/*
    * 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.custom.aliasbean;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.io.IOException;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.myfaces.shared_tomahawk.util._ComponentUtils;
  import org.apache.myfaces.shared_tomahawk.util.RestoreStateUtils;
  import org.apache.myfaces.shared_tomahawk.component.BindingAware;
  
  import javax.faces.component.UIComponent;
  import javax.faces.component.UIComponentBase;
  import javax.faces.context.FacesContext;
  import javax.faces.el.ValueBinding;
  import javax.faces.event.AbortProcessingException;
  import javax.faces.event.FacesEvent;
  
  /**
   * The aliasBean tag allows you to create a temporary name for a real bean.
   * The temporary name exists (is visible) only to the children of the aliasBean.
   * <p>
   * One use of this feature is to pass "parameters" from an including page to an
   * included one. The included page can use any name it desires for beans it needs to
   * reference, and the including page can then use aliasBean to make those names
   * refer to the beans it wishes to "pass" as parameters.
   * </p>
   * <p>
   * Suppose you have a block of components you use often but with different beans. You
   * can create a separate JSP page (or equivalent) containing these beans, where the
   * value-bindings refer to some fictive bean name. Document these names as the required
   * "parameters" for this JSP page. Wherever you wish to use this block you then declare
   * an alias component mapping each of these "parameters" to whatever beans (or literal
   * values) you really want to apply the block to, then use jsp:include (or equivalent)
   * to include the reusable block of components.
   * </p>
   * <p>
   * Note, however, that AliasBean does not work for component bindings; JSF1.1
   * just has no mechanism available to set up the alias during the "restore view"
   * phase while the bindings of its children are being re-established, and then
   * remove the alias after the child bindings are done.
   * </p>
   * <p>
   * As a special case, if this component's direct parent is an AliasBeansScope
   * then the alias (temporary name) is active until the end of the parent
   * component, rather than the end of this component.
   * </p>
   *
   * @JSFComponent
   *   name = "t:aliasBean"
   *   tagClass = "org.apache.myfaces.custom.aliasbean.AliasBeanTag"
   *   tagHandler = "org.apache.myfaces.custom.aliasbean.AliasBeanTagHandler"
   * 
   * @JSFJspProperty 
   *   name = "rendered"
   *   returnType = "boolean" 
   *   tagExcluded = "true"
   *   
   * @JSFJspProperty
   *   name = "binding"
   *   returnType = "java.lang.String"
   *   tagExcluded = "true"
   * 
   * @author Sylvain Vieujot (latest modification by $Author: lu4242 $)
   * @version $Revision: 672986 $ $Date: 2008-06-30 23:13:55 -0500 (Mon, 30 Jun 2008) $
   */
  public class AliasBean extends UIComponentBase implements BindingAware
  {
      private static final Log log = LogFactory.getLog(AliasBean.class);
  
      public static final String COMPONENT_TYPE = "org.apache.myfaces.AliasBean";
      public static final String COMPONENT_FAMILY = "javax.faces.Data";
  
      private Alias alias;
      
      // Indicates whether withinScope has been initialised or not.
      private boolean scopeSearched = false;
     
     // True if this is a direct child of an AliasBeansScope component.
     private boolean withinScope;
 
     private transient FacesContext _context = null;
 
     public AliasBean()
     {
         alias = new Alias(this);
     }
 
     public String getFamily()
     {
         return COMPONENT_FAMILY;
     }
 
     public String getRendererType() {
         return null;
     }
 
     /**
      * Define the "fictive" name which will be visible to the children
      * of this component as an alias to the "real" object specified
      * by the value attribute of this component.
      *
      * @JSFProperty
      * @param aliasBeanExpression
      */
     public void setAlias(String aliasBeanExpression)
     {
         alias.setAliasBeanExpression(aliasBeanExpression);
     }
 
     /**
      * The existing value that the alias can be set to. This can be 
      * a literal string (like "toto") or a reference to an existing 
      * bean (like "#{myBean.member1}").
      * 
      * @JSFProperty
      */
     public String getValue()
     {
         String valueExpression = alias.getValueExpression();
         if (valueExpression != null)
             return valueExpression;
 
         // Normally, this component will have no value, because the setValue method always
         // passes that data on to the alias instead. However it is possible for someone
         // to use f:attribute (or other mechanism?) to set the value instead. So when the
         // alias has no value, look for it there.
         ValueBinding vb = getValueBinding("value");
         return vb != null ? _ComponentUtils.getStringValue(getFacesContext(), vb) : null;
     }
 
     public void setValue(String valueExpression)
     {
         alias.setValueExpression(valueExpression);
     }
 
     public Object saveState(FacesContext context)
     {
         log.debug("saveState");
 
         _context = context;
 
         return new Object[]{super.saveState(context), alias.saveState()};
     }
 
     public void restoreState(FacesContext context, Object state)
     {
         log.debug("restoreState");
 
         _context = context;
 
         Object values[] = (Object[]) state;
         super.restoreState(context, values[0]);
         alias.restoreState(values[1]);
     }
 
     public Object processSaveState(FacesContext context)
     {
         if (context == null)
             throw new NullPointerException("context");
         if (isTransient())
             return null;
 
         makeAlias(context);
 
         Map facetMap = null;
         for (Iterator it = getFacets().entrySet().iterator(); it.hasNext();)
         {
             Map.Entry entry = (Map.Entry) it.next();
             if (facetMap == null)
                 facetMap = new HashMap();
             UIComponent component = (UIComponent) entry.getValue();
             if (!component.isTransient())
             {
                 facetMap.put(entry.getKey(), component.processSaveState(context));
             }
         }
         List childrenList = null;
         if (getChildCount() > 0)
         {
             for (Iterator it = getChildren().iterator(); it.hasNext();)
             {
                 UIComponent child = (UIComponent) it.next();
                 if (!child.isTransient())
                 {
                     if (childrenList == null)
                         childrenList = new ArrayList(getChildCount());
                     childrenList.add(child.processSaveState(context));
                 }
             }
         }
 
         removeAlias(context);
 
         return new Object[]{saveState(context), facetMap, childrenList};
     }
 
     public void processRestoreState(FacesContext context, Object state)
     {
         if (context == null)
             throw new NullPointerException("context");
         Object myState = ((Object[]) state)[0];
 
         restoreState(context, myState);
         makeAlias(context);
 
         Map facetMap = (Map) ((Object[]) state)[1];
         List childrenList = (List) ((Object[]) state)[2];
         for (Iterator it = getFacets().entrySet().iterator(); it.hasNext();)
         {
             Map.Entry entry = (Map.Entry) it.next();
             Object facetState = facetMap.get(entry.getKey());
             if (facetState != null)
             {
                 ((UIComponent) entry.getValue()).processRestoreState(context, facetState);
             }
             else
             {
                 context.getExternalContext().log("No state found to restore facet " + entry.getKey());
             }
         }
         if (getChildCount() > 0)
         {
             int idx = 0;
             for (Iterator it = getChildren().iterator(); it.hasNext();)
             {
                 UIComponent child = (UIComponent) it.next();
                 Object childState = childrenList.get(idx++);
                 if (childState != null)
                 {
                     child.processRestoreState(context, childState);
                 }
                 else
                 {
                     context.getExternalContext().log("No state found to restore child of component " + getId());
                 }
             }
         }
 
         removeAlias(context);
     }
 
     public void processValidators(FacesContext context)
     {
         if (withinScope)
             return;
 
         log.debug("processValidators");
         makeAlias(context);
         super.processValidators(context);
         removeAlias(context);
     }
 
     public void processDecodes(FacesContext context)
     {
         log.debug("processDecodes");
         if (withinScope)
         {
             if (! alias.isActive())
                 makeAlias(context);
 
             super.processDecodes(context);
             return;
         }
 
         makeAlias(context);
         super.processDecodes(context);
         removeAlias(context);
     }
 
     public void processUpdates(FacesContext context)
     {
         if (withinScope)
             return;
 
         log.debug("processUpdates");
         makeAlias(context);
         super.processUpdates(context);
         removeAlias(context);
     }
 
 
   public void encodeBegin(FacesContext context) throws IOException {
     makeAlias(context);
   }
 
 
   public void encodeEnd(FacesContext context) throws IOException {
     removeAlias();
   }
 
   public void queueEvent(FacesEvent event)
     {
         super.queueEvent(new FacesEventWrapper(event, this));
     }
 
     public void broadcast(FacesEvent event) throws AbortProcessingException
     {
         makeAlias();
 
         if (event instanceof FacesEventWrapper)
         {
             FacesEvent originalEvent = ((FacesEventWrapper) event).getWrappedFacesEvent();
             originalEvent.getComponent().broadcast(originalEvent);
         }
         else
         {
             super.broadcast(event);
         }
 
         removeAlias();
     }
 
     void makeAlias(FacesContext context)
     {
         _context = context;
         makeAlias();
     }
 
     private void makeAlias()
     {
         if (! scopeSearched)
         {
             withinScope = getParent() instanceof AliasBeansScope;
             if (withinScope)
             {
                 AliasBeansScope aliasScope = (AliasBeansScope) getParent();
                 aliasScope.addAlias(alias);
             }
             scopeSearched = true;
         }
         alias.make(_context);
     }
 
     void removeAlias(FacesContext context)
     {
         _context = context;
         removeAlias();
     }
 
     private void removeAlias()
     {
         if (! withinScope)
             alias.remove(_context);
     }
 
 
     public void handleBindings()
     {
         makeAlias(getFacesContext());
 
         RestoreStateUtils.recursivelyHandleComponentReferencesAndSetValid(getFacesContext(),this,true);
 
         removeAlias(getFacesContext());
     }
 }