package org.eclipse.aether.internal.impl;
   
   /*
    * 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.io.PrintWriter;
  import java.util.ArrayList;
  import java.util.IdentityHashMap;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  
  import org.eclipse.aether.graph.Dependency;
  import org.eclipse.aether.graph.DependencyNode;
  
  /**
   * A helper to visualize dependency graphs.
   */
  public class DependencyGraphDumper
  {
  
      public static void dump( PrintWriter writer, DependencyNode node )
      {
          Context context = new Context();
          dump( context, node, 0, true );
  
          LinkedList<Indent> indents = new LinkedList<>();
          for ( Line line : context.lines )
          {
              if ( line.depth > indents.size() )
              {
                  if ( !indents.isEmpty() )
                  {
                      if ( indents.getLast() == Indent.CHILD )
                      {
                          indents.removeLast();
                          indents.addLast( Indent.CHILDREN );
                      }
                      else if ( indents.getLast() == Indent.LAST_CHILD )
                      {
                          indents.removeLast();
                          indents.addLast( Indent.NO_CHILDREN );
                      }
                  }
                  indents.addLast( line.last ? Indent.LAST_CHILD : Indent.CHILD );
              }
              else if ( line.depth < indents.size() )
              {
                  while ( line.depth <= indents.size() )
                  {
                      indents.removeLast();
                  }
                  indents.addLast( line.last ? Indent.LAST_CHILD : Indent.CHILD );
              }
              else if ( line.last && !indents.isEmpty() )
              {
                  indents.removeLast();
                  indents.addLast( Indent.LAST_CHILD );
              }
  
              for ( Indent indent : indents )
              {
                  writer.print( indent );
              }
  
              line.print( writer );
          }
  
          writer.flush();
      }
  
      private static void dump( Context context, DependencyNode node, int depth, boolean last )
      {
          Line line = context.nodes.get( node );
          if ( line != null )
          {
              if ( line.id <= 0 )
              {
                  line.id = ++context.ids;
              }
              context.lines.add( new Line( null, line.id, depth, last ) );
              return;
         }
 
         Dependency dependency = node.getDependency();
 
         if ( dependency == null )
         {
             line = new Line( null, 0, depth, last );
         }
         else
         {
             line = new Line( dependency, 0, depth, last );
         }
 
         context.lines.add( line );
 
         context.nodes.put( node, line );
 
         depth++;
 
         for ( Iterator<DependencyNode> it = node.getChildren().iterator(); it.hasNext(); )
         {
             DependencyNode child = it.next();
             dump( context, child, depth, !it.hasNext() );
         }
     }
 
     enum Indent
     {
 
         NO_CHILDREN( "   " ),
 
         CHILDREN( "|  " ),
 
         CHILD( "+- " ),
 
         LAST_CHILD( "\\- " );
 
         private final String chars;
 
         Indent( String chars )
         {
             this.chars = chars;
         }
 
         @Override
         public String toString()
         {
             return chars;
         }
 
     }
 
     static class Context
     {
 
         int ids;
 
         List<Line> lines;
 
         Map<DependencyNode, Line> nodes;
 
         Context()
         {
             this.lines = new ArrayList<>();
             this.nodes = new IdentityHashMap<>( 1024 );
         }
 
     }
 
     static class Line
     {
 
         Dependency dependency;
 
         int id;
 
         int depth;
 
         boolean last;
 
         Line( Dependency dependency, int id, int depth, boolean last )
         {
             this.dependency = dependency;
             this.id = id;
             this.depth = depth;
             this.last = last;
         }
 
         void print( PrintWriter writer )
         {
             if ( dependency == null )
             {
                 if ( id > 0 )
                 {
                     writer.print( "^" );
                     writer.print( id );
                 }
                 else
                 {
                     writer.print( "(null)" );
                 }
             }
             else
             {
                 if ( id > 0 )
                 {
                     writer.print( "(" );
                     writer.print( id );
                     writer.print( ")" );
                 }
                 writer.print( dependency.getArtifact() );
                 if ( dependency.getScope().length() > 0 )
                 {
                     writer.print( ":" );
                     writer.print( dependency.getScope() );
                 }
             }
             writer.println();
         }
 
     }
 
 }