package org.apache.maven.shared.dependency.graph.traversal;

 /*

  * 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.io.Writer;

 import java.util.List;

 import org.apache.maven.shared.dependency.graph.DependencyNode;

 /**

  * A dependency node visitor that serializes visited nodes to a writer.

  * 

  * @author <a href="mailto:markhobson@gmail.com">Mark Hobson</a>

  */

 public class SerializingDependencyNodeVisitor

     implements DependencyNodeVisitor

 {

     // classes ----------------------------------------------------------------

     /**

      * Provides tokens to use when serializing the dependency tree.

      */

     public static class TreeTokens

     {

         private final String nodeIndent;

         private final String lastNodeIndent;

         private final String fillIndent;

         private final String lastFillIndent;

         public TreeTokens( String nodeIndent, String lastNodeIndent, String fillIndent, String lastFillIndent )

         {

             this.nodeIndent = nodeIndent;

             this.lastNodeIndent = lastNodeIndent;

             this.fillIndent = fillIndent;

             this.lastFillIndent = lastFillIndent;

         }

         public String getNodeIndent( boolean last )

         {

             return last ? lastNodeIndent : nodeIndent;

         }

         public String getFillIndent( boolean last )

         {

             return last ? lastFillIndent : fillIndent;

         }

     }

     // constants --------------------------------------------------------------

     /**

      * Whitespace tokens to use when outputing the dependency tree.

      */

     public static final TreeTokens WHITESPACE_TOKENS = new TreeTokens( "   ", "   ", "   ", "   " );

     /**

      * The standard ASCII tokens to use when outputing the dependency tree.

      */

     public static final TreeTokens STANDARD_TOKENS = new TreeTokens( "+- ", "\\- ", "|  ", "   " );

     /**

      * The extended ASCII tokens to use when outputing the dependency tree.

      */

     public static final TreeTokens EXTENDED_TOKENS =

         new TreeTokens( "\u00c3\u00c4 ", "\u00c0\u00c4 ", "\u00b3  ", "   " );

     // fields -----------------------------------------------------------------

     /**

      * The writer to serialize to.

      */

     private final PrintWriter writer;

     /**

      * The tokens to use when serializing the dependency tree.

      */

     private final TreeTokens tokens;

     /**

      * The depth of the currently visited dependency node.

      */

     private int depth;

     // constructors -----------------------------------------------------------

     /**

      * Creates a dependency node visitor that serializes visited nodes to the specified writer using whitespace tokens.

      * 

      * @param writer

      *            the writer to serialize to

      */

     public SerializingDependencyNodeVisitor( Writer writer )

     {

         this( writer, WHITESPACE_TOKENS );

     }

     /**

      * Creates a dependency node visitor that serializes visited nodes to the specified writer using the specified

      * tokens.

      * 

      * @param writer

      *            the writer to serialize to

      * @param tokens

      *            the tokens to use when serializing the dependency tree

      */

     public SerializingDependencyNodeVisitor( Writer writer, TreeTokens tokens )

     {

         if ( writer instanceof PrintWriter )

         {

             this.writer = (PrintWriter) writer;

         }

         else

         {

             this.writer = new PrintWriter( writer, true );

         }

         this.tokens = tokens;

         depth = 0;

     }

     // DependencyNodeVisitor methods ------------------------------------------

     /**

      * {@inheritDoc}

      */

     public boolean visit( DependencyNode node )

     {

         indent( node );

         writer.println( node.toNodeString() );

         depth++;

         return true;

     }

     /**

      * {@inheritDoc}

      */

     public boolean endVisit( DependencyNode node )

     {

         depth--;

         return true;

     }

     // private methods --------------------------------------------------------

     /**

      * Writes the necessary tokens to indent the specified dependency node to this visitor's writer.

      * 

      * @param node

      *            the dependency node to indent

      */

     private void indent( DependencyNode node )

     {

         for ( int i = 1; i < depth; i++ )

         {

             writer.write( tokens.getFillIndent( isLast( node, i ) ) );

         }

         if ( depth > 0 )

         {

             writer.write( tokens.getNodeIndent( isLast( node ) ) );

         }

     }

     /**

      * Gets whether the specified dependency node is the last of its siblings.

      * 

      * @param node

      *            the dependency node to check

      * @return <code>true</code> if the specified dependency node is the last of its last siblings

      */

     private boolean isLast( DependencyNode node )

     {

         // TODO: remove node argument and calculate from visitor calls only

         DependencyNode parent = node.getParent();

         boolean last;

         if ( parent == null )

         {

             last = true;

         }

         else

         {

             List<DependencyNode> siblings = parent.getChildren();

             last = ( siblings.indexOf( node ) == siblings.size() - 1 );

         }

         return last;

     }

     /**

      * Gets whether the specified dependency node ancestor is the last of its siblings.

      * 

      * @param node

      *            the dependency node whose ancestor to check

      * @param ancestorDepth

      *            the depth of the ancestor of the specified dependency node to check

      * @return <code>true</code> if the specified dependency node ancestor is the last of its siblings

      */

     private boolean isLast( DependencyNode node, int ancestorDepth )

     {

         // TODO: remove node argument and calculate from visitor calls only

         int distance = depth - ancestorDepth;

         while ( distance-- > 0 )

         {

             node = node.getParent();

         }

         return isLast( node );

     }

 }