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.tree;
  
  import java.io.Serializable;
  import java.util.Optional;
  
  import org.apache.wicket.Component;
  import org.apache.wicket.MarkupContainer;
  import org.apache.wicket.ajax.AjaxRequestTarget;
  import org.apache.wicket.ajax.markup.html.AjaxFallbackLink;
  import org.apache.wicket.extensions.markup.html.repeater.tree.NestedTree;
  import org.apache.wicket.extensions.markup.html.repeater.tree.Node;
  import org.apache.wicket.markup.html.WebMarkupContainer;
  import org.apache.wicket.model.IModel;
  
  import org.apache.causeway.applib.graph.tree.TreeNode;
  import org.apache.causeway.core.metamodel.context.HasMetaModelContext;
  import org.apache.causeway.core.metamodel.object.ManagedObject;
  import org.apache.causeway.core.metamodel.object.ManagedObjects;
  import org.apache.causeway.core.metamodel.tree.TreeNodeMemento;
  import org.apache.causeway.viewer.wicket.model.models.UiObjectWkt;
  import org.apache.causeway.viewer.wicket.ui.components.object.icontitle.ObjectIconAndTitlePanelFactory;
  import org.apache.causeway.viewer.wicket.ui.util.Wkt;
  
  /**
   * Wicket's tree component implemented for bookmarkable nodes,
   * where the tree is modeled by a root {@link TreeNode} (and its child-nodes recursively).
   */
  class DomainObjectTree extends NestedTree<TreeNodeMemento>
  implements HasMetaModelContext {
  
      private static final long serialVersionUID = 1L;
  
      // -- FACTORIES
  
      static MarkupContainer emptyTreeComponent(final String id) {
          return new WebMarkupContainer(id);
      }
  
      /**
       * @param rootModel - ManagedObject representing a {@link TreeNode}
       */
      static MarkupContainer createComponent(final String id, final IModel<ManagedObject> rootModel) {
          return rootModel==null
                  || ManagedObjects.isNullOrUnspecifiedOrEmpty(rootModel.getObject())
              ? emptyTreeComponent(id)
              : new DomainObjectTree(id, (TreeNode<?>)rootModel.getObject().getPojo());
      }
  
      // -- CONSTRUCTION
  
      private DomainObjectTree(
              final String id,
              final TreeNode<?> treeNode) {
          super(id, new TreeProvider(treeNode), TreeExpansionModel.of(treeNode.treeState()));
      }
  
      /**
       * To use a custom component for the representation of a node's content we override this method.
       */
      @Override
      protected Component newContentComponent(final String id, final IModel<TreeNodeMemento> node) {
          final TreeNodeMemento treeModel = node.getObject();
          final Component entityIconAndTitle = ObjectIconAndTitlePanelFactory.entityIconAndTitlePanel(
                  id, UiObjectWkt.ofBookmark(treeModel.bookmark()));
          if(treeExpansionModel().isSelected(treeModel.treePath())) {
              Wkt.cssAppend(entityIconAndTitle, "tree-node-selected");
          }
          return entityIconAndTitle;
      }
  
      /**
       * To hardcode Node's <pre>AjaxFallbackLink.isEnabledInHierarchy()->true</pre> we override this method.
       */
      @Override
      public Component newNodeComponent(final String id, final IModel<TreeNodeMemento> model) {
  
          final Node<TreeNodeMemento> node =  new Node<TreeNodeMemento>(id, this, model) {
              private static final long serialVersionUID = 1L;
  
              @Override
              protected Component createContent(final String id, final IModel<TreeNodeMemento> model) {
                  return DomainObjectTree.this.newContentComponent(id, model);
              }
  
              @Override
              protected MarkupContainer createJunctionComponent(final String id) {
  
                  final Node<TreeNodeMemento> node = this;
                  final Runnable toggleExpandCollapse = (Runnable & Serializable) this::toggle;
  
                  return new AjaxFallbackLink<Void>(id) {
                      private static final long serialVersionUID = 1L;
  
                      @Override
                      public void onClick(final Optional<AjaxRequestTarget> target) {
                          toggleExpandCollapse.run();
                      }
  
                      @Override
                      public boolean isEnabled() {
                          return DomainObjectTree.this.getProvider().hasChildren(node.getModelObject());
                      }
  
                      @Override
                      public boolean isEnabledInHierarchy() {
                          return true; // hardcoded -> true
                      }
                  };
              }
          };
  
          node.setOutputMarkupId(true);
          return node;
      }
  
      /**
       * To utilize the custom TreeExpansionModel for deciding a node's collapse/expand state,
       * we override this method.
       */
      @Override
      public State getState(final TreeNodeMemento t) {
          return treeExpansionModel().contains(t.treePath()) ? State.EXPANDED : State.COLLAPSED;
      }
  
      /**
       * To utilize the custom TreeExpansionModel for hooking into a node's expand event,
       * we override this method.
       */
      @Override
      public void expand(final TreeNodeMemento t) {
          treeExpansionModel().onExpand(t);
          super.expand(t);
      }
  
      /**
       * To utilize the custom TreeExpansionModel for hooking into a node's collapse event,
       * we override this method.
       */
      @Override
      public void collapse(final TreeNodeMemento t) {
          treeExpansionModel().onCollapse(t);
          super.collapse(t);
      }
  
      private TreeExpansionModel treeExpansionModel() {
          return (TreeExpansionModel) getModel();
      }
  
  }