<?php

/**
 * @file
 * Contains \Drupal\Core\Entity\Entity.
 */

namespace Drupal\Core\Entity;

use Drupal\Core\Cache\Cache;
use Drupal\Core\DependencyInjection\DependencySerialization;
use Drupal\Component\Utility\NestedArray;
use Drupal\Component\Utility\String;
use Drupal\Component\Utility\Unicode;
use Drupal\Core\Config\Entity\Exception\ConfigEntityIdLengthException;
use Drupal\Core\Entity\Exception\AmbiguousEntityClassException;
use Drupal\Core\Entity\Exception\NoCorrespondingEntityClassException;
use Drupal\Core\Entity\Exception\UndefinedLinkTemplateException;
use Drupal\Core\Language\Language;
use Drupal\Core\Session\AccountInterface;
use Drupal\Core\Url;

/**
 * Defines a base entity class.
 */
abstract class Entity extends DependencySerialization implements EntityInterface {

  /**
   * The entity type.
   *
   * @var string
   */
  protected $entityTypeId;

  /**
   * Boolean indicating whether the entity should be forced to be new.
   *
   * @var bool
   */
  protected $enforceIsNew;

  /**
   * Constructs an Entity object.
   *
   * @param array $values
   *   An array of values to set, keyed by property name. If the entity type
   *   has bundles, the bundle key has to be specified.
   * @param string $entity_type
   *   The type of the entity to create.
   */
  public function __construct(array $values, $entity_type) {
    $this->entityTypeId = $entity_type;
    // Set initial values.
    foreach ($values as $key => $value) {
      $this->$key = $value;
    }
  }

  /**
   * Returns the entity manager.
   *
   * @return \Drupal\Core\Entity\EntityManagerInterface
   */
  protected function entityManager() {
    return \Drupal::entityManager();
  }

  /**
   * Returns the language manager.
   *
   * @return \Drupal\Core\Language\LanguageManagerInterface
   */
  protected function languageManager() {
    return \Drupal::languageManager();
  }

  /**
   * Returns the UUID generator.
   *
   * @return \Drupal\Component\Uuid\UuidInterface
   */
  protected function uuidGenerator() {
    return \Drupal::service('uuid');
  }

  /**
   * {@inheritdoc}
   */
  public function id() {
    return isset($this->id) ? $this->id : NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function uuid() {
    return isset($this->uuid) ? $this->uuid : NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function isNew() {
    return !empty($this->enforceIsNew) || !$this->id();
  }

  /**
   * {@inheritdoc}
   */
  public function enforceIsNew($value = TRUE) {
    $this->enforceIsNew = $value;

    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function getEntityTypeId() {
    return $this->entityTypeId;
  }

  /**
   * {@inheritdoc}
   */
  public function bundle() {
    return $this->entityTypeId;
  }

  /**
   * {@inheritdoc}
   */
  public function label() {
    $label = NULL;
    $entity_type = $this->getEntityType();
    if (($label_callback = $entity_type->getLabelCallback()) && is_callable($label_callback)) {
      $label = call_user_func($label_callback, $this);
    }
    elseif (($label_key = $entity_type->getKey('label')) && isset($this->{$label_key})) {
      $label = $this->{$label_key};
    }
    return $label;
  }

  /**
   * {@inheritdoc}
   */
  public function urlInfo($rel = 'canonical') {
    if ($this->isNew()) {
      throw new EntityMalformedException(sprintf('The "%s" entity type has not been saved, and cannot have a URI.', $this->getEntityTypeId()));
    }

    // The links array might contain URI templates set in annotations.
    $link_templates = $this->linkTemplates();

    if (isset($link_templates[$rel])) {
      // If there is a template for the given relationship type, generate the path.
      $uri = new Url($link_templates[$rel], $this->urlRouteParameters($rel));
    }
    else {
      $bundle = $this->bundle();
      // A bundle-specific callback takes precedence over the generic one for
      // the entity type.
      $bundles = $this->entityManager()->getBundleInfo($this->getEntityTypeId());
      if (isset($bundles[$bundle]['uri_callback'])) {
        $uri_callback = $bundles[$bundle]['uri_callback'];
      }
      elseif ($entity_uri_callback = $this->getEntityType()->getUriCallback()) {
        $uri_callback = $entity_uri_callback;
      }

      // Invoke the callback to get the URI. If there is no callback, use the
      // default URI format.
      if (isset($uri_callback) && is_callable($uri_callback)) {
        $uri = call_user_func($uri_callback, $this);
      }
      else {
        throw new UndefinedLinkTemplateException(String::format('No link template "@rel" found for the "@entity_type" entity type', array(
          '@rel' => $rel,
          '@entity_type' => $this->getEntityTypeId(),
        )));
      }
    }

    // Pass the entity data to url() so that alter functions do not need to
    // look up this entity again.
    $uri
      ->setOption('entity_type', $this->getEntityTypeId())
      ->setOption('entity', $this);

    return $uri;
  }

  /**
   * {@inheritdoc}
   */
  public function getSystemPath($rel = 'canonical') {
    if ($this->hasLinkTemplate($rel) && $uri = $this->urlInfo($rel)) {
      return $uri->getInternalPath();
    }
    return '';
  }

  /**
   * {@inheritdoc}
   */
  public function hasLinkTemplate($rel) {
    $link_templates = $this->linkTemplates();
    return isset($link_templates[$rel]);
  }

  /**
   * Returns an array link templates.
   *
   * @return array
   *   An array of link templates containing route names.
   */
  protected function linkTemplates() {
    return $this->getEntityType()->getLinkTemplates();
  }

  /**
   * {@inheritdoc}
   */
  public function url($rel = 'canonical', $options = array()) {
    // While self::urlInfo() will throw an exception if the entity is new,
    // the expected result for a URL is always a string.
    if ($this->isNew() || !$this->hasLinkTemplate($rel)) {
      return '';
    }

    $uri = $this->urlInfo($rel);
    $options += $uri->getOptions();
    $uri->setOptions($options);
    return $uri->toString();
  }

  /**
   * Returns an array of placeholders for this entity.
   *
   * Individual entity classes may override this method to add additional
   * placeholders if desired. If so, they should be sure to replicate the
   * property caching logic.
   *
   * @param string $rel
   *   The link relationship type, for example: canonical or edit-form.
   *
   * @return array
   *   An array of URI placeholders.
   */
  protected function urlRouteParameters($rel) {
    // The entity ID is needed as a route parameter.
    $uri_route_parameters[$this->getEntityTypeId()] = $this->id();

    // The 'admin-form' link requires the bundle as a route parameter if the
    // entity type uses bundles.
    if ($rel == 'admin-form' && $this->getEntityType()->getBundleEntityType() != 'bundle') {
      $uri_route_parameters[$this->getEntityType()->getBundleEntityType()] = $this->bundle();
    }
    return $uri_route_parameters;
  }

  /**
   * {@inheritdoc}
   *
   * Returns a list of URI relationships supported by this entity.
   *
   * @return array
   *   An array of link relationships supported by this entity.
   */
  public function uriRelationships() {
    return array_keys($this->linkTemplates());
  }

  /**
   * {@inheritdoc}
   */
  public function access($operation, AccountInterface $account = NULL) {
    if ($operation == 'create') {
      return $this->entityManager()
        ->getAccessController($this->entityTypeId)
        ->createAccess($this->bundle(), $account);
    }
    return $this->entityManager()
      ->getAccessController($this->entityTypeId)
      ->access($this, $operation, Language::LANGCODE_DEFAULT, $account);
  }

  /**
   * {@inheritdoc}
   */
  public function language() {
    $language = $this->languageManager()->getLanguage($this->langcode);
    if (!$language) {
      // Make sure we return a proper language object.
      $language = new Language(array('id' => Language::LANGCODE_NOT_SPECIFIED));
    }
    return $language;
  }

  /**
   * {@inheritdoc}
   */
  public function save() {
    return $this->entityManager()->getStorage($this->entityTypeId)->save($this);
  }

  /**
   * {@inheritdoc}
   */
  public function delete() {
    if (!$this->isNew()) {
      $this->entityManager()->getStorage($this->entityTypeId)->delete(array($this->id() => $this));
    }
  }

  /**
   * {@inheritdoc}
   */
  public function createDuplicate() {
    $duplicate = clone $this;
    $entity_type = $this->getEntityType();
    // Reset the entity ID and indicate that this is a new entity.
    $duplicate->{$entity_type->getKey('id')} = NULL;
    $duplicate->enforceIsNew();

    // Check if the entity type supports UUIDs and generate a new one if so.
    if ($entity_type->hasKey('uuid')) {
      $duplicate->{$entity_type->getKey('uuid')} = $this->uuidGenerator()->generate();
    }
    return $duplicate;
  }

  /**
   * {@inheritdoc}
   */
  public function getEntityType() {
    return $this->entityManager()->getDefinition($this->getEntityTypeId());
  }

  /**
   * {@inheritdoc}
   */
  public function preSave(EntityStorageInterface $storage) {
    // Check if this is an entity bundle.
    if ($this->getEntityType()->getBundleOf()) {
      // Throw an exception if the bundle ID is longer than 32 characters.
      if (Unicode::strlen($this->id()) > EntityTypeInterface::BUNDLE_MAX_LENGTH) {
        throw new ConfigEntityIdLengthException(String::format(
          'Attempt to create a bundle with an ID longer than @max characters: @id.', array(
            '@max' => EntityTypeInterface::BUNDLE_MAX_LENGTH,
            '@id' => $this->id(),
          )
        ));
      }
    }
  }

  /**
   * {@inheritdoc}
   */
  public function postSave(EntityStorageInterface $storage, $update = TRUE) {
    $this->onSaveOrDelete();
    $this->invalidateTagsOnSave($update);
  }

  /**
   * {@inheritdoc}
   */
  public static function preCreate(EntityStorageInterface $storage, array &$values) {
  }

  /**
   * {@inheritdoc}
   */
  public function postCreate(EntityStorageInterface $storage) {
  }

  /**
   * {@inheritdoc}
   */
  public static function preDelete(EntityStorageInterface $storage, array $entities) {
  }

  /**
   * {@inheritdoc}
   */
  public static function postDelete(EntityStorageInterface $storage, array $entities) {
    self::invalidateTagsOnDelete($entities);
  }

  /**
   * {@inheritdoc}
   */
  public static function postLoad(EntityStorageInterface $storage, array &$entities) {
  }

  /**
   * {@inheritdoc}
   */
  public function referencedEntities() {
    return array();
  }

  /**
   * {@inheritdoc}
   */
  public function getCacheTag() {
    return array($this->entityTypeId => array($this->id()));
  }

  /**
   * {@inheritdoc}
   */
  public function getListCacheTags() {
    // @todo Add bundle-specific listing cache tag? https://drupal.org/node/2145751
    return array($this->entityTypeId . 's' => TRUE);
  }

  /**
   * {@inheritdoc}
   */
  public static function load($id) {
    return \Drupal::entityManager()->getStorage(static::getEntityTypeFromStaticClass())->load($id);
  }

  /**
   * {@inheritdoc}
   */
  public static function loadMultiple(array $ids = NULL) {
    return \Drupal::entityManager()->getStorage(static::getEntityTypeFromStaticClass())->loadMultiple($ids);
  }

  /**
   * Returns the entity type ID based on the class that is called on.
   *
   * Compares the class this is called on against the known entity classes
   * and returns the entity type ID of a direct match or a subclass as fallback,
   * to support entity type definitions that were altered.
   *
   * @return string
   *   The entity type ID.
   *
   * @throws \Drupal\Core\Entity\Exception\AmbiguousEntityClassException
   *   Thrown when multiple subclasses correspond to the called class.
   * @throws \Drupal\Core\Entity\Exception\NoCorrespondingEntityClassException
   *   Thrown when no entity class corresponds to the called class.
   *
   * @see \Drupal\Core\Entity\Entity::load()
   * @see \Drupal\Core\Entity\Entity::loadMultiple()
   */
  protected static function getEntityTypeFromStaticClass() {
    $called_class = get_called_class();
    $subclasses = 0;
    $same_class = 0;
    $entity_type_id = NULL;
    $subclass_entity_type_id = NULL;
    foreach (\Drupal::entityManager()->getDefinitions() as $entity_type) {
      // Check if this is the same class, throw an exception if there is more
      // than one match.
      if ($entity_type->getClass() == $called_class) {
        $entity_type_id = $entity_type->id();
        if ($same_class++) {
          throw new AmbiguousEntityClassException($called_class);
        }
      }
      // Check for entity types that are subclasses of the called class, but
      // throw an exception if we have multiple matches.
      elseif (is_subclass_of($entity_type->getClass(), $called_class)) {
        $subclass_entity_type_id = $entity_type->id();
        if ($subclasses++) {
          throw new AmbiguousEntityClassException($called_class);
        }
      }
    }

    // Return the matching entity type ID or the subclass match if there is one
    // as a secondary priority.
    if ($entity_type_id) {
      return $entity_type_id;
    }
    if ($subclass_entity_type_id) {
      return $subclass_entity_type_id;
    }
    throw new NoCorrespondingEntityClassException($called_class);
  }

  /**
   * Acts on an entity after it was saved or deleted.
   */
  protected function onSaveOrDelete() {
    $referenced_entities = array(
      $this->getEntityTypeId() => array($this->id() => $this),
    );

    foreach ($this->referencedEntities() as $referenced_entity) {
      $referenced_entities[$referenced_entity->getEntityTypeId()][$referenced_entity->id()] = $referenced_entity;
    }

    foreach ($referenced_entities as $entity_type => $entities) {
      if ($this->entityManager()->hasController($entity_type, 'view_builder')) {
        $this->entityManager()->getViewBuilder($entity_type)->resetCache($entities);
      }
    }
  }

  /**
   * Invalidates an entity's cache tags upon save.
   *
   * @param bool $update
   *   TRUE if the entity has been updated, or FALSE if it has been inserted.
   */
  protected function invalidateTagsOnSave($update) {
    // An entity was created or updated: invalidate its list cache tags. (An
    // updated entity may start to appear in a listing because it now meets that
    // listing's filtering requirements. A newly created entity may start to
    // appear in listings because it did not exist before.)
    $tags = $this->getListCacheTags();
    if ($update) {
      // An existing entity was updated, also invalidate its unique cache tag.
      $tags = NestedArray::mergeDeep($tags, $this->getCacheTag());
      $this->onUpdateBundleEntity();
    }
    Cache::invalidateTags($tags);
  }

  /**
   * Invalidates an entity's cache tags upon delete.
   *
   * @param \Drupal\Core\Entity\EntityInterface[] $entities
   *   An array of entities.
   */
  protected static function invalidateTagsOnDelete(array $entities) {
    $tags = array();
    foreach ($entities as $entity) {
      // An entity was deleted: invalidate its own cache tag, but also its list
      // cache tags. (A deleted entity may cause changes in a paged list on
      // other pages than the one it's on. The one it's on is handled by its own
      // cache tag, but subsequent list pages would not be invalidated, hence we
      // must invalidate its list cache tags as well.)
      $tags = NestedArray::mergeDeepArray(array($tags, $entity->getCacheTag(), $entity->getListCacheTags()));
      $entity->onSaveOrDelete();
    }
    Cache::invalidateTags($tags);
  }

  /**
   * Acts on entities of which this entity is a bundle entity type.
   */
  protected function onUpdateBundleEntity() {
    // If this entity is a bundle entity type of another entity type, and we're
    // updating an existing entity, and that other entity type has a view
    // builder class, then invalidate the render cache of entities for which
    // this entity is a bundle.
    $bundle_of = $this->getEntityType()->getBundleOf();
    $entity_manager = \Drupal::entityManager();
    if ($bundle_of !== FALSE && $entity_manager->hasController($bundle_of, 'view_builder')) {
      $entity_manager->getViewBuilder($bundle_of)->resetCache();
    }
  }

  /**
   * {@inheritdoc}
   */
  public function getOriginalId() {
    // By default, entities do not support renames and do not have original IDs.
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function setOriginalId($id) {
    // By default, entities do not support renames and do not have original IDs.
    // If the specified ID is anything except NULL, this should mark this entity
    // as no longer new.
    if ($id !== NULL) {
      $this->enforceIsNew(FALSE);
    }

    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function toArray() {
    return array();
  }

}