/*
    *  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.io.Serializable;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map.Entry;
  import java.util.NoSuchElementException;
  import java.util.Set;
  import org.apache.myfaces.trinidad.logging.TrinidadLogger;
  
  /**
   * Implements a collection of rowKeys from a TreeModel.
   * The methods on this class are optimized such that it is possible
   * to add/remove all the rowkeys in a subtree in constant time.
   * <P>
   * The generic type E is the type of a rowKey.
   */
  public class RowKeySetTreeImpl extends RowKeySet implements Serializable 
  {
    /**
     * Creates a new Set that is initially empty.
     */
    public RowKeySetTreeImpl()
    {
      this(false);
    }
    
    /**
     * Creates a new Set, that may contain every rowKey by default.
     * @param addAll if this is true, every rowKey is initially added to this set.
     */
    public RowKeySetTreeImpl(boolean addAll)
    {
      _root = new Node<Object>(addAll);
    }
      
    /**
     * Tests to see if the given rowKey is included in this Set.
     * @return true If the rowKey is included in this Set.
     */
    @Override
    public boolean contains(Object rowKey)
    {
      return _isContained(rowKey);
    }
    
    /**
     * @deprecated do not use. this will be removed post Tier 1.
     */
    @Override
    @Deprecated
    public boolean isContainedByDefault()
    {
      TreeModel model = getCollectionModel();
      Object rowkey = model.getRowKey();
      return new Search().find(rowkey).isDefaultContained;
    }
  
    @Override
    public Iterator<Object> iterator()
    {
      return new PathIterator();
    }
      
    /**
     * Adds the given rowKey to this Set.
     * @return false if the given rowKey was already in this Set.
     * @see #remove(Object)
     * @see #addAll()
     */
    @Override
    public boolean add(Object rowKey)
    {
      return _setContained(rowKey, true);    
    }
    
   /**
    * Removes the given rowKey from this Set.
    * @return false if the given rowKey was already not in this Set.
    * @see #add
    * @see #removeAll()
    */
   @Override
   public boolean remove(Object rowKey)
   {
     return _setContained(rowKey, false);    
   }
 
   /**
    * Adds the current rowKey and all rowKeys beneath the current rowKey to this Set.
    * This method executes in constant time.
    * @see #add
    * @see #removeAll()
    */
   @Override
   public void addAll()
   {
     _selectAll(true);
   }
 
   /**
    * Removes the current rowKey and all rowKeys beneath the current rowKey to this Set.
    * This method executes in constant time.
    * @see #remove(Object)
    * @see #clear()
    * @see #addAll()
    */
   @Override
   public void removeAll()
   {
     _selectAll(false);
   }
 
   /**
    * {@inheritDoc}
    * <P>
    * If the parameter is another RowKeySetTreeImpl, this method is
    * optimized to give superior performance and avoid iteration.
    */
   @Override
   public boolean addAll(Collection<? extends Object> other)
   {
     if (other instanceof RowKeySetTreeImpl)
     {
       RowKeySetTreeImpl otherset = (RowKeySetTreeImpl) other;
       return _processOperation(this._root, otherset._root, true);
     }
     return super.addAll(other);
   }
 
   /**
    * {@inheritDoc}
    * <P>
    * If the parameter is another RowKeySetTreeImpl, this method is
    * optimized to give superior performance and avoid iteration.
    */
   @Override
   public boolean removeAll(Collection<?> other)
   {
     if (other instanceof RowKeySetTreeImpl)
     {
       RowKeySetTreeImpl otherset = (RowKeySetTreeImpl) other;
       return _processOperation(this._root, otherset._root, false);
     }
     return super.removeAll(other);
   }
 
   private boolean _processOperation(Node<Object> set1, Node<Object> set2, boolean add)
   {
     /*      
      * setXdef = setX.isDefaultContained
      * setXdif = setX.isDifferent
      * asterisks (*) indicate changes.
      * 
      * TABLE ---------------------------------------------------
      |-----------Inputs---------|--------Outputs---------------|
      | set1def | set2def | add  | removeAll | addAll | set1def |
      |    0    |    0    |  1   |     0     |   1    |    0    |
      |    0    |    1    |  1   |     1     |   1    |    1*   |
      |    1    |    0    |  1   |     0     |   0    |    1    |
      |    1    |    1    |  1   |     1     |   0    |    1    |
      |    0    |    0    |  0   |     0     |   0    |    0    |
      |    0    |    1    |  0   |     1     |   0    |    0    |
      |    1    |    0    |  0   |     0     |   1    |    1    |
      |    1    |    1    |  0   |     1     |   1    |    0*   |
      |---------------------------------------------------------|
      */
   
     boolean hasChanges = false;
 
     // See TABLE (above) 'removeAll' column:
     // if set2 contains everything, then there is no point hanging on to
     // any set1-deltas that are not in set2, so remove them:
     if (set2.isDefaultContained && set1.keySet().retainAll(set2.keySet()))
         hasChanges = true;
 
     // See TABLE (above) 'addAll' column:
     // this "addAll" flag controls whether to process any set2-deltas that are not
     // already in set1. If set1 has everything by default and we're adding set2,
     // then there is no point processing any set2-deltas not already in set1.
     // Similarly, if set1 has nothing by default and we're removing set2,
     // then there is no point processing any set2-deltas not already in set1.
     // So only process the set2-deltas if we're doing an add (and set1
     // does not contain everything) or we're doing a remove (and set1 
     // has everything):
     boolean addAll = add ^ set1.isDefaultContained;
     
     for(Entry<Object, Node<Object>> en:set2.entrySet())
     {
       Object segment = en.getKey();
       Node<Object> subset2 = en.getValue();
       Node<Object> subset1 = set1.get(segment);
       
       if (subset1 == null)
       {
         if (addAll)
         {
           subset1 = new Node<Object>(set1, segment);
           hasChanges = true;
         }
         else
           continue;
       }
       if (_processOperation(subset1, subset2, add))
         hasChanges = true;
     }
 
     // See TABLE (above) 'Outputs/set1Def' column:
     // if set2 contains everything by default, then that will affect
     // the default flag of set1:
     if (set2.isDefaultContained && (set1.isDefaultContained != add))
     {
       set1.isDefaultContained = add;
       // since we toggled the default state, toggle the diff state
       // as well so that we maintain the status for this node:
       set1.isDifferent = !set1.isDifferent;
       hasChanges = true;
     }
 
     // if this node is contained by set2, then depending on the
     // add flag, this node should (not) be contained by set1:
     if ((set2.isDefaultContained ^ set2.isDifferent) &&
         ((set1.isDefaultContained ^ set1.isDifferent) != add))
     {
       set1.isDifferent = !set1.isDifferent;
       hasChanges = true;
     }
 
     return hasChanges;
   }
 
   /**
    * Removes all rowKeys from this Set.
    * This method executes in the same time as
    * {@link HashMap#clear()}
    */
   @Override
   public void clear()
   {
     _root.clear();
     _root.isDefaultContained = _root.isDifferent = false;
   }
 
   /**
    * Gets the number of elements contained by this set.
    * Does not force the underlying model to compute its size. 
    * @return -1 if the number of elements is unknown.
    */
   @Override
   public int getSize()
   {
     return _getSize(null, _root, getCollectionModel(), false);
   }
 
   /**
    * Gets the number of elements in this Set.
    * This might force the underlying model to compute its size.
    * @return a non-negative number.
    */
   @Override
   public int size()
   {
     return _getSize(null, _root, getCollectionModel(), true);
   }
 
   @Override
   public boolean isEmpty() 
   {
     return (getSize() == 0);
   }
 
   /**
    * Sets the TreeModel associated with this Set.
    * @param model This must be of type {@link TreeModel}
    */
   @Override
   public final void setCollectionModel(CollectionModel model)
   {
     if (!(model instanceof TreeModel))
       throw new IllegalArgumentException();
 
     _model = (TreeModel) model;
   }
 
   /**
    * Creates a clone of this Set. RowKeys may be added/removed from the
    * clone without affecting this instance.
    */
   @Override
   public RowKeySetTreeImpl clone()
   {
     RowKeySetTreeImpl clone = (RowKeySetTreeImpl) super.clone();
     clone._root = _root.clone();
     return clone;
   }
 
   /**
    * @deprecated not implemented.
    */
   @Deprecated
   @Override
   public void invertAll()
   {
     // TODO
     throw new UnsupportedOperationException();
   }
 
   /**
    * Gets the TreeModel associated with this set.
    * This TreeModel will be used to get the current rowKey, and also to
    * get parent rowKeys, from child rowKeys.
    * @see TreeModel#getRowKey
    */
   @Override
   protected TreeModel getCollectionModel()
   {
     return _model;
   }
 
   /**
    * Gets the total number of nodes in the subtree of the given TreeModel.
    * 
    * WARNING: this method changes the TreeModel's currency.
    * The caller is responsible for restoring the model currency.
    * 
    * @param exclusions any rowKeys present in this Set are excluded from the count.
    */
   @SuppressWarnings("unchecked")
   private int _getTreeSize(TreeModel model, Set<Object> exclusions)
   {
     int sz = 0;
     for(int i=0;true;i++)
     {
       model.setRowIndex(i);
       if (model.isRowAvailable())
       {
         Object rowkey = model.getRowKey();
         if (exclusions.contains(rowkey))
           continue;
         sz++;
         if (model.isContainer())
         {
           model.enterContainer();
           Set<Object> empty = Collections.emptySet();
           sz += _getTreeSize(model, empty);
           model.exitContainer();
         }
       }
       else
         return sz;
     }
   }
 
   private int _getSize(Object rowkey, Node<Object> set, TreeModel model,  boolean fetchall)
   {
     // special-case the root collection:
     int sz = ((rowkey != null) && (set.isDefaultContained ^ set.isDifferent)) ? 1 : 0;
     if (set.isDefaultContained)
     {
       if (!fetchall)
         return -1;
         
       Object old = model.getRowKey();
       try
       {
         model.setRowKey(rowkey);
         // special-case the root collection:
         if (rowkey == null)
         {
           sz += _getTreeSize(model, set.keySet());
         }
         else if (model.isContainer())
         {
           model.enterContainer();
           sz += _getTreeSize(model, set.keySet());
         }
       }
       finally
       {
         model.setRowKey(old);
       }
     }
     
     for(Entry<Object, Node<Object>> en:set.entrySet())
     {
       Object newrowkey = en.getKey();
       Node<Object> subset = en.getValue();
       int size = _getSize(newrowkey, subset, model, fetchall);
       if (size < 0)
         return -1;
       sz+= size;
     }
     return sz;
   }
 
   /**
    * adds or removes all the paths rooted at the current path 
    * @param isSelectAll if true does an add-all. else does remove-all.
    */
   private void _selectAll(final boolean isSelectAll)
   {
     Search search = new Search()
     {
       @Override
       protected boolean create(Node<Object> parent, Object rowkey)
       {
         // if the parent does not have the correct default, then
         // we need to add entries for the children, since we need
         // to store a delta:
         return (parent.isDefaultContained != isSelectAll);
       }
       
       @Override
       protected Node<Object> found(Node<Object> child)
       {
         child.isDefaultContained = isSelectAll;
         child.isDifferent = false;
         child.clear();
         return null;
       }
     };
 
     TreeModel model = getCollectionModel();
     Object rowkey = model.getRowKey();
     search.find(rowkey);    
   }
 
   private boolean _isContained(Object rowkey)
   {
     Search search = new Search()
     {
       @Override
       protected Node<Object> notFound(Node<Object> parent, Object rowkey)
       {
         return parent.isDefaultContained ? parent : null;
       }
       
       @Override
       protected Node<Object> found(Node<Object> child)
       {
         return (child.isDefaultContained ^ child.isDifferent) ? child : null;
       }
     };
     
     return (search.find(rowkey) != null);
   }
   
   /**
    * Adds or removes the given path from this set.
    * @param isContained If true, the current path is added. Otherwise,
    * it is removed.
    * @return true if this Set changed due to this operation. 
    */
   private boolean _setContained(Object rowkey, final boolean isContained)
   {
     Search search = new Search()
     {
       @Override
       protected boolean create(Node<Object> parent, Object rowkey)
       {
         // only need to create child deltas, if the parent's
         // default is wrong:
         return parent.isDefaultContained != isContained;
       }
       
       @Override
       protected Node<Object> notFound(Node<Object> parent, Object rowkey)
       {
         return null;
       }
     };
 
     Node<Object> current = search.find(rowkey);
     if ((current != null) &&
         ((current.isDefaultContained ^ current.isDifferent) != isContained))
     {
       current.isDifferent = !current.isDifferent;
       return true;
     }
     return false;
   }
 
   /**
    * Advances the currency of the given TreeModel to the next node in a
    * depth-first walk of the tree.
    * @param minDepth the minimum depth of the rowkey. use this to
    * walk within a subtree. Use 0 to walk entire tree.
    * @param recurseChildren if true, will walk children.
    * @return true if the currency of the model was successfully advanced to
    * the next rowData.
    */
   private static boolean _advanceToNextItem(
     TreeModel model, int minDepth, boolean recurseChildren)
   {
     assert minDepth >= 0;
     
     if (recurseChildren && model.isRowAvailable() && model.isContainer())
     {
       model.enterContainer();
       model.setRowIndex(-1);
     }
     while(true)
     {
       int ri = model.getRowIndex();
       model.setRowIndex(ri+1);
       if (model.isRowAvailable())
         return true;
         
       int depth = model.getDepth();
       if (depth <= minDepth)
         return false;
         
       model.exitContainer();
     }
   }
 
   // Needs to be Serializable and Cloneable - but HashMap already is
   private static final class Node<K> extends HashMap<K, Node<K>>
      /* implements Serializable, Cloneable */
   {
     public boolean isDifferent = false;
     public boolean isDefaultContained = false;
 
     public Node(boolean isDefaultContained)
     {
       this.isDefaultContained = isDefaultContained;
     }
     
     public Node(Node<K> parent, K segment)
     {
       this(parent.isDefaultContained);
       parent.put(segment, this);
     }
     
     // clone all the values as well:
     private void _deepClone(Node<K> root)
     {
       for(Entry<K, Node<K>> en:root.entrySet())
       {
         Node<K> original = en.getValue();
         Node<K> clone = original.clone();
         en.setValue(clone);
       }
     }
     
     @SuppressWarnings("unchecked")
     @Override
     public Node<K> clone()
     {
       Node<K> clone = (Node<K>) super.clone();
       _deepClone(clone);
       return clone;
     }
 
     private static final long serialVersionUID = 1L;
   }
 
   private class Search
   {
     public Search()
     {
     }
     
     protected boolean create(Node<Object> parent, Object rowkey)
     {
       return false;
     }
 
     protected Node<Object> notFound(Node<Object> parent, Object rowkey)
     {
       return parent;
     }
 
     protected Node<Object> found(Node<Object> result)
     {
       return result;
     }
 
     public Node<Object> find(Object rowkey)
     {
       Node<Object> current = _root;
       if (rowkey != null)
       {
         TreeModel model = getCollectionModel();
         List<Object> parentkeys = model.getAllAncestorContainerRowKeys(rowkey);
         List<Object> allkeys = new ArrayList<Object>(parentkeys.size() + 1);
         allkeys.addAll(parentkeys);
         allkeys.add(rowkey);
         for(Object key:allkeys)
         {
           Node<Object> next = current.get(key);
           if (next == null)
           {
             if (create(current, key))
               next = new Node<Object>(current, key);       
             else
               return notFound(current, key);
           }
           current = next;
         }
       }
       return found(current);
     }
   }
 
   private final class PathIterator implements Iterator<Object>
   {
     PathIterator()
     {
       _value = _next(); // initialize;
     }
 
     public Object next()
     {
       if (!hasNext())
         throw new NoSuchElementException();
       Object value = _value;
       _value = _next();
       return value;
     }
     
     public boolean hasNext()
     {
       return (_value != null);
     }
     
     public void remove()
     {
       throw new UnsupportedOperationException();
     }
     
     private boolean _containsSubtree(Object rowkey)
     {
       Search search = new Search()
       {
         @Override
         protected Node<Object> notFound(Node<Object> parent, Object rowkey)
         {
           return parent.isDefaultContained ? parent : null;
         }
       };
       Node<Object> current = search.find(rowkey);
       return (current != null) && 
         ((!current.isEmpty()) || current.isDefaultContained);
     }
     
     private Object _next()
     {
       TreeModel model = getCollectionModel();
       if (model == null)
         return null;
 
       Object oldPath = model.getRowKey();
       try 
       {
         model.setRowKey(_currPath);
         while(true)
         {
           boolean searchChildren = _containsSubtree(_currPath);
           boolean hasMore = _advanceToNextItem(model, 0, searchChildren);
           if (!hasMore)
             return null;
 
           _currPath = model.getRowKey();
           if (contains(_currPath))
             return _currPath;
         }
       } finally 
       {
         model.setRowKey(oldPath);
       }
     }
     
     private Object _value;
     private Object _currPath = null;
   }
   
   private Node<Object> _root;
   private transient TreeModel _model = null;
   private static final long serialVersionUID = 1L;
   private static final TrinidadLogger _LOG =
     TrinidadLogger.createTrinidadLogger(RowKeySetTreeImpl.class);
 }