/*
    * 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.artifact.resolver;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Set;
  import org.apache.maven.artifact.Artifact;
  import org.apache.maven.artifact.repository.ArtifactRepository;
  import org.apache.maven.artifact.resolver.filter.ArtifactFilter;
  import org.apache.maven.artifact.versioning.ArtifactVersion;
  import org.apache.maven.artifact.versioning.OverConstrainedVersionException;
  
  /**
   * ResolutionNode
   */
  public class ResolutionNode {
      private Artifact artifact;
  
      private List<ResolutionNode> children;
  
      private final List<Object> parents;
  
      private final int depth;
  
      private final ResolutionNode parent;
  
      private final List<ArtifactRepository> remoteRepositories;
  
      private boolean active = true;
  
      private List<Artifact> trail;
  
      public ResolutionNode(Artifact artifact, List<ArtifactRepository> remoteRepositories) {
          this.artifact = artifact;
          this.remoteRepositories = remoteRepositories;
          depth = 0;
          parents = Collections.emptyList();
          parent = null;
      }
  
      public ResolutionNode(Artifact artifact, List<ArtifactRepository> remoteRepositories, ResolutionNode parent) {
          this.artifact = artifact;
          this.remoteRepositories = remoteRepositories;
          depth = parent.depth + 1;
          parents = new ArrayList<>();
          parents.addAll(parent.parents);
          parents.add(parent.getKey());
          this.parent = parent;
      }
  
      public Artifact getArtifact() {
          return artifact;
      }
  
      public Object getKey() {
          return artifact.getDependencyConflictId();
      }
  
      public void addDependencies(
              Set<Artifact> artifacts, List<ArtifactRepository> remoteRepositories, ArtifactFilter filter)
              throws CyclicDependencyException, OverConstrainedVersionException {
          if (artifacts != null && !artifacts.isEmpty()) {
              children = new ArrayList<>(artifacts.size());
  
              for (Artifact a : artifacts) {
                  if (parents.contains(a.getDependencyConflictId())) {
                      a.setDependencyTrail(getDependencyTrail());
  
                      throw new CyclicDependencyException("A dependency has introduced a cycle", a);
                  }
  
                  children.add(new ResolutionNode(a, remoteRepositories, this));
              }
              children = Collections.unmodifiableList(children);
          } else {
              children = Collections.emptyList();
          }
          trail = null;
      }
 
     /**
      * @return {@link List} &lt; {@link String} &gt; with artifact ids
      * @throws OverConstrainedVersionException if version specification is over constrained
      */
     public List<String> getDependencyTrail() throws OverConstrainedVersionException {
         List<Artifact> trial = getTrail();
 
         List<String> ret = new ArrayList<>(trial.size());
 
         for (Artifact artifact : trial) {
             ret.add(artifact.getId());
         }
 
         return ret;
     }
 
     private List<Artifact> getTrail() throws OverConstrainedVersionException {
         if (trail == null) {
             List<Artifact> ids = new LinkedList<>();
             ResolutionNode node = this;
             while (node != null) {
                 Artifact artifact = node.getArtifact();
                 if (artifact.getVersion() == null) {
                     // set the recommended version
                     ArtifactVersion selected = artifact.getSelectedVersion();
                     // MNG-2123: null is a valid response to getSelectedVersion, don't
                     // assume it won't ever be.
                     if (selected != null) {
                         artifact.selectVersion(selected.toString());
                     } else {
                         throw new OverConstrainedVersionException(
                                 "Unable to get a selected Version for " + artifact.getArtifactId(), artifact);
                     }
                 }
 
                 ids.add(0, artifact);
                 node = node.parent;
             }
             trail = ids;
         }
         return trail;
     }
 
     public boolean isResolved() {
         return children != null;
     }
 
     /**
      * Test whether the node is direct or transitive dependency.
      *
      * @return whether the node is direct or transitive dependency
      */
     public boolean isChildOfRootNode() {
         return parent != null && parent.parent == null;
     }
 
     public Iterator<ResolutionNode> getChildrenIterator() {
         return children.iterator();
     }
 
     public int getDepth() {
         return depth;
     }
 
     public List<ArtifactRepository> getRemoteRepositories() {
         return remoteRepositories;
     }
 
     public boolean isActive() {
         return active;
     }
 
     public void enable() {
         active = true;
 
         // TODO if it was null, we really need to go find them now... or is this taken care of by the ordering?
         if (children != null) {
             for (ResolutionNode node : children) {
                 node.enable();
             }
         }
     }
 
     public void disable() {
         active = false;
         if (children != null) {
             for (ResolutionNode node : children) {
                 node.disable();
             }
         }
     }
 
     public boolean filterTrail(ArtifactFilter filter) throws OverConstrainedVersionException {
         boolean success = true;
         if (filter != null) {
             for (Artifact artifact : getTrail()) {
                 if (!filter.include(artifact)) {
                     success = false;
                 }
             }
         }
         return success;
     }
 
     @Override
     public String toString() {
         return artifact.toString() + " (" + depth + "; " + (active ? "enabled" : "disabled") + ")";
     }
 
     public void setArtifact(Artifact artifact) {
         this.artifact = artifact;
     }
 }