/*
    * 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.view.facelets.impl;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Hierarchical counter to generate unique ids.
   * 
   * @author Leonardo Uribe
   *
   */
  public class SectionUniqueIdCounter
  {
      private List<Section> _counterStack;
      
      private int _activeSection;
      
      private final String _prefix;
      
      private final StringBuilder _builder;
      
      private char[] _bufferConversion;
      
      private final int _radix;
      
      private String[] _uniqueIdsCache;
      
      public SectionUniqueIdCounter()
      {
          _activeSection = 0;
          _radix = Character.MAX_RADIX;
          _counterStack = new ArrayList<Section>();
          _counterStack.add(new Section(null,1,_radix));
          _prefix = null;
          _builder = new StringBuilder(30);
          _bufferConversion = new char[15];
      }
      
      public SectionUniqueIdCounter(String prefix)
      {
          _activeSection = 0;
          _radix = Character.MAX_RADIX;
          _counterStack = new ArrayList<Section>();
          _counterStack.add(new Section(null,1,_radix));
          _prefix = prefix;
          _builder = new StringBuilder(30);
          _bufferConversion = new char[15];
      }
      
      public SectionUniqueIdCounter(String prefix, String[] cache)
      {
          _activeSection = 0;
          _radix = Character.MAX_RADIX;
          _counterStack = new ArrayList<Section>();
          _counterStack.add(new Section(null,1,_radix));
          _prefix = prefix;
          _builder = new StringBuilder(30);
          _bufferConversion = new char[15];
          _uniqueIdsCache = cache;
      }
      
      public SectionUniqueIdCounter(String prefix, int radix)
      {
          _activeSection = 0;
          _radix = radix;
          _counterStack = new ArrayList<Section>();
          _counterStack.add(new Section(null,1,_radix));
          _prefix = prefix;
          _builder = new StringBuilder(30);
          _bufferConversion = new char[15];
      }
  
      /**
       * Creates an array of the generated unique ids for an specified prefix,
       * than can be used later to prevent calculate the same String over and over.
       * 
       * @param prefix
       * @param count
       * @return 
       */
      public static String[] generateUniqueIdCache(String prefix, int count)
     {
         String[] cache = new String[count];
         SectionUniqueIdCounter counter = new SectionUniqueIdCounter(prefix);
         for (int i = 0; i < count ; i++)
         {
             cache[i] = counter.generateUniqueId();
         }
         return cache;
     }
 
     public String startUniqueIdSection()
     {
         //1. Calculate prefix
         _builder.delete(0, _builder.length());
         boolean added = false;
         for (int i = 0; i < _counterStack.size(); i++)
         {
             if (added)
             {
                 _builder.append('_');
             }
             //_builder.append(Long.toString(_counterStack.get(i).getCounter(), _radix));
             appendToBuilder(_counterStack.get(i).getCounter(), _radix, _builder, _bufferConversion);
             added = true;
         }
         
         _counterStack.add(new Section(_builder.toString(),1,_radix));
         _activeSection++;
         return _builder.toString();
     }
     
     public String startUniqueIdSection(String base)
     {
         //1. Calculate prefix
         _builder.delete(0, _builder.length());
         boolean added = false;
         for (int i = 0; i < _counterStack.size(); i++)
         {
             if (added)
             {
                 _builder.append('_');
             }
             //_builder.append(Long.toString(_counterStack.get(i).getCounter(), _radix));
             appendToBuilder(_counterStack.get(i).getCounter(), _radix, _builder, _bufferConversion);
             added = true;
         }
         if (base != null && base.length() > 0)
         {
             _builder.append('_');
             _builder.append(base);
         }
         _counterStack.add(new Section(_builder.toString(),1,_radix));
         _activeSection++;
         return _builder.toString();
     }
 
     public String generateUniqueId()
     {
         if (_activeSection == 0 && _uniqueIdsCache != null)
         {
             long i = _counterStack.get(_activeSection).getCounter();
             if (((int)i) < (long)_uniqueIdsCache.length)
             {
                 _counterStack.get(_activeSection).incrementUniqueId();
                 return _uniqueIdsCache[((int)i)-1];
             }
             else
             {
                 return _counterStack.get(_activeSection).generateUniqueId(_prefix);
             }
         }
         else
         {
             return _counterStack.get(_activeSection).generateUniqueId(_prefix);
         }
     }
     
     public void generateUniqueId(StringBuilder builderToAdd)
     {
         _counterStack.get(_activeSection).generateUniqueId(_prefix, builderToAdd);
     }
     
     public void incrementUniqueId()
     {
         _counterStack.get(_activeSection).incrementUniqueId();
     }
     
     public void endUniqueIdSection()
     {
         if (_activeSection <= 0)
         {
             _counterStack.get(_activeSection).generateUniqueId(_prefix);
             return;
         }
         else
         {
             _counterStack.remove(_activeSection);
             _activeSection--;
             _counterStack.get(_activeSection).generateUniqueId(_prefix);
         }
     }
     
     private static class Section
     {
         
         private String prefix;
         private long counter;
         private final StringBuilder _builder;
         private char[] _bufferConversion;
         private final int _radix;
         
         public Section(String prefix, long counter, int radix)
         {
             super();
             this.prefix = prefix;
             this.counter = counter;
             _builder = new StringBuilder(30);
             _bufferConversion = new char[15];
             _radix = radix;
         }
 
         public long getCounter()
         {
             return counter;
         }
         
         public void incrementUniqueId()
         {
             this.counter++;
         }
 
         public void generateUniqueId(String base, StringBuilder builder)
         {
             long i = this.counter;
             this.counter++;
             //_builder.delete(0, _builder.length());
             if (base != null)
             {
                 builder.append(base);
             }
             if (this.prefix != null)
             {
                 builder.append(this.prefix);
                 builder.append('_');
             }
             // By performance reasons, Long.toString is a very expensive
             // operation in this location, because it triggers a new String()
             //_builder.append(Long.toString(i, _radix));
             appendToBuilder(i, _radix, builder, _bufferConversion);
             //return _builder.toString();
         }
         
         public String generateUniqueId(String base)
         {
             long i = this.counter;
             this.counter++;
             _builder.delete(0, _builder.length());
             if (base != null)
             {
                 _builder.append(base);
             }
             if (this.prefix != null)
             {
                 _builder.append(this.prefix);
                 _builder.append('_');
             }
             // By performance reasons, Long.toString is a very expensive
             // operation in this location, because it triggers a new String()
             //_builder.append(Long.toString(i, _radix));
             appendToBuilder(i, _radix, _builder, _bufferConversion);
             return _builder.toString();
         }
     }
     
     //From Harmony Long.toString(l,radix)
     private static void appendToBuilder(long l, int radix, StringBuilder builder, char[] bufferConversion)
     {
         if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
         {
             radix = 10;
         }
         if (l == 0)
         {
             builder.append('0');
             return;
         }
 
         int count = 2;
         long j = l;
         boolean negative = l < 0;
         if (!negative)
         {
             count = 1;
             j = -l;
         }
         while ((l /= radix) != 0)
         {
             count++;
         }
 
         if (bufferConversion.length < count)
         {
             bufferConversion = new char[count];
         }
         int finalCount = count;
 
         char[] buffer = bufferConversion;
         do 
         {
             int ch = 0 - (int) (j % radix);
             if (ch > 9)
             {
                 ch = ch - 10 + 'a';
             }
             else
             {
                 ch += '0';
             }
             buffer[--count] = (char) ch;
             j /= radix;
         }
         while (j != 0);
         if (negative)
         {
             buffer[0] = '-';
         }
         for (int i = 0; i < finalCount; i++)
         {
             builder.append(buffer[i]);
         }
         //return new String(0, buffer.length, buffer);
     }
 }