/*
    * 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.maven.plugins.dependency.tree;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Stack;
  
  import org.apache.maven.artifact.Artifact;
  import org.apache.maven.model.Exclusion;
  import org.apache.maven.shared.dependency.graph.DependencyNode;
  import org.apache.maven.shared.dependency.graph.traversal.DependencyNodeVisitor;
  
  /**
   * A dependency node visitor that clones visited nodes into a new dependency tree. This can be used in conjunction with
   * a dependency node filter to construct subtrees.
   *
   * @author <a href="mailto:markhobson@gmail.com">Mark Hobson</a>
   */
  public class BuildingDependencyNodeVisitor implements DependencyNodeVisitor {
      // fields -----------------------------------------------------------------
  
      /**
       * The dependency node visitor to apply on the resultant dependency tree, or <code>null</code> for none.
       */
      private final DependencyNodeVisitor visitor;
  
      /**
       * The resultant tree parent nodes for the currently visited node.
       */
      private final Stack<DependencyNode> parentNodes;
  
      /**
       * The root node of the resultant tree.
       */
      private DependencyNode rootNode;
  
      // constructors -----------------------------------------------------------
  
      /**
       * Creates a dependency node visitor that clones visited nodes into a new dependency tree.
       */
      public BuildingDependencyNodeVisitor() {
          this(null);
      }
  
      /**
       * Creates a dependency node visitor that clones visited nodes into a new dependency tree, and then applies the
       * specified dependency node visitor on the resultant dependency tree.
       *
       * @param visitor the dependency node visitor to apply on the resultant dependency tree, or <code>null</code> for
       *            none
       */
      public BuildingDependencyNodeVisitor(DependencyNodeVisitor visitor) {
          this.visitor = visitor;
  
          parentNodes = new Stack<>();
      }
  
      // DependencyNodeVisitor methods ------------------------------------------
  
      /**
       * {@inheritDoc}
       */
      @Override
      public boolean visit(DependencyNode node) {
          // clone the node
          WrapperNode newNode = new WrapperNode(
                  parentNodes.isEmpty() ? null : parentNodes.peek(),
                  node.getArtifact(),
                  node.getPremanagedVersion(),
                  node.getPremanagedScope(),
                  node.getVersionConstraint(),
                  node.getOptional(),
                  node.getExclusions(),
                  node.toNodeString());
          newNode.setChildren(new ArrayList<>());
  
          if (parentNodes.empty()) {
              rootNode = newNode;
          } else {
              DependencyNode parentNode = parentNodes.peek();
              parentNode.getChildren().add(newNode);
         }
 
         parentNodes.push(newNode);
 
         return true;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean endVisit(DependencyNode node) {
         parentNodes.pop();
 
         // apply the visitor to the resultant tree on the last visit
         if (parentNodes.empty() && visitor != null) {
             rootNode.accept(visitor);
         }
 
         return true;
     }
 
     // public methods ---------------------------------------------------------
 
     /**
      * Gets the dependency node visitor that this visitor applies on the resultant dependency tree.
      *
      * @return the dependency node visitor, or <code>null</code> for none
      */
     public DependencyNodeVisitor getDependencyNodeVisitor() {
         return visitor;
     }
 
     /**
      * Gets the root node of the resultant dependency tree constructed by this visitor.
      *
      * @return the root node, or <code>null</code> if the source tree has not yet been visited
      */
     public DependencyNode getDependencyTree() {
         return rootNode;
     }
 
     private static class WrapperNode implements DependencyNode {
 
         private final Artifact artifact;
 
         private final DependencyNode parent;
 
         private final String premanagedVersion;
 
         private final String premanagedScope;
 
         private final String versionConstraint;
 
         private List<DependencyNode> children;
 
         private final Boolean optional;
 
         private final List<Exclusion> exclusions;
 
         private final String nodeString;
 
         private WrapperNode(
                 DependencyNode parent,
                 Artifact artifact,
                 String premanagedVersion,
                 String premanagedScope,
                 String versionConstraint,
                 Boolean optional,
                 List<Exclusion> exclusions,
                 String nodeString) {
             this.artifact = artifact;
             this.parent = parent;
             this.premanagedVersion = premanagedVersion;
             this.premanagedScope = premanagedScope;
             this.versionConstraint = versionConstraint;
             this.optional = optional;
             this.exclusions = exclusions;
             this.nodeString = nodeString;
         }
 
         @Override
         public Artifact getArtifact() {
             return artifact;
         }
 
         @Override
         public List<DependencyNode> getChildren() {
             return children;
         }
 
         @Override
         public boolean accept(DependencyNodeVisitor visitor) {
             if (visitor.visit(this)) {
                 for (DependencyNode child : getChildren()) {
                     if (!child.accept(visitor)) {
                         break;
                     }
                 }
             }
 
             return visitor.endVisit(this);
         }
 
         @Override
         public DependencyNode getParent() {
             return parent;
         }
 
         @Override
         public String getPremanagedVersion() {
             return premanagedVersion;
         }
 
         @Override
         public String getPremanagedScope() {
             return premanagedScope;
         }
 
         @Override
         public String getVersionConstraint() {
             return versionConstraint;
         }
 
         @Override
         public String toNodeString() {
             return nodeString;
         }
 
         @Override
         public Boolean getOptional() {
             return optional;
         }
 
         @Override
         public List<Exclusion> getExclusions() {
             return exclusions;
         }
 
         public void setChildren(List<DependencyNode> children) {
             this.children = children;
         }
     }
 }