class ImageFormatter

class ImageFormatter extends ImageFormatterBase implements ContainerFactoryPluginInterface {
    
    /**
     * The current user.
     *
     * @var \Drupal\Core\Session\AccountInterface
     */
    protected $currentUser;
    
    /**
     * The image style entity storage.
     *
     * @var \Drupal\image\ImageStyleStorageInterface
     */
    protected $imageStyleStorage;
    
    /**
     * Constructs an ImageFormatter object.
     *
     * @param string $plugin_id
     *   The plugin_id for the formatter.
     * @param mixed $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
     *   The definition of the field to which the formatter is associated.
     * @param array $settings
     *   The formatter settings.
     * @param string $label
     *   The formatter label display setting.
     * @param string $view_mode
     *   The view mode.
     * @param array $third_party_settings
     *   Any third party settings settings.
     * @param \Drupal\Core\Session\AccountInterface $current_user
     *   The current user.
     * @param \Drupal\Core\Entity\EntityStorageInterface $image_style_storage
     *   The image style storage.
     */
    public function __construct($plugin_id, $plugin_definition, FieldDefinitionInterface $field_definition, array $settings, $label, $view_mode, array $third_party_settings, AccountInterface $current_user, EntityStorageInterface $image_style_storage) {
        parent::__construct($plugin_id, $plugin_definition, $field_definition, $settings, $label, $view_mode, $third_party_settings);
        $this->currentUser = $current_user;
        $this->imageStyleStorage = $image_style_storage;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($plugin_id, $plugin_definition, $configuration['field_definition'], $configuration['settings'], $configuration['label'], $configuration['view_mode'], $configuration['third_party_settings'], $container->get('current_user'), $container->get('entity_type.manager')
            ->getStorage('image_style'));
    }
    
    /**
     * {@inheritdoc}
     */
    public static function defaultSettings() {
        return [
            'image_style' => '',
            'image_link' => '',
        ] + parent::defaultSettings();
    }
    
    /**
     * {@inheritdoc}
     */
    public function settingsForm(array $form, FormStateInterface $form_state) {
        $image_styles = image_style_options(FALSE);
        $description_link = Link::fromTextAndUrl($this->t('Configure Image Styles'), Url::fromRoute('entity.image_style.collection'));
        $element['image_style'] = [
            '#title' => t('Image style'),
            '#type' => 'select',
            '#default_value' => $this->getSetting('image_style'),
            '#empty_option' => t('None (original image)'),
            '#options' => $image_styles,
            '#description' => $description_link->toRenderable() + [
                '#access' => $this->currentUser
                    ->hasPermission('administer image styles'),
            ],
        ];
        $link_types = [
            'content' => t('Content'),
            'file' => t('File'),
        ];
        $element['image_link'] = [
            '#title' => t('Link image to'),
            '#type' => 'select',
            '#default_value' => $this->getSetting('image_link'),
            '#empty_option' => t('Nothing'),
            '#options' => $link_types,
        ];
        return $element;
    }
    
    /**
     * {@inheritdoc}
     */
    public function settingsSummary() {
        $summary = [];
        $image_styles = image_style_options(FALSE);
        // Unset possible 'No defined styles' option.
        unset($image_styles['']);
        // Styles could be lost because of enabled/disabled modules that defines
        // their styles in code.
        $image_style_setting = $this->getSetting('image_style');
        if (isset($image_styles[$image_style_setting])) {
            $summary[] = t('Image style: @style', [
                '@style' => $image_styles[$image_style_setting],
            ]);
        }
        else {
            $summary[] = t('Original image');
        }
        $link_types = [
            'content' => t('Linked to content'),
            'file' => t('Linked to file'),
        ];
        // Display this setting only if image is linked.
        $image_link_setting = $this->getSetting('image_link');
        if (isset($link_types[$image_link_setting])) {
            $summary[] = $link_types[$image_link_setting];
        }
        return $summary;
    }
    
    /**
     * {@inheritdoc}
     */
    public function viewElements(FieldItemListInterface $items, $langcode) {
        $elements = [];
        $files = $this->getEntitiesToView($items, $langcode);
        // Early opt-out if the field is empty.
        if (empty($files)) {
            return $elements;
        }
        $url = NULL;
        $image_link_setting = $this->getSetting('image_link');
        // Check if the formatter involves a link.
        if ($image_link_setting == 'content') {
            $entity = $items->getEntity();
            if (!$entity->isNew()) {
                $url = $entity->toUrl();
            }
        }
        elseif ($image_link_setting == 'file') {
            $link_file = TRUE;
        }
        $image_style_setting = $this->getSetting('image_style');
        // Collect cache tags to be added for each item in the field.
        $base_cache_tags = [];
        if (!empty($image_style_setting)) {
            $image_style = $this->imageStyleStorage
                ->load($image_style_setting);
            $base_cache_tags = $image_style->getCacheTags();
        }
        foreach ($files as $delta => $file) {
            $cache_contexts = [];
            if (isset($link_file)) {
                $image_uri = $file->getFileUri();
                // @todo Wrap in file_url_transform_relative(). This is currently
                // impossible. As a work-around, we currently add the 'url.site' cache
                // context to ensure different file URLs are generated for different
                // sites in a multisite setup, including HTTP and HTTPS versions of the
                // same site. Fix in https://www.drupal.org/node/2646744.
                $url = Url::fromUri(file_create_url($image_uri));
                $cache_contexts[] = 'url.site';
            }
            $cache_tags = Cache::mergeTags($base_cache_tags, $file->getCacheTags());
            // Extract field item attributes for the theme function, and unset them
            // from the $item so that the field template does not re-render them.
            $item = $file->_referringItem;
            $item_attributes = $item->_attributes;
            unset($item->_attributes);
            $elements[$delta] = [
                '#theme' => 'image_formatter',
                '#item' => $item,
                '#item_attributes' => $item_attributes,
                '#image_style' => $image_style_setting,
                '#url' => $url,
                '#cache' => [
                    'tags' => $cache_tags,
                    'contexts' => $cache_contexts,
                ],
            ];
        }
        return $elements;
    }
    
    /**
     * {@inheritdoc}
     */
    public function calculateDependencies() {
        $dependencies = parent::calculateDependencies();
        $style_id = $this->getSetting('image_style');
        
        /** @var \Drupal\image\ImageStyleInterface $style */
        if ($style_id && ($style = ImageStyle::load($style_id))) {
            // If this formatter uses a valid image style to display the image, add
            // the image style configuration entity as dependency of this formatter.
            $dependencies[$style->getConfigDependencyKey()][] = $style->getConfigDependencyName();
        }
        return $dependencies;
    }
    
    /**
     * {@inheritdoc}
     */
    public function onDependencyRemoval(array $dependencies) {
        $changed = parent::onDependencyRemoval($dependencies);
        $style_id = $this->getSetting('image_style');
        
        /** @var \Drupal\image\ImageStyleInterface $style */
        if ($style_id && ($style = ImageStyle::load($style_id))) {
            if (!empty($dependencies[$style->getConfigDependencyKey()][$style->getConfigDependencyName()])) {
                $replacement_id = $this->imageStyleStorage
                    ->getReplacementId($style_id);
                // If a valid replacement has been provided in the storage, replace the
                // image style with the replacement and signal that the formatter plugin
                // settings were updated.
                if ($replacement_id && ImageStyle::load($replacement_id)) {
                    $this->setSetting('image_style', $replacement_id);
                    $changed = TRUE;
                }
            }
        }
        return $changed;
    }

}