<?php

/**
 * @file
 * Entity API for handling entities like nodes or users.
 */

use \InvalidArgumentException;
use Drupal\Core\Entity\EntityFieldQuery;
use Drupal\Core\Entity\EntityMalformedException;
use Drupal\Core\Entity\EntityStorageException;
use Drupal\Core\Entity\EntityInterface;

/**
 * Gets the entity info array of an entity type.
 *
 * @param $entity_type
 *   The entity type, e.g. node, for which the info shall be returned, or NULL
 *   to return an array with info about all types.
 *
 * @see hook_entity_info()
 * @see hook_entity_info_alter()
 */
function entity_get_info($entity_type = NULL) {
  $language_interface = language(LANGUAGE_TYPE_INTERFACE);

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

  // hook_entity_info() includes translated strings, so each language is cached
  // separately.
  $langcode = $language_interface->langcode;

  if (empty($entity_info)) {
    if ($cache = cache()->get("entity_info:$langcode")) {
      $entity_info = $cache->data;
    }
    else {
      $entity_info = module_invoke_all('entity_info');
      // Merge in default values.
      foreach ($entity_info as $name => $data) {
        $entity_info[$name] += array(
          'fieldable' => FALSE,
          'entity class' => 'Drupal\Core\Entity\Entity',
          'controller class' => 'Drupal\Core\Entity\DatabaseStorageController',
          'form controller class' => array(
            'default' => 'Drupal\Core\Entity\EntityFormController',
          ),
          'static cache' => TRUE,
          'field cache' => TRUE,
          'bundles' => array(),
          'view modes' => array(),
          'entity keys' => array(),
          'translation' => array(),
        );
        $entity_info[$name]['entity keys'] += array(
          'revision' => '',
          'bundle' => '',
        );
        foreach ($entity_info[$name]['view modes'] as $view_mode => $view_mode_info) {
          $entity_info[$name]['view modes'][$view_mode] += array(
            'custom settings' => FALSE,
          );
        }
        // If no bundle key is provided, assume a single bundle, named after
        // the entity type.
        if (empty($entity_info[$name]['entity keys']['bundle']) && empty($entity_info[$name]['bundles'])) {
          $entity_info[$name]['bundles'] = array($name => array('label' => $entity_info[$name]['label']));
        }
        // Prepare entity schema fields SQL info for
        // Drupal\Core\Entity\DatabaseStorageControllerInterface::buildQuery().
        if (isset($entity_info[$name]['base table'])) {
          $entity_info[$name]['schema_fields_sql']['base table'] = drupal_schema_fields_sql($entity_info[$name]['base table']);
          if (isset($entity_info[$name]['revision table'])) {
            $entity_info[$name]['schema_fields_sql']['revision table'] = drupal_schema_fields_sql($entity_info[$name]['revision table']);
          }
        }
      }
      // Let other modules alter the entity info.
      drupal_alter('entity_info', $entity_info);
      cache()->set("entity_info:$langcode", $entity_info);
    }
  }

  if (empty($entity_type)) {
    return $entity_info;
  }
  elseif (isset($entity_info[$entity_type])) {
    return $entity_info[$entity_type];
  }
}

/**
 * Resets the cached information about entity types.
 */
function entity_info_cache_clear() {
  drupal_static_reset('entity_get_info');
  // Clear all languages.
  cache()->deletePrefix('entity_info:');
}

/**
 * Loads an entity from the database.
 *
 * @param string $entity_type
 *   The entity type to load, e.g. node or user.
 * @param int $id
 *   The id of the entity to load.
 * @param bool $reset
 *   Whether to reset the internal cache for the requested entity type.
 *
 * @return Drupal\Core\Entity\EntityInterface
 *   The entity object, or FALSE if there is no entity with the given id.
 *
 * @see hook_entity_info()
 * @see entity_load_multiple()
 * @see Drupal\Core\Entity\EntityStorageControllerInterface
 * @see Drupal\Core\Entity\DatabaseStorageController
 * @see Drupal\Core\Entity\EntityFieldQuery
 */
function entity_load($entity_type, $id, $reset = FALSE) {
  $entities = entity_load_multiple($entity_type, array($id), $reset);
  return isset($entities[$id]) ? $entities[$id] : FALSE;
}

/**
 * Loads an entity from the database.
 *
 * @param string $entity_type
 *   The entity type to load, e.g. node or user.
 * @param int $revision_id
 *   The id of the entity to load.
 *
 * @return Drupal\Core\Entity\EntityInterface
 *   The entity object, or FALSE if there is no entity with the given revision
 *   id.
 *
 * @see hook_entity_info()
 * @see Drupal\Core\Entity\EntityStorageControllerInterface
 * @see Drupal\Core\Entity\DatabaseStorageController
 */
function entity_revision_load($entity_type, $revision_id) {
  return entity_get_controller($entity_type)->loadRevision($revision_id);
}

/**
 * Loads an entity by UUID.
 *
 * Note that some entity types may not support UUIDs.
 *
 * @param string $entity_type
 *   The entity type to load; e.g., 'node' or 'user'.
 * @param string $uuid
 *   The UUID of the entity to load.
 * @param bool $reset
 *   Whether to reset the internal cache for the requested entity type.
 *
 * @return EntityInterface|FALSE
 *   The entity object, or FALSE if there is no entity with the given UUID.
 *
 * @throws Drupal\Core\Entity\EntityStorageException
 *   Thrown in case the requested entity type does not support UUIDs.
 *
 * @see hook_entity_info()
 */
function entity_load_by_uuid($entity_type, $uuid, $reset = FALSE) {
  $entity_info = entity_get_info($entity_type);
  if (empty($entity_info['entity keys']['uuid'])) {
    throw new EntityStorageException("Entity type $entity_type does not support UUIDs.");
  }
  $uuid_key = $entity_info['entity keys']['uuid'];

  $controller = entity_get_controller($entity_type);
  if ($reset) {
    $controller->resetCache();
  }
  $entities = $controller->loadByProperties(array($uuid_key => $uuid));
  return reset($entities);
}

/**
 * Loads multiple entities from the database.
 *
 * This function should be used whenever you need to load more than one entity
 * from the database. The entities are loaded into memory and will not require
 * database access if loaded again during the same page request.
 *
 * The actual loading is done through a class that has to implement the
 * Drupal\Core\Entity\EntityStorageControllerInterface interface. By default,
 * Drupal\Core\Entity\DatabaseStorageController is used. Entity types can
 * specify that a different class should be used by setting the
 * 'controller class' key in hook_entity_info(). These classes can either
 * implement the Drupal\Core\Entity\EntityStorageControllerInterface interface, or,
 * most commonly, extend the Drupal\Core\Entity\DatabaseStorageController
 * class. See node_entity_info() and the NodeStorageController in node.module as
 * an example.
 *
 * @param string $entity_type
 *   The entity type to load, e.g. node or user.
 * @param array $ids
 *   (optional) An array of entity IDs. If omitted, all entities are loaded.
 * @param bool $reset
 *   Whether to reset the internal cache for the requested entity type.
 *
 * @return array
 *   An array of entity objects indexed by their ids.
 *
 * @see hook_entity_info()
 * @see Drupal\Core\Entity\EntityStorageControllerInterface
 * @see Drupal\Core\Entity\DatabaseStorageController
 * @see Drupal\Core\Entity\EntityFieldQuery
 */
function entity_load_multiple($entity_type, array $ids = NULL, $reset = FALSE) {
  if ($reset) {
    entity_get_controller($entity_type)->resetCache();
  }
  return entity_get_controller($entity_type)->load($ids);
}

/**
 * Load entities by their property values.
 *
 * @param string $entity_type
 *   The entity type to load, e.g. node or user.
 * @param array $values
 *   An associative array where the keys are the property names and the
 *   values are the values those properties must have.
 *
 * @return array
 *   An array of entity objects indexed by their ids.
 */
function entity_load_multiple_by_properties($entity_type, array $values) {
  return entity_get_controller($entity_type)->loadByProperties($values);
}

/**
 * Loads the unchanged, i.e. not modified, entity from the database.
 *
 * Unlike entity_load() this function ensures the entity is directly loaded from
 * the database, thus bypassing any static cache. In particular, this function
 * is useful to determine changes by comparing the entity being saved to the
 * stored entity.
 *
 * @param $entity_type
 *   The entity type to load, e.g. node or user.
 * @param $id
 *   The ID of the entity to load.
 *
 * @return
 *   The unchanged entity, or FALSE if the entity cannot be loaded.
 */
function entity_load_unchanged($entity_type, $id) {
  entity_get_controller($entity_type)->resetCache(array($id));
  $result = entity_get_controller($entity_type)->load(array($id));
  return reset($result);
}

/**
 * Deletes multiple entities permanently.
 *
 * @param $entity_type
 *   The type of the entity.
 * @param $ids
 *   An array of entity IDs of the entities to delete.
 */
function entity_delete_multiple($entity_type, $ids) {
  entity_get_controller($entity_type)->delete($ids);
}

/**
 * Constructs a new entity object, without permanently saving it.
 *
 * @param $entity_type
 *   The type of the entity.
 * @param $values
 *   An array of values to set, keyed by property name. If the entity type has
 *   bundles the bundle key has to be specified.
 *
 * @return Drupal\Core\Entity\EntityInterface
 *   A new entity object.
 */
function entity_create($entity_type, array $values) {
  return entity_get_controller($entity_type)->create($values);
}

/**
 * Gets the entity controller class for an entity type.
 *
 * @return Drupal\Core\Entity\EntityStorageControllerInterface
 */
function entity_get_controller($entity_type) {
  $controllers = &drupal_static(__FUNCTION__, array());
  if (!isset($controllers[$entity_type])) {
    $type_info = entity_get_info($entity_type);
    $class = $type_info['controller class'];
    $controllers[$entity_type] = new $class($entity_type);
  }
  return $controllers[$entity_type];
}

/**
 * Invokes hook_entity_prepare_view().
 *
 * If adding a new entity similar to nodes, comments or users, you should
 * invoke this function during the ENTITY_build_content() or
 * ENTITY_view_multiple() phases of rendering to allow other modules to alter
 * the objects during this phase. This is needed for situations where
 * information needs to be loaded outside of ENTITY_load() - particularly
 * when loading entities into one another - i.e. a user object into a node, due
 * to the potential for unwanted side-effects such as caching and infinite
 * recursion. By convention, entity_prepare_view() is called after
 * field_attach_prepare_view() to allow entity level hooks to act on content
 * loaded by field API.
 *
 * @param $entity_type
 *   The type of entity, i.e. 'node', 'user'.
 * @param $entities
 *   The entity objects which are being prepared for view, keyed by object ID.
 *
 * @see hook_entity_prepare_view()
 */
function entity_prepare_view($entity_type, $entities) {
  // To ensure hooks are only run once per entity, check for an
  // entity_view_prepared flag and only process items without it.
  // @todo: resolve this more generally for both entity and field level hooks.
  $prepare = array();
  foreach ($entities as $id => $entity) {
    if (empty($entity->entity_view_prepared)) {
      // Add this entity to the items to be prepared.
      $prepare[$id] = $entity;

      // Mark this item as prepared.
      $entity->entity_view_prepared = TRUE;
    }
  }

  if (!empty($prepare)) {
    module_invoke_all('entity_prepare_view', $prepare, $entity_type);
  }
}

/**
 * Returns the label of an entity.
 *
 * This is a wrapper for Drupal\Core\Entity\EntityInterface::label(). This function
 * should only be used as a callback, e.g. for menu title callbacks.
 *
 * @param Drupal\Core\Entity\EntityInterface $entity
 *   The entity for which to generate the label.
 * @param $langcode
 *   (optional) The language code of the language that should be used for
 *   getting the label. If set to NULL, the entity's default language is
 *   used.
 *
 * @return
 *   The label of the entity, or NULL if there is no label defined.
 *
 * @see Drupal\Core\Entity\EntityInterface::label()
 */
function entity_page_label(EntityInterface $entity, $langcode = NULL) {
  return $entity->label($langcode);
}

/**
 * Returns an entity form controller for the given operation.
 *
 * Since there might be different scenarios in which an entity is edited,
 * multiple form controllers suitable to the different operations may be defined.
 * If no controller is found for the default operation, the base class will be
 * used. If a non-existing non-default operation is specified an exception will
 * be thrown.
 *
 * @see hook_entity_info()
 *
 * @param $entity_type
 *   The type of the entity.
 * @param $operation
 *   (optional) The name of an operation, such as creation, editing or deletion,
 *   identifying the controlled form. Defaults to 'default' which is the usual
 *   create/edit form.
 *
 * @return Drupal\Core\Entity\EntityFormControllerInterface
 *   An entity form controller instance.
 */
function entity_form_controller($entity_type, $operation = 'default') {
  $info = entity_get_info($entity_type);

  // Check whether there is a form controller class for the specified operation.
  if (!empty($info['form controller class'][$operation])) {
    $class = $info['form controller class'][$operation];
  }
  // If no controller is specified default to the base implementation.
  elseif (empty($info['form controller class']) && $operation == 'default') {
    $class = 'Drupal\Core\Entity\EntityFormController';
  }
  // If a non-existing operation has been specified stop.
  else {
    throw new InvalidArgumentException("Missing form controller for '$entity_type', operation '$operation'");
  }

  return new $class($operation);
}

/**
 * Returns the form id for the given entity and operation.
 *
 * @param EntityInterface $entity
 *   The entity to be created or edited.
 * @param $operation
 *   (optional) The operation for the form to be processed.
 *
 * @return
 *   A string representing the entity form id.
 */
function entity_form_id(EntityInterface $entity, $operation = 'default') {
  $entity_type = $entity->entityType();
  $bundle = $entity->bundle();
  $form_id = $entity_type;
  if ($bundle != $entity_type) {
    $form_id = $bundle . '_' . $form_id;
  }
  if ($operation != 'default') {
    $form_id = $form_id . '_' . $operation;
  }
  return $form_id . '_form';
}

/**
 * Returns the default form state for the given entity and operation.
 *
 * @param EntityInterface $entity
 *   The entity to be created or edited.
 * @param $operation
 *   (optional) The operation identifying the form to be processed.
 *
 * @return
 *   A $form_state array already filled the entity form controller.
 */
function entity_form_state_defaults(EntityInterface $entity, $operation = 'default', $langcode = NULL) {
  $form_state = array();
  $controller = entity_form_controller($entity->entityType(), $operation);
  $form_state['build_info']['callback'] = array($controller, 'build');
  $form_state['build_info']['base_form_id'] = $entity->entityType() . '_form';
  $form_state['build_info']['args'] = array($entity);
  $form_state['langcode'] = $langcode;
  return $form_state;
}

/**
 * Retrieves, populates, and processes an entity form.
 *
 * @param EntityInterface $entity
 *   The entity to be created or edited.
 * @param $operation
 *   (optional) The operation identifying the form to be submitted.
 * @param $form_state
 *   (optional) A keyed array containing the current state of the form.
 *
 * @return
 *   A $form_state array already filled with the entity form controller.
 */
function entity_form_submit(EntityInterface $entity, $operation = 'default', &$form_state = array()) {
  $form_state += entity_form_state_defaults($entity, $operation);
  $form_id = entity_form_id($entity, $operation);
  drupal_form_submit($form_id, $form_state);
}

/**
 * Returns the built and processed entity form for the given entity.
 *
 * @param EntityInterface $entity
 *   The entity to be created or edited.
 * @param $operation
 *   (optional) The operation identifying the form variation to be returned.
 *
 * @return
 *   The processed form for the given entity and operation.
 */
function entity_get_form(EntityInterface $entity, $operation = 'default', $langcode = NULL) {
  $form_state = entity_form_state_defaults($entity, $operation, $langcode);
  $form_id = entity_form_id($entity, $operation);
  return drupal_build_form($form_id, $form_state);
}

/**
 * Copies submitted values to entity properties for simple entity forms.
 *
 * During the submission handling of an entity form's "Save", "Preview", and
 * possibly other buttons, the form state's entity needs to be updated with the
 * submitted form values. Each entity form implements its own builder function
 * for doing this, appropriate for the particular entity and form, whereas
 * modules may specify additional builder functions in $form['#entity_builders']
 * for copying the form values of added form elements to entity properties.
 * Many of the main entity builder functions can call this helper function to
 * re-use its logic of copying $form_state['values'][PROPERTY] values to
 * $entity->PROPERTY for all entries in $form_state['values'] that are not field
 * data, and calling field_attach_submit() to copy field data. Apart from that
 * this helper invokes any additional builder functions that have been specified
 * in $form['#entity_builders'].
 *
 * For some entity forms (e.g., forms with complex non-field data and forms that
 * simultaneously edit multiple entities), this behavior may be inappropriate,
 * so the builder function for such forms needs to implement the required
 * functionality instead of calling this function.
 */
function entity_form_submit_build_entity($entity_type, $entity, $form, &$form_state) {
  $info = entity_get_info($entity_type);

  // Copy top-level form values that are not for fields to entity properties,
  // without changing existing entity properties that are not being edited by
  // this form. Copying field values must be done using field_attach_submit().
  $values_excluding_fields = $info['fieldable'] ? array_diff_key($form_state['values'], field_info_instances($entity_type, $entity->bundle())) : $form_state['values'];
  foreach ($values_excluding_fields as $key => $value) {
    $entity->$key = $value;
  }

  // Invoke all specified builders for copying form values to entity properties.
  if (isset($form['#entity_builders'])) {
    foreach ($form['#entity_builders'] as $function) {
      $function($entity_type, $entity, $form, $form_state);
    }
  }

  // Copy field values to the entity.
  if ($info['fieldable']) {
    field_attach_submit($entity_type, $entity, $form, $form_state);
  }
}