<?php

/**
 * @file
 * Allows for caching of core entities.
 */

/**
 * Implements hook_entity_info_alter().
 */
function entitycache_entity_info_alter(&$entity_info) {
  foreach (entitycache_supported_core_entities(TRUE) as $type => $controller) {
    $entity_info[$type]['field cache'] = FALSE;
    $entity_info[$type]['entity cache'] = TRUE;
    $entity_info[$type]['controller class'] = $controller;
  }
}

/**
 * Entity cache helper.
 *
 * Note: while this class is not a real entity controller it needs to extend
 * DrupalDefaultEntityController to get access to protected properties.
 */
class EntityCacheControllerHelper extends DrupalDefaultEntityController {

  public static function resetEntityCache($controller, array $ids = NULL) {
    // Reset the persistent cache.
    if (!empty($ids)) {
      cache_clear_all($ids, 'cache_entity_' . $controller->entityType);
    }
    else {
      // Force all cached entries to be deleted.
      cache_clear_all('*', 'cache_entity_' . $controller->entityType, TRUE);
    }

    // Give modules the chance to act on any entity.
    foreach (module_implements('entitycache_reset') as $module) {
      $function = $module . '_entitycache_reset';
      $function($ids, $controller->entityType);
    }
    // Give modules the chance to act on a specific entity type.
    foreach (module_implements('entitycache_' . $controller->entityType . '_reset') as $module) {
      $function = $module . '_entitycache_' . $controller->entityType . '_reset';
      $function($ids);
    }
  }

  public static function entityCacheLoad($controller, $ids = array(), $conditions = array()) {
    $entities = array();
    $cached_entities = array();
    $queried_entities = array();

    // Revisions are not statically cached, and require a different query to
    // other conditions, so separate the revision id into its own variable.
    if ($controller->revisionKey && isset($conditions[$controller->revisionKey])) {
      $revision_id = $conditions[$controller->revisionKey];
      unset($conditions[$controller->revisionKey]);
    }
    else {
      $revision_id = FALSE;
    }

    // Create a new variable which is either a prepared version of the $ids
    // array for later comparison with the entity cache, or FALSE if no $ids
    // were passed. The $ids array is reduced as items are loaded from cache,
    // and we need to know if it's empty for this reason to avoid querying the
    // database when all requested entities are loaded from cache.
    $passed_ids = !empty($ids) ? array_flip($ids) : FALSE;
    // Try to load entities from the static cache, if the entity type supports
    // static caching.
    if ($controller->cache && !$revision_id) {
      $entities += $controller->cacheGet($ids, $conditions);
      // If any entities were loaded, remove them from the ids still to load.
      if ($passed_ids) {
        $ids = array_keys(array_diff_key($passed_ids, $entities));
      }
    }

    if (!empty($controller->entityInfo['entity cache']) && !$revision_id && $ids && !$conditions) {
      $entities += $cached_entities = self::entityCacheGet($controller, $ids, $conditions);
      // If any entities were loaded, remove them from the ids still to load.
      $ids = array_diff($ids, array_keys($cached_entities));

      if ($controller->cache) {
        // Add entities to the cache if we are not loading a revision.
        if (!empty($cached_entities) && !$revision_id) {
          $controller->cacheSet($cached_entities);
        }
      }
    }

    // Load any remaining entities from the database. This is the case if $ids
    // is set to FALSE (so we load all entities), if there are any ids left to
    // load, if loading a revision, or if $conditions was passed without $ids.
    if ($ids === FALSE || $ids || $revision_id || ($conditions && !$passed_ids)) {
      // Build the query.
      $query = $controller->buildQuery($ids, $conditions, $revision_id);
      $queried_entities = $query
        ->execute()
        ->fetchAllAssoc($controller->idKey);
    }

    // Pass all entities loaded from the database through $controller->attachLoad(),
    // which attaches fields (if supported by the entity type) and calls the
    // entity type specific load callback, for example hook_node_load().
    if (!empty($queried_entities)) {
      $controller->attachLoad($queried_entities, $revision_id);
      $entities += $queried_entities;
    }

    if (!empty($controller->entityInfo['entity cache'])) {
      // Add entities to the entity cache if we are not loading a revision.
      if (!empty($queried_entities) && !$revision_id) {
        self::entityCacheSet($controller, $queried_entities);
      }
    }

    if ($controller->cache) {
      // Add entities to the cache if we are not loading a revision.
      if (!empty($queried_entities) && !$revision_id) {
        $controller->cacheSet($queried_entities);
      }
    }

    // Ensure that the returned array is ordered the same as the original
    // $ids array if this was passed in and remove any invalid ids.
    if ($passed_ids) {
      // Remove any invalid ids from the array.
      $passed_ids = array_intersect_key($passed_ids, $entities);
      foreach ($entities as $entity) {
        $passed_ids[$entity->{$controller->idKey}] = $entity;
      }
      $entities = $passed_ids;
    }

    return $entities;
  }

  public static function entityCacheGet($controller, $ids, $conditions = array()) {
    $cached_entities = array();
    if ($ids && !$conditions) {
      $cached = cache_get_multiple($ids, 'cache_entity_' . $controller->entityType);
      if ($cached) {
        foreach ($cached as $item) {
          $cached_entities[$item->cid] = $item->data;
        }
        self::entityCacheAttachLoad($controller, $cached_entities);
      }
    }
    return $cached_entities;
  }

  public static function entityCacheSet($controller, $entities) {
    foreach ($entities as $item) {
      cache_set($item->{$controller->idKey}, $item, 'cache_entity_' . $controller->entityType);
    }
  }

  /**
   * Allow modules to implement uncached entity hooks.
   *
   * Perform two additional hook invocations for modules needing to add
   * uncacheable data to objects while serving the request.
   *
   * @see entitycache_entitycache_node_load()
   */
  public static function entityCacheAttachLoad($controller, $entities) {
    // Give modules the chance to act on any entity.
    foreach (module_implements('entitycache_load') as $module) {
      $function = $module . '_entitycache_load';
      $function($entities, $controller->entityType);
    }
    // Give modules the chance to act on a specific entity type.
    foreach (module_implements('entitycache_' . $controller->entityType . '_load') as $module) {
      $function = $module . '_entitycache_' . $controller->entityType . '_load';
      $function($entities);
    }
  }
}

/**
 * Default entity controller with persistent cache.
 */
class EntityCacheDefaultEntityController extends DrupalDefaultEntityController {
  public function resetCache(array $ids = NULL) {
    EntityCacheControllerHelper::resetEntityCache($this, $ids);
    parent::resetCache($ids);
  }
  public function load($ids = array(), $conditions = array()) {
    return EntityCacheControllerHelper::entityCacheLoad($this, $ids, $conditions);
  }
}

/**
 * Node entity controller with persistent cache.
 */
class EntityCacheNodeController extends NodeController {
  public function resetCache(array $ids = NULL) {
    EntityCacheControllerHelper::resetEntityCache($this, $ids);
    parent::resetCache($ids);
  }
  public function load($ids = array(), $conditions = array()) {
    return EntityCacheControllerHelper::entityCacheLoad($this, $ids, $conditions);
  }
}

/**
 * Implements hook_flush_caches().
 */
function entitycache_flush_caches() {
  $bins = array();
  $entities = entitycache_supported_core_entities(TRUE);
  foreach (array_keys($entities) as $type) {
    $bins[] = 'cache_entity_' . $type;
  }
  return $bins;
}

/**
 * User entity controller with persistent cache.
 */
class EntityCacheUserController extends UserController {
  public function resetCache(array $ids = NULL) {
    EntityCacheControllerHelper::resetEntityCache($this, $ids);
    parent::resetCache($ids);
  }
  public function load($ids = array(), $conditions = array()) {
    return EntityCacheControllerHelper::entityCacheLoad($this, $ids, $conditions);
  }
}

/**
 * Helper function to list all supported core entities.
 *
 * @param $enabled
 *   If set, only return enabled modules.
 *
 * @return
 *   An array of core entities.
 */
function entitycache_supported_core_entities($enabled = FALSE) {
  $return = array(
    'comment' => 'EntityCacheCommentController',
    'file' => 'EntityCacheDefaultEntityController',
    'node' => 'EntityCacheNodeController',
    'taxonomy_term' => 'EntityCacheTaxonomyTermController',
    'taxonomy_vocabulary' => 'EntityCacheTaxonomyVocabularyController',
    'user' => 'EntityCacheUserController',
  );
  // If the $enabled param is past, remove modules from the array if they're
  // not enabled.
  if ($enabled) {
    if (!module_exists('comment')) {
      unset($return['comment']);
    }
    if (!module_exists('taxonomy')) {
      unset($return['taxonomy_term']);
      unset($return['taxonomy_vocabulary']);
    }
    $return = array_diff_key($return, drupal_map_assoc(variable_get('entitycache_disabled_entity_types', array())));
  }
  return $return;
}

/**
 * Implements hook_entity_insert().
 */
function entitycache_entity_insert($entity, $type) {
  // It is possible for other _insert() hooks to load an entity before it has
  // been properly saved, for example file_field_insert(). This may cause
  // an incomplete entity to be cached, since hooks which run after the one
  // loading the entity do not have a chance to run. Therefore ensure the cache
  // is always cleared when inserting new entities.
  // Since hook_entity_insert() runs last, there's a good chance of acting
  // after other modules are finished loading.
  $info = entity_get_info($type);
  list($id) = entity_extract_ids($type, $entity);
  if (!empty($info['entity cache']) && empty($entity->migrate)) {
    // file_field_insert() no longer exists. Don't take this out
    // just yet though because other modules might also misbehave.
    // cache_clear_all($id, 'cache_entity_' . $type);
  }
}

/**
 * Implements hook_entity_delete().
 */
function entitycache_entity_delete($entity, $type) {
  $info = entity_get_info($type);
  list($id) = entity_extract_ids($type, $entity);
  if (!empty($info['entity cache'])) {
    cache_clear_all($id, 'cache_entity_' . $type);
  }
}

/**
 * Implements hook_entity_update().
 */
function entitycache_entity_update($entity, $type) {
  // It is possible for other _update() hooks to load an entity before it has
  // been properly saved, for example file_field_update(). This may cause
  // an incomplete entity to be cached, since hooks which run after the one
  // loading the entity do not have a chance to run. Therefore ensure the cache
  // is always cleared when updating entities.
  // Since hook_entity_insert() runs last, there's a good chance of acting
  // after other modules are finished loading.
  $info = entity_get_info($type);
  list($id) = entity_extract_ids($type, $entity);
  if (!empty($info['entity cache']) && empty($entity->migrate)) {
    cache_clear_all($id, 'cache_entity_' . $type);
  }
}

/**
 * Implements hook_entitycache_node_load().
 *
 * This forces book information to be added on each request, to avoid expensive
 * cache clears.
 */
function book_entitycache_node_load($nodes) {
  book_node_load($nodes, array());
}

/**
 * Implements hook_entitycache_node_load().
 *
 * This forces poll information to be loaded on each request, since it loads
 * user-specific information during the request.
 */
function poll_entitycache_node_load($nodes) {
  $polls = array();
  foreach ($nodes as $node) {
    if ($node->type == 'poll') {
      $polls[$node->nid] = $node;
    }
  }
  if (!empty($polls)) {
    poll_load($polls);
  }
}

/**
 * Implements hook_comment_publish().
 *
 * @todo: core should not call this hook outside of a comment_save().
 */
function entitycache_comment_publish($comment) {
  if (empty($comment->migrate)) {
    cache_clear_all($comment->cid, 'cache_entity_comment');
    cache_clear_all($comment->nid, 'cache_entity_node');
  }
}

/**
 * Implements hook_comment_unpublish().
 *
 * @todo: core should not call this hook outside of a comment_save().
 */
function entitycache_comment_unpublish($comment) {
  if (empty($comment->migrate)) {
    cache_clear_all($comment->cid, 'cache_entity_comment');
    cache_clear_all($comment->nid, 'cache_entity_node');
  }
}

/**
 * Implements hook_comment_insert().
 */
function entitycache_comment_insert($comment) {
  cache_clear_all($comment->nid, 'cache_entity_node');
}

/**
 * Implements hook_comment_update().
 */
function entitycache_comment_update($comment) {
  cache_clear_all($comment->nid, 'cache_entity_node');
}

/**
 * Implements hook_entitycache_ENTITY_TYPE_load().
 */
function entitycache_entitycache_comment_load($comments) {
  foreach ($comments as $comment) {
    $comment->new = $comment->new = node_mark($comment->nid, $comment->changed);
  }
}

/**
 * Implements hook_comment_update().
 */
function entitycache_comment_delete($comment) {
  cache_clear_all($comment->nid, 'cache_entity_node');
}

/**
 * Implements hook_user_cancel().
 */
function entitycache_user_cancel($edit, $account, $method) {
  cache_clear_all($account->uid, 'cache_entity_user');
}

/**
 * Implements hook_user_logout().
 */
function entitycache_user_logout($account) {
  cache_clear_all($account->uid, 'cache_entity_user');
}

/**
 * Implements hook_user_login().
 */
function entitycache_user_login(&$edit, $account) {
  cache_clear_all($account->uid, 'cache_entity_user');
}