package org.apache.maven.shared.dependency.tree;
   
   /*
    * 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.
   */
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.IdentityHashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Stack;
  
  import org.apache.maven.artifact.Artifact;
  import org.apache.maven.artifact.resolver.ResolutionListener;
  import org.apache.maven.artifact.resolver.ResolutionListenerForDepMgmt;
  import org.apache.maven.artifact.versioning.VersionRange;
  import org.apache.maven.shared.dependency.tree.traversal.CollectingDependencyNodeVisitor;
  import org.codehaus.plexus.logging.Logger;
  
  /**
   * An artifact resolution listener that constructs a dependency tree.
   * 
   * @author Edwin Punzalan
   * @author <a href="mailto:markhobson@gmail.com">Mark Hobson</a>
   * @version $Id: DependencyTreeResolutionListener.java 661727 2008-05-30 14:21:49Z bentmann $
   */
  public class DependencyTreeResolutionListener implements ResolutionListener, ResolutionListenerForDepMgmt
  {
      // fields -----------------------------------------------------------------
      
      /**
       * The log to write debug messages to.
       */
      private final Logger logger;
  
      /**
       * The parent dependency nodes of the current dependency node.
       */
      private final Stack parentNodes;
  
      /**
       * A map of dependency nodes by their attached artifact.
       */
      private final Map nodesByArtifact;
  
      /**
       * The root dependency node of the computed dependency tree.
       */
      private DependencyNode rootNode;
  
      /**
       * The dependency node currently being processed by this listener.
       */
      private DependencyNode currentNode;
      
      /**
       * Map &lt; String replacementId, String premanaged version >
       */
      private Map managedVersions = new HashMap();
  
      /**
       * Map &lt; String replacementId, String premanaged scope >
       */
      private Map managedScopes = new HashMap();
  
      // constructors -----------------------------------------------------------
  
      /**
       * Creates a new dependency tree resolution listener that writes to the specified log.
       * 
       * @param logger
       *            the log to write debug messages to
       */
      public DependencyTreeResolutionListener( Logger logger )
      {
          this.logger = logger;
          
          parentNodes = new Stack();
          nodesByArtifact = new IdentityHashMap();
          rootNode = null;
          currentNode = null;
      }
 
     // ResolutionListener methods ---------------------------------------------
 
     /**
      * {@inheritDoc}
      */
     public void testArtifact( Artifact artifact )
     {
         log( "testArtifact: artifact=" + artifact );
     }
 
     /**
      * {@inheritDoc}
      */
     public void startProcessChildren( Artifact artifact )
     {
         log( "startProcessChildren: artifact=" + artifact );
         
         if ( !currentNode.getArtifact().equals( artifact ) )
         {
             throw new IllegalStateException( "Artifact was expected to be " + currentNode.getArtifact() + " but was "
                             + artifact );
         }
 
         parentNodes.push( currentNode );
     }
 
     /**
      * {@inheritDoc}
      */
     public void endProcessChildren( Artifact artifact )
     {
         DependencyNode node = (DependencyNode) parentNodes.pop();
 
         log( "endProcessChildren: artifact=" + artifact );
         
         if ( node == null )
         {
             throw new IllegalStateException( "Parent dependency node was null" );
         }
 
         if ( !node.getArtifact().equals( artifact ) )
         {
             throw new IllegalStateException( "Parent dependency node artifact was expected to be " + node.getArtifact()
                             + " but was " + artifact );
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public void includeArtifact( Artifact artifact )
     {
         log( "includeArtifact: artifact=" + artifact );
         
         DependencyNode existingNode = getNode( artifact );
 
         /*
          * Ignore duplicate includeArtifact calls since omitForNearer can be called prior to includeArtifact on the same
          * artifact, and we don't wish to include it twice.
          */
         if ( existingNode == null && isCurrentNodeIncluded() )
         {
             DependencyNode node = addNode( artifact );
 
             /*
              * Add the dependency management information cached in any prior manageArtifact calls, since includeArtifact
              * is always called after manageArtifact.
              */
             flushDependencyManagement( node );
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public void omitForNearer( Artifact omitted, Artifact kept )
     {
         log( "omitForNearer: omitted=" + omitted + " kept=" + kept );
         
         if ( !omitted.getDependencyConflictId().equals( kept.getDependencyConflictId() ) )
         {
             throw new IllegalArgumentException( "Omitted artifact dependency conflict id "
                             + omitted.getDependencyConflictId() + " differs from kept artifact dependency conflict id "
                             + kept.getDependencyConflictId() );
         }
 
         if ( isCurrentNodeIncluded() )
         {
             DependencyNode omittedNode = getNode( omitted );
 
             if ( omittedNode != null )
             {
                 removeNode( omitted );
             }
             else
             {
                 omittedNode = createNode( omitted );
 
                 currentNode = omittedNode;
             }
 
             omittedNode.omitForConflict( kept );
             
             /*
              * Add the dependency management information cached in any prior manageArtifact calls, since omitForNearer
              * is always called after manageArtifact.
              */
             flushDependencyManagement( omittedNode );
             
             DependencyNode keptNode = getNode( kept );
             
             if ( keptNode == null )
             {
                 addNode( kept );
             }
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public void updateScope( Artifact artifact, String scope )
     {
         log( "updateScope: artifact=" + artifact + ", scope=" + scope );
         
         DependencyNode node = getNode( artifact );
 
         if ( node == null )
         {
             // updateScope events can be received prior to includeArtifact events
             node = addNode( artifact );
         }
 
         node.setOriginalScope( artifact.getScope() );
     }
 
     /**
      * {@inheritDoc}
      */
     public void manageArtifact( Artifact artifact, Artifact replacement )
     {
         // TODO: remove when ResolutionListenerForDepMgmt merged into ResolutionListener
         
         log( "manageArtifact: artifact=" + artifact + ", replacement=" + replacement );
         
         if ( replacement.getVersion() != null )
         {
             manageArtifactVersion( artifact, replacement );
         }
         
         if ( replacement.getScope() != null )
         {
             manageArtifactScope( artifact, replacement );
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public void omitForCycle( Artifact artifact )
     {
         log( "omitForCycle: artifact=" + artifact );
         
         if ( isCurrentNodeIncluded() )
         {
             DependencyNode node = createNode( artifact );
 
             node.omitForCycle();
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public void updateScopeCurrentPom( Artifact artifact, String scopeIgnored )
     {
         log( "updateScopeCurrentPom: artifact=" + artifact + ", scopeIgnored=" + scopeIgnored );
         
         DependencyNode node = getNode( artifact );
 
         if ( node == null )
         {
             // updateScopeCurrentPom events can be received prior to includeArtifact events
             node = addNode( artifact );
             // TODO remove the node that tried to impose its scope and add some info
         }
 
         node.setFailedUpdateScope( scopeIgnored );
     }
 
     /**
      * {@inheritDoc}
      */
     public void selectVersionFromRange( Artifact artifact )
     {
         log( "selectVersionFromRange: artifact=" + artifact );
 
         DependencyNode node = getNode( artifact );
 
         /*
          * selectVersionFromRange is called before includeArtifact
          */
         if ( node == null && isCurrentNodeIncluded() )
         {
             node = addNode( artifact );
         }
 
         node.setVersionSelectedFromRange( artifact.getVersionRange() );
         node.setAvailableVersions( artifact.getAvailableVersions() );
     }
 
     /**
      * {@inheritDoc}
      */
     public void restrictRange( Artifact artifact, Artifact replacement, VersionRange versionRange )
     {
         log( "restrictRange: artifact=" + artifact + ", replacement=" + replacement + ", versionRange=" + versionRange );
         
         // TODO: track range restriction in node (MNG-3093)
     }
     
     // ResolutionListenerForDepMgmt methods -----------------------------------
     
     /**
      * {@inheritDoc}
      */
     public void manageArtifactVersion( Artifact artifact, Artifact replacement )
     {
         log( "manageArtifactVersion: artifact=" + artifact + ", replacement=" + replacement );
         
         /*
          * DefaultArtifactCollector calls manageArtifact twice: first with the change; then subsequently with no change.
          * We ignore the second call when the versions are equal.
          */
         if ( isCurrentNodeIncluded() && !replacement.getVersion().equals( artifact.getVersion() ) )
         {
             /*
              * Cache management information and apply in includeArtifact, since DefaultArtifactCollector mutates the
              * artifact and then calls includeArtifact after manageArtifact.
              */
             managedVersions.put( replacement.getId(), artifact.getVersion() );
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public void manageArtifactScope( Artifact artifact, Artifact replacement )
     {
         log( "manageArtifactScope: artifact=" + artifact + ", replacement=" + replacement );
         
         /*
          * DefaultArtifactCollector calls manageArtifact twice: first with the change; then subsequently with no change.
          * We ignore the second call when the scopes are equal.
          */
         if ( isCurrentNodeIncluded() && !replacement.getScope().equals( artifact.getScope() ) )
         {
             /*
              * Cache management information and apply in includeArtifact, since DefaultArtifactCollector mutates the
              * artifact and then calls includeArtifact after manageArtifact.
              */
             managedScopes.put( replacement.getId(), artifact.getScope() );
         }
     }
     
     // public methods ---------------------------------------------------------
 
     /**
      * Gets a list of all dependency nodes in the computed dependency tree.
      * 
      * @return a list of dependency nodes
      * @deprecated As of 1.1, use a {@link CollectingDependencyNodeVisitor} on the root dependency node
      */
     public Collection getNodes()
     {
         return Collections.unmodifiableCollection( nodesByArtifact.values() );
     }
 
     /**
      * Gets the root dependency node of the computed dependency tree.
      * 
      * @return the root node
      */
     public DependencyNode getRootNode()
     {
         return rootNode;
     }
 
     // private methods --------------------------------------------------------
     
     /**
      * Writes the specified message to the log at debug level with indentation for the current node's depth.
      * 
      * @param message
      *            the message to write to the log
      */
     private void log( String message )
     {
         int depth = parentNodes.size();
 
         StringBuffer buffer = new StringBuffer();
 
         for ( int i = 0; i < depth; i++ )
         {
             buffer.append( "  " );
         }
 
         buffer.append( message );
 
         logger.debug( buffer.toString() );
     }
 
     /**
      * Creates a new dependency node for the specified artifact and appends it to the current parent dependency node.
      * 
      * @param artifact
      *            the attached artifact for the new dependency node
      * @return the new dependency node
      */
     private DependencyNode createNode( Artifact artifact )
     {
         DependencyNode node = new DependencyNode( artifact );
 
         if ( !parentNodes.isEmpty() )
         {
             DependencyNode parent = (DependencyNode) parentNodes.peek();
 
             parent.addChild( node );
         }
 
         return node;
     }
     
     /**
      * Creates a new dependency node for the specified artifact, appends it to the current parent dependency node and
      * puts it into the dependency node cache.
      * 
      * @param artifact
      *            the attached artifact for the new dependency node
      * @return the new dependency node
      */
     // package protected for unit test
     DependencyNode addNode( Artifact artifact )
     {
         DependencyNode node = createNode( artifact );
 
         DependencyNode previousNode = (DependencyNode) nodesByArtifact.put( node.getArtifact(), node );
         
         if ( previousNode != null )
         {
             throw new IllegalStateException( "Duplicate node registered for artifact: " + node.getArtifact() );
         }
         
         if ( rootNode == null )
         {
             rootNode = node;
         }
 
         currentNode = node;
         
         return node;
     }
 
     /**
      * Gets the dependency node for the specified artifact from the dependency node cache.
      * 
      * @param artifact
      *            the artifact to find the dependency node for
      * @return the dependency node, or <code>null</code> if the specified artifact has no corresponding dependency
      *         node
      */
     private DependencyNode getNode( Artifact artifact )
     {
         return (DependencyNode) nodesByArtifact.get( artifact );
     }
 
     /**
      * Removes the dependency node for the specified artifact from the dependency node cache.
      * 
      * @param artifact
      *            the artifact to remove the dependency node for
      */
     private void removeNode( Artifact artifact )
     {
         DependencyNode node = (DependencyNode) nodesByArtifact.remove( artifact );
 
         if ( !artifact.equals( node.getArtifact() ) )
         {
             throw new IllegalStateException( "Removed dependency node artifact was expected to be " + artifact
                             + " but was " + node.getArtifact() );
         }
     }
 
     /**
      * Gets whether the all the ancestors of the dependency node currently being processed by this listener have an
      * included state.
      * 
      * @return <code>true</code> if all the ancestors of the current dependency node have a state of
      *         <code>INCLUDED</code>
      */
     private boolean isCurrentNodeIncluded()
     {
         boolean included = true;
 
         for ( Iterator iterator = parentNodes.iterator(); included && iterator.hasNext(); )
         {
             DependencyNode node = (DependencyNode) iterator.next();
 
             if ( node.getState() != DependencyNode.INCLUDED )
             {
                 included = false;
             }
         }
 
         return included;
     }
 
     /**
      * Updates the specified node with any dependency management information cached in prior <code>manageArtifact</code>
      * calls.
      * 
      * @param node
      *            the node to update
      */
     private void flushDependencyManagement( DependencyNode node )
     {
         Artifact artifact = node.getArtifact();
         String premanagedVersion = (String) managedVersions.get( artifact.getId() );
         String premanagedScope = (String) managedScopes.get( artifact.getId() );
         
         if ( premanagedVersion != null || premanagedScope != null )
         {
             if ( premanagedVersion != null )
             {
                 node.setPremanagedVersion( premanagedVersion );
             }
             
             if ( premanagedScope != null )
             {
                 node.setPremanagedScope( premanagedScope );
             }
             
             premanagedVersion = null;
             premanagedScope = null;
         }
     }
 }