content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you under the Apache License, Version 2.0 (the
   *  "License"); you may not use this file except in compliance
   *  with the License.  You may obtain a copy of the License at
   *
   *        http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing,
   *  software distributed under the License is distributed on an
   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   *  KIND, either express or implied.  See the License for the
   *  specific language governing permissions and limitations
   *  under the License.
   */
  package org.apache.causeway.viewer.wicket.ui.components.widgets.breadcrumbs;
  
  import java.io.Serializable;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.wicket.request.mapper.parameter.PageParameters;
  
  import org.apache.causeway.applib.services.bookmark.Bookmark;
  import org.apache.causeway.commons.internal.collections._Lists;
  import org.apache.causeway.commons.internal.collections._Maps;
  import org.apache.causeway.core.metamodel.context.HasMetaModelContext;
  import org.apache.causeway.viewer.wicket.model.mementos.PageParameterNames;
  import org.apache.causeway.viewer.wicket.model.models.UiObjectWkt;
  
  public class BreadcrumbModel implements HasMetaModelContext, Serializable {
  
      private static final long serialVersionUID = 1L;
  
      private static final int MAX_SIZE = 5;
  
      private final Map<String, Bookmark> bookmarkByOidStr = _Maps.newHashMap();
      private final Map<Bookmark, String> oidStrByBookmark = _Maps.newHashMap();
      private final List<Bookmark> list = _Lists.newArrayList();
  
      public List<UiObjectWkt> getList() {
          List<UiObjectWkt> entityModels = _Lists.newArrayList();
          for (Bookmark bookmark : list) {
              UiObjectWkt objectModel = toEntityModel(bookmark);
              entityModels.add(objectModel);
          }
          return Collections.unmodifiableList(entityModels);
      }
  
      /**
       * May be null if called for a view model or for home page.
       */
      private String mostRecentlyVisitedOidStr;
  
      public void visitedHomePage() {
          mostRecentlyVisitedOidStr = null;
      }
  
      public UiObjectWkt getMostRecentlyVisited() {
          return mostRecentlyVisitedOidStr != null ? lookup(mostRecentlyVisitedOidStr) : null;
      }
  
      public void visited(final UiObjectWkt objectModel) {
  
          // ignore view models
          if(objectModel.getTypeOfSpecification().isViewModel()) {
              mostRecentlyVisitedOidStr = null;
              return;
          }
  
          final String oidStr = oidStrFrom(objectModel);
          mostRecentlyVisitedOidStr = oidStr;
  
          remove(oidStr);
          addToStart(oidStr, objectModel);
  
          trimTo(MAX_SIZE);
      }
  
      private String oidStrFrom(final UiObjectWkt objectModel) {
          final PageParameters pageParameters = objectModel.getPageParametersWithoutUiHints();
          return oidStrFrom(pageParameters);
      }
  
      private String oidStrFrom(final PageParameters pageParameters) {
          String oidStr = PageParameterNames.OBJECT_OID.getStringFrom(pageParameters);
          if(oidStr == null) {
              return null;
          }
          try {
              return Bookmark.parse(oidStr)
              .map(Bookmark::stringify)
              .orElse(null);
          } catch(Exception ex) {
              return null;
          }
      }
  
      private void addToStart(final String oidStr, final UiObjectWkt objectModel) {
          Bookmark bookmark = objectModel.getOwnerBookmark();
          bookmarkByOidStr.put(oidStr, bookmark);
          oidStrByBookmark.put(bookmark, oidStr);
          list.add(0, bookmark);
      }
  
      private void trimTo(final int size) {
          if(list.size() <= size) {
              return;
          }
          final List<Bookmark> bookmarksToRemove = list.subList(size, list.size());
          for (final Bookmark bookmark : bookmarksToRemove) {
              final String oidStr = oidStrByBookmark.get(bookmark);
              remove(oidStr, bookmark);
          }
      }
  
      public UiObjectWkt lookup(final String oidStr) {
          if(oidStr == null) {
              return null;
          }
          final Bookmark bookmark = bookmarkByOidStr.get(oidStr);
          if(bookmark == null) {
              return null;
          }
          return toEntityModel(bookmark);
      }
  
      public void detach() {
          // previously list held EntityModels rather than Bookmarks
          // this code is now redundant, I think.
  
          // for (EntityModel objectModel : list) {
          //     objectModel.detach();
          // }
      }
  
      void remove(final String oid) {
          Bookmark existingBookmark = bookmarkByOidStr.get(oid);
          if(existingBookmark != null) {
              remove(oid, existingBookmark);
          }
      }
  
      public void remove(final UiObjectWkt objectModel) {
          Bookmark bookmark = objectModel.getOwnerBookmark();
          final String oidStr = oidStrByBookmark.get(bookmark);
          if(oidStr != null) {
              remove(oidStr, bookmark);
          }
      }
  
      protected UiObjectWkt toEntityModel(final Bookmark bookmark) {
          return UiObjectWkt.ofBookmark(bookmark);
      }
  
      private void remove(final String oid, final Bookmark bookmark) {
          bookmarkByOidStr.remove(oid);
          oidStrByBookmark.remove(bookmark);
          list.remove(bookmark);
      }
  
      public synchronized void clear() {
          bookmarkByOidStr.clear();
          oidStrByBookmark.clear();
          list.clear();
          mostRecentlyVisitedOidStr = null;
      }
  
  }
  