/*
    * 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.bean;
  
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.ArrayList;
  
  import java.util.Collection;
  import java.util.Collections;
  
  import javax.faces.component.PartialStateHolder;
  
  import javax.faces.component.StateHolder;
  import javax.faces.context.FacesContext;
  
  import org.apache.myfaces.trinidad.bean.util.StateUtils;
  
  /**
   * Class for managing attached object on the component that are maintained as a Map of Lists
   */
  public class AttachedObjects<K, T> implements PartialStateHolder
  {
    /**
     * Adds attached object to this collection. The key for the object does not have to be unique.
     * @param key Object key
     * @param obj Object value
     */
    final public void addAttachedObject(K key, T obj)
    {    
      List<T> objects = _objectMap.get(key);
      if (objects == null)
      {
        objects = new ArrayList<T>(5);
        _objectMap.put(key, objects);
      }
      
      objects.add(obj);
      
      if (initialStateMarked())
      {
        // Clear initial state marker for the attached objects so that their full state is saved
        clearInitialState();
      }
    }
    /**
     * Removes an object from this collection
     * @param key Object key
     * @param obj Object value
     * @return true if the object fas found and removed, false otherwise
     */
    final public boolean removeAttachedObject(K key, T obj)
    {
      List<T> objects = _objectMap.get(key);
      if (objects == null)
      {
        return false;
      }
      
      boolean removed = objects.remove(obj);
      if (removed)
      {
        if (initialStateMarked())
        {
          // Clear initial state marker for the attached objects so that their full state is saved
          clearInitialState();
        }
      }
      return removed;
    }
    
    /**
     * Retrieves a non-null immutable list of objects for this key from the collection.
     * @param key Key value shared by all the objects in the List
     * @return a list of objects for the given key
     */
    final public List<T> getAttachedObjectList(K key)
    {
      List<T> objects = _objectMap.get(key);
      if (objects == null)
      {
        return Collections.emptyList();
     }
     return Collections.unmodifiableList(objects);
   }
   
   /**
    * Retreives a map of objects contained in this collection.
    * @return a non-null immutable map of objects
    */
   final public Map<K, List<T>> getAttachedObjectMap()
   {
     if (_readOnlyObjectMap == null)
     {
       _readOnlyObjectMap = Collections.unmodifiableMap(_objectMap);
     }
     return _readOnlyObjectMap;
   }
         
   @Override
   public void markInitialState()
   {
     for (Map.Entry<K, List<T>> e : _objectMap.entrySet())
     {
       for (T obj : e.getValue())
       {
         if (obj instanceof PartialStateHolder)
         {
           ((PartialStateHolder)obj).markInitialState();
         }
       }
     }
     _initialStateMarked = true;
   }
   
   @Override
   public void clearInitialState()
   {
     _initialStateMarked = false;
     for (Map.Entry<K, List<T>> e : _objectMap.entrySet())
     {
       for (T obj : e.getValue())
       {
         if (obj instanceof PartialStateHolder)
         {
           ((PartialStateHolder)obj).clearInitialState();
         }
       }
     }
   }
   
   @Override
   public boolean initialStateMarked()
   {
     return _initialStateMarked;
   }
 
   @Override
   public Object saveState(
     FacesContext facesContext)
   {
     Map<K, Object[]> state = new HashMap<K, Object[]>(_objectMap.size());
     for (Map.Entry<K, List<T>> e : _objectMap.entrySet())
     {
       List<T> l = e.getValue();
       Object[] entryState = new Object[l.size()];
       boolean stateWasSaved = false;
       for (int i = 0, size = entryState.length; i < size; ++i)
       {
         T obj = l.get(i);
         if (_initialStateMarked)
         {
           // JSF 2 state saving, only save the attched object's state if it is a state holder,
           // otherwise the re-application of the template will handle the re-creation of the
           // object in the correct state
           if (obj instanceof StateHolder)
           {
             entryState[i] = ((StateHolder)obj).saveState(facesContext);
           }
         }
         else
         {
           // Use JSF <= 1.2 state saving method as the initial state was not marked
           entryState[i] = StateUtils.saveStateHolder(facesContext, obj);
         }
 
         stateWasSaved = (entryState[i] != null) ? true : stateWasSaved;
       }
 
       if (stateWasSaved)
       {
         state.put(e.getKey(), entryState);
       }
     }
     
     Object [] savedState = null;
     if (!state.isEmpty())
     {
     
       // Record whether we used full state saving. This is necessary because methods like addClientBehvior() force
       // full state saving under certain circumstances.
       // To avoid using partial state restoration with the fully-saved state during restoreView(),  we will be using
       // the saved flag instead of _initialStateMarked 
       savedState = new Object[2];
       savedState[0] = _initialStateMarked; 
       savedState[1] = state;
     }
     return savedState;
   }
 
   @Override
   public void restoreState(
     FacesContext facesContext,
     Object       state)
   {
     if (state == null)
       return;
     
     Object stateArray[] = (Object [])state;
     boolean usePartialStateSaving = (Boolean)stateArray[0];
     
     @SuppressWarnings("unchecked")
     Map<K, Object[]> savedState = (Map<K, Object[]>) stateArray[1];
 
     if (usePartialStateSaving)
     {
       // In JSF 2 state saving, we only need to super impose the state onto the existing
       // attached object list of the current map as the attached objects will already be restored in
       // the same order that they were in the previous request (if not there is an application
       // bug).
       for (Map.Entry<K, Object[]> e : savedState.entrySet())
       {
         // Assume that the objects were correctly re-attached to the component and we only
         // need to restore the state onto the objects. The order must be maintained.
         List<T> l = _objectMap.get(e.getKey());
         Object[] entryState = e.getValue();
         for (int i = 0, size = entryState.length; i < size; ++i)
         {
           if (entryState[i] != null)
           {
             T obj = l.get(i);
             if (obj instanceof StateHolder)
             {
               ((StateHolder)obj).restoreState(facesContext, entryState[i]);
             }
           }
         }
       }
     }
     else
     {
       // For JSF <= 1.2 style state saving, we should ensure that we are empty and then
       // re-hydrate the attched objects directly from the state
       _objectMap.clear();
 
       for (Map.Entry<K, Object[]> e : savedState.entrySet())
       {
         Object[] entryState = e.getValue();
         // Assume the list is not going to grow in this request, so only allocate the size
         // of the list from the previous request
         List<T> list = new ArrayList<T>(entryState.length);
         for (int i = 0, size = entryState.length; i < size; ++i)
         {
           list.add((T)StateUtils.restoreStateHolder(facesContext, entryState[i]));
         }
 
         _objectMap.put(e.getKey(), list);
       }
     }
   }
 
   public boolean isTransient()
   {
     return _transient;
   }
 
   public void setTransient(
     boolean newTransientValue)
   {
     _transient = newTransientValue;
   }
 
      
   
   private Map<K, List<T>> _objectMap = new HashMap<K, List<T>>(5, 1.0f);
   
   private Map<K, List<T>> _readOnlyObjectMap = null;
   
   private boolean _initialStateMarked = false;
   private boolean _transient = false;
 }