/**
    * This file Copyright (c) 2018 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.ui.preview;
  
  
  import info.magnolia.i18nsystem.SimpleTranslator;
  import info.magnolia.ui.contentapp.browser.preview.PreviewProvider;
  import info.magnolia.ui.datasource.PropertySetFactory;
  
  import java.util.Map;
  import java.util.Optional;
  
  import javax.inject.Inject;
  
  import org.apache.commons.collections4.MapUtils;
  
  import com.vaadin.data.PropertySet;
  import com.vaadin.server.Resource;
  import com.vaadin.ui.Component;
  import com.vaadin.ui.CustomComponent;
  import com.vaadin.ui.FormLayout;
  import com.vaadin.ui.HorizontalLayout;
  import com.vaadin.ui.Image;
  import com.vaadin.ui.Layout;
  
  /**
   * Abstract implementation of {@link ItemPreviewComponent}.
   * An item preview usually consists of two parts
   * <ul>
   *     <li> image preview: an image, if any, representing the item
   *     <li> details: e.g. item properties and their respective values
   * </ul>
   *
   * @param <T> the item type to preview.
   */
  public abstract class AbstractItemPreviewComponent<T> extends CustomComponent implements ItemPreviewComponent<T> {
  
      private Component itemDetail;
      private Component itemPreview;
      private final Layout rootLayout;
      private final PreviewProvider<T> previewProvider;
      private final SimpleTranslator i18n;
      private final PropertySet<T> propertySet;
  
  
      @Inject
      public AbstractItemPreviewComponent(SimpleTranslator i18n, PropertySetFactory<T> propertySetFactory, PreviewProvider<T> previewProvider, Map<String, Class> properties) {
          if (MapUtils.isEmpty(properties)) {
              throw new IllegalArgumentException("Map containing properties to be displayed can't be empty or null.");
          }
          this.previewProvider = previewProvider;
          this.i18n = i18n;
          this.propertySet = propertySetFactory.withProperties(properties);
          this.rootLayout = new HorizontalLayout();
          setCompositionRoot(rootLayout);
      }
  
      @Override
      public void onValueChange(T item) {
          clearRootLayout();
          Optional.ofNullable(item).ifPresent(i -> {
              itemDetail = refreshItemDetail(i);
              itemPreview = refreshItemPreview(i);
              refreshRootLayout();
          });
      }
  
      /**
      * Refreshes the item detail.
      * This method is triggered by {@link ItemPreviewComponent#onValueChange(Object)} in case of value changes.
      */
     protected Component refreshItemDetail(T item) {
         FormLayout itemDetail = new FormLayout();
         itemDetail.addStyleName("file-details");
 
         getPropertySet().getProperties()
                 .map(property -> this.createDetailComponent(property.getName(), property.getGetter().apply(item)))
                 .forEach(itemDetail::addComponent);
 
         return itemDetail;
     }
 
     /**
      * @return typically a Label displaying an i18n-ised, human-readable property name and its value.
      */
     protected abstract Component createDetailComponent(String propertyName, Object value);
 
     /**
      * Refreshes the item preview.
      * This method is triggered by {@link ItemPreviewComponent#onValueChange(Object)}} in case of value changes.
      */
     protected Component refreshItemPreview(T item) {
         return getPreviewProvider().getResource(item).map(this::createPreviewImageComponent).orElse(null);
     }
 
     protected void clearRootLayout() {
         rootLayout.setVisible(false);
         rootLayout.removeAllComponents();
         removeStyleName("done");
     }
 
     protected void refreshRootLayout() {
         rootLayout.setVisible(true);
         addStyleName("done");
 
         Optional.ofNullable(itemPreview).ifPresent(rootLayout::addComponent);
         Optional.ofNullable(itemDetail).ifPresent(rootLayout::addComponent);
     }
 
     protected PropertySet<T> getPropertySet() {
         return propertySet;
     }
 
     protected SimpleTranslator getI18n() {
         return i18n;
     }
 
     protected PreviewProvider<T> getPreviewProvider() {
         return previewProvider;
     }
 
     private Image createPreviewImageComponent(Resource res) {
         final Image image =  new Image("", res);
         image.addStyleName("file-preview-area");
         return image;
     }
 }