _token_menu_link_translate($item);
    }
    $cache[$mlid] = $item;
  }

  return $cache[$mlid];
}

function _token_menu_link_translate(&$item) {
  $map = array();

  if (!is_array($item['options'])) {
    $item['options'] = unserialize($item['options']);
  }

  if ($item['external']) {
    $item['access'] = 1;
    $item['href'] = $item['link_path'];
    $item['title'] = $item['link_title'];
    $item['localized_options'] = $item['options'];
  }
  else {
    // Complete the path of the menu link with elements from the current path,
    // if it contains dynamic placeholders (%).
    $map = explode('/', $item['link_path']);
    if (strpos($item['link_path'], '%') !== FALSE) {
      // Invoke registered to_arg callbacks.
      if (!empty($item['to_arg_functions'])) {
        _menu_link_map_translate($map, $item['to_arg_functions']);
      }
    }
    $item['href'] = implode('/', $map);

    // Skip links containing untranslated arguments.
    if (strpos($item['href'], '%') !== FALSE) {
      $item['access'] = FALSE;
      return FALSE;
    }

    $item['access'] = TRUE;
    _menu_item_localize($item, $map, TRUE);
  }

  // Allow other customizations - e.g. adding a page-specific query string to the
  // options array. For performance reasons we only invoke this hook if the link
  // has the 'alter' flag set in the options array.
  if (!empty($item['options']['alter'])) {
    drupal_alter('translated_menu_link', $item, $map);
  }

  return $map;
}

/**
 * Prepare a string for use as a valid token name.
 *
 * @param $name
 *   The token name to clean.
 * @return
 *   The cleaned token name.
 */
function token_clean_token_name($name) {
  static $names = array();

  if (!isset($names[$name])) {
    $cleaned_name = strtr($name, array(' ' => '-', '_' => '-', '/' => '-', '[' => '-', ']' => ''));
    $cleaned_name = preg_replace('/[^\w\-]/i', '', $cleaned_name);
    $cleaned_name = trim($cleaned_name, '-');
    $names[$name] = $cleaned_name;
  }

  return $names[$name];
}

/**
 * Do not use this function yet. Its API has not been finalized.
 */
function token_render_array(array $array, array $options = array()) {
  $rendered = array();
  foreach (element_children($array) as $key) {
    $value = $array[$key];
    $rendered[] = is_array($value) ? render($value) : (string) $value;
  }
  if (!empty($options['sanitize'])) {
    $rendered = array_map('check_plain', $rendered);
  }
  $join = isset($options['join']) ? $options['join'] : ', ';
  return implode($join, $rendered);
}

/**
 * Do not use this function yet. Its API has not been finalized.
 */
function token_render_array_value($value, array $options = array()) {
  $rendered = is_array($value) ? render($value) : (string) $value;
  if (!empty($options['sanitize'])) {
    $rendered = check_plain($rendered);
  }
  return $rendered;
}

/**
 * Copy of drupal_render_cache_get() that does not care about request method.
 */
function token_render_cache_get($elements) {
  if (!$cid = drupal_render_cid_create($elements)) {
    return FALSE;
  }
  $bin = isset($elements['#cache']['bin']) ? $elements['#cache']['bin'] : 'cache';

  if (!empty($cid) && $cache = cache_get($cid, $bin)) {
    // Add additional libraries, JavaScript, CSS and other data attached
    // to this element.
    if (isset($cache->data['#attached'])) {
      drupal_process_attached($cache->data);
    }
    // Return the rendered output.
    return $cache->data['#markup'];
  }
  return FALSE;
}

/**
 * Coyp of drupal_render_cache_set() that does not care about request method.
 */
function token_render_cache_set(&$markup, $elements) {
  // This should only run of drupal_render_cache_set() did not.
  if (in_array($_SERVER['REQUEST_METHOD'], array('GET', 'HEAD'))) {
    return FALSE;
  }

  $original_method = $_SERVER['REQUEST_METHOD'];
  $_SERVER['REQUEST_METHOD'] = 'GET';
  drupal_render_cache_set($markup, $elements);
  $_SERVER['REQUEST_METHOD'] = $original_method;
}

function token_menu_link_load_all_parents($mlid) {
  $cache = &drupal_static(__FUNCTION__, array());

  if (!is_numeric($mlid)) {
    return array();
  }

  if (!isset($cache[$mlid])) {
    $cache[$mlid] = array();
    $plid = db_query("SELECT plid FROM {menu_links} WHERE mlid = :mlid", array(':mlid' => $mlid))->fetchField();
    while ($plid && $parent = token_menu_link_load($plid)) {
      $cache[$mlid] = array($plid => $parent['title']) + $cache[$mlid];
      $plid = $parent['plid'];
    }
  }

  return $cache[$mlid];
}

function token_taxonomy_term_load_all_parents($tid) {
  $cache = &drupal_static(__FUNCTION__, array());

  if (!is_numeric($tid)) {
    return array();
  }

  if (!isset($cache[$tid])) {
    $cache[$tid] = array();
    $parents = taxonomy_get_parents_all($tid);
    array_shift($parents); // Remove this term from the array.
    $parents = array_reverse($parents);
    foreach ($parents as $term) {
      $cache[$tid][$term->tid] = entity_label('taxonomy_term', $term);
    }
  }

  return $cache[$tid];
}

/**
 * Load the preferred menu link associated with a node.
 *
 * @param $node
 *   A node object.
 *
 * @return
 *   A menu link array from token_menu_link_load() or FALSE if a menu link was
 *   not found.
 *
 * @see menu_node_prepare()
 * @see token_menu_link_load()
 */
function token_node_menu_link_load($node) {
  $cache = &drupal_static(__FUNCTIon__, array());

  if (!isset($cache[$node->nid])) {
    $mlid = FALSE;

    // Nodes do not have their menu links loaded via menu_node_load().
    if (!isset($node->menu)) {
      // We need to clone the node as menu_node_prepare() may cause data loss.
      // @see http://drupal.org/node/1317926
      $menu_node = clone $node;
      menu_node_prepare($menu_node);
      $mlid = !empty($menu_node->menu['mlid']) ? $menu_node->menu['mlid'] : FALSE;
    }
    else {
      $mlid = !empty($node->menu['mlid']) ? $node->menu['mlid'] : FALSE;
    }

    $cache[$node->nid] = $mlid;
  }

  return $cache[$node->nid] ? token_menu_link_load($cache[$node->nid]) : FALSE;
}