/*
    * 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.myfaces.trinidad.model;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import org.apache.myfaces.trinidad.logging.TrinidadLogger;
  
  /**
   */
  class PathHelper 
  {
    protected PathHelper()
    {
      _path = Collections.emptyList();
      _rowKey = null;
    }
    
    /**
     * Sets the current rowKey.
     * @param rowKey
     */
    public final void setRowKey(String rowKey)
    {
      _rowKey = rowKey;
    }
    
    /**
     * @return the current row key
     */
    public final String getRowKey()
    {
      return _rowKey;
    }
    
    /**
     * @return the current size of the path
     */
    public final int getPathSize()
    {
      return _path.size();
    }
    
    /**
     * Gets the current path.
     * @return a List, with each element a rowKey String
     */
    public final List<String> getPath()
    {
      int sz = _path.size();
      List<String> path = new ArrayList<String>(sz+1);
      if (sz > 0)
      {
        for(int i=0; i<sz; i++)
        {
          path.add(getPath(i));
        }
      }
      path.add(getRowKey());
      return path;
    }
  
    /**
     * Gets a rowKey at the specified location in the path.
     * @param index
     * @return the rowKey String
     */
    public final String getPath(int index)
    {
      return _getPathElement(index).rowKey;
    }
    
    /**
     * Sets the path.
     * @param path a List with each element a rowKey String
     */
    public final void setPath(List<String> path)
    {
      int sz = (path==null) ? 0 : path.size();
  
      if (sz > 0)
      {
       _path = new ArrayList<PathElement>(sz);
       int lastIndex = sz - 1;
   
       for(int i=0; i<lastIndex; i++)
       {
         setRowKey(path.get(i));
         pushPath();
       }
       setRowKey(path.get(lastIndex));
     }
     else
     {
       _path = Collections.emptyList();
       setRowKey(null);
     }
   }
 
   /**
    * Gets the path data at the specified index.
    * @param index
    * @return this is the path data that was set using 
    * {@link #pushPath(Object,String)}
    */
   protected final Object getPathData(int index)
   {
     return _getPathElement(index).node;
   }
 
   /**
    * @return the path data for the last element in the path.
    */
   protected Object getLastPathData()
   {
     int sz = getPathSize();
     return (sz > 0) ? getPathData(sz - 1) : null;
   }
   
   /**
    * Pushes the current rowKey onto the path.
    */
   public final void pushPath()
   {
     if (_rowKey == null)
       throw new IllegalStateException(_LOG.getMessage(
         "NULL_ROWKEY"));
   
     Object parentData = getLastPathData();
     Object data = pushPath(parentData, _rowKey);
 
     List<PathElement> comparant = Collections.emptyList();
     if (_path == comparant)
       _path = new ArrayList<PathElement>(5);
 
     _path.add(new PathHelper.PathElement(_rowKey, data));
     
     _rowKey = null;
   }
   
   /**
    * Gets the path data to use for a new path segment.
    * @param parentData the path data of the previous path segment
    * @param rowKey the path segment that is just about to be added.
    * @return new path data, which can be retrieved using
    * {@link #getPathData(int)}
    */
   protected Object pushPath(Object parentData, String rowKey)
   {
     return null;
   }
   
   /**
    * Removes the last rowKey from the end of this path.
    * The current rowKey is set to be this last rowKey.
    */
   public final void popPath()
   {
     int sz = _path.size();
     if (sz > 0)
     {
       PathHelper.PathElement lastPath = _path.remove(sz-1);
       _rowKey = lastPath.rowKey;
     }
     else
       throw new IllegalStateException(_LOG.getMessage(
         "NO_PATH_ELEMENT_TO_POP"));
   }
 
   private PathHelper.PathElement _getPathElement(int index)
   {
     return _path.get(index);
   }
   
   private String _rowKey;
   private List<PathElement> _path;
   
   private static final class PathElement
   {
     public final Object node;
     public final String rowKey;
     
     public PathElement(String rowKey, Object data)
     {
       this.rowKey = rowKey;
       this.node = data;
     }
   }
   private static final TrinidadLogger _LOG = TrinidadLogger.createTrinidadLogger(
     PathHelper.class);
 }