/*
    * $Id: BasicAttributeContext.java 616498 2008-01-29 19:40:35Z apetrelli $
    *
    * 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.tiles.context;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Set;
  import java.util.Stack;
  
  import org.apache.tiles.Attribute;
  import org.apache.tiles.AttributeContext;
  
  /***
   * Basic implementation for <code>AttributeContext</code>.
   *
   * @version $Rev: 616498 $ $Date: 2008-01-29 20:40:35 +0100 (Tue, 29 Jan 2008) $
   */
  public class BasicAttributeContext implements AttributeContext, Serializable {
  
      /***
       * Name used to store attribute context stack.
       */
      private static final String ATTRIBUTE_CONTEXT_STACK =
          "org.apache.tiles.AttributeContext.STACK";
  
      /***
       * Template attributes.
       */
      private Map<String, Attribute> attributes = null;
  
      /***
       * Constructor.
       */
      public BasicAttributeContext() {
          super();
      }
  
      /***
       * Constructor.
       * Create a context and set specified attributes.
       *
       * @param attributes Attributes to initialize context.
       */
      public BasicAttributeContext(Map<String, Attribute> attributes) {
          if (attributes != null) {
              this.attributes = new HashMap<String, Attribute>(attributes);
          }
      }
  
  
      /***
       * Copy constructor.
       *
       * @param context The constructor to copy.
       */
      public BasicAttributeContext(AttributeContext context) {
          this.attributes = new HashMap<String, Attribute>();
          Iterator<String> names = context.getAttributeNames();
          while (names.hasNext()) {
              String name = names.next();
              attributes.put(name, context.getAttribute(name));
          }
      }
  
      /***
       * Add all attributes to this context.
       * Copies all of the mappings from the specified attribute map to this context.
       * New attribute mappings will replace any mappings that this context had for any of the keys
       * currently in the specified attribute map.
       *
       * @param newAttributes Attributes to add.
       */
      public void addAll(Map<String, Attribute> newAttributes) {
          if (newAttributes == null) {
              return;
          }
  
         if (attributes == null) {
             attributes = new HashMap<String, Attribute>(newAttributes);
             return;
         }
 
         attributes.putAll(newAttributes);
     }
 
     /***
      * Add all missing attributes to this context.
      * Copies all of the mappings from the specified attributes map to this context.
      * New attribute mappings will be added only if they don't already exist in
      * this context.
      *
      * @param defaultAttributes Attributes to add.
      */
     public void addMissing(Map<String, Attribute> defaultAttributes) {
         if (defaultAttributes == null) {
             return;
         }
 
         if (attributes == null) {
             attributes = new HashMap<String, Attribute>(defaultAttributes);
             return;
         }
 
         Set<Map.Entry<String, Attribute>> entries = defaultAttributes.entrySet();
         for (Map.Entry<String, Attribute> entry : entries) {
             if (!attributes.containsKey(entry.getKey())) {
                 attributes.put(entry.getKey(), entry.getValue());
             }
         }
     }
 
     /***
      * Get an attribute from context.
      *
      * @param name Name of the attribute.
      * @return <{Attribute}>
      */
     public Attribute getAttribute(String name) {
         if (attributes == null) {
             return null;
         }
 
         return attributes.get(name);
     }
 
     /***
      * Get names of all attributes.
      *
      * @return <{Attribute}>
      */
     public Iterator<String> getAttributeNames() {
         if (attributes == null) {
             return new ArrayList<String>().iterator();
         }
 
         return attributes.keySet().iterator();
     }
 
     /***
      * Put a new attribute to context.
      *
      * @param name  Name of the attribute.
      * @param value Value of the attribute.
      */
     public void putAttribute(String name, Attribute value) {
         if (attributes == null) {
             attributes = new HashMap<String, Attribute>();
         }
 
         attributes.put(name, value);
     }
 
     /***
      * Get attribute context from request.
      *
      * @param tilesContext current Tiles application context.
      * @return BasicAttributeContext or null if context is not found or an
      *         jspException is present in the request.
      * @deprecated Use {@link TilesContainer#getAttributeContext(Object...)}.
      */
     @Deprecated
     public static AttributeContext getContext(TilesRequestContext tilesContext) {
         Stack<AttributeContext> contextStack = getContextStack(tilesContext);
         if (!contextStack.isEmpty()) {
             return contextStack.peek();
         } else {
             return null;
         }
     }
 
     /***
      * Returns the context stack.
      *
      * @param tilesContext The Tiles context object to use.
      * @return The needed stack of contexts.
      * @deprecated Use {@link TilesContainer#getAttributeContext(Object...)},
      * {@link TilesContainer#startContext(Object...)} or
      * {@link TilesContainer#endContext(Object...)}.
      */
     @Deprecated
     @SuppressWarnings("unchecked")
     public static Stack<AttributeContext> getContextStack(TilesRequestContext tilesContext) {
         Stack<AttributeContext> contextStack =
             (Stack<AttributeContext>) tilesContext.getRequestScope().get(
                 BasicAttributeContext.ATTRIBUTE_CONTEXT_STACK);
         if (contextStack == null) {
             contextStack = new Stack<AttributeContext>();
             tilesContext.getRequestScope().put(BasicAttributeContext.ATTRIBUTE_CONTEXT_STACK,
                     contextStack);
         }
 
         return contextStack;
     }
 
     /***
      * Pushes a context object in the stack.
      *
      * @param context The context to push.
      * @param tilesContext The Tiles context object to use.
      * @deprecated Use {@link TilesContainer#startContext(Object...)}.
      */
     @Deprecated
     public static void pushContext(AttributeContext context,
             TilesRequestContext tilesContext) {
         Stack<AttributeContext> contextStack = getContextStack(tilesContext);
         contextStack.push(context);
     }
 
     /***
      * Pops a context object out of the stack.
      *
      * @param tilesContext The Tiles context object to use.
      * @return The popped context object.
      * @deprecated Use {@link TilesContainer#endContext(Object...)}.
      */
     public static AttributeContext popContext(TilesRequestContext tilesContext) {
         Stack<AttributeContext> contextStack = getContextStack(tilesContext);
         return contextStack.pop();
     }
 
     /*** {@inheritDoc} */
     public void clear() {
         attributes.clear();
     }
 }