<?php

/**
 * @file
 * Allows entities to be translated into different languages.
 */

module_load_include('inc', 'entity_translation', 'entity_translation.node');
module_load_include('inc', 'entity_translation', 'entity_translation.taxonomy');


/**
 * Language code identifying the site default language.
 */
define('ENTITY_TRANSLATION_LANGUAGE_DEFAULT', 'xx-et-default');

/**
 * Language code identifying the current content language.
 */
define('ENTITY_TRANSLATION_LANGUAGE_CURRENT', 'xx-et-current');

/**
 * Language code identifying the author's preferred language.
 */
define('ENTITY_TRANSLATION_LANGUAGE_AUTHOR', 'xx-et-author');

/**
 * Defines an i18n translation mode for Entity Translation.
 */
define('I18N_MODE_ENTITY_TRANSLATION', 32768);


/**
 * Implements hook_hook_info().
 */
function entity_translation_hook_info() {
  $hooks['entity_translation_insert'] = array(
    'group' => 'entity_translation',
  );
  $hooks['entity_translation_update'] = array(
    'group' => 'entity_translation',
  );
  $hooks['entity_translation_delete'] = array(
    'group' => 'entity_translation',
  );
  return $hooks;
}

/**
 * Implements hook_module_implements_alter().
 */
function entity_translation_module_implements_alter(&$implementations, $hook) {
  switch ($hook) {
    case 'menu_alter':
    case 'entity_info_alter':
      // Move some of our hook implementations to the end of the list.
      $group = $implementations['entity_translation'];
      unset($implementations['entity_translation']);
      $implementations['entity_translation'] = $group;
      break;
  }
}

/**
 * Implements hook_language_type_info_alter().
 */
function entity_translation_language_types_info_alter(array &$language_types) {
  unset($language_types[LANGUAGE_TYPE_CONTENT]['fixed']);
}

/**
 * Implements hook_entity_info().
 */
function entity_translation_entity_info() {
  $info = array();

  $info['node'] = array(
    'translation' => array(
      'entity_translation' => array(
        'class' => 'EntityTranslationNodeHandler',
        'access callback' => 'entity_translation_node_tab_access',
        'access arguments' => array(1),
        'admin theme' => variable_get('node_admin_theme'),
        'bundle callback' => 'entity_translation_node_supported_type',
        'default settings' => array(
          'default_language' => LANGUAGE_NONE,
          'hide_language_selector' => FALSE,
        ),
      ),
    ),
  );

  if (module_exists('comment')) {
    $info['comment'] = array(
      'translation' => array(
        'entity_translation' => array(
          'class' => 'EntityTranslationCommentHandler',
          'admin theme' => FALSE,
          'bundle callback' => 'entity_translation_comment_supported_type',
          'default settings' => array(
            'default_language' => ENTITY_TRANSLATION_LANGUAGE_CURRENT,
            'hide_language_selector' => TRUE,
          ),
        ),
      ),
    );
  }

  if (module_exists('taxonomy')) {
    $info['taxonomy_term'] = array(
      'translation' => array(
        'entity_translation' => array(
          'class' => 'EntityTranslationTaxonomyTermHandler',
          'access callback' => 'entity_translation_taxonomy_term_tab_access',
          'access arguments' => array(1),
          'base path' => 'taxonomy/term/%taxonomy_term',
          'edit form' => 'term',
          'bundle callback' => 'entity_translation_taxonomy_term_enabled_vocabulary',
        ),
      ),
    );
  }

  $info['user'] = array(
    'translation' => array(
      'entity_translation' => array(
        'class' => 'EntityTranslationUserHandler',
        'skip original values access' => TRUE,
        'skip shared fields access' => TRUE,
      ),
    ),
  );

  return $info;
}

/**
 * Processes the given path schemes and fill-in default values.
 */
function _entity_translation_process_path_schemes($entity_type, &$et_info) {
  $path_scheme_keys = array_flip(array('base path', 'view path', 'edit path', 'translate path', 'path wildcard', 'admin theme', 'edit tabs'));

  // Insert the default path scheme into the 'path schemes' array and remove
  // respective elements from the entity_translation info array.
  $default_scheme = array_intersect_key($et_info, $path_scheme_keys);
  if (!empty($default_scheme)) {
    $et_info['path schemes']['default'] = $default_scheme;
    $et_info = array_diff_key($et_info, $path_scheme_keys);
  }

  // If no base path is provided we default to the common "node/%node"
  // pattern.
  if (empty($et_info['path schemes']['default']['base path'])) {
    $et_info['path schemes']['default']['base path'] = "$entity_type/%$entity_type";
  }

  foreach ($et_info['path schemes'] as $delta => $scheme) {
    // If there is a base path, then we automatically create the other path
    // elements based on the base path.
    if (!empty($scheme['base path'])) {
      $view_path = $scheme['base path'];
      $edit_path = $scheme['base path'] . '/edit';
      $translate_path = $scheme['base path'] . '/translate';

      $et_info['path schemes'][$delta] += array(
        'view path' => $view_path,
        'edit path' => $edit_path,
        'translate path' => $translate_path,
      );
    }

    // Merge in default values for other scheme elements.
    $et_info['path schemes'][$delta] += array(
      'admin theme' => TRUE,
      'path wildcard' => "%$entity_type",
      'edit tabs' => TRUE,
    );
  }
}

/**
 * Implements hook_entity_info_alter().
 */
function entity_translation_entity_info_alter(&$entity_info) {
  // Provide defaults for translation info.
  foreach ($entity_info as $entity_type => $info) {
    if (!isset($entity_info[$entity_type]['translation']['entity_translation'])) {
      $entity_info[$entity_type]['translation']['entity_translation'] = array();
    }
    $et_info = &$entity_info[$entity_type]['translation']['entity_translation'];

    // Every fieldable entity type must have a translation handler class and
    // translation keys defined, no matter if it is enabled for translation or
    // not. As a matter of fact we might need them to correctly switch field
    // translatability when a field is shared across different entity types.
    $et_info += array('class' => 'EntityTranslationDefaultHandler');
    if (!isset($entity_info[$entity_type]['entity keys'])) {
      $entity_info[$entity_type]['entity keys'] = array();
    }
    $entity_info[$entity_type]['entity keys'] += array('translations' => 'translations');

    if (entity_translation_enabled($entity_type, NULL, TRUE)) {
      $entity_info[$entity_type]['language callback'] = 'entity_translation_language';

      // Process path schemes and fill-in defaults.
      _entity_translation_process_path_schemes($entity_type, $et_info);

      // Merge in default values for remaining keys.
      $et_info += array(
        'access callback' => 'entity_translation_tab_access',
        'access arguments' => array($entity_type),
      );

      // Interpret a TRUE value for the 'edit form' key as the default value.
      if (!isset($et_info['edit form']) || $et_info['edit form'] === TRUE) {
        $et_info['edit form'] = $entity_type;
      }
    }
  }
}

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

  $items['admin/config/regional/entity_translation'] = array(
    'title' => 'Entity translation',
    'description' => 'Configure which entities can be translated and enable or disable language fallback.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('entity_translation_admin_form'),
    'access arguments' => array('administer entity translation'),
    'file' => 'entity_translation.admin.inc',
    'module' => 'entity_translation',
  );

  $items['admin/config/regional/entity_translation/translatable/%'] = array(
    'title' => 'Confirm change in translatability.',
    'description' => 'Confirmation page for changing field translatability.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('entity_translation_translatable_form', 5),
    'access arguments' => array('toggle field translatability'),
    'file' => 'entity_translation.admin.inc',
  );

  return $items;
}

/**
 * Validate the given set of path schemes and remove invalid elements.
 *
 * Each path scheme needs to fulfill the following requirements:
 * - The 'path wildcard' key needs to be specified.
 * - Every path (base/view/edit/translate) needs to contain the path wildcard.
 * - The following path definitions (if specified) need to match existing menu
 *   items: 'base path', 'view path', 'edit path'.
 * - The 'translate path' definition needs to have an existing parent menu item.
 *
 * This function needs to be called once with a list of menu items passed as the
 * last parameter, before it can be used for validation.
 *
 * @param $schemes
 *   The array of path schemes.
 * @param $entity_type_label
 *   The label of the current entity type. This is used in error messages.
 * @param $items
 *   A list of menu items.
 * @param $warnings
 *   (optional) Displays warnings when a path scheme does not validate.
 */
function _entity_translation_validate_path_schemes(&$schemes, $entity_type_label, $items = FALSE, $warnings = FALSE) {
  $paths = &drupal_static(__FUNCTION__);
  static $regex = '|%[^/]+|';

  if (!empty($items)) {
    // Some menu loaders in the item paths might have been altered: we need to
    // replace any menu loader with a plain % to check if base paths are still
    // compatible.
    $paths = array();
    foreach ($items as $path => $item) {
      $stripped_path = preg_replace($regex, '%', $path);
      $paths[$stripped_path] = $path;
    }
  }

  if (empty($schemes)) {
    return;
  }

  // Make sure we have a set of paths to validate the scheme against.
  if (empty($paths)) {
    // This should never happen.
    throw new Exception('The Entity Translation path scheme validation function has not been initialized properly.');
  }

  foreach ($schemes as $delta => &$scheme) {
    // Every path scheme needs to declare a path wildcard for the entity id.
    if (empty($scheme['path wildcard'])) {
      if ($warnings) {
        $t_args = array('%scheme' => $delta, '%entity_type' => $entity_type_label);
        watchdog('entity_translation', 'Entity Translation path scheme %scheme for entities of type %entity_type does not declare a path wildcard.', $t_args);
      }
      unset($schemes[$delta]);
      continue;
    }

    $wildcard = $scheme['path wildcard'];
    $validate_keys = array('base path' => FALSE, 'view path' => FALSE, 'edit path' => FALSE, 'translate path' => TRUE);

    foreach ($validate_keys as $key => $check_parent) {
      if (isset($scheme[$key])) {
        $path = $scheme[$key];
        $parts = explode('/', $path);
        $scheme[$key . ' parts'] = $parts;

        // Check that the path contains the path wildcard. Required for
        // determining the position of the entity id in the path (see
        // entity_translation_menu_alter()).
        if (!in_array($wildcard, $parts)) {
          if ($warnings) {
            $t_args = array('%path_key' => $key, '%entity_type' => $entity_type_label, '%wildcard' => $wildcard, '%path' => $path);
            drupal_set_message(t('Invalid %path_key defined for entities of type %entity_type: entity wildcard %wildcard not found in %path.', $t_args), 'warning');
          }
          unset($scheme[$key]);
          continue;
        }

        // Remove the trailing path element for paths requiring an existing
        // parent menu item (i.e. the "translate path").
        $trailing_path_element = FALSE;
        if ($check_parent) {
          $trailing_path_element = array_pop($parts);
          $path = implode('/', $parts);
        }
        $stripped_path = preg_replace($regex, '%', $path);

        if (!isset($paths[$stripped_path])) {
          if ($warnings) {
            $t_args = array('%path_key' => $key, '%entity_type' => $entity_type_label, '%path' => $path);
            $msg = $check_parent ?
              t('Invalid %path_key defined for entities of type %entity_type: parent menu item not found for %path', $t_args) :
              t('Invalid %path_key defined for entities of type %entity_type: matching menu item not found for %path', $t_args);
            drupal_set_message($msg, 'warning');
          }
          unset($scheme[$key]);
        }
        // If there is a matching menu item for the current scheme key, save
        // the real path, i.e. the path of the matching menu item.
        else {
          $real_path = $paths[$stripped_path];
          $real_parts = explode('/', $real_path);

          // Restore previously removed trailing path element.
          if ($trailing_path_element) {
            $real_path .= '/' . $trailing_path_element;
            $real_parts[] = $trailing_path_element;
          }

          $scheme['real ' . $key] = $real_path;
          $scheme['real ' . $key . ' parts'] = $real_parts;
        }
      }
    }
  }
}

/**
 * Implements hook_menu_alter().
 */
function entity_translation_menu_alter(&$items) {
  $backup = array();

  // Initialize path schemes validation function with set of current menu items.
  $_null = NULL;
  _entity_translation_validate_path_schemes($_null, FALSE, $items);

  // Create tabs for all possible entity types.
  foreach (entity_get_info() as $entity_type => $info) {
    // Menu is rebuilt while determining entity translation base paths and
    // callbacks so we might not have them available yet.
    if (entity_translation_enabled($entity_type)) {
      $et_info = $info['translation']['entity_translation'];

      // Flag for tracking whether we have managed to attach the translate UI
      // successfully at least once.
      $translate_ui_attached = FALSE;

      // Validate path schemes for current entity type. Also removes invalid
      // ones and adds '... path parts' elements.
      _entity_translation_validate_path_schemes($et_info['path schemes'], $info['label'], FALSE, TRUE);

      foreach ($et_info['path schemes'] as $scheme) {
        $translate_item = NULL;
        $edit_item = NULL;

        // If we have a translate path then attach the translation UI, and
        // register the callback for deleting a translation.
        if (isset($scheme['translate path'])) {
          $translate_path = $scheme['translate path'];

          $keys = array('theme callback', 'theme arguments', 'access callback', 'access arguments', 'load arguments');
          $item = array_intersect_key($info['translation']['entity_translation'], drupal_map_assoc($keys));

          $item += array(
            'file' => 'entity_translation.admin.inc',
            'module' => 'entity_translation',
          );

          $entity_position = array_search($scheme['path wildcard'], $scheme['translate path parts']);

          if ($item['access callback'] == 'entity_translation_tab_access') {
            $item['access arguments'][] = $entity_position;
          }

          // Backup existing values for the translate overview page.
          if (isset($items[$translate_path])) {
            $backup[$entity_type] = $items[$translate_path];
          }

          $items[$translate_path] = array(
            'title' => 'Translate',
            'page callback' => 'entity_translation_overview',
            'page arguments' => array($entity_type, $entity_position),
            'type' => MENU_LOCAL_TASK,
            'weight' => 2,
            'context' => MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE,
          ) + $item;

          // Delete translation callback.
          $language_position = count($scheme['translate path parts']) + 1;
          $items["$translate_path/delete/%entity_translation_language"] = array(
            'title' => 'Delete',
            'page callback' => 'drupal_get_form',
            'page arguments' => array('entity_translation_delete_confirm', $entity_type, $entity_position, $language_position),
          ) + $item;

          $translate_item = &$items[$translate_path];
        }

        // If we have an edit path, then replace the menu edit form with our
        // proxy implementation, and register new callbacks for adding and
        // editing a translation.
        if (isset($scheme['edit path'])) {
          // Find the edit item. If the edit path is a default local task we
          // need to find the parent item.
          $real_edit_path_parts = $scheme['real edit path parts'];
          do {
            $edit_item = &$items[implode('/', $real_edit_path_parts)];
            array_pop($real_edit_path_parts);
          }
          while (!empty($edit_item['type']) && $edit_item['type'] == MENU_DEFAULT_LOCAL_TASK);

          $edit_path = $scheme['edit path'];
          $edit_path_parts = $scheme['edit path parts'];

          // Replace the main edit callback with our proxy implementation to set
          // form language to the current language and check access.
          $entity_position = array_search($scheme['path wildcard'], $edit_path_parts);
          $original_item = $edit_item;
          $args = array($entity_type, $entity_position, FALSE, $original_item);
          $edit_item['page callback'] = 'entity_translation_edit_page';
          $edit_item['page arguments'] = array_merge($args, $original_item['page arguments']);
          $edit_item['access callback'] = 'entity_translation_edit_access';
          $edit_item['access arguments'] = array_merge($args, $original_item['access arguments']);

          // Edit translation callback.
          if ($scheme['edit tabs'] !== FALSE) {
            $translation_position = count($edit_path_parts);
            $args = array($entity_type, $entity_position, $translation_position, $original_item);
            $items["$edit_path/%entity_translation_language"] = array(
              'type' => MENU_DEFAULT_LOCAL_TASK,
              'title callback' => 'entity_translation_edit_title',
              'title arguments' => array($translation_position),
              'page callback' => 'entity_translation_edit_page',
              'page arguments' => array_merge($args, $original_item['page arguments']),
              'access callback' => 'entity_translation_edit_access',
              'access arguments' => array_merge($args, $original_item['access arguments']),
            )
            // We need to inherit the remaining menu item keys, mostly 'module'
            // and 'file' to keep ajax callbacks working (see form_get_cache() and
            // drupal_retrieve_form()).
            + $original_item;
          }

          // Add translation callback.
          $add_path = "$edit_path/add/%entity_translation_language/%entity_translation_language";
          $source_position = count($edit_path_parts) + 1;
          $target_position = count($edit_path_parts) + 2;
          $args = array($entity_type, $entity_position, $source_position, $target_position, $original_item);
          $items[$add_path] = array(
            'title callback' => 'Add translation',
            'page callback' => 'entity_translation_add_page',
            'page arguments' => array_merge($args, $original_item['page arguments']),
            'type' => MENU_LOCAL_TASK,
            'access callback' => 'entity_translation_add_access',
            'access arguments' => array_merge($args, $original_item['access arguments']),
          ) + $original_item;
        }

        // Make the "Translate" tab follow the "Edit" tab if possible.
        if ($translate_item && $edit_item && isset($edit_item['weight'])) {
          $translate_item['weight'] = $edit_item['weight'] + 1;
        }

        // If we have both an edit item and a translate item, then we know that
        // the translate UI has been attached properly (at least once).
        $translate_ui_attached = $translate_ui_attached || ($translate_item && $edit_item);

        // Cleanup reference variables, so we don't accidentially overwrite
        // something in a later iteration.
        unset($translate_item, $edit_item);
      }

      if ($translate_ui_attached == FALSE) {
        watchdog('entity_translation', 'The entities of type %entity_type do not define a valid path scheme: it will not be possible to translate them.', array('%entity_type' => $info['label']));
      }

      // Entity-type-specific menu alterations.
      $function = 'entity_translation_' . $entity_type . '_menu_alter';
      if (function_exists($function)) {
        $function($items, $backup);
      }
    }
  }

  // Avoid bloating memory with unused data.
  drupal_static_reset('_entity_translation_validate_path_schemes');
}

/**
 * Title callback.
 */
function entity_translation_edit_title($langcode) {
  $languages = entity_translation_languages();
  return isset($languages[$langcode]) ? t($languages[$langcode]->name) : '';
}

/**
 * Page callback.
 */
function entity_translation_edit_page() {
  $args = func_get_args();
  $entity_type = array_shift($args);
  $entity = array_shift($args);
  $langcode = array_shift($args);
  $edit_form_item = array_shift($args);

  // Set the current form language.
  $handler = entity_translation_get_handler($entity_type, $entity);
  $handler->initPathScheme();
  $langcode = entity_translation_get_existing_language($entity_type, $entity, $langcode);
  $handler->setFormLanguage($langcode);

  // Display the entity edit form.
  return _entity_translation_callback($edit_form_item['page callback'], $args, $edit_form_item);
}

/**
 * Access callback.
 */
function entity_translation_edit_access() {
  $args = func_get_args();
  $entity_type = array_shift($args);
  $entity = array_shift($args);
  $langcode = array_shift($args);
  $edit_form_item = array_shift($args);
  $access_callback = isset($edit_form_item['access callback']) ? $edit_form_item['access callback'] : 'user_access';

  $handler = entity_translation_get_handler($entity_type, $entity);

  // First, check a handler has been loaded. This could be empty if a
  // non-existent entity edit path has been requested, for example. Delegate
  // directly to the edit form item access callback in this case.
  if (empty($handler)) {
    return _entity_translation_callback($access_callback, $args, $edit_form_item);
  }

  $translations = $handler->getTranslations();
  $langcode = entity_translation_get_existing_language($entity_type, $entity, $langcode);

  // The user must be explicitly allowed to access the original values if
  // workflow permissions are enabled.
  if (!$handler->getTranslationAccess($langcode)) {
    return FALSE;
  }

  // If the translation exists or no translation was specified, we can show the
  // corresponding local task. If translations have not been initialized yet, we
  // need to grant access to the user.
  if (empty($translations->data) || isset($translations->data[$langcode])) {
    // Check that the requested language is actually accessible. If the entity
    // is language neutral we need to let editors access it.
    $enabled_languages = entity_translation_languages($entity_type, $entity);
    if (isset($enabled_languages[$langcode]) || $langcode == LANGUAGE_NONE) {
      return _entity_translation_callback($access_callback, $args, $edit_form_item);
    }
  }

  return FALSE;
}

/**
 * Determines the current form language.
 *
 * @param $langcode
 *   The requested language code.
 * @param EntityTranslationHandlerInterface $handler
 *   A translation handler instance.
 *
 * @return
 *   A valid language code.
 *
 * @deprecated This is no longer used and will be removed in the first stable
 *   release.
 */
function entity_translation_form_language($langcode, $handler) {
  return entity_translation_get_existing_language($handler->getEntity(), $handler->getEntityType(), $langcode);
}

/**
 * Determines an existing translation language.
 *
 * Based on the requested language and the translations available for the given
 * entity, determines an existing translation language. This takes into account
 * language fallback rules.
 *
 * @param $entity_type
 *    The type of the entity.
 * @param $entity
 *    The entity whose existing translation language has to be returned.
 * @param $langcode
 *   (optional) The requested language code. Defaults to the current content
 *   language.
 *
 * @return
 *   A valid language code.
 */
function entity_translation_get_existing_language($entity_type, $entity, $langcode = NULL) {
  $handler = entity_translation_get_handler($entity_type, $entity);

  if (empty($langcode)) {
    $langcode = $GLOBALS['language_content']->language;
  }

  $translations = $handler->getTranslations();
  $fallback = drupal_multilingual() ? language_fallback_get_candidates() : array(LANGUAGE_NONE);
  while (!empty($langcode) && !isset($translations->data[$langcode])) {
    $langcode = array_shift($fallback);
  }

  // If no translation is available fall back to the entity language.
  return !empty($langcode) ? $langcode : $handler->getLanguage();
}

/**
 * Access callback.
 */
function entity_translation_add_access() {
  $args = func_get_args();
  $entity_type = array_shift($args);
  $entity = array_shift($args);
  $source = array_shift($args);
  $langcode = array_shift($args);

  $handler = entity_translation_get_handler($entity_type, $entity);
  $translations = $handler->getTranslations();

  // If the translation does not exist we can show the tab.
  if (!isset($translations->data[$langcode]) && $langcode != $source) {
    // Check that the requested language is actually accessible.
    $enabled_languages = entity_translation_languages($entity_type, $entity);
    if (isset($enabled_languages[$langcode])) {
      $edit_form_item = array_shift($args);
      $access_callback = isset($edit_form_item['access callback']) ? $edit_form_item['access callback'] : 'user_access';
      return _entity_translation_callback($access_callback, $args, $edit_form_item);
    }
  }

  return FALSE;
}

/**
 * Page callback.
 */
function entity_translation_add_page() {
  $args = func_get_args();
  $entity_type = array_shift($args);
  $entity = array_shift($args);
  $source = array_shift($args);
  $langcode = array_shift($args);
  $edit_form_item = array_shift($args);

  $handler = entity_translation_get_handler($entity_type, $entity);
  $handler->initPathScheme();
  $handler->setFormLanguage($langcode);
  $handler->setSourceLanguage($source);

  // Display the entity edit form.
  return _entity_translation_callback($edit_form_item['page callback'], $args, $edit_form_item);
}

/**
 * Helper function. Proxies a callback call including any needed file.
 */
function _entity_translation_callback($callback, $args, $info = array()) {
  if (isset($info['file'])) {
    $path = isset($info['file path']) ? $info['file path'] : drupal_get_path('module', $info['module']);
    include_once DRUPAL_ROOT . '/' . $path . '/' . $info['file'];
  }
  return call_user_func_array($callback, $args);
}

/**
 * Implements hook_admin_paths().
 */
function entity_translation_admin_paths() {
  $paths = array();
  foreach (entity_get_info() as $entity_type => $info) {
    if (isset($info['translation']['entity_translation']['path schemes']) && entity_translation_enabled($entity_type, NULL, TRUE)) {
      foreach ($info['translation']['entity_translation']['path schemes'] as $scheme) {
        if (!empty($scheme['admin theme'])) {
          if (isset($scheme['translate path'])) {
            $translate_path = preg_replace('|%[^/]*|', '*', $scheme['translate path']);
            $paths[$translate_path] = TRUE;
            $paths["$translate_path/*"] = TRUE;
          }
          if (isset($scheme['edit path'])) {
            $edit_path = preg_replace('|%[^/]*|', '*', $scheme['edit path']);
            $paths["$edit_path/*"] = TRUE;
          }
        }
      }
    }
  }
  return $paths;
}

/**
 * Access callback.
 */
function entity_translation_tab_access($entity_type, $entity) {
  if (drupal_multilingual() && (user_access('translate any entity') || user_access("translate $entity_type entities"))) {
    $handler = entity_translation_get_handler($entity_type, $entity);
    // Ensure $entity holds an entity object and not an id.
    $entity = $handler->getEntity();

    $enabled = entity_translation_enabled($entity_type, $entity);
    return $enabled && $handler->getLanguage() != LANGUAGE_NONE;
  }
  return FALSE;
}

/**
 * Menu loader callback.
 */
function entity_translation_language_load($langcode, $entity_type = NULL, $entity = NULL) {
  $enabled_languages = entity_translation_languages($entity_type, $entity);
  return isset($enabled_languages[$langcode]) ? $langcode : FALSE;
}

/**
 * Menu loader callback.
 */
function entity_translation_menu_entity_load($entity_id, $entity_type) {
  $entities = entity_load($entity_type, array($entity_id));
  return $entities[$entity_id];
}

/**
 * Implements hook_permission().
 */
function entity_translation_permission() {
  $permission = array(
    'administer entity translation' => array(
      'title' => t('Administer entity translation'),
      'description' => t('Select which entities can be translated.'),
    ),
    'toggle field translatability' => array(
      'title' => t('Toggle field translatability'),
      'description' => t('Toggle translatability of fields performing a bulk update.'),
    ),
    'translate any entity' => array(
      'title' => t('Translate any entity'),
      'description' => t('Translate field content for any fieldable entity.'),
    ),
  );

  $workflow = entity_translation_workflow_enabled();
  if ($workflow) {
    $permission += array(
      'edit translation shared fields' => array(
        'title' => t('Edit shared values'),
        'description' => t('Edit values shared between translations on the entity form.'),
      ),
      'edit original values' => array(
        'title' => t('Edit original values'),
        'description' => t('Access any entity form in the original language.'),
      ),
    );
  }

  foreach (entity_get_info() as $entity_type => $info) {
    if ($info['fieldable'] && entity_translation_enabled($entity_type)) {
      $label = !empty($info['label']) ? t($info['label']) : $entity_type;
      $permission["translate $entity_type entities"] = array(
        'title' => t('Translate entities of type @type', array('@type' => $label)),
        'description' => t('Translate field content for entities of type @type.', array('@type' => $label)),
      );

      if ($workflow) {
        // Avoid access control for original values on the current entity.
        if (empty($info['translation']['entity_translation']['skip original values access'])) {
          $permission["edit $entity_type original values"] = array(
            'title' => t('Edit original values on entities of type @type', array('@type' => $label)),
            'description' => t('Access the entity form in the original language for entities of type @type.', array('@type' => $label)),
          );
        }

        // Avoid access control for shared fields on the current entity.
        if (empty($info['translation']['entity_translation']['skip shared fields access'])) {
          $permission["edit $entity_type translation shared fields"] = array(
            'title' => t('Edit @type shared values.', array('@type' => $label)),
            'description' => t('Edit values shared between translations on @type forms.', array('@type' => $label)),
          );
        }
      }
    }
  }

  return $permission;
}

/**
 * Returns TRUE if the translation workflow is enabled.
 */
function entity_translation_workflow_enabled() {
  return variable_get('entity_translation_workflow_enabled', FALSE);
}

/**
 * Implements hook_theme().
 */
function entity_translation_theme() {
  return array(
    'entity_translation_unavailable' => array(
      'variables' => array('element' => NULL),
    ),
    'entity_translation_language_tabs' => array(
      'render element' => 'element',
    ),
    'entity_translation_overview' => array(
      'variables' => array('rows' => NULL, 'header' => NULL),
      'file' => 'entity_translation.admin.inc'
    ),
    'entity_translation_overview_outdated' => array(
      'variables' => array('message' => NULL),
      'file' => 'entity_translation.admin.inc'
    ),
  );
}

/**
 * Implements hook_entity_load().
 */
function entity_translation_entity_load($entities, $entity_type) {
  if (entity_translation_enabled($entity_type)) {
    EntityTranslationDefaultHandler::loadMultiple($entity_type, $entities);
  }
}

/**
 * Implements hook_field_extra_fields().
 */
function entity_translation_field_extra_fields() {
  $extra = array();
  $enabled = variable_get('entity_translation_entity_types', array());
  $info = entity_get_info();

  foreach ($enabled as $entity_type) {
    if (entity_translation_enabled($entity_type)) {
      $bundles = !empty($info[$entity_type]['bundles']) ? array_keys($info[$entity_type]['bundles']) : array($entity_type);
      foreach ($bundles as $bundle) {
        $settings = entity_translation_settings($entity_type, $bundle);
        if (empty($settings['hide_language_selector']) && entity_translation_enabled_bundle($entity_type, $bundle) && ($handler = entity_translation_get_handler($entity_type, $bundle))) {
          $language_key = $handler->getLanguageKey();
          $extra[$entity_type][$bundle] = array(
            'form' => array(
              $language_key => array(
                'label' => t('Language'),
                'description' => t('Language selection'),
                'weight' => 5,
              ),
            ),
          );
        }
      }
    }
  }

  return $extra;
}

/**
 * Implements hook_field_language_alter().
 *
 * Performs language fallback for unaccessible translations.
 */
function entity_translation_field_language_alter(&$display_language, $context) {
  if (variable_get('locale_field_language_fallback', TRUE) && entity_translation_enabled($context['entity_type'])) {
    $entity = $context['entity'];
    $entity_type = $context['entity_type'];
    $handler = entity_translation_get_handler($entity_type, $entity);
    $translations = $handler->getTranslations();

    // Apply fallback only on unpublished translations as missing translations
    // are already handled in locale_field_language_alter().
    if (isset($translations->data[$context['language']]) && !entity_translation_access($entity_type, $translations->data[$context['language']])) {
      list(, , $bundle) = entity_extract_ids($entity_type, $entity);
      $instances = field_info_instances($entity_type, $bundle);
      $entity = clone($entity);

      foreach ($translations->data as $langcode => $translation) {
        if ($langcode == $context['language'] || !entity_translation_access($entity_type, $translations->data[$langcode])) {
          // Unset unaccessible field translations: if the field is
          // untranslatable unsetting a language different from LANGUAGE_NONE
          // has no effect.
          foreach ($instances as $instance) {
            unset($entity->{$instance['field_name']}[$langcode]);
          }
        }
      }

      // Find the new fallback values.
      locale_field_language_fallback($display_language, $entity, $context['language']);
    }
    elseif (!field_has_translation_handler($entity_type, 'locale')) {
      // If not handled by the Locale translation handler trigger fallback too.
      locale_field_language_fallback($display_language, $entity, $context['language']);
    }
  }
}

/**
 * Implements hook_field_attach_view_alter().
 *
 * Hide the entity if no translation is available for the current language and
 * language fallback is disabled.
 */
function entity_translation_field_attach_view_alter(&$output, $context) {
  if (!variable_get('locale_field_language_fallback', TRUE) && entity_translation_enabled($context['entity_type'])) {
    $handler = entity_translation_get_handler($context['entity_type'], $context['entity']);
    $translations = $handler->getTranslations();
    $langcode = !empty($context['language']) ? $context['language'] : $GLOBALS['language_content']->language;

    // If fallback is disabled we need to notify the user that the translation
    // is unavailable (missing or unpublished).
    if (!empty($translations->data) && ((!isset($translations->data[$langcode]) && !isset($translations->data[LANGUAGE_NONE])) || ((isset($translations->data[$langcode]) && !entity_translation_access($context['entity_type'], $translations->data[$langcode]))))) {
      // Provide context for rendering.
      $output['#entity'] = $context['entity'];
      $output['#entity_type'] = $context['entity_type'];
      $output['#view_mode'] = $context['view_mode'];
      // We perform theming here because the theming function might need to set
      // system messages. It would be too late in the #post_render callback.
      $output['#entity_translation_unavailable'] = theme('entity_translation_unavailable', array('element' => $output));
      // As we used a string key, other modules implementing
      // hook_field_attach_view_alter() may unset/override this.
      $output['#post_render']['entity_translation'] = 'entity_translation_unavailable';
    }
  }
}

/**
 * Override the entity output with the unavailable translation one.
 */
function entity_translation_unavailable($children, $element) {
  return $element['#entity_translation_unavailable'];
}

/**
 * Theme an unvailable translation.
 */
function theme_entity_translation_unavailable($variables) {
  $element = $variables['element'];
  $handler = entity_translation_get_handler($element['#entity_type'], $element['#entity']);
  $args = array('%language' => t($GLOBALS['language_content']->name), '%label' => $handler->getLabel());
  $message = t('%language translation unavailable for %label.', $args);
  $classes = $element['#entity_type'] . ' ' . $element['#entity_type'] . '-' . $element['#view_mode'];
  return "<div class=\"$classes\"><div class=\"messages warning\">$message</div></div>";
}

/**
 * Implements hook_field_info_alter().
 */
function entity_translation_field_info_alter(&$info) {
  $columns = array('fid');
  $supported_types = array('file' => $columns, 'image' => $columns);

  foreach ($info as $field_type => &$field_type_info) {
    // Store columns to be synchronized.
    if (!isset($field_type_info['settings'])) {
      $field_type_info['settings'] = array();
    }
    $field_type_info['settings'] += array(
      'entity_translation_sync' => isset($supported_types[$field_type]) ? $supported_types[$field_type] : FALSE,
    );
    // Synchronization can be enabled per instance.
    if (!isset($field_type_info['instance_settings'])) {
      $field_type_info['instance_settings'] = array();
    }
    $field_type_info['instance_settings'] += array(
      'entity_translation_sync' => FALSE,
    );
  }
}

/**
 * Implements hook_field_attach_presave().
 */
function entity_translation_field_attach_presave($entity_type, $entity) {
  if (entity_translation_enabled($entity_type, $entity)) {
    entity_translation_sync($entity_type, $entity);
  }
}

/**
 * Performs field column synchronization.
 */
function entity_translation_sync($entity_type, $entity) {
  // If we are creating a new entity or if we have no translations for the
  // current entity, there is nothing to synchronize.
  $handler = entity_translation_get_handler($entity_type, $entity, TRUE);
  $translations = $handler->getTranslations();
  $original_langcode = $handler->getSourceLanguage();
  if ($handler->isNewEntity() || (count($translations->data) < 2 && !$original_langcode)) {
    return;
  }

  list($id, , $bundle) = entity_extract_ids($entity_type, $entity);
  $instances = field_info_instances($entity_type, $bundle);
  $entity_unchanged = isset($entity->original) ? $entity->original : entity_load_unchanged($entity_type, $id);

  // If the entity language is being changed there is nothing to synchronize.
  $langcode = $handler->getLanguage();
  $handler->setEntity($entity_unchanged);
  if ($langcode != $handler->getLanguage()) {
    return;
  }

  foreach ($instances as $field_name => $instance) {
    $field = field_info_field($field_name);

    // If the field is empty there is nothing to synchronize. Synchronization
    // makes sense only for translatable fields.
    if (!empty($entity->{$field_name}) && !empty($instance['settings']['entity_translation_sync']) && field_is_translatable($entity_type, $field)) {
      $columns = $field['settings']['entity_translation_sync'];
      $change_map = array();
      $source_langcode = entity_language($entity_type, $entity);
      $source_items = $entity->{$field_name}[$source_langcode];

      // If a translation is being created, the original values should be used
      // as the unchanged items. In fact there are no unchanged items to check
      // against.
      $langcode = $original_langcode ? $original_langcode : $source_langcode;
      $unchanged_items = !empty($entity_unchanged->{$field_name}[$langcode]) ? $entity_unchanged->{$field_name}[$langcode] : array();

      // By picking the maximum size between updated and unchanged items, we
      // make sure to process also removed items.
      $total = max(array(count($source_items), count($unchanged_items)));

      // Make sure we can detect any change in the source items.
      for ($delta = 0; $delta < $total; $delta++) {
        foreach ($columns as $column) {
          // Store the delta for the unchanged column value.
          if (isset($unchanged_items[$delta][$column])) {
            $value = $unchanged_items[$delta][$column];
            $change_map[$column][$value]['old'] = $delta;
          }
          // Store the delta for the new column value.
          if (isset($source_items[$delta][$column])) {
            $value = $source_items[$delta][$column];
            $change_map[$column][$value]['new'] = $delta;
          }
        }
      }

      // Backup field values.
      $field_values = $entity->{$field_name};

      // Reset field values so that no spurious translation value is stored.
      // Source values and anything else must be preserved in any case.
      $entity->{$field_name} = array($source_langcode => $source_items) + array_diff_key($entity->{$field_name}, $translations->data);

      // Update translations.
      foreach ($translations->data as $langcode => $translation) {
        // We need to synchronize only values different from the source ones.
        if ($langcode != $source_langcode) {
          // Process even removed items.
          for ($delta = 0; $delta < $total; $delta++) {
            $created = TRUE;
            $removed = TRUE;

            foreach ($columns as $column) {
              if (isset($source_items[$delta][$column])) {
                $value = $source_items[$delta][$column];
                $created = $created && !isset($change_map[$column][$value]['old']);
                $removed = $removed && !isset($change_map[$column][$value]['new']);
              }
            }

            // If an item has been removed we do not store its translations.
            if ($removed) {
              // Ensure items are actually removed.
              if (!isset($entity->{$field_name}[$langcode])) {
                $entity->{$field_name}[$langcode] = array();
              }
              continue;
            }
            // If a synchronized column has changed we need to override the full
            // items array for all languages.
            elseif ($created) {
              $entity->{$field_name}[$langcode][$delta] = $source_items[$delta];
            }
            // The current item might have been reordered.
            elseif (!empty($change_map[$column][$value])) {
              $old_delta = $change_map[$column][$value]['old'];
              $new_delta = $change_map[$column][$value]['new'];
              // If for nay reason the old value is not defined for the current
              // we language we fall back to the new source value.
              $items = isset($field_values[$langcode][$old_delta]) ? $field_values[$langcode][$old_delta] : $source_items[$new_delta];
              $entity->{$field_name}[$langcode][$new_delta] = $items;
            }
          }
        }
      }
    }
  }
}

/**
 * Implements hook_field_attach_insert().
 */
function entity_translation_field_attach_insert($entity_type, $entity) {
  // Store entity translation metadata only if the entity bundle is
  // translatable.
  if (entity_translation_enabled($entity_type, $entity)) {
    $handler = entity_translation_get_handler($entity_type, $entity);
    $handler->initTranslations();
    $handler->saveTranslations();
  }
}

/**
 * Implements hook_field_attach_update().
 */
function entity_translation_field_attach_update($entity_type, $entity) {
  // Store entity translation metadata only if the entity bundle is
  // translatable.
  if (entity_translation_enabled($entity_type, $entity)) {
    $handler = entity_translation_get_handler($entity_type, $entity, TRUE);
    $handler->updateTranslations();
    $handler->saveTranslations();
  }
}

/**
 * Implements hook_field_attach_delete().
 */
function entity_translation_field_attach_delete($entity_type, $entity) {
  if (entity_translation_enabled($entity_type, $entity)) {
    $handler = entity_translation_get_handler($entity_type, $entity);
    $handler->removeTranslations();
    $handler->saveTranslations();
  }
}

/**
 * Implements hook_field_attach_delete_revision().
 */
function entity_translation_field_attach_delete_revision($entity_type, $entity) {
  if (entity_translation_enabled($entity_type, $entity)) {
    $handler = entity_translation_get_handler($entity_type, $entity);
    $handler->removeRevisionTranslations();
    $handler->saveTranslations();
  }
}

/**
 * Implementation of hook_field_attach_form().
 */
function entity_translation_field_attach_form($entity_type, $entity, &$form, &$form_state, $langcode) {
  // Avoid recursing into the source form.
  list($id, , $bundle) = entity_extract_ids($entity_type, $entity);
  if (empty($form['#entity_translation_source_form']) && entity_translation_enabled($entity_type, $bundle)) {
    $handler = entity_translation_get_handler($entity_type, $entity);
    $langcode = !empty($langcode) ? $langcode : $handler->getLanguage();
    $form_langcode = $handler->getFormLanguage();
    $translations = $handler->getTranslations();
    $update_langcode = $form_langcode && ($form_langcode != $langcode);
    $source = $handler->getSourceLanguage();
    $new_translation = !isset($translations->data[$form_langcode]);

    // If we are creating a new translation we need to retrieve form elements
    // populated with the source language values, but only if form is not being
    // rebuilt. In this case source values have already been populated, so we
    // need to preserve possible changes. There might be situations, e.g. ajax
    // calls, where the form language has not been properly initialized before
    // calling field_attach_form(). In this case we need to rebuild the form
    // with the correct form language and replace the field elements with the
    // correct ones.
    if ($update_langcode || ($source && !isset($translations->data[$form_langcode]) && isset($translations->data[$source]) && empty($form_state['rebuild']))) {
      foreach (field_info_instances($entity_type, $bundle) as $instance) {
        $field_name = $instance['field_name'];
        $field = field_info_field($field_name);

        // If we are creating a new translation we have to change the form item
        // language information from source to target language, this way the
        // user can find the form items already populated with the source values
        // while the field form element holds the correct language information.
        if ($field['translatable']) {
          $element = &$form[$field_name];
          $element['#entity_type'] = $entity_type;
          $element['#entity'] = $entity;
          $element['#entity_id'] = $id;
          $element['#field_name'] = $field_name;
          $element['#source'] = $update_langcode ? $form_langcode : $source;
          $element['#previous'] = NULL;
          $element['#form_parents'] = $form['#parents'];

          // If we are updating the form language we need to make sure that the
          // wrong language is unset and the right one is stored in the field
          // element (see entity_translation_prepare_element()).
          if ($update_langcode) {
            $element['#previous'] = $element['#language'];
            $element['#language'] = $form_langcode;
          }

          // Swap default values during form processing to avoid recursion. We
          // try to act before any other callback so that the correct values are
          // already in place for them.
          if (!isset($element['#process'])) {
            $element['#process'] = array();
          }
          array_unshift($element['#process'], 'entity_translation_prepare_element');
        }
      }
    }

    // Handle fields shared between translations when there is at least one
    // translation available or a new one is being created.
    if (!$handler->isNewEntity() && ($new_translation || count($translations->data) > 1)) {
      $shared_access = $handler->getSharedFieldsAccess();
      list(, , $bundle) = entity_extract_ids($entity_type, $entity);
      foreach (field_info_instances($entity_type, $bundle) as $instance) {
        $field_name = $instance['field_name'];
        $field = field_info_field($field_name);
        // If access is not set or is granted we check whether the user has
        // access to shared fields.
        $form[$field_name]['#access'] = (!isset($form[$field_name]['#access']) || $form[$field_name]['#access']) && ($field['translatable'] || $shared_access);
        $form[$field_name]['#multilingual'] = (boolean) $field['translatable'];
      }
    }

    // If a translation is being created and no path alias exists for its
    // language, by default an alias needs to be generated. The standard
    // behavior is defaulting to FALSE when an entity already exists, hence we
    // need to override it here.
    if (module_exists('pathauto') && $handler->getSourceLanguage()) {
      $entity->path['pathauto'] = TRUE;
    }
  }
}

/**
 * Form element process callback.
 */
function entity_translation_prepare_element($element, &$form_state) {
  static $drupal_static_fast;
  if (!isset($drupal_static_fast)) {
    $drupal_static_fast = &drupal_static(__FUNCTION__, array(
      'source_forms' => array(),
      'source_form_states' => array(),
    ));
  }

  $source_forms = &$drupal_static_fast['source_forms'];
  $source_form_states = &$drupal_static_fast['source_form_states'];
  $form = $form_state['complete form'];
  $build_id = $form['#build_id'];
  $source = $element['#source'];
  $entity_type = $element['#entity_type'];
  $id = $element['#entity_id'];

  // Key the source form cache per entity type and entity id to allow for
  // multiple entities on the same entity form.
  if (!isset($source_forms[$build_id][$source][$entity_type][$id])) {
    $source_form = array(
      '#entity_translation_source_form' => TRUE,
      '#parents' => $element['#form_parents'],
    );
    $source_form_state = $form_state;
    field_attach_form($entity_type, $element['#entity'], $source_form, $source_form_state, $source);
    $source_forms[$build_id][$source][$entity_type][$id] = &$source_form;
    $source_form_states[$build_id][$source][$entity_type][$id] = &$source_form_state;
  }

  $source_form = &$source_forms[$build_id][$source][$entity_type][$id];
  $source_form_state = $source_form_states[$build_id][$source][$entity_type][$id];
  $langcode = $element['#language'];
  $field_name = $element['#field_name'];

  // If we are creating a new translation we have to change the form item
  // language information from source to target language, this way the user can
  // find the form items already populated with the source values while the
  // field form element holds the correct language information.
  if (isset($source_form[$field_name][$source])) {
    $element[$langcode] = $source_form[$field_name][$source];
    entity_translation_form_element_language_replace($element, $source, $langcode);
    entity_translation_form_element_state_replace($element, $source_form[$field_name], $field_name, $source_form_state, $form_state);
    unset($element[$element['#previous']]);
  }

  return $element;
}

/**
 * Helper function. Sets the right values in $form_state['field'] when using
 * source language values as defaults.
 */
function entity_translation_form_element_state_replace($element, $source_element, $field_name, $source_form_state, &$form_state) {
  if (isset($source_element['#language'])) {
    $source = $source_element['#language'];

    // Iterate through the form structure recursively.
    foreach (element_children($element) as $key) {
      if (isset($source_element[$key])) {
        entity_translation_form_element_state_replace($element[$key], $source_element[$key], $key, $source_form_state, $form_state);
      }
      elseif (isset($source_element[$source])) {
        entity_translation_form_element_state_replace($element[$key], $source_element[$source], $key, $source_form_state, $form_state);
      }
    }

    if (isset($source_element[$source]['#field_parents'])) {
      $source_parents = $source_element[$source]['#field_parents'];
      $langcode = $element['#language'];
      $parents = $element[$langcode]['#field_parents'];
      $source_state = field_form_get_state($source_parents, $field_name, $source, $source_form_state);
      drupal_alter('entity_translation_source_field_state', $source_state);
      field_form_set_state($parents, $field_name, $langcode, $form_state, $source_state);
    }
  }
}

/**
 * Helper function. Recursively replaces the source language with the given one.
 */
function entity_translation_form_element_language_replace(&$element, $source, $langcode) {
  // Iterate through the form structure recursively.
  foreach (element_children($element) as $key) {
    entity_translation_form_element_language_replace($element[$key], $source, $langcode);
  }

  // Replace specific occurrences of the source language with the target
  // language.
  foreach (element_properties($element) as $key) {
    if ($key === '#language' && $element[$key] != LANGUAGE_NONE) {
      $element[$key] = $langcode;
    }
    elseif ($key === '#parents' || $key === '#field_parents') {
      foreach ($element[$key] as $delta => $value) {
        if ($value === $source) {
          $element[$key][$delta] = $langcode;
        }
      }
    }
    elseif ($key === '#limit_validation_errors') {
      foreach ($element[$key] as $section => $section_value) {
        foreach ($element[$key][$section] as $delta => $value) {
          if ($value === $source) {
            $element[$key][$section][$delta] = $langcode;
          }
        }
      }
    }
  }
}

/**
 * Adds visual clues about the translatability of a field to the given element.
 *
 * Field titles are appended with the string "Shared" for fields which are
 * shared between different translations. Moreover fields receive a CSS class to
 * distinguish between translatable and shared fields.
 */
function entity_translation_element_translatability_clue($element) {
  // Append language to element title.
  if (empty($element['#multilingual'])) {
    _entity_translation_element_title_append($element, ' (' . t('all languages') . ')');
  }

  // Add CSS class names.
  if (!isset($element['#attributes'])) {
    $element['#attributes'] = array();
  }
  if (!isset($element['#attributes']['class'])) {
    $element['#attributes']['class'] = array();
  }
  $element['#attributes']['class'][] = 'entity-translation-' . (!empty($element['#multilingual']) ? 'field-translatable' : 'field-shared');

  return $element;
}

/**
 * Adds a callback function to the given FAPI element.
 *
 * Drupal core only adds default element callbacks if the respective handler
 * type is not defined yet. This function ensures that our callback is only
 * prepended/appended to the default set of callbacks instead of replacing it.
 *
 * @param $element
 *   The FAPI element.
 * @param $type
 *   The callback type, e.g. '#pre_render' or '#process'.
 * @param $function
 *   The name of the callback to add.
 * @param $prepend
 *   Set to TRUE to add the new callback to the beginning of the existing set of
 *   callbacks, and set it to FALSE to append it at the end.
 */
function _entity_translation_element_add_callback(&$element, $type, $function, $prepend = TRUE) {
  // If handler type has not been set, add defaults from element_info().
  if (!isset($element[$type])) {
    $element_type = isset($element['#type']) ? $element['#type'] : 'markup';
    $element_info = element_info($element_type);
    $element[$type] = isset($element_info[$type]) ? $element_info[$type] : array();
  }
  if ($prepend) {
    array_unshift($element[$type], $function);
  }
  else {
    $element[$type][] = $function;
  }
}

/**
 * Appends the given $suffix string to the title of the given form element.
 *
 * If the given element does not have a #title attribute, the function is
 * recursively applied to child elements.
 */
function _entity_translation_element_title_append(&$element, $suffix) {
  static $fapi_title_elements;

  // Elements which can have a #title attribute according to FAPI Reference.
  if (!isset($fapi_title_elements)) {
    $fapi_title_elements = array_flip(array('checkbox', 'checkboxes', 'date', 'fieldset', 'file', 'item', 'password', 'password_confirm', 'radio', 'radios', 'select', 'text_format', 'textarea', 'textfield', 'weight'));
  }

  // Update #title attribute for all elements that are allowed to have a #title
  // attribute according to the Form API Reference. The reason for this check
  // is because some elements have a #title attribute even though it is not
  // rendered, e.g. field containers.
  if (isset($element['#type']) && isset($fapi_title_elements[$element['#type']]) && isset($element['#title'])) {
    $element['#title'] .= $suffix;
  }
  // If this is a multi-valued field, apply the suffix to the container.
  elseif (isset($element['#title']) && isset($element['#cardinality']) && $element['#cardinality'] != 1) {
    $element['#title'] .= $suffix;
  }
  // If the current element does not have a (valid) title, try child elements.
  elseif ($children = element_children($element)) {
    foreach ($children as $delta) {
      _entity_translation_element_title_append($element[$delta], $suffix);
    }
  }
  // If there are no children, fall back to the current #title attribute if it
  // exists.
  elseif (isset($element['#title'])) {
    $element['#title'] .= $suffix;
  }
}

/**
 * Implements hook_form_alter().
 */
function entity_translation_form_alter(&$form, &$form_state) {
  if ($info = entity_translation_edit_form_info($form, $form_state)) {
    $handler = entity_translation_get_handler($info['entity type'], $info['entity']);
    if (entity_translation_enabled($info['entity type'], $info['entity'])) {
      if (!$handler->isNewEntity()) {
        $handler->entityForm($form, $form_state);
        $translations = $handler->getTranslations();
        $form_langcode = $handler->getFormLanguage();
        if (!isset($translations->data[$form_langcode]) || count($translations->data) > 1) {
          // Hide shared form elements if the user is not allowed to edit them.
          $handler->entityFormSharedElements($form);
        }
      }
      else {
        $handler->entityFormLanguageWidget($form, $form_state);
      }
      // We need to process the posted form as early as possible to update the
      // form language value.
      array_unshift($form['#validate'], 'entity_translation_entity_form_validate');
    }
    // We might have an entity form for an entity or a bundle not enabled for
    // translation. In this case we might need to deal with entity and field
    // languages anyway, since fields may be shared among different bundles and
    // entity types.
    else {
      $handler->entityFormLanguageWidget($form, $form_state);
    }
  }
}

/**
 * Submit handler for the source language selector.
 */
function entity_translation_entity_form_source_language_submit($form, &$form_state) {
  $handler = entity_translation_entity_form_get_handler($form, $form_state);
  $langcode = $form_state['values']['source_language']['language'];
  $path = "{$handler->getEditPath()}/add/$langcode/{$handler->getFormLanguage()}";
  $options = array();
  if (isset($_GET['destination'])) {
    $options['query'] = drupal_get_destination();
    unset($_GET['destination']);
  }
  $form_state['redirect'] = array($path, $options);
  $languages = language_list();
  drupal_set_message(t('Source translation set to: %language', array('%language' => t($languages[$langcode]->name))));
}

/**
 * Submit handler for the translation deletion.
 */
function entity_translation_entity_form_delete_translation_submit($form, &$form_state) {
  $handler = entity_translation_entity_form_get_handler($form, $form_state);
  $path = "{$handler->getTranslatePath()}/delete/{$handler->getFormLanguage()}";
  $options = array();
  if (isset($_GET['destination'])) {
    $options['query'] = drupal_get_destination();
    unset($_GET['destination']);
  }
  $form_state['redirect'] = array($path, $options);
}

/**
 * Validation handler for the entity edit form.
 */
function entity_translation_entity_form_validate($form, &$form_state) {
  $handler = entity_translation_entity_form_get_handler($form, $form_state);
  if (!empty($handler)) {
    $handler->entityFormValidate($form, $form_state);
  }
}

/**
 * Validation handler for the entity language widget.
 */
function entity_translation_entity_form_language_update($element, &$form_state, $form) {
  $handler = entity_translation_entity_form_get_handler($form, $form_state);
  // Ensure the handler form language match the actual one. This is mainly
  // needed when responding to an AJAX request where the languages cannot be set
  // from the usual page callback.
  if (!empty($form_state['entity_translation']['form_langcode'])) {
    $handler->setFormLanguage($form_state['entity_translation']['form_langcode']);
  }
  // When responding to an AJAX request we should ignore any change in the
  // language widget as it may alter the field language expected by the AJAX
  // callback.
  if (empty($form_state['triggering_element']['#ajax'])) {
    $handler->entityFormLanguageWidgetSubmit($form, $form_state);
  }
}

/**
 * Submit handler for the entity deletion.
 */
function entity_translation_entity_form_submit($form, &$form_state) {
  if ($form_state['clicked_button']['#value'] == t('Delete')) {
    $handler = entity_translation_entity_form_get_handler($form, $form_state);
    if (count($handler->getTranslations()->data) > 1) {
      $info = entity_get_info($form['#entity_type']);
      drupal_set_message(t('This will delete all the @entity_type translations.', array('@entity_type' => drupal_strtolower($info['label']))), 'warning');
    }
  }
}

/**
 * Implementation of hook_field_attach_submit().
 *
 * Mark translations as outdated if the submitted value is true.
 */
function entity_translation_field_attach_submit($entity_type, $entity, $form, &$form_state) {
  if (($handler = entity_translation_entity_form_get_handler($form, $form_state)) && entity_translation_enabled($entity_type, $entity)) {
    // Update the wrapped entity with the submitted values.
    $handler->setEntity($entity);
    $handler->entityFormSubmit($form, $form_state);
  }
}

/**
 * Implements hook_menu_local_tasks_alter().
 */
function entity_translation_menu_local_tasks_alter(&$data, $router_item, $root_path) {
  // When displaying the main edit form, we need to craft an additional level of
  // local tasks for each available translation.
  $handler = entity_translation_get_handler();
  if (!empty($handler) && $handler->isEntityForm() && $handler->getLanguage() != LANGUAGE_NONE && drupal_multilingual()) {
    $handler->localTasksAlter($data, $router_item, $root_path);
  }
}

/**
 * Preprocess variables for 'page.tpl.php'.
 */
function entity_translation_preprocess_page(&$variables) {
  if (!empty($variables['tabs']['#secondary'])) {
    $language_tabs = array();

    foreach ($variables['tabs']['#secondary'] as $index => $tab) {
      if (!empty($tab['#language_tab'])) {
        $language_tabs[] = $tab;
        unset($variables['tabs']['#secondary'][$index]);
      }
    }

    if (!empty($language_tabs)) {
      if (count($variables['tabs']['#secondary']) <= 1) {
        $variables['tabs']['#secondary'] = $language_tabs;
      }
      else {
        // If secondary tabs are already defined we need to add another level
        // and wrap it so that it will be positioned on its own row.
        $variables['tabs']['#secondary']['#language_tabs'] = $language_tabs;
        $variables['tabs']['#secondary']['#pre_render']['entity_translation'] = 'entity_translation_language_tabs_render';
      }
    }
  }
}

/**
 * Pre render callback.
 *
 * Appends the language tabs to the current local tasks area.
 */
function entity_translation_language_tabs_render($element) {
  $build = array(
    '#theme' => 'menu_local_tasks',
    '#theme_wrappers' => array('entity_translation_language_tabs'),
    '#secondary' => $element['#language_tabs'],
    '#attached' => array(
      'css' => array(drupal_get_path('module', 'entity_translation') . '/entity-translation.css'),
     ),
  );
  $element['#suffix'] .= drupal_render($build);
  return $element;
}

/**
 * Theme wrapper for the entity translation language tabs.
 */
function theme_entity_translation_language_tabs($variables) {
  return '<div class="entity-translation-language-tabs">' . $variables['element']['#children'] . '</div>';
}

/**
 * Implements hook_form_FORM_ID_alter().
 *
 * Adds an option to enable field synchronization.
 * Enable a selector to choose whether a field is translatable.
 */
function entity_translation_form_field_ui_field_edit_form_alter(&$form, $form_state) {
  $instance = $form['#instance'];
  $entity_type = $instance['entity_type'];
  $field_name = $instance['field_name'];
  $field = field_info_field($field_name);

  if (!empty($field['settings']['entity_translation_sync']) && field_is_translatable($entity_type, $field)) {
    $form['instance']['settings']['entity_translation_sync'] = array(
      '#prefix' => '<label>' . t('Field synchronization') . '</label>',
      '#type' => 'checkbox',
      '#title' => t('Enable field synchronization'),
      '#description' => t('Check this option if you wish to synchronize the value of this field across its translations.'),
      '#default_value' => !empty($instance['settings']['entity_translation_sync']),
    );
  }

  $translatable = $field['translatable'];
  $label = t('Field translation');
  $title = t('Users may translate all occurrences of this field:') . _entity_translation_field_desc($field);

  if (field_has_data($field)) {
    $path = "admin/config/regional/entity_translation/translatable/$field_name";
    $status = $translatable ? $title : (t('All occurrences of this field are untranslatable:') . _entity_translation_field_desc($field));
    $link_title = !$translatable ? t('Enable translation') : t('Disable translation');

    $form['field']['translatable'] = array(
      '#prefix' => '<div class="translatable"><label>' . $label . '</label>',
      '#suffix' => '</div>',
      'message' => array(
        '#markup' => $status . ' ',
      ),
      'link' => array(
        '#type' => 'link',
        '#title' => $link_title,
        '#href' => $path,
        '#options' => array('query' => drupal_get_destination()),
        '#access' => user_access('toggle field translatability'),
      ),
    );
  }
  else {
    $form['field']['translatable'] = array(
      '#prefix' => '<label>' . $label . '</label>',
      '#type' => 'checkbox',
      '#title' => $title,
      '#default_value' => $translatable,
    );
  }
}

/**
 * Returns a human-readable, localized, bullet list of instances of a field.
 *
 * @param field
 *   A field data structure.
 *
 * @return
 *    A themed list of field instances with the bundle they are attached to.
 */
function _entity_translation_field_desc($field) {
  $instances = array();
  foreach ($field['bundles'] as $entity_type => $bundle_names) {
    $entity_type_info = entity_get_info($entity_type);
    foreach ($bundle_names as $bundle_name) {
      $instance_info = field_info_instance($entity_type, $field['field_name'], $bundle_name);
      $instances[] = t('@instance_label in %entity_label', array('@instance_label' => $instance_info['label'], '%entity_label' => $entity_type_info['bundles'][$bundle_name]['label']));
    }
  }
  return theme('item_list', array('items' => $instances));
}

/**
 * Determines whether the given entity type is translatable.
 *
 * @param $entity_type
 *   The entity type enabled for translation.
 * @param $entity
 *   (optional) The entity belonging to the bundle enabled for translation. A
 *   bundle name can alternatively be passed. If an empty value is passed the
 *   bundle-level check is skipped. Defaults to NULL.
 * @param $skip_handler
 *   (optional) A boolean indicating whether skip checking if the entity type is
 *   registered as a field translation handler. Defaults to FALSE.
 */
function entity_translation_enabled($entity_type, $entity = NULL, $skip_handler = FALSE) {
  $enabled_types = variable_get('entity_translation_entity_types', array());
  $enabled = !empty($enabled_types[$entity_type]) && ($skip_handler || field_has_translation_handler($entity_type, 'entity_translation'));

  // If the entity type is not enabled or we are not checking bundle status, we
  // have a result.
  if (!$enabled || !isset($entity)) {
    return $enabled;
  }

  // Determine the bundle to check for translatability.
  $bundle = FALSE;
  if (is_object($entity)) {
    list(, , $bundle) = entity_extract_ids($entity_type, $entity);
  }
  elseif (is_string($entity)) {
    $bundle = $entity;
  }
  return $bundle && entity_translation_enabled_bundle($entity_type, $bundle);
}

/**
 * Determines whether the given entity bundle is translatable.
 *
 * NOTE: Does not check for whether the entity type is translatable.
 * Consider using entity_translation_enabled() instead.
 *
 * @param $entity_type
 *   The entity type the bundle to be checked belongs to.
 * @param $bundle
 *   The name of the bundle to be checked.
 */
function entity_translation_enabled_bundle($entity_type, $bundle) {
  $info = entity_get_info($entity_type);
  $bundle_callback = isset($info['translation']['entity_translation']['bundle callback']) ? $info['translation']['entity_translation']['bundle callback'] : FALSE;
  return empty($bundle_callback) || call_user_func($bundle_callback, $bundle);
}

/**
 * Return the entity translation settings for the given entity type and bundle.
 */
function entity_translation_settings($entity_type, $bundle) {
  $settings = variable_get('entity_translation_settings_' . $entity_type . '__' . $bundle, array());

  if (empty($settings)) {
    $info = entity_get_info($entity_type);
    if (!empty($info['translation']['entity_translation']['default settings'])) {
      $settings = $info['translation']['entity_translation']['default settings'];
    }
  }

  $settings += array(
    'default_language' => ENTITY_TRANSLATION_LANGUAGE_DEFAULT,
    'hide_language_selector' => TRUE,
    'exclude_language_none' => FALSE,
    'lock_language' => FALSE,
    'shared_fields_original_only' => FALSE,
  );

  return $settings;
}

/**
 * Entity language callback.
 *
 * This callback changes the entity language from the actual one to the active
 * form language. This overriding allows to obtain language dependent form
 * widgets where multilingual values are supported (e.g. field or path alias
 * widgets) even if the code was not originally written with supporting multiple
 * values per language in mind.
 *
 * The main drawback of this approach is that code needing to access the actual
 * language in the entity form build/validation/submit workflow cannot rely on
 * the entity_language() function. On the other hand in these scenarios assuming
 * the presence of Entity translation should be safe, thus being able to rely on
 * the EntityTranslationHandlerInterface::getLanguage() method.
 *
 * @param $entity_type
 *    The the type of the entity.
 * @param $entity
 *    The entity whose language has to be returned.
 *
 * @return
 *   A valid language code.
 */
function entity_translation_language($entity_type, $entity) {
  $handler = entity_translation_get_handler($entity_type, $entity);
  if (empty($handler)) {
    return LANGUAGE_NONE;
  }
  $langcode = $handler->getFormLanguage();
  return !empty($langcode) ? $langcode : $handler->getLanguage();
}

/**
 * Translation handler factory.
 *
 * @param $entity_type
 *   (optional) The type of $entity; e.g. 'node' or 'user'.
 * @param $entity
 *   (optional) The entity to be translated. A bundle name may be passed to
 *   instantiate an empty entity.
 *
 * @return EntityTranslationHandlerInterface
 *   A class implementing EntityTranslationHandlerInterface.
 */
function entity_translation_get_handler($entity_type = NULL, $entity = NULL) {
  if (class_exists('EntityTranslationHandlerFactory')) {
    $factory = EntityTranslationHandlerFactory::getInstance();
    return empty($entity) ? $factory->getLastHandler($entity_type) : $factory->getHandler($entity_type, $entity);
  }
  // @todo BC layer. Remove before the first stable release.
  elseif (!empty($entity_type) && is_object($entity)) {
    $entity_info = entity_get_info($entity_type);
    return new EntityTranslationDefaultHandler($entity_type, $entity_info, $entity);
  }
}

/**
 * Returns the translation handler wrapping the entity being edited.
 *
 * @param $form
 *   The entity form.
 * @param $form_state
 *   A keyed array containing the current state of the form.
 *
 * @return EntityTranslationHandlerInterface
 *   A class implementing EntityTranslationHandlerInterface.
 */
function entity_translation_entity_form_get_handler($form, $form_state) {
  $handler = FALSE;
  if ($info = entity_translation_edit_form_info($form, $form_state)) {
    $handler = entity_translation_get_handler($info['entity type'], $info['entity']);
  }
  return $handler;
}

/**
 * Returns the translation handler associated to the currently submitted form.
 *
 * @return EntityTranslationHandlerInterface
 *   A translation handler instance if available, FALSE oterwise.
 *
 * @deprecated This is no longer used and will be removed in the first stable
 *   release.
 */
function entity_translation_current_form_get_handler() {
  $handler = FALSE;

  if (!empty($_POST['form_build_id'])) {
    $form_state = form_state_defaults();
    if ($form = form_get_cache($_POST['form_build_id'], $form_state)) {
      $handler = entity_translation_entity_form_get_handler($form, $form_state);
    }
  }

  return $handler;
}

/**
 * Returns an array of edit form info as defined in hook_translation_info().
 *
 * @param $form
 *   The entity edit form.
 * @param $form_state
 *   The entity edit form state.
 *
 * @return
 *   An edit form info array containing the entity to be translated in the
 *   'entity' key.
 */
function entity_translation_edit_form_info($form, $form_state) {
  $info = FALSE;
  $entity_type = isset($form['#entity_type']) && is_string($form['#entity_type']) ? $form['#entity_type'] : FALSE;

  if ($entity_type) {
    $entity_info = entity_get_info($form['#entity_type']);
    if (!empty($entity_info['translation']['entity_translation']['edit form'])) {
      $entity_keys = explode('][', $entity_info['translation']['entity_translation']['edit form']);
      $key_exists = FALSE;
      $entity = drupal_array_get_nested_value($form_state, $entity_keys, $key_exists);
      if ($key_exists) {
        $info = array(
          'entity type' => $form['#entity_type'],
          'entity' => (object) $entity,
        );
      }
    }
  }

  return $info;
}

/**
 * Checks whether an entity translation is accessible.
 *
 * @param $translation
 *   An array representing an entity translation.
 *
 * @return
 *   TRUE if the current user is allowed to view the translation.
 */
function entity_translation_access($entity_type, $translation) {
  return $translation['status'] || user_access('translate any entity') || user_access("translate $entity_type entities");
}

/**
 * Returns the set of languages available for translations.
 */
function entity_translation_languages($entity_type = NULL, $entity = NULL) {
  if (isset($entity) && $entity_type == 'node' && module_exists('i18n_node')) {
    // @todo Inherit i18n language settings.
  }
  elseif (variable_get('entity_translation_languages_enabled', FALSE)) {
    $languages = language_list('enabled');
    return $languages[1];
  }
  return language_list();
}

/**
 * Implements hook_views_api().
 */
function entity_translation_views_api() {
  return array(
    'api' => 3,
    'path' => drupal_get_path('module', 'entity_translation') . '/views',
  );
}

/**
 * Implements hook_uuid_entities_features_export_entity_alter().
 */
function entity_translation_uuid_entities_features_export_entity_alter($entity, $entity_type) {
  // We do not need to export most of the keys:
  // - The entity type is determined from the entity the translations are
  //   attached to.
  // - The entity id will change from one site to another.
  // - The user id needs to be removed because it will change as well.
  // - Created and changed could be left but the UUID module removes created and
  //   changed values from the entities it exports, hence we do the same for
  //   consistency.
  if (entity_translation_enabled($entity_type, $entity)) {
    $fields = array('entity_type', 'entity_id', 'uid', 'created', 'changed');
    $handler = entity_translation_get_handler($entity_type, $entity);
    $translations = $handler->getTranslations();
    if ($translations && isset($translations->data)) {
      foreach ($translations->data as &$translation) {
        foreach ($fields as $field) {
          unset($translation[$field]);
        }
      }
    }
  }
}

/**
 * Implements hook_entity_uuid_presave().
 */
function entity_translation_entity_uuid_presave(&$entity, $entity_type) {
  // UUID exports entities as arrays, therefore we need to cast the translations
  // array back into an object.
  $entity_info = entity_get_info($entity_type);
  if (isset($entity_info['entity keys']) && isset($entity_info['entity keys']['translations'])) {
    $key = $entity_info['entity keys']['translations'];
    if (isset($entity->{$key})) {
      $entity->{$key} = (object) $entity->{$key};
    }
  }
}

/**
 * Implement hook_pathauto_alias_alter().
 *
 * When bulk-updating aliases for nodes automatically create a path for every
 * translation.
 */
function entity_translation_pathauto_alias_alter(&$alias, array &$context) {
  $info = entity_get_info();
  $entity_type = $context['module'];

  // Ensure that we are dealing with a bundle having entity translation enabled.
  if ($context['op'] == 'bulkupdate' && !empty($info[$entity_type]['token type']) && !empty($context['data'][$info[$entity_type]['token type']])) {
    $entity = $context['data'][$info[$entity_type]['token type']];
    if (entity_translation_enabled($entity_type, $entity)) {
      $translations = entity_translation_get_handler($entity_type, $entity)->getTranslations();
      // Only create extra aliases if we are working on the original language to
      // avoid infinite recursion.
      if ($context['language'] == $translations->original) {
        foreach ($translations->data as $language => $translation) {
          // We already have an alias for the original language, so let's not
          // create another one.
          if ($language == $translations->original) {
            continue;
          }
          pathauto_create_alias($entity_type, $context['op'], $context['source'], $context['data'], $context['type'], $language);
        }
      }
    }
  }
}

/**
 * Implements hook_entity_translation_delete().
 */
function path_entity_translation_delete($entity_type, $entity, $langcode) {
  // Remove any existing path alias for the removed translation.
  $handler = entity_translation_get_handler($entity_type, $entity);
  path_delete(array('source' => $handler->getViewPath(), 'language' => $langcode));
}

/**
 * Wrapper for entity_save().
 *
 * @param $entity_type
 *   The entity type.
 * @param $entity
 *   The entity object.
 */
function entity_translation_entity_save($entity_type, $entity) {
  // Entity module isn't required, but use it if it's available.
  if (module_exists('entity')) {
    entity_save($entity_type, $entity);
  }
  // Fall back to field_attach_* functions otherwise.
  else {
    field_attach_presave($entity_type, $entity);
    field_attach_update($entity_type, $entity);
  }
}