class FieldDefinition

class FieldDefinition extends ListDataDefinition implements FieldDefinitionInterface {
    use UnchangingCacheableDependencyTrait;
    use FieldInputValueNormalizerTrait;
    
    /**
     * The associated field storage definition.
     *
     * @var \Drupal\Core\Field\FieldStorageDefinitionInterface
     */
    protected $fieldStorageDefinition;
    
    /**
     * Creates a new field definition.
     *
     * @param \Drupal\Core\Field\FieldStorageDefinitionInterface $storageDefinition
     *   The associated field storage definition.
     *
     * @return static
     */
    public static function createFromFieldStorageDefinition(FieldStorageDefinitionInterface $storageDefinition) {
        $field_definition = new static();
        $field_definition->setFieldStorageDefinition($storageDefinition);
        return $field_definition;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getName() {
        return $this->getFieldStorageDefinition()
            ->getName();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getType() {
        return $this->getFieldStorageDefinition()
            ->getType();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTargetEntityTypeId() {
        return $this->getFieldStorageDefinition()
            ->getTargetEntityTypeId();
    }
    
    /**
     * Set the target bundle.
     *
     * @param string $bundle
     *   The target bundle.
     *
     * @return $this
     */
    public function setTargetBundle($bundle) {
        $this->definition['bundle'] = $bundle;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTargetBundle() {
        return $this->definition['bundle'];
    }
    
    /**
     * Sets whether the display for the field can be configured.
     *
     * @param string $display_context
     *   The display context. Either 'view' or 'form'.
     * @param bool $configurable
     *   Whether the display options can be configured (e.g., via the "Manage
     *   display" / "Manage form display" UI screens). If TRUE, the options
     *   specified via getDisplayOptions() act as defaults.
     *
     * @return $this
     */
    public function setDisplayConfigurable($display_context, $configurable) {
        // If no explicit display options have been specified, default to 'hidden'.
        if (empty($this->definition['display'][$display_context])) {
            $this->definition['display'][$display_context]['options'] = [
                'region' => 'hidden',
            ];
        }
        $this->definition['display'][$display_context]['configurable'] = $configurable;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isDisplayConfigurable($display_context) {
        return isset($this->definition['display'][$display_context]['configurable']) ? $this->definition['display'][$display_context]['configurable'] : FALSE;
    }
    
    /**
     * Sets the display options for the field in forms or rendered entities.
     *
     * This enables generic rendering of the field with widgets / formatters,
     * including automated support for "In place editing", and with optional
     * configurability in the "Manage display" / "Manage form display" UI screens.
     *
     * Unless this method is called, the field remains invisible (or requires
     * ad-hoc rendering logic).
     *
     * @param string $display_context
     *   The display context. Either 'view' or 'form'.
     * @param array $options
     *   An array of display options. Refer to
     *   \Drupal\Core\Field\FieldDefinitionInterface::getDisplayOptions() for
     *   a list of supported keys. The options should include at least a 'weight',
     *   or specify 'region' = 'hidden'. The 'default_widget'/'default_formatter'
     *   for the field type will be used if no 'type' is specified.
     *
     * @return $this
     */
    public function setDisplayOptions($display_context, array $options) {
        $this->definition['display'][$display_context]['options'] = $options;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDisplayOptions($display_context) {
        return isset($this->definition['display'][$display_context]['options']) ? $this->definition['display'][$display_context]['options'] : NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDefaultValueLiteral() {
        return isset($this->definition['default_value']) ? $this->definition['default_value'] : [];
    }
    
    /**
     * Set the default value callback for the field.
     *
     * @param string $callback
     *   The default value callback.
     *
     * @return $this
     */
    public function setDefaultValueCallback($callback) {
        if (isset($callback) && !is_string($callback)) {
            throw new \InvalidArgumentException('Default value callback must be a string, like "function_name" or "ClassName::methodName"');
        }
        $this->definition['default_value_callback'] = $callback;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDefaultValueCallback() {
        return isset($this->definition['default_value_callback']) ? $this->definition['default_value_callback'] : NULL;
    }
    
    /**
     * Set a default value for the field.
     *
     * @param mixed $value
     *   The default value.
     *
     * @return $this
     */
    public function setDefaultValue($value) {
        $this->definition['default_value'] = $this->normalizeValue($value, $this->getFieldStorageDefinition()
            ->getMainPropertyName());
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDefaultValue(FieldableEntityInterface $entity) {
        // Allow custom default values function.
        if ($callback = $this->getDefaultValueCallback()) {
            $value = call_user_func($callback, $entity, $this);
        }
        else {
            $value = $this->getDefaultValueLiteral();
        }
        $value = $this->normalizeValue($value, $this->getFieldStorageDefinition()
            ->getMainPropertyName());
        // Allow the field type to process default values.
        $field_item_list_class = $this->getClass();
        return $field_item_list_class::processDefaultValue($value, $entity, $this);
    }
    
    /**
     * Sets whether the field is translatable.
     *
     * @param bool $translatable
     *   Whether the field is translatable.
     *
     * @return $this
     */
    public function setTranslatable($translatable) {
        $this->definition['translatable'] = $translatable;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isTranslatable() {
        return !empty($this->definition['translatable']) && $this->getFieldStorageDefinition()
            ->isTranslatable();
    }
    
    /**
     * Set the field storage definition.
     *
     * @param \Drupal\Core\Field\FieldStorageDefinitionInterface $storageDefinition
     *   The field storage definition associated with this field definition.
     *
     * @return $this
     */
    public function setFieldStorageDefinition(FieldStorageDefinitionInterface $storageDefinition) {
        $this->fieldStorageDefinition = $storageDefinition;
        $this->itemDefinition = FieldItemDataDefinition::create($this);
        // Create a definition for the items, and initialize it with the default
        // settings for the field type.
        $field_type_manager = \Drupal::service('plugin.manager.field.field_type');
        $default_settings = $field_type_manager->getDefaultFieldSettings($storageDefinition->getType());
        $this->itemDefinition
            ->setSettings($default_settings);
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFieldStorageDefinition() {
        return $this->fieldStorageDefinition;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConfig($bundle) {
        // @todo provide a FieldDefinitionOverride config entity in
        // https://www.drupal.org/project/drupal/issues/2935978.
        throw new \Exception('Field definitions do not currently have an override config entity.');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getUniqueIdentifier() {
        return $this->getTargetEntityTypeId() . '-' . $this->getTargetBundle() . '-' . $this->getName();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSetting($setting_name) {
        if (array_key_exists($setting_name, $this->itemDefinition
            ->getSettings())) {
            return $this->itemDefinition
                ->getSetting($setting_name);
        }
        else {
            return $this->getFieldStorageDefinition()
                ->getSetting($setting_name);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSettings() {
        return $this->getItemDefinition()
            ->getSettings() + $this->getFieldStorageDefinition()
            ->getSettings();
    }
    
    /**
     * {@inheritdoc}
     */
    public function setSetting($setting_name, $value) {
        $this->getItemDefinition()
            ->setSetting($setting_name, $value);
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setSettings(array $settings) {
        // Assign settings individually, in order to keep the current values
        // of settings not specified in $settings.
        foreach ($settings as $setting_name => $setting) {
            $this->getItemDefinition()
                ->setSetting($setting_name, $setting);
        }
        return $this;
    }

}