<?php

/**
 * Implements hook_ctools_plugin_directory().
 */
function entityreference_ctools_plugin_directory($module, $plugin) {
  if ($module == 'entityreference') {
    return 'plugins/' . $plugin;
  }
}

/**
 * Implements hook_init().
 */
function entityreference_init() {
  // Include feeds.module integration.
  if (module_exists('feeds')) {
    module_load_include('inc', 'entityreference', 'entityreference.feeds');
  }
}

/**
 * Implements hook_ctools_plugin_type().
 */
function entityreference_ctools_plugin_type() {
  $plugins['selection'] = array(
    'classes' => array('class'),
  );
  $plugins['behavior'] = array(
    'classes' => array('class'),
    'process' => 'entityreference_behavior_plugin_process',
  );
  return $plugins;
}

/**
 * CTools callback; Process the behavoir plugins.
 */
function entityreference_behavior_plugin_process(&$plugin, $info) {
  $plugin += array(
    'description' => '',
    'behavior type' => 'field',
    'access callback' => FALSE,
    'force enabled' => FALSE,
  );
}

/**
 * Implements hook_field_info().
 */
function entityreference_field_info() {
  $field_info['entityreference'] = array(
    'label' => t('Entity Reference'),
    'description' => t('This field reference another entity.'),
    'settings' => array(
      // Default to the core target entity type node.
      'target_type' => 'node',
      // The handler for this field.
      'handler' => 'base',
      // The handler settings.
      'handler_settings' => array(),
    ),
    'instance_settings' => array(),
    'default_widget' => 'entityreference_autocomplete',
    'default_formatter' => 'entityreference_label',
    'property_callbacks' => array('entityreference_field_property_callback'),
  );
  return $field_info;
}

/**
 * Implements hook_flush_caches().
 */
function entityreference_flush_caches() {
  // Because of the intricacies of the info hooks, we are forced to keep a
  // separate list of the base tables of each entities, so that we can use
  // it in entityreference_field_schema() without calling entity_get_info().
  // See http://drupal.org/node/1416558 for details.
  $base_tables = array();
  foreach (entity_get_info() as $entity_type => $entity_info) {
    if (!empty($entity_info['base table']) && !empty($entity_info['entity keys']['id'])) {
      $base_tables[$entity_type] = array($entity_info['base table'], $entity_info['entity keys']['id']);
    }
  }
  // We are using a variable because cache is going to be cleared right after
  // hook_flush_caches() is finished.
  variable_set('entityreference:base-tables', $base_tables);
}

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

  $items['entityreference/autocomplete/single/%/%/%'] = array(
    'title' => 'Entity Reference Autocomplete',
    'page callback' => 'entityreference_autocomplete_callback',
    'page arguments' => array(2, 3, 4, 5),
    'access callback' => 'entityreference_autocomplete_access_callback',
    'access arguments' => array(2, 3, 4, 5),
    'type' => MENU_CALLBACK,
  );
  $items['entityreference/autocomplete/tags/%/%/%'] = array(
    'title' => 'Entity Reference Autocomplete',
    'page callback' => 'entityreference_autocomplete_callback',
    'page arguments' => array(2, 3, 4, 5),
    'access callback' => 'entityreference_autocomplete_access_callback',
    'access arguments' => array(2, 3, 4, 5),
    'type' => MENU_CALLBACK,
  );

  return $items;
}

/**
 * Implements hook_field_is_empty().
 */
function entityreference_field_is_empty($item, $field) {
  $empty = !isset($item['target_id']) || !is_numeric($item['target_id']);

  // Invoke the behaviors to allow them to override the empty status.
  foreach (entityreference_get_behavior_handlers($field) as $handler) {
    $handler->is_empty_alter($empty, $item, $field);
  }
  return $empty;
}

/**
 * Get the behavior handlers for a given entityreference field.
 */
function entityreference_get_behavior_handlers($field, $instance = NULL) {
  $object_cache = drupal_static(__FUNCTION__);
  $identifier = $field['field_name'];
  if (!empty($instance)) {
    $identifier .= ':' . $instance['entity_type'] . ':' . $instance['bundle'];
  }

  if (!isset($object_cache[$identifier])) {
    $object_cache[$identifier] = array();

    // Merge in defaults.
    $field['settings'] += array('behaviors' => array());

    $object_cache[$field['field_name']] = array();
    $behaviors = !empty($field['settings']['handler_settings']['behaviors']) ? $field['settings']['handler_settings']['behaviors'] : array();
    if (!empty($instance['settings']['behaviors'])) {
      $behaviors = array_merge($behaviors, $instance['settings']['behaviors']);
    }
    foreach ($behaviors as $behavior => $settings) {
      if (empty($settings['status'])) {
        // Behavior is not enabled.
        continue;
      }

      $object_cache[$identifier][] = _entityreference_get_behavior_handler($behavior);
    }
  }

  return $object_cache[$identifier];
}

/**
 * Get the behavior handler for a given entityreference field and instance.
 *
 * @param $handler
 *   The behavior handler name.
 */
function _entityreference_get_behavior_handler($behavior) {
  $object_cache = drupal_static(__FUNCTION__);

  if (!isset($object_cache[$behavior])) {
    ctools_include('plugins');
    $class = ctools_plugin_load_class('entityreference', 'behavior', $behavior, 'class');

    $class = class_exists($class) ? $class : 'EntityReference_BehaviorHandler_Broken';
    $object_cache[$behavior] = new $class($behavior);
  }

  return $object_cache[$behavior];
}

/**
 * Get the selection handler for a given entityreference field.
 */
function entityreference_get_selection_handler($field, $instance = NULL, $entity_type = NULL, $entity = NULL) {
  ctools_include('plugins');
  $handler = $field['settings']['handler'];
  $class = ctools_plugin_load_class('entityreference', 'selection', $handler, 'class');

  if (class_exists($class)) {
    return call_user_func(array($class, 'getInstance'), $field, $instance, $entity_type, $entity);
  }
  else {
    return EntityReference_SelectionHandler_Broken::getInstance($field, $instance, $entity_type, $entity);
  }
}

/**
 * Implements hook_field_load().
 */
function entityreference_field_load($entity_type, $entities, $field, $instances, $langcode, &$items) {
  // Invoke the behaviors.
  foreach (entityreference_get_behavior_handlers($field) as $handler) {
    $handler->load($entity_type, $entities, $field, $instances, $langcode, $items);
  }
}

/**
 * Implements hook_field_validate().
 */
function entityreference_field_validate($entity_type, $entity, $field, $instance, $langcode, $items, &$errors) {
  $ids = array();
  foreach ($items as $delta => $item) {
    if (!entityreference_field_is_empty($item, $field) && $item['target_id'] !== NULL) {
      $ids[$item['target_id']] = $delta;
    }
  }

  if ($ids) {
    $valid_ids = entityreference_get_selection_handler($field, $instance, $entity_type, $entity)->validateReferencableEntities(array_keys($ids));

    $invalid_entities = array_diff_key($ids, array_flip($valid_ids));
    if ($invalid_entities) {
      foreach ($invalid_entities as $id => $delta) {
        $errors[$field['field_name']][$langcode][$delta][] = array(
          'error' => 'entityreference_invalid_entity',
          'message' => t('The referenced entity (@type: @id) is invalid.', array('@type' => $field['settings']['target_type'], '@id' => $id)),
        );
      }
    }
  }

  // Invoke the behaviors.
  foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
    $handler->validate($entity_type, $entity, $field, $instance, $langcode, $items, $errors);
  }
}

/**
 * Implements hook_field_presave().
 *
 * Adds the target type to the field data structure when saving.
 */
function entityreference_field_presave($entity_type, $entity, $field, $instance, $langcode, &$items) {
  // Invoke the behaviors.
  foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
    $handler->presave($entity_type, $entity, $field, $instance, $langcode, $items);
  }
}

/**
 * Implements hook_field_insert().
 */
function entityreference_field_insert($entity_type, $entity, $field, $instance, $langcode, &$items) {
  // Invoke the behaviors.
  foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
    $handler->insert($entity_type, $entity, $field, $instance, $langcode, $items);
  }
}

/**
 * Implements hook_field_attach_insert().
 *
 * Emulates a post-insert hook.
 */
function entityreference_field_attach_insert($entity_type, $entity) {
  list(, , $bundle) = entity_extract_ids($entity_type, $entity);
  foreach (field_info_instances($entity_type, $bundle) as $field_name => $instance) {
    $field = field_info_field($field_name);
    if ($field['type'] == 'entityreference') {
      foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
        $handler->postInsert($entity_type, $entity, $field, $instance);
      }
    }
  }
}

/**
 * Implements hook_field_update().
 */
function entityreference_field_update($entity_type, $entity, $field, $instance, $langcode, &$items) {
  // Invoke the behaviors.
  foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
    $handler->update($entity_type, $entity, $field, $instance, $langcode, $items);
  }
}

/**
 * Implements hook_field_attach_update().
 *
 * Emulates a post-update hook.
 */
function entityreference_field_attach_update($entity_type, $entity) {
  list(, , $bundle) = entity_extract_ids($entity_type, $entity);
  foreach (field_info_instances($entity_type, $bundle) as $field_name => $instance) {
    $field = field_info_field($field_name);
    if ($field['type'] == 'entityreference') {
      foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
        $handler->postUpdate($entity_type, $entity, $field, $instance);
      }
    }
  }
}

/**
 * Implements hook_field_delete().
 */
function entityreference_field_delete($entity_type, $entity, $field, $instance, $langcode, &$items) {
  // Invoke the behaviors.
  foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
    $handler->delete($entity_type, $entity, $field, $instance, $langcode, $items);
  }
}

/**
 * Implements hook_field_attach_delete().
 *
 * Emulates a post-delete hook.
 */
function entityreference_field_attach_delete($entity_type, $entity) {
  list(, , $bundle) = entity_extract_ids($entity_type, $entity);
  foreach (field_info_instances($entity_type, $bundle) as $field_name => $instance) {
    $field = field_info_field($field_name);
    if ($field['type'] == 'entityreference') {
      foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
        $handler->postDelete($entity_type, $entity, $field, $instance);
      }
    }
  }
}

/**
 * Implements hook_entity_insert().
 */
function entityreference_entity_insert($entity, $entity_type) {
  entityreference_entity_crud($entity, $entity_type, 'entityPostInsert');
}

/**
 * Implements hook_entity_update().
 */
function entityreference_entity_update($entity, $entity_type) {
  entityreference_entity_crud($entity, $entity_type, 'entityPostUpdate');
}

/**
 * Implements hook_entity_delete().
 */
function entityreference_entity_delete($entity, $entity_type) {
  entityreference_entity_crud($entity, $entity_type, 'entityPostDelete');
}

/**
 * Invoke a behavior based on entity CRUD.
 *
 * @param $entity
 *   The entity object.
 * @param $entity_type
 *   The entity type.
 * @param $method_name
 *   The method to invoke.
 */
function entityreference_entity_crud($entity, $entity_type, $method_name) {
  list(, , $bundle) = entity_extract_ids($entity_type, $entity);
  foreach (field_info_instances($entity_type, $bundle) as $field_name => $instance) {
    $field = field_info_field($field_name);
    if ($field['type'] == 'entityreference') {
      foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
        $handler->{$method_name}($entity_type, $entity, $field, $instance);
      }
    }
  }
}

/**
 * Implements hook_field_settings_form().
 */
function entityreference_field_settings_form($field, $instance, $has_data) {
  // The field settings infrastructure is not AJAX enabled by default,
  // because it doesn't pass over the $form_state.
  // Build the whole form into a #process in which we actually have access
  // to the form state.
  $form = array(
    '#type' => 'container',
    '#attached' => array(
      'css' => array(drupal_get_path('module', 'entityreference') . '/entityreference.admin.css'),
    ),
    '#process' => array(
      '_entityreference_field_settings_process',
      '_entityreference_field_settings_ajax_process',
    ),
    '#element_validate' => array('_entityreference_field_settings_validate'),
    '#field' => $field,
    '#instance' => $instance,
    '#has_data' => $has_data,
  );
  return $form;
}

function _entityreference_field_settings_process($form, $form_state) {
  $field = isset($form_state['entityreference']['field']) ? $form_state['entityreference']['field'] : $form['#field'];
  $instance = isset($form_state['entityreference']['instance']) ? $form_state['entityreference']['instance'] : $form['#instance'];
  $has_data = $form['#has_data'];

  $settings = $field['settings'];
  $settings += array('handler' => 'base');

  // Select the target entity type.
  $entity_type_options = array();
  foreach (entity_get_info() as $entity_type => $entity_info) {
    $entity_type_options[$entity_type] = $entity_info['label'];
  }

  $form['target_type'] = array(
    '#type' => 'select',
    '#title' => t('Target type'),
    '#options' => $entity_type_options,
    '#default_value' => $field['settings']['target_type'],
    '#required' => TRUE,
    '#description' => t('The entity type that can be referenced through this field.'),
    '#disabled' => $has_data,
    '#size' => 1,
    '#ajax' => TRUE,
    '#limit_validation_errors' => array(),
  );

  ctools_include('plugins');
  $handlers = ctools_get_plugins('entityreference', 'selection');
  uasort($handlers, 'ctools_plugin_sort');
  $handlers_options = array();
  foreach ($handlers as $handler => $handler_info) {
    $handlers_options[$handler] = check_plain($handler_info['title']);
  }

  $form['handler'] = array(
    '#type' => 'fieldset',
    '#title' => t('Entity selection'),
    '#tree' => TRUE,
    '#process' => array('_entityreference_form_process_merge_parent'),
  );

  $form['handler']['handler'] = array(
    '#type' => 'select',
    '#title' => t('Mode'),
    '#options' => $handlers_options,
    '#default_value' => $settings['handler'],
    '#required' => TRUE,
    '#ajax' => TRUE,
    '#limit_validation_errors' => array(),
  );
  $form['handler_submit'] = array(
    '#type' => 'submit',
    '#value' => t('Change handler'),
    '#limit_validation_errors' => array(),
    '#attributes' => array(
      'class' => array('js-hide'),
    ),
    '#submit' => array('entityreference_settings_ajax_submit'),
  );

  $form['handler']['handler_settings'] = array(
    '#type' => 'container',
    '#attributes' => array('class' => array('entityreference-settings')),
  );

  $handler = entityreference_get_selection_handler($field, $instance);
  $form['handler']['handler_settings'] += $handler->settingsForm($field, $instance);

  _entityreference_get_behavior_elements($form, $field, $instance, 'field');
  if (!empty($form['behaviors'])) {
    $form['behaviors'] += array(
      '#type' => 'fieldset',
      '#title' => t('Additional behaviors'),
      '#parents' => array_merge($form['#parents'], array('handler_settings', 'behaviors')),
    );
  }

  return $form;
}

function _entityreference_field_settings_ajax_process($form, $form_state) {
  _entityreference_field_settings_ajax_process_element($form, $form);
  return $form;
}

function _entityreference_field_settings_ajax_process_element(&$element, $main_form) {
  if (isset($element['#ajax']) && $element['#ajax'] === TRUE) {
    $element['#ajax'] = array(
      'callback' => 'entityreference_settings_ajax',
      'wrapper' => $main_form['#id'],
      'element' => $main_form['#array_parents'],
    );
  }

  foreach (element_children($element) as $key) {
    _entityreference_field_settings_ajax_process_element($element[$key], $main_form);
  }
}

function _entityreference_form_process_merge_parent($element) {
  $parents = $element['#parents'];
  array_pop($parents);
  $element['#parents'] = $parents;
  return $element;
}

function _entityreference_element_validate_filter(&$element, &$form_state) {
  $element['#value'] = array_filter($element['#value']);
  form_set_value($element, $element['#value'], $form_state);
}

function _entityreference_field_settings_validate($form, &$form_state) {
  // Store the new values in the form state.
  $field = $form['#field'];
  if (isset($form_state['values']['field'])) {
    $field['settings'] = $form_state['values']['field']['settings'];
  }
  $form_state['entityreference']['field'] = $field;

  unset($form_state['values']['field']['settings']['handler_submit']);
}

/**
 * Implements hook_field_instance_settings_form().
 */
function entityreference_field_instance_settings_form($field, $instance) {
  $form['settings'] = array(
    '#type' => 'container',
    '#attached' => array(
      'css' => array(drupal_get_path('module', 'entityreference') . '/entityreference.admin.css'),
    ),
    '#weight' => 10,
    '#tree' => TRUE,
    '#process' => array(
      '_entityreference_form_process_merge_parent',
      '_entityreference_field_instance_settings_form',
      '_entityreference_field_settings_ajax_process',
    ),
    '#element_validate' => array('_entityreference_field_instance_settings_validate'),
    '#field' => $field,
    '#instance' => $instance,
  );

  return $form;
}

function _entityreference_field_instance_settings_form($form, $form_state) {
  $field = isset($form_state['entityreference']['field']) ? $form_state['entityreference']['field'] : $form['#field'];
  $instance = isset($form_state['entityreference']['instance']) ? $form_state['entityreference']['instance'] : $form['#instance'];

  _entityreference_get_behavior_elements($form, $field, $instance, 'instance');
  if (!empty($form['behaviors'])) {
    $form['behaviors'] += array(
      '#type' => 'fieldset',
      '#title' => t('Additional behaviors'),
      '#process' => array(
        '_entityreference_field_settings_ajax_process',
      ),
    );
  }
  return $form;
}

function _entityreference_field_instance_settings_validate($form, &$form_state) {
  // Store the new values in the form state.
  $instance = $form['#instance'];
  if (isset($form_state['values']['instance'])) {
    $instance = drupal_array_merge_deep($instance, $form_state['values']['instance']);
  }
  $form_state['entityreference']['instance'] = $instance;
}

/**
 * Get the field or instance elements for the field configuration.
 */
function _entityreference_get_behavior_elements(&$element, $field, $instance, $level) {
  // Add the accessible behavior handlers.
  $behavior_plugins = entityreference_get_accessible_behavior_plugins($field, $instance);

  if ($behavior_plugins[$level]) {
    $element['behaviors'] = array();

    foreach ($behavior_plugins[$level] as $name => $plugin) {
      if ($level == 'field') {
        $settings = !empty($field['settings']['handler_settings']['behaviors'][$name]) ? $field['settings']['handler_settings']['behaviors'][$name] : array();
      }
      else {
        $settings = !empty($instance['settings']['behaviors'][$name]) ? $instance['settings']['behaviors'][$name] : array();
      }
      $settings += array('status' => $plugin['force enabled']);

      // Render the checkbox.
      $element['behaviors'][$name] = array(
        '#tree' => TRUE,
      );
      $element['behaviors'][$name]['status'] = array(
        '#type' => 'checkbox',
        '#title' => check_plain($plugin['title']),
        '#description' => $plugin['description'],
        '#default_value' => $settings['status'],
        '#disabled' => $plugin['force enabled'],
        '#ajax' => TRUE,
      );

      if ($settings['status']) {
        $handler = _entityreference_get_behavior_handler($name);
        if ($behavior_elements = $handler->settingsForm($field, $instance)) {
          foreach ($behavior_elements as $key => &$behavior_element) {
            $behavior_element += array(
              '#default_value' => !empty($settings[$key]) ? $settings[$key] : NULL,
            );
          }

          // Get the behavior settings.
          $behavior_elements += array(
            '#type' => 'container',
            '#process' => array('_entityreference_form_process_merge_parent'),
            '#attributes' => array(
              'class' => array('entityreference-settings'),
            ),
          );
          $element['behaviors'][$name]['settings'] = $behavior_elements;
        }
      }
    }
  }
}

/**
 * Get all accessible behavior plugins.
 */
function entityreference_get_accessible_behavior_plugins($field, $instance) {
  ctools_include('plugins');
  $plugins = array('field' => array(), 'instance' => array());
  foreach (ctools_get_plugins('entityreference', 'behavior') as $name => $plugin) {
    $handler = _entityreference_get_behavior_handler($name);
    $level = $plugin['behavior type'];
    if ($handler->access($field, $instance)) {
      $plugins[$level][$name] = $plugin;
    }
  }
  return $plugins;
}

/**
 * Ajax callback for the handler settings form.
 *
 * @see entityreference_field_settings_form()
 */
function entityreference_settings_ajax($form, $form_state) {
  $trigger = $form_state['triggering_element'];
  return drupal_array_get_nested_value($form, $trigger['#ajax']['element']);
}

/**
 * Submit handler for the non-JS case.
 *
 * @see entityreference_field_settings_form()
 */
function entityreference_settings_ajax_submit($form, &$form_state) {
  $form_state['rebuild'] = TRUE;
}

/**
 * Property callback for the Entity Metadata framework.
 */
function entityreference_field_property_callback(&$info, $entity_type, $field, $instance, $field_type) {
  // Set the property type based on the targe type.
  $field_type['property_type'] = $field['settings']['target_type'];

  // Then apply the default.
  entity_metadata_field_default_property_callback($info, $entity_type, $field, $instance, $field_type);

  // Invoke the behaviors to allow them to change the properties.
  foreach (entityreference_get_behavior_handlers($field, $instance) as $handler) {
    $handler->property_info_alter($info, $entity_type, $field, $instance, $field_type);
  }
}

/**
 * Implements hook_field_widget_info().
 */
function entityreference_field_widget_info() {
  $widgets['entityreference_autocomplete'] = array(
    'label' => t('Autocomplete'),
    'description' => t('An autocomplete text field.'),
    'field types' => array('entityreference'),
    'settings' => array(
      'match_operator' => 'CONTAINS',
      'size' => 60,
      // We don't have a default here, because it's not the same between
      // the two widgets, and the Field API doesn't update default
      // settings when the widget changes.
      'path' => '',
    ),
  );

  $widgets['entityreference_autocomplete_tags'] = array(
    'label' => t('Autocomplete (Tags style)'),
    'description' => t('An autocomplete text field.'),
    'field types' => array('entityreference'),
    'settings' => array(
      'match_operator' => 'CONTAINS',
      'size' => 60,
      // We don't have a default here, because it's not the same between
      // the two widgets, and the Field API doesn't update default
      // settings when the widget changes.
      'path' => '',
    ),
    'behaviors' => array(
      'multiple values' => FIELD_BEHAVIOR_CUSTOM,
    ),
  );

  return $widgets;
}

/**
 * Implements hook_field_widget_info_alter().
 */
function entityreference_field_widget_info_alter(&$info) {
  if (module_exists('options')) {
    $info['options_select']['field types'][] = 'entityreference';
    $info['options_buttons']['field types'][] = 'entityreference';
  }
}

/**
 * Implements hook_field_widget_settings_form().
 */
function entityreference_field_widget_settings_form($field, $instance) {
  $widget = $instance['widget'];
  $settings = $widget['settings'] + field_info_widget_settings($widget['type']);

  $form = array();

  if ($widget['type'] == 'entityreference_autocomplete' || $widget['type'] == 'entityreference_autocomplete_tags') {
    $form['match_operator'] = array(
      '#type' => 'select',
      '#title' => t('Autocomplete matching'),
      '#default_value' => $settings['match_operator'],
      '#options' => array(
        'STARTS_WITH' => t('Starts with'),
        'CONTAINS' => t('Contains'),
      ),
      '#description' => t('Select the method used to collect autocomplete suggestions. Note that <em>Contains</em> can cause performance issues on sites with thousands of nodes.'),
    );
    $form['size'] = array(
      '#type' => 'textfield',
      '#title' => t('Size of textfield'),
      '#default_value' => $settings['size'],
      '#element_validate' => array('_element_validate_integer_positive'),
      '#required' => TRUE,
    );
  }

  return $form;
}

/**
 * Implements hook_options_list().
 */
function entityreference_options_list($field, $instance = NULL, $entity_type = NULL, $entity = NULL) {
  if (!$options = entityreference_get_selection_handler($field, $instance, $entity_type, $entity)->getReferencableEntities()) {
    return array();
  }

  // Rebuild the array, by changing the bundle key into the bundle label.
  $target_type = $field['settings']['target_type'];
  $entity_info = entity_get_info($target_type);

  $return = array();
  foreach ($options as $bundle => $entity_ids) {
    $bundle_label = check_plain($entity_info['bundles'][$bundle]['label']);
    $return[$bundle_label] = $entity_ids;
  }

  return count($return) == 1 ? reset($return) : $return;
}

/**
 * Implements hook_query_TAG_alter().
 */
function entityreference_query_entityreference_alter(QueryAlterableInterface $query) {
  $handler = $query->getMetadata('entityreference_selection_handler');
  $handler->entityFieldQueryAlter($query);
}

/**
 * Implements hook_field_widget_form().
 */
function entityreference_field_widget_form(&$form, &$form_state, $field, $instance, $langcode, $items, $delta, $element) {
  $entity_type = $instance['entity_type'];
  $entity = isset($element['#entity']) ? $element['#entity'] : NULL;
  $handler = entityreference_get_selection_handler($field, $instance, $entity_type, $entity);

  if ($instance['widget']['type'] == 'entityreference_autocomplete' || $instance['widget']['type'] == 'entityreference_autocomplete_tags') {

    if ($instance['widget']['type'] == 'entityreference_autocomplete') {
      // We let the Field API handles multiple values for us, only take
      // care of the one matching our delta.
      if (isset($items[$delta])) {
        $items = array($items[$delta]);
      }
      else {
        $items = array();
      }
    }

    $entity_ids = array();
    $entity_labels = array();

    // Build an array of entities ID.
    foreach ($items as $item) {
      $entity_ids[] = $item['target_id'];
    }

    // Load those entities and loop through them to extract their labels.
    $entities = entity_load($field['settings']['target_type'], $entity_ids);

    foreach ($entities as $entity_id => $entity_item) {
      $label = $handler->getLabel($entity_item);
      $key = "$label ($entity_id)";
      // Labels containing commas or quotes must be wrapped in quotes.
      if (strpos($key, ',') !== FALSE || strpos($key, '"') !== FALSE) {
        $key = '"' . str_replace('"', '""', $key) . '"';
      }
      $entity_labels[] = $key;
    }

    // Prepare the autocomplete path.
    if (!empty($instance['widget']['settings']['path'])) {
      $autocomplete_path = $instance['widget']['settings']['path'];
    }
    else {
      $autocomplete_path = $instance['widget']['type'] == 'entityreference_autocomplete' ? 'entityreference/autocomplete/single' : 'entityreference/autocomplete/tags';
    }

    $autocomplete_path .= '/' . $field['field_name'] . '/' . $instance['entity_type'] . '/' . $instance['bundle'] . '/';
    // Use <NULL> as a placeholder in the URL when we don't have an entity.
    // Most webservers collapse two consecutive slashes.
    $id = 'NULL';
    if ($entity) {
      list($eid) = entity_extract_ids($entity_type, $entity);
      if ($eid) {
        $id = $eid;
      }
    }
    $autocomplete_path .= $id;

    if ($instance['widget']['type'] == 'entityreference_autocomplete') {
      $element += array(
        '#type' => 'textfield',
        '#maxlength' => 1024,
        '#default_value' => implode(', ', $entity_labels),
        '#autocomplete_path' => $autocomplete_path,
        '#size' => $instance['widget']['settings']['size'],
        '#element_validate' => array('_entityreference_autocomplete_validate'),
      );
      return array('target_id' => $element);
    }
    else {
      $element += array(
        '#type' => 'textfield',
        '#maxlength' => 1024,
        '#default_value' => implode(', ', $entity_labels),
        '#autocomplete_path' => $autocomplete_path,
        '#size' => $instance['widget']['settings']['size'],
        '#element_validate' => array('_entityreference_autocomplete_tags_validate'),
      );
      return $element;
    }
  }
}

function _entityreference_autocomplete_validate($element, &$form_state, $form) {
  // If a value was entered into the autocomplete...
  $value = '';
  if (!empty($element['#value'])) {
    // Take "label (entity id)', match the id from parenthesis.
    if (preg_match("/.+\((\d+)\)/", $element['#value'], $matches)) {
      $value = $matches[1];
    }
    else {
      // Try to get a match from the input string when the user didn't use the
      // autocomplete but filled in a value manually.
      $field = field_info_field($element['#field_name']);
      $handler = entityreference_get_selection_handler($field);
      $field_name = $element['#field_name'];
      $field = field_info_field($field_name);
      $instance = field_info_instance($element['#entity_type'], $field_name, $element['#bundle']);
      $handler = entityreference_get_selection_handler($field, $instance);
      $value = $handler->validateAutocompleteInput($element['#value'], $element, $form_state, $form);
    }
  }
  // Update the value of this element so the field can validate the product IDs.
  form_set_value($element, $value, $form_state);
}

function _entityreference_autocomplete_tags_validate($element, &$form_state, $form) {
  $value = array();
  // If a value was entered into the autocomplete...
  if (!empty($element['#value'])) {
    $entities = drupal_explode_tags($element['#value']);
    $value = array();
    foreach ($entities as $entity) {
      // Take "label (entity id)', match the id from parenthesis.
      if (preg_match("/.+\((\d+)\)/", $entity, $matches)) {
        $value[] = array(
          'target_id' => $matches[1],
        );
      }
      else {
        // Try to get a match from the input string when the user didn't use the
        // autocomplete but filled in a value manually.
        $field = field_info_field($element['#field_name']);
        $handler = entityreference_get_selection_handler($field);
        $value[] = array(
          'target_id' => $handler->validateAutocompleteInput($entity, $element, $form_state, $form),
        );
      }
    }
  }
  // Update the value of this element so the field can validate the product IDs.
  form_set_value($element, $value, $form_state);
}

/**
 * Implements hook_field_widget_error().
 */
function entityreference_field_widget_error($element, $error) {
  form_error($element, $error['message']);
}

/**
 * Menu Access callback for the autocomplete widget.
 *
 * @param $type
 *   The widget type (i.e. 'single' or 'tags').
 * @param $field_name
 *   The name of the entity-reference field.
 * @param $entity_type
 *   The entity type.
 * @param $bundle_name
 *   The bundle name.
 * @return
 *   True if user can access this menu item.
 */
function entityreference_autocomplete_access_callback($type, $field_name, $entity_type, $bundle_name) {
  $field = field_info_field($field_name);
  $instance = field_info_instance($entity_type, $field_name, $bundle_name);

  if (!$field || !$instance || $field['type'] != 'entityreference' || !field_access('edit', $field, $entity_type)) {
    return FALSE;
  }
  return TRUE;
}

/**
 * Menu callback: autocomplete the label of an entity.
 *
 * @param $type
 *   The widget type (i.e. 'single' or 'tags').
 * @param $field_name
 *   The name of the entity-reference field.
 * @param $entity_type
 *   The entity type.
 * @param $bundle_name
 *   The bundle name.
 * @param $entity_id
 *   Optional; The entity ID the entity-reference field is attached to.
 *   Defaults to ''.
 * @param $string
 *   The label of the entity to query by.
 */
function entityreference_autocomplete_callback($type, $field_name, $entity_type, $bundle_name, $entity_id = '', $string = '') {
  $field = field_info_field($field_name);
  $instance = field_info_instance($entity_type, $field_name, $bundle_name);

  return entityreference_autocomplete_callback_get_matches($type, $field, $instance, $entity_type, $entity_id, $string);
}

/**
 * Return JSON based on given field, instance and string.
 *
 * This function can be used by other modules that wish to pass a mocked
 * definition of the field on instance.
 *
 * @param $type
 *   The widget type (i.e. 'single' or 'tags').
 * @param $field
 *   The field array defintion.
 * @param $instance
 *   The instance array defintion.
 * @param $entity_type
 *   The entity type.
 * @param $entity_id
 *   Optional; The entity ID the entity-reference field is attached to.
 *   Defaults to ''.
 * @param $string
 *   The label of the entity to query by.
 */
function entityreference_autocomplete_callback_get_matches($type, $field, $instance, $entity_type, $entity_id = '', $string = '') {
  $matches = array();

  $entity = NULL;
  if ($entity_id !== 'NULL') {
    $entity = entity_load_single($entity_type, $entity_id);
    if (!$entity || !entity_access('view', $entity_type, $entity)) {
      return MENU_ACCESS_DENIED;
    }
  }

  $handler = entityreference_get_selection_handler($field, $instance, $entity_type, $entity);

  if ($type == 'tags') {
    // The user enters a comma-separated list of tags. We only autocomplete the last tag.
    $tags_typed = drupal_explode_tags($string);
    $tag_last = drupal_strtolower(array_pop($tags_typed));
    if (!empty($tag_last)) {
      $prefix = count($tags_typed) ? implode(', ', $tags_typed) . ', ' : '';
    }
  }
  else {
    // The user enters a single tag.
    $prefix = '';
    $tag_last = $string;
  }

  if (isset($tag_last)) {
    // Get an array of matching entities.
    $entity_labels = $handler->getReferencableEntities($tag_last, $instance['widget']['settings']['match_operator'], 10);

    // Loop through the products and convert them into autocomplete output.
    foreach ($entity_labels as $values) {
      foreach ($values as $entity_id => $label) {
        $key = "$label ($entity_id)";
        // Strip things like starting/trailing white spaces, line breaks and tags.
        $key = preg_replace('/\s\s+/', ' ', str_replace("\n", '', trim(decode_entities(strip_tags($key)))));
        // Names containing commas or quotes must be wrapped in quotes.
        if (strpos($key, ',') !== FALSE || strpos($key, '"') !== FALSE) {
          $key = '"' . str_replace('"', '""', $key) . '"';
        }
        $matches[$prefix . $key] = '<div class="reference-autocomplete">' . $label . '</div>';
      }
    }
  }

  drupal_json_output($matches);
}

/**
 * Introspects field and instance settings, and determines the correct settings
 * for the functioning of the formatter.
 *
 * Settings:
 *   - entity_type - The entity_type being loaded.
 *   - column - The name of the ref. field column that stores the entity id.
 */
function entityreference_field_type_settings($field) {
  $settings = array(
    'entity_type' => NULL,
    'column' => NULL,
  );

  if ($field['type'] == 'entityreference') {
    $settings['entity_type'] = $field['settings']['target_type'];
    $settings['column'] = 'target_id';
  }
  elseif ($field['type'] == 'taxonomy_term_reference') {
    $settings['entity_type'] = 'taxonomy_term';
    $settings['column'] = 'tid';
  }

  return $settings;
}

/**
 * Implements hook_field_formatter_info().
 */
function entityreference_field_formatter_info() {
  return array(
    'entityreference_label' => array(
      'label' => t('Label'),
      'description' => t('Display the label of the referenced entities.'),
      'field types' => array('entityreference'),
      'settings' => array(
        'link' => FALSE,
      ),
    ),
    'entityreference_entity_id' => array(
      'label' => t('Entity id'),
      'description' => t('Display the id of the referenced entities.'),
      'field types' => array('entityreference'),
    ),
    'entityreference_entity_view' => array(
      'label' => t('Rendered entity'),
      'description' => t('Display the referenced entities rendered by entity_view().'),
      'field types' => array('entityreference', 'taxonomy_term_reference'),
      'settings' => array(
        'view_mode' => '',
        'links' => TRUE,
      ),
    ),
  );
}

/**
 * Implements hook_field_formatter_settings_form().
 */
function entityreference_field_formatter_settings_form($field, $instance, $view_mode, $form, &$form_state) {
  $display = $instance['display'][$view_mode];
  $settings = $display['settings'];
  $field_type_settings = entityreference_field_type_settings($field);

  if ($display['type'] == 'entityreference_label') {
    $element['link'] = array(
      '#title' => t('Link label to the referenced entity'),
      '#type' => 'checkbox',
      '#default_value' => $settings['link'],
    );
  }

  if ($display['type'] == 'entityreference_entity_view') {
    $entity_info = entity_get_info($field_type_settings['entity_type']);
    $options = array();
    if (!empty($entity_info['view modes'])) {
      foreach ($entity_info['view modes'] as $view_mode => $view_mode_settings) {
        $options[$view_mode] = $view_mode_settings['label'];
      }
    }

    if (count($options) > 1) {
      $element['view_mode'] = array(
        '#type' => 'select',
        '#options' => $options,
        '#title' => t('View mode'),
        '#default_value' => $settings['view_mode'],
      );
    }

    $element['links'] = array(
      '#type' => 'checkbox',
      '#title' => t('Show links'),
      '#default_value' => $settings['links'],
    );
  }

  return $element;
}

/**
 * Implements hook_field_formatter_settings_summary().
 */
function entityreference_field_formatter_settings_summary($field, $instance, $view_mode) {
  $display = $instance['display'][$view_mode];
  $settings = $display['settings'];
  $field_type_settings = entityreference_field_type_settings($field);

  $summary = array();

  if ($display['type'] == 'entityreference_label') {
    $summary[] = $settings['link'] ? t('Link to the referenced entity') : t('No link');
  }

  if ($display['type'] == 'entityreference_entity_view') {
    $entity_info = entity_get_info($field_type_settings['entity_type']);
    $summary[] = t('Rendered as @mode', array('@mode' => isset($entity_info['view modes'][$settings['view_mode']]['label']) ? $entity_info['view modes'][$settings['view_mode']]['label'] : $settings['view_mode']));
    $summary[] = !empty($settings['links']) ? t('Display links') : t('Do not display links');
  }

  return implode('<br />', $summary);
}

/**
 * Implements hook_field_formatter_prepare_view().
 */
function entityreference_field_formatter_prepare_view($entity_type, $entities, $field, $instances, $langcode, &$items, $displays) {
  $field_type_settings = entityreference_field_type_settings($field);
  $target_type = $field_type_settings['entity_type'];
  $column = $field_type_settings['column'];
  $target_ids = array();

  // Collect every possible entity attached to any of the entities.
  foreach ($entities as $id => $entity) {
    foreach ($items[$id] as $delta => $item) {
      if (isset($item[$column])) {
        $target_ids[] = $item[$column];
      }
    }
  }

  if ($target_ids) {
    $target_entities = entity_load($target_type, $target_ids);
  }
  else {
    $target_entities = array();
  }

  // Iterate through the fieldable entities again to attach the loaded data.
  foreach ($entities as $id => $entity) {
    $rekey = FALSE;

    foreach ($items[$id] as $delta => $item) {
      // Check whether the referenced entity could be loaded.
      if (isset($target_entities[$item[$column]])) {
        // Replace the instance value with the term data.
        $items[$id][$delta]['entity'] = $target_entities[$item[$column]];
        // Check whether the user has access to the referenced entity.
        $items[$id][$delta]['access'] =  entity_access('view', $target_type, $target_entities[$item[$column]]);
      }
      // Otherwise, unset the instance value, since the entity does not exist.
      else {
        unset($items[$id][$delta]);
        $rekey = TRUE;
      }
    }

    if ($rekey) {
      // Rekey the items array.
      $items[$id] = array_values($items[$id]);
    }
  }
}

/**
 * Implements hook_field_formatter_view().
 */
function entityreference_field_formatter_view($entity_type, $entity, $field, $instance, $langcode, $items, $display) {
  $result = array();
  $settings = $display['settings'];
  $field_type_settings = entityreference_field_type_settings($field);
  $target_type = $field_type_settings['entity_type'];
  $column = $field_type_settings['column'];

  // Rebuild the items list to contain only those with access.
  foreach ($items as $key => $item) {
    if (empty($item['access'])) {
      unset($items[$key]);
    }
  }

  switch ($display['type']) {
    case 'entityreference_label':
      $handler = entityreference_get_selection_handler($field, $instance, $entity_type, $entity);

      foreach ($items as $delta => $item) {
        $label = $handler->getLabel($item['entity']);
        // If the link is to be displayed and the entity has a uri, display a link.
        // Note the assignment ($url = ) here is intended to be an assignment.
        if ($display['settings']['link'] && ($uri = entity_uri($target_type, $item['entity']))) {
          $result[$delta] = array('#markup' => l($label, $uri['path'], $uri['options']));
        }
        else {
          $result[$delta] = array('#markup' => check_plain($label));
        }
      }
      break;

    case 'entityreference_entity_id':
      foreach ($items as $delta => $item) {
        $result[$delta] = array('#markup' => check_plain($item[$column]));
      }
      break;

    case 'entityreference_entity_view':
      foreach ($items as $delta => $item) {
        // Protect ourselves from recursive rendering.
        static $depth = 0;
        $depth++;
        if ($depth > 20) {
          throw new EntityReferenceRecursiveRenderingException(t('Recursive rendering detected when rendering entity @entity_type(@entity_id). Aborting rendering.', array('@entity_type' => $target_type, '@entity_id' => $item[$column])));
        }

        $entity = clone $item['entity'];
        unset($entity->content);
        $result[$delta] = entity_view($target_type, array($item[$column] => $entity), $settings['view_mode'], $langcode, FALSE);

        if (empty($settings['links']) && isset($result[$delta][$target_type][$column]['links'])) {
          $result[$delta][$target_type][$item[$column]]['links']['#access'] = FALSE;
        }
        $depth = 0;
      }
      break;
  }

  return $result;
}

/**
 * Exception thrown when the entity view renderer goes into a potentially infinite loop.
 */
class EntityReferenceRecursiveRenderingException extends Exception {}

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