class FieldStorageConfig

class FieldStorageConfig extends ConfigEntityBase implements FieldStorageConfigInterface {

  /**
   * The maximum length of the field name, in characters.
   *
   * For fields created through Field UI, this includes the 'field_' prefix.
   */
  const NAME_MAX_LENGTH = 32;

  /**
   * The field ID.
   *
   * The ID consists of 2 parts: the entity type and the field name.
   *
   * Example: node.body, user.field_main_image.
   *
   * @var string
   */
  protected $id;

  /**
   * The field name.
   *
   * This is the name of the property under which the field values are placed in
   * an entity: $entity->{$field_name}. The maximum length is
   * Field:NAME_MAX_LENGTH.
   *
   * Example: body, field_main_image.
   *
   * @var string
   */
  protected $field_name;

  /**
   * The name of the entity type the field can be attached to.
   *
   * @var string
   */
  protected $entity_type;

  /**
   * The field type.
   *
   * Example: text, integer.
   *
   * @var string
   */
  protected $type;

  /**
   * The name of the module that provides the field type.
   *
   * @var string
   */
  protected $module;

  /**
   * Field-type specific settings.
   *
   * An array of key/value pairs, The keys and default values are defined by the
   * field type.
   *
   * @var array
   */
  protected $settings = [];

  /**
   * The field cardinality.
   *
   * The maximum number of values the field can hold. Possible values are
   * positive integers or
   * FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED. Defaults to 1.
   *
   * @var int
   */
  protected $cardinality = 1;

  /**
   * Flag indicating whether the field is translatable.
   *
   * Defaults to TRUE.
   *
   * @var bool
   */
  protected $translatable = TRUE;

  /**
   * Flag indicating whether the field is available for editing.
   *
   * If TRUE, some actions not available though the UI (but are still possible
   * through direct API manipulation):
   * - field settings cannot be changed,
   * - new fields cannot be created
   * - existing fields cannot be deleted.
   * Defaults to FALSE.
   *
   * @var bool
   */
  protected $locked = FALSE;

  /**
   * Flag indicating whether the field storage should be deleted when orphaned.
   *
   * By default field storages for configurable fields are removed when there
   * are no remaining fields using them. If multiple modules provide bundles
   * which need to use the same field storage then setting this to TRUE will
   * preserve the field storage regardless of what happens to the bundles. The
   * classic use case for this is node body field storage since Book, Forum, the
   * Standard profile and bundle (node type) creation through the UI all use
   * same field storage.
   *
   * @var bool
   */
  protected $persist_with_no_fields = FALSE;

  /**
   * A boolean indicating whether or not the field item uses custom storage.
   *
   * @var bool
   */
  public $custom_storage = FALSE;

  /**
   * The custom storage indexes for the field data storage.
   *
   * This set of indexes is merged with the "default" indexes specified by the
   * field type in the class implementing
   * \Drupal\Core\Field\FieldItemInterface::schema() method to determine the
   * actual set of indexes that get created.
   *
   * The indexes are defined using the same definition format as Schema API
   * index specifications. Only columns that are part of the field schema, as
   * defined by the field type in the class implementing
   * \Drupal\Core\Field\FieldItemInterface::schema() method, are allowed.
   *
   * Some storage backends might not support indexes, and discard that
   * information.
   *
   * @var array
   */
  protected $indexes = [];

  /**
   * Flag indicating whether the field is deleted.
   *
   * The delete() method marks the field as "deleted" and removes the
   * corresponding entry from the config storage, but keeps its definition in
   * the state storage while field data is purged by a separate
   * garbage-collection process.
   *
   * Deleted fields stay out of the regular entity lifecycle (notably, their
   * values are not populated in loaded entities, and are not saved back).
   *
   * @var bool
   */
  protected $deleted = FALSE;

  /**
   * The field schema.
   *
   * @var array
   */
  protected $schema;

  /**
   * An array of field property definitions.
   *
   * @var \Drupal\Core\TypedData\DataDefinitionInterface[]
   *
   * @see \Drupal\Core\TypedData\ComplexDataDefinitionInterface::getPropertyDefinitions()
   */
  protected $propertyDefinitions;

  /**
   * Static flag set to prevent recursion during field deletes.
   *
   * @var bool
   */
  protected static $inDeletion = FALSE;

  /**
   * Constructs a FieldStorageConfig object.
   *
   * In most cases, Field entities are created via
   * FieldStorageConfig::create($values)), where $values is the same parameter
   * as in this constructor.
   *
   * @param array $values
   *   An array of field properties, keyed by property name. Most array
   *   elements will be used to set the corresponding properties on the class;
   *   see the class property documentation for details. Some array elements
   *   have special meanings and a few are required. Special elements are:
   *   - name: required. As a temporary Backwards Compatibility layer right now,
   *     a 'field_name' property can be accepted in place of 'id'.
   *   - entity_type: required.
   *   - type: required.
   */
  public function __construct(array $values, $entity_type = 'field_storage_config') {

    // Check required properties.
    if (empty($values['field_name'])) {
      throw new FieldException('Attempt to create a field storage without a field name.');
    }
    if (!preg_match('/^[_a-z]+[_a-z0-9]*$/', $values['field_name'])) {
      throw new FieldException("Attempt to create a field storage {$values['field_name']} with invalid characters. Only lowercase alphanumeric characters and underscores are allowed, and only lowercase letters and underscore are allowed as the first character");
    }
    if (empty($values['type'])) {
      throw new FieldException("Attempt to create a field storage {$values['field_name']} with no type.");
    }
    if (empty($values['entity_type'])) {
      throw new FieldException("Attempt to create a field storage {$values['field_name']} with no entity_type.");
    }
    parent::__construct($values, $entity_type);
  }

  /**
   * {@inheritdoc}
   */
  public function id() {
    return $this
      ->getTargetEntityTypeId() . '.' . $this
      ->getName();
  }

  /**
   * Overrides \Drupal\Core\Entity\Entity::preSave().
   *
   * @throws \Drupal\Core\Field\FieldException
   *   If the field definition is invalid.
   * @throws \Drupal\Core\Entity\EntityStorageException
   *   In case of failures at the configuration storage level.
   */
  public function preSave(EntityStorageInterface $storage) {

    // Clear the derived data about the field.
    unset($this->schema);

    // Filter out unknown settings and make sure all settings are present, so
    // that a complete field definition is passed to the various hooks and
    // written to config.
    $field_type_manager = \Drupal::service('plugin.manager.field.field_type');
    $default_settings = $field_type_manager
      ->getDefaultStorageSettings($this->type);
    $this->settings = array_intersect_key($this->settings, $default_settings) + $default_settings;
    if ($this
      ->isNew()) {
      $this
        ->preSaveNew($storage);
    }
    else {
      $this
        ->preSaveUpdated($storage);
    }
    parent::preSave($storage);
  }

  /**
   * Prepares saving a new field definition.
   *
   * @param \Drupal\Core\Entity\EntityStorageInterface $storage
   *   The entity storage.
   *
   * @throws \Drupal\Core\Field\FieldException
   *   If the field definition is invalid.
   */
  protected function preSaveNew(EntityStorageInterface $storage) {
    $entity_field_manager = \Drupal::service('entity_field.manager');
    $field_type_manager = \Drupal::service('plugin.manager.field.field_type');

    // Assign the ID.
    $this->id = $this
      ->id();

    // Field name cannot be longer than FieldStorageConfig::NAME_MAX_LENGTH
    // characters. We use mb_strlen() because the DB layer assumes that column
    // widths are given in characters rather than bytes.
    if (mb_strlen($this
      ->getName()) > static::NAME_MAX_LENGTH) {
      throw new FieldException('Attempt to create a field storage with an name longer than ' . static::NAME_MAX_LENGTH . ' characters: ' . $this
        ->getName());
    }

    // Disallow reserved field names.
    $disallowed_field_names = array_keys($entity_field_manager
      ->getBaseFieldDefinitions($this
      ->getTargetEntityTypeId()));
    if (in_array($this
      ->getName(), $disallowed_field_names)) {
      throw new FieldException("Attempt to create field storage {$this->getName()} which is reserved by entity type {$this->getTargetEntityTypeId()}.");
    }

    // Check that the field type is known.
    $field_type = $field_type_manager
      ->getDefinition($this
      ->getType(), FALSE);
    if (!$field_type) {
      throw new FieldException("Attempt to create a field storage of unknown type {$this->getType()}.");
    }
    $this->module = $field_type['provider'];

    // Notify the field storage definition listener.
    \Drupal::service('field_storage_definition.listener')
      ->onFieldStorageDefinitionCreate($this);
  }

  /**
   * {@inheritdoc}
   */
  public function calculateDependencies() {
    parent::calculateDependencies();

    // Ensure the field is dependent on the providing module.
    $this
      ->addDependency('module', $this
      ->getTypeProvider());

    // Ask the field type for any additional storage dependencies.
    // @see \Drupal\Core\Field\FieldItemInterface::calculateStorageDependencies()
    $definition = \Drupal::service('plugin.manager.field.field_type')
      ->getDefinition($this
      ->getType(), FALSE);
    $this
      ->addDependencies($definition['class']::calculateStorageDependencies($this));

    // Ensure the field is dependent on the provider of the entity type.
    $entity_type = \Drupal::entityTypeManager()
      ->getDefinition($this->entity_type);
    $this
      ->addDependency('module', $entity_type
      ->getProvider());
    return $this;
  }

  /**
   * Prepares saving an updated field definition.
   *
   * @param \Drupal\Core\Entity\EntityStorageInterface $storage
   *   The entity storage.
   */
  protected function preSaveUpdated(EntityStorageInterface $storage) {
    $module_handler = \Drupal::moduleHandler();

    // Some updates are always disallowed.
    if ($this
      ->getType() != $this->original
      ->getType()) {
      throw new FieldException(sprintf('Cannot change the field type for an existing field storage. The field storage %s has the type %s.', $this
        ->id(), $this->original
        ->getType()));
    }
    if ($this
      ->getTargetEntityTypeId() != $this->original
      ->getTargetEntityTypeId()) {
      throw new FieldException(sprintf('Cannot change the entity type for an existing field storage. The field storage %s has the type %s.', $this
        ->id(), $this->original
        ->getTargetEntityTypeId()));
    }

    // See if any module forbids the update by throwing an exception. This
    // invokes hook_field_storage_config_update_forbid().
    $module_handler
      ->invokeAll('field_storage_config_update_forbid', [
      $this,
      $this->original,
    ]);

    // Notify the entity manager. A listener can reject the definition
    // update as invalid by raising an exception, which stops execution before
    // the definition is written to config.
    \Drupal::service('field_storage_definition.listener')
      ->onFieldStorageDefinitionUpdate($this, $this->original);
  }

  /**
   * {@inheritdoc}
   */
  public function postSave(EntityStorageInterface $storage, $update = TRUE) {
    if ($update) {

      // Invalidate the render cache for all affected entities.
      $entity_type_manager = \Drupal::entityTypeManager();
      $entity_type = $this
        ->getTargetEntityTypeId();
      if ($entity_type_manager
        ->hasHandler($entity_type, 'view_builder')) {
        $entity_type_manager
          ->getViewBuilder($entity_type)
          ->resetCache();
      }
    }
  }

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

    /** @var \Drupal\Core\Field\DeletedFieldsRepositoryInterface $deleted_fields_repository */
    $deleted_fields_repository = \Drupal::service('entity_field.deleted_fields_repository');

    // Set the static flag so that we don't delete field storages whilst
    // deleting fields.
    static::$inDeletion = TRUE;

    // Delete or fix any configuration that is dependent, for example, fields.
    parent::preDelete($storage, $field_storages);

    // Keep the field storage definitions in the deleted fields repository so we
    // can use them later during field_purge_batch().

    /** @var \Drupal\field\FieldStorageConfigInterface $field_storage */
    foreach ($field_storages as $field_storage) {

      // Only mark a field for purging if there is data. Otherwise, just remove
      // it.
      $target_entity_storage = \Drupal::entityTypeManager()
        ->getStorage($field_storage
        ->getTargetEntityTypeId());
      if (!$field_storage->deleted && $target_entity_storage instanceof FieldableEntityStorageInterface && $target_entity_storage
        ->countFieldData($field_storage, TRUE)) {
        $storage_definition = clone $field_storage;
        $storage_definition->deleted = TRUE;
        $deleted_fields_repository
          ->addFieldStorageDefinition($storage_definition);
      }
    }
  }

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

    // Notify the storage.
    foreach ($fields as $field) {
      if (!$field->deleted) {
        \Drupal::service('field_storage_definition.listener')
          ->onFieldStorageDefinitionDelete($field);
        $field->deleted = TRUE;
      }
    }

    // Unset static flag.
    static::$inDeletion = FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function getSchema() {
    if (!isset($this->schema)) {

      // Get the schema from the field item class.
      $class = $this
        ->getFieldItemClass();
      $schema = $class::schema($this);

      // Fill in default values for optional entries.
      $schema += [
        'columns' => [],
        'unique keys' => [],
        'indexes' => [],
        'foreign keys' => [],
      ];

      // Merge custom indexes with those specified by the field type. Custom
      // indexes prevail.
      $schema['indexes'] = $this->indexes + $schema['indexes'];
      $this->schema = $schema;
    }
    return $this->schema;
  }

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

  /**
   * {@inheritdoc}
   */
  public function isBaseField() {
    return FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function getColumns() {
    $schema = $this
      ->getSchema();
    return $schema['columns'];
  }

  /**
   * {@inheritdoc}
   */
  public function getBundles() {
    if (!$this
      ->isDeleted()) {
      $map = \Drupal::service('entity_field.manager')
        ->getFieldMap();
      if (isset($map[$this
        ->getTargetEntityTypeId()][$this
        ->getName()]['bundles'])) {
        return $map[$this
          ->getTargetEntityTypeId()][$this
          ->getName()]['bundles'];
      }
    }
    return [];
  }

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

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

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

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

  /**
   * {@inheritdoc}
   */
  public function getSettings() {

    // @todo FieldTypePluginManager maintains its own static cache. However, do
    //   some CPU and memory profiling to see if it's worth statically caching
    //   $field_type_info, or the default field storage and field settings,
    //   within $this.
    $field_type_manager = \Drupal::service('plugin.manager.field.field_type');
    $settings = $field_type_manager
      ->getDefaultStorageSettings($this
      ->getType());
    return $this->settings + $settings;
  }

  /**
   * {@inheritdoc}
   */
  public function getSetting($setting_name) {

    // @todo See getSettings() about potentially statically caching this.
    // We assume here that one call to array_key_exists() is more efficient
    // than calling getSettings() when all we need is a single setting.
    if (array_key_exists($setting_name, $this->settings)) {
      return $this->settings[$setting_name];
    }
    $settings = $this
      ->getSettings();
    if (array_key_exists($setting_name, $settings)) {
      return $settings[$setting_name];
    }
    else {
      return NULL;
    }
  }

  /**
   * {@inheritdoc}
   */
  public function setSetting($setting_name, $value) {
    $this->settings[$setting_name] = $value;
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function setSettings(array $settings) {
    $this->settings = $settings + $this->settings;
    return $this;
  }

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

  /**
   * {@inheritdoc}
   */
  public function isRevisionable() {

    // All configurable fields are revisionable.
    return TRUE;
  }

  /**
   * {@inheritdoc}
   */
  public function setTranslatable($translatable) {
    $this->translatable = $translatable;
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function getProvider() {
    return 'field';
  }

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

  /**
   * {@inheritdoc}
   */
  public function getDescription() {
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function getCardinality() {

    /** @var \Drupal\Core\Field\FieldTypePluginManager $field_type_manager */
    $field_type_manager = \Drupal::service('plugin.manager.field.field_type');
    $definition = $field_type_manager
      ->getDefinition($this
      ->getType());
    $enforced_cardinality = isset($definition['cardinality']) ? $definition['cardinality'] : NULL;

    // Enforced cardinality is a positive integer or -1.
    if ($enforced_cardinality !== NULL && $enforced_cardinality < 1 && $enforced_cardinality !== FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED) {
      throw new FieldException("Invalid enforced cardinality '{$enforced_cardinality}'. Allowed values: a positive integer or -1.");
    }
    return $enforced_cardinality ?: $this->cardinality;
  }

  /**
   * {@inheritdoc}
   */
  public function setCardinality($cardinality) {
    $this->cardinality = $cardinality;
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function getOptionsProvider($property_name, FieldableEntityInterface $entity) {

    // If the field item class implements the interface, create an orphaned
    // runtime item object, so that it can be used as the options provider
    // without modifying the entity being worked on.
    if (is_subclass_of($this
      ->getFieldItemClass(), OptionsProviderInterface::class)) {
      $items = $entity
        ->get($this
        ->getName());
      return \Drupal::service('plugin.manager.field.field_type')
        ->createFieldItem($items, 0);
    }

    // @todo: Allow setting custom options provider, see
    // https://www.drupal.org/node/2002138.
  }

  /**
   * {@inheritdoc}
   */
  public function isMultiple() {
    $cardinality = $this
      ->getCardinality();
    return $cardinality == FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED || $cardinality > 1;
  }

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

  /**
   * {@inheritdoc}
   */
  public function setLocked($locked) {
    $this->locked = $locked;
    return $this;
  }

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

  /**
   * {@inheritdoc}
   */
  public function isQueryable() {
    return TRUE;
  }

  /**
   * Determines whether a field has any data.
   *
   * @return bool
   *   TRUE if the field has data for any entity; FALSE otherwise.
   */
  public function hasData() {
    return \Drupal::entityTypeManager()
      ->getStorage($this->entity_type)
      ->countFieldData($this, TRUE);
  }

  /**
   * Implements the magic __sleep() method.
   *
   * Using the Serialize interface and serialize() / unserialize() methods
   * breaks entity forms in PHP 5.4.
   * @todo Investigate in https://www.drupal.org/node/1977206.
   */
  public function __sleep() {

    // Only serialize necessary properties, excluding those that can be
    // recalculated.
    $properties = get_object_vars($this);
    unset($properties['schema'], $properties['propertyDefinitions'], $properties['original']);
    return array_keys($properties);
  }

  /**
   * {@inheritdoc}
   */
  public function getConstraints() {
    return [];
  }

  /**
   * {@inheritdoc}
   */
  public function getConstraint($constraint_name) {
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function getPropertyDefinition($name) {
    if (!isset($this->propertyDefinitions)) {
      $this
        ->getPropertyDefinitions();
    }
    if (isset($this->propertyDefinitions[$name])) {
      return $this->propertyDefinitions[$name];
    }
  }

  /**
   * {@inheritdoc}
   */
  public function getPropertyDefinitions() {
    if (!isset($this->propertyDefinitions)) {
      $class = $this
        ->getFieldItemClass();
      $this->propertyDefinitions = $class::propertyDefinitions($this);
    }
    return $this->propertyDefinitions;
  }

  /**
   * {@inheritdoc}
   */
  public function getPropertyNames() {
    return array_keys($this
      ->getPropertyDefinitions());
  }

  /**
   * {@inheritdoc}
   */
  public function getMainPropertyName() {
    $class = $this
      ->getFieldItemClass();
    return $class::mainPropertyName();
  }

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

  /**
   * Helper to retrieve the field item class.
   */
  protected function getFieldItemClass() {
    $type_definition = \Drupal::typedDataManager()
      ->getDefinition('field_item:' . $this
      ->getType());
    return $type_definition['class'];
  }

  /**
   * Loads a field config entity based on the entity type and field name.
   *
   * @param string $entity_type_id
   *   ID of the entity type.
   * @param string $field_name
   *   Name of the field.
   *
   * @return static
   *   The field config entity if one exists for the provided field name,
   *   otherwise NULL.
   */
  public static function loadByName($entity_type_id, $field_name) {
    return \Drupal::entityTypeManager()
      ->getStorage('field_storage_config')
      ->load($entity_type_id . '.' . $field_name);
  }

  /**
   * {@inheritdoc}
   */
  public function isDeletable() {

    // The field storage is not deleted, is configured to be removed when there
    // are no fields, the field storage has no bundles, and field storages are
    // not in the process of being deleted.
    return !$this->deleted && !$this->persist_with_no_fields && count($this
      ->getBundles()) == 0 && !static::$inDeletion;
  }

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

  /**
   * {@inheritdoc}
   */
  public function setIndexes(array $indexes) {
    $this->indexes = $indexes;
    return $this;
  }

}