/**
    * 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.framework.ioc;
  
  import info.magnolia.ui.framework.UiFrameworkView;
  import info.magnolia.ui.api.view.View;
  
  import java.util.Collection;
  import java.util.Optional;
  import java.util.stream.Stream;
  
  import com.google.common.collect.ArrayListMultimap;
  import com.google.common.collect.BiMap;
  import com.google.common.collect.HashBiMap;
  import com.google.common.collect.Multimap;
  
  /**
   * Vaadin UI - scoped registry which tracks the currently running views.
   */
  public class ViewContextKeyRegistry {
  
      public static ViewContextKeyRegistry access() {
          final BeanStore uiBeanStore = SessionStore.access().getBeanStore(UiContextReference.ofCurrentUi());
          ViewContextKeyRegistry viewContextKeyRegistry = uiBeanStore.get(ViewContextKeyRegistry.class);
          if (viewContextKeyRegistry == null) {
              viewContextKeyRegistry = new ViewContextKeyRegistry();
              uiBeanStore.put(ViewContextKeyRegistry.class, viewContextKeyRegistry);
          }
  
          return viewContextKeyRegistry;
      }
  
      private final Multimap<UiContextReference, UiContextReference> viewHierarchy = ArrayListMultimap.create();
      private final BiMap<UiFrameworkView, UiContextReference> viewKeys = HashBiMap.create();
  
      public void register(UiFrameworkView view, UiContextReference key) {
          this.viewKeys.put(view, key);
          key.getParentReferences().stream()
                  // TODO - bug-fix the parent key resolution
                  .filter(UiContextReference.ViewContextReference.class::isInstance)
                  .findFirst()
                  .ifPresent(parentViewKey -> viewHierarchy.put(parentViewKey, key));
      }
  
      public Stream<UiFrameworkView> getChildViews(UiContextReference parentReference) {
          return this.getChildViewReferences(parentReference).stream().filter(this.viewKeys.inverse()::containsKey).map(this.viewKeys.inverse()::get);
      }
  
      public Collection<UiContextReference> getChildViewReferences(UiContextReference parentReference) {
          return this.viewHierarchy.get(parentReference);
      }
  
      public void unRegister(UiFrameworkView view) {
          lookUp(view).ifPresent(this.viewHierarchy::removeAll);
          this.viewKeys.remove(view);
      }
  
      public Optional<UiContextReference> lookUp(final View view) {
          return Optional.ofNullable(this.viewKeys.get(view));
      }
  
      public boolean isRegistered(UiContextReference viewContextReference) {
          return viewKeys.containsValue(viewContextReference);
      }
  }