/*
    * 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.application;
  
  import java.io.IOException;
  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.Locale;
  import java.util.Map;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  import java.util.stream.Stream;
  
  import javax.faces.FacesException;
  import javax.faces.FactoryFinder;
  import javax.faces.application.Application;
  import javax.faces.application.StateManager;
  import javax.faces.application.ViewHandler;
  import javax.faces.application.ViewVisitOption;
  import javax.faces.component.UIViewParameter;
  import javax.faces.component.UIViewRoot;
  import javax.faces.context.ExternalContext;
  import javax.faces.context.FacesContext;
  import javax.faces.render.RenderKitFactory;
  import javax.faces.render.ResponseStateManager;
  import javax.faces.view.ViewDeclarationLanguage;
  import javax.faces.view.ViewDeclarationLanguageFactory;
  import javax.faces.view.ViewMetadata;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.myfaces.application.viewstate.StateCacheUtils;
  import org.apache.myfaces.shared.application.DefaultViewHandlerSupport;
  import org.apache.myfaces.shared.application.InvalidViewIdException;
  import org.apache.myfaces.shared.application.ViewHandlerSupport;
  import org.apache.myfaces.view.facelets.StateWriter;
  
  /**
   * JSF 2.0 ViewHandler implementation 
   *
   * @since 2.0
   */
  public class ViewHandlerImpl extends ViewHandler
  {
      private static final Logger log = Logger.getLogger(ViewHandlerImpl.class.getName());
      
      public static final String FORM_STATE_MARKER = "<!--@@JSF_FORM_STATE_MARKER@@-->";
      private ViewHandlerSupport _viewHandlerSupport;
      private ViewDeclarationLanguageFactory _vdlFactory;
      
      private Set<String> _protectedViewsSet;
      private Set<String> _unmodifiableProtectedViewsSet;
      
      /**
       * Gets the current ViewHandler via FacesContext.getApplication().getViewHandler().
       * We have to use this method to invoke any other specified ViewHandler-method
       * in the code, because direct access (this.method()) will cause problems if
       * the ViewHandler is wrapped.
       * @param facesContext
       * @return
       */
      public static ViewHandler getViewHandler(FacesContext facesContext)
      {
          return facesContext.getApplication().getViewHandler();
      }
  
      public ViewHandlerImpl()
      {
          _protectedViewsSet = Collections.newSetFromMap(new ConcurrentHashMap<String,Boolean>());
          _unmodifiableProtectedViewsSet = Collections.unmodifiableSet(_protectedViewsSet);
          _vdlFactory = (ViewDeclarationLanguageFactory)
                  FactoryFinder.getFactory(FactoryFinder.VIEW_DECLARATION_LANGUAGE_FACTORY);
          if (log.isLoggable(Level.FINEST))
          {
              log.finest("New ViewHandler instance created");
          }
      }
  
     @Override
     public String deriveViewId(FacesContext context, String input)
     {
         if(input != null)
         {
             try
             {
                 return getViewHandlerSupport(context).calculateAndCheckViewId(context, input);
             }
             catch (InvalidViewIdException e)
             {
                 sendSourceNotFound(context, e.getMessage());
             }
         }
         return input;   // If the argument input is null, return null.
     }
     
     @Override
     public String deriveLogicalViewId(FacesContext context, String rawViewId)
     {
         if(rawViewId != null)
         {
             try
             {
                 return getViewHandlerSupport(context).calculateViewId(context, rawViewId);
             }
             catch (InvalidViewIdException e)
             {
                 sendSourceNotFound(context, e.getMessage());
             }
         }
         return rawViewId;   // If the argument input is null, return null.
     }
 
     @Override
     public String getBookmarkableURL(FacesContext context, String viewId,
             Map<String, List<String>> parameters, boolean includeViewParams)
     {
         Map<String, List<String>> viewParameters;
         if (includeViewParams)
         {
             viewParameters = getViewParameterList(context, viewId, parameters);
         }
         else
         {
             viewParameters = parameters;
         }
         
         // note that we cannot use this.getActionURL(), because this will
         // cause problems if the ViewHandler is wrapped
         String actionEncodedViewId = getViewHandler(context).getActionURL(context, viewId);
         
         ExternalContext externalContext = context.getExternalContext();
         String bookmarkEncodedURL = externalContext.encodeBookmarkableURL(actionEncodedViewId, viewParameters);
         return externalContext.encodeActionURL(bookmarkEncodedURL);
     }
 
     @Override
     public String getRedirectURL(FacesContext context, String viewId,
             Map<String, List<String>> parameters, boolean includeViewParams)
     {
         Map<String, List<String>> viewParameters;
         if (includeViewParams)
         {
             viewParameters = getViewParameterList(context, viewId, parameters);
         }
         else
         {
             viewParameters = parameters;
         }
         
         // note that we cannot use this.getActionURL(), because this will
         // cause problems if the ViewHandler is wrapped
         String actionEncodedViewId = getViewHandler(context).getActionURL(context, viewId);
         
         ExternalContext externalContext = context.getExternalContext();
         String redirectEncodedURL = externalContext.encodeRedirectURL(actionEncodedViewId, viewParameters);
         return externalContext.encodeActionURL(redirectEncodedURL);
     }
 
     @Override
     public ViewDeclarationLanguage getViewDeclarationLanguage(
             FacesContext context, String viewId)
     {
         // return a suitable ViewDeclarationLanguage implementation for the given viewId
         return _vdlFactory.getViewDeclarationLanguage(viewId);
     }
 
     @Override
     public void initView(FacesContext context) throws FacesException
     {
         if(context.getExternalContext().getRequestCharacterEncoding() == null)
         {
             super.initView(context);    
         }
     }
 
     /**
      * Get the locales specified as acceptable by the original request, compare them to the
      * locales supported by this Application and return the best match.
      */
     @Override
     public Locale calculateLocale(FacesContext facesContext)
     {
         Application application = facesContext.getApplication();
         for (Iterator<Locale> requestLocales = facesContext.getExternalContext().getRequestLocales(); requestLocales
                 .hasNext();)
         {
             Locale requestLocale = requestLocales.next();
             for (Iterator<Locale> supportedLocales = application.getSupportedLocales(); supportedLocales.hasNext();)
             {
                 Locale supportedLocale = supportedLocales.next();
                 // higher priority to a language match over an exact match
                 // that occurs further down (see JSTL Reference 1.0 8.3.1)
                 if (requestLocale.getLanguage().equals(supportedLocale.getLanguage())
                         && (supportedLocale.getCountry() == null || supportedLocale.getCountry().length() == 0))
                 {
                     return supportedLocale;
                 }
                 else if (supportedLocale.equals(requestLocale))
                 {
                     return supportedLocale;
                 }
             }
         }
 
         Locale defaultLocale = application.getDefaultLocale();
         return defaultLocale != null ? defaultLocale : Locale.getDefault();
     }
 
     @Override
     public String calculateRenderKitId(FacesContext facesContext)
     {
         Object renderKitId = facesContext.getExternalContext().getRequestMap().get(
                 ResponseStateManager.RENDER_KIT_ID_PARAM);
         if (renderKitId == null)
         {
             renderKitId = facesContext.getApplication().getDefaultRenderKitId();
         }
         if (renderKitId == null)
         {
             renderKitId = RenderKitFactory.HTML_BASIC_RENDER_KIT;
         }
         return renderKitId.toString();
     }
     
     @Override
     public UIViewRoot createView(FacesContext context, String viewId)
     {
        checkNull(context, "facesContext");
        String calculatedViewId = getViewHandlerSupport(context).calculateViewId(context, viewId);
        
        // we cannot use this.getVDL() directly (see getViewHandler())
        //return getViewHandler(context)
        //        .getViewDeclarationLanguage(context, calculatedViewId)
        //            .createView(context, calculatedViewId);
        // -= Leonardo Uribe =- Temporally reverted by TCK issues.
        ViewDeclarationLanguage vdl = getViewDeclarationLanguage(context,calculatedViewId);
        if (vdl == null)
        {
            // If there is no VDL that can handle the view, throw 404 response.
            sendSourceNotFound(context, viewId);
            return null;
        }
        return vdl.createView(context,calculatedViewId);
     }
 
     @Override
     public String getActionURL(FacesContext context, String viewId)
     {
         checkNull(context, "facesContext");
         checkNull(viewId, "viewId");
         return getViewHandlerSupport(context).calculateActionURL(context, viewId);
     }
 
     @Override
     public String getResourceURL(FacesContext facesContext, String path)
     {
         checkNull(facesContext, "facesContext");
         checkNull(path, "path");
         if (path.length() > 0 && path.charAt(0) == '/')
         {
             String contextPath = facesContext.getExternalContext().getRequestContextPath();
             if (contextPath == null)
             {
                 return path;
             }
             else if (contextPath.length() == 1 && contextPath.charAt(0) == '/')
             {
                 // If the context path is root, it is not necessary to append it, otherwise
                 // and extra '/' will be set.
                 return path;
             }
             else
             {
                 return  contextPath + path;
             }
         }
         return path;
 
     }
 
     @Override
     public void renderView(FacesContext context, UIViewRoot viewToRender)
             throws IOException, FacesException
     {
 
         checkNull(context, "context");
         checkNull(viewToRender, "viewToRender");
 
         // we cannot use this.getVDL() directly (see getViewHandler())
         //String viewId = viewToRender.getViewId();
         //getViewHandler(context).getViewDeclarationLanguage(context, viewId)
         //        .renderView(context, viewToRender);
         // -= Leonardo Uribe =- Temporally reverted by TCK issues.
         getViewDeclarationLanguage(context,viewToRender.getViewId()).renderView(context, viewToRender);
     }
 
     @Override
     public UIViewRoot restoreView(FacesContext context, String viewId)
     {
         checkNull(context, "context");
     
         String calculatedViewId = getViewHandlerSupport(context).calculateViewId(context, viewId);
         
         // we cannot use this.getVDL() directly (see getViewHandler())
         //return getViewHandler(context)
         //        .getViewDeclarationLanguage(context,calculatedViewId)
         //            .restoreView(context, calculatedViewId);
         // -= Leonardo Uribe =- Temporally reverted by TCK issues.
         ViewDeclarationLanguage vdl = getViewDeclarationLanguage(context,calculatedViewId);
         if (vdl == null)
         {
             // If there is no VDL that can handle the view, throw 404 response.
             sendSourceNotFound(context, viewId);
             return null;
             
         }
         return vdl.restoreView(context, calculatedViewId); 
     }
     
     @Override
     public void writeState(FacesContext context) throws IOException
     {
         checkNull(context, "context");
 
         if(context.getPartialViewContext().isAjaxRequest())
         {
             return;
         }
 
         ResponseStateManager responseStateManager = context.getRenderKit().getResponseStateManager();
         
         setWritingState(context, responseStateManager);
 
         StateManager stateManager = context.getApplication().getStateManager();
         
         // By the spec, it is necessary to use a writer to write FORM_STATE_MARKER, 
         // after the view is rendered, to preserve changes done on the component tree
         // on rendering time. But if server side state saving is used, this is not 
         // really necessary, because a token could be used and after the view is
         // rendered, a simple call to StateManager.saveState() could do the trick.
         // The code below check if we are using MyFacesResponseStateManager and if
         // that so, check if the current one support the trick.
         if (StateCacheUtils.isMyFacesResponseStateManager(responseStateManager))
         {
             if (StateCacheUtils.getMyFacesResponseStateManager(responseStateManager).
                     isWriteStateAfterRenderViewRequired(context))
             {
                 // Only write state marker if javascript view state is disabled
                 context.getResponseWriter().write(FORM_STATE_MARKER);
             }
             else
             {
                 stateManager.writeState(context, new Object[2]);
             }
         }
         else
         {
             // Only write state marker if javascript view state is disabled
             context.getResponseWriter().write(FORM_STATE_MARKER);
         }
     }
 
     @Override
     public void addProtectedView(String urlPattern)
     {
         _protectedViewsSet.add(urlPattern);
     }
 
     @Override
     public boolean removeProtectedView(String urlPattern)
     {
         return _protectedViewsSet.remove(urlPattern);
     }
 
     @Override
     public Set<String> getProtectedViewsUnmodifiable()
     {
         return _unmodifiableProtectedViewsSet;
     }
     
     private void setWritingState(FacesContext context, ResponseStateManager rsm)
     {
         // Facelets specific hack:
         // Tell the StateWriter that we're about to write state
         StateWriter stateWriter = StateWriter.getCurrentInstance(context);
         if (stateWriter != null)
         {
             // Write the STATE_KEY out. Unfortunately, this will
             // be wasteful for pure server-side state managers where nothing
             // is actually written into the output, but this cannot
             // programatically be discovered
             // -= Leonardo Uribe =- On MyFacesResponseStateManager was added
             // some methods to discover it programatically.
             if (StateCacheUtils.isMyFacesResponseStateManager(rsm))
             {
                 if (StateCacheUtils.getMyFacesResponseStateManager(rsm).isWriteStateAfterRenderViewRequired(context))
                 {
                     stateWriter.writingState();
                 }
                 else
                 {
                     stateWriter.writingStateWithoutWrapper();
                 }
             }
             else
             {
                 stateWriter.writingState();
             }
             
             
         }
         //else
         //{
             //we're in a JSP, let the JSPStatemanager know that we need to actually write the state
         //}        
     }
     
     private Map<String, List<String>> getViewParameterList(FacesContext context,
             String viewId, Map<String, List<String>> parametersFromArg)
     {
         UIViewRoot viewRoot = context.getViewRoot();
         String currentViewId = viewRoot.getViewId();
         Collection<UIViewParameter> toViewParams = null;
         Collection<UIViewParameter> currentViewParams = ViewMetadata.getViewParameters(viewRoot);
 
         if (currentViewId.equals(viewId))
         {
             toViewParams = currentViewParams;
         }
         else
         {
             String calculatedViewId = getViewHandlerSupport(context).calculateViewId(context, viewId);  
             // we cannot use this.getVDL() directly (see getViewHandler())
             //ViewDeclarationLanguage vdl = getViewHandler(context).
             //        getViewDeclarationLanguage(context, calculatedViewId);
             // -= Leonardo Uribe =- Temporally reverted by TCK issues.
             ViewDeclarationLanguage vdl = getViewDeclarationLanguage(context,calculatedViewId);
             ViewMetadata viewMetadata = vdl.getViewMetadata(context, viewId);
             // getViewMetadata() returns null on JSP
             if (viewMetadata != null)
             {
                 UIViewRoot viewFromMetaData = viewMetadata.createMetadataView(context);
                 toViewParams = ViewMetadata.getViewParameters(viewFromMetaData);
             }
         }
 
         if (toViewParams == null || toViewParams.isEmpty())
         {
             return parametersFromArg;
         }
         
         // we need to use a custom Map to add the view parameters,
         // otherwise the current value of the view parameter will be added to
         // the navigation case as a static (!!!) parameter, thus the value
         // won't be updated on any following request
         // (Note that parametersFromArg is the Map from the NavigationCase)
         // Also note that we don't have to copy the Lists, because they won't be changed
         Map<String, List<String>> parameters = new HashMap<String, List<String>>();
         parameters.putAll(parametersFromArg);
 
         for (UIViewParameter viewParameter : toViewParams)
         {
             if (!parameters.containsKey(viewParameter.getName()))
             {
                 String parameterValue = viewParameter.getStringValueFromModel(context);
                 if (parameterValue == null)
                 {
                     if(currentViewId.equals(viewId))
                     {
                         parameterValue = viewParameter.getStringValue(context);
                     }
                     else
                     {
                         if (viewParameter.getName() != null)
                         {
                             for (UIViewParameter curParam : currentViewParams)
                             {
                                 if (viewParameter.getName().equals(curParam.getName())) 
                                 {
                                     parameterValue = curParam.getStringValue(context);
                                     break;
                                 }
                             }
                         }
                     }
                 }
 
                 if (parameterValue != null)
                 {
                     // since we have checked !parameters.containsKey(viewParameter.getName())
                     // here already, the parameters Map will never contain a List under the
                     // key viewParameter.getName(), thus we do not have to check it here (again).
                     List<String> parameterValueList = new ArrayList<String>(1);
                     parameterValueList.add(parameterValue);
                     parameters.put(viewParameter.getName(), parameterValueList);
                 }
             }
         }        
         return parameters;
     }
     
     private void checkNull(final Object o, final String param)
     {
         if (o == null)
         {
             throw new NullPointerException(param + " can not be null.");
         }
     }
     
     private void sendSourceNotFound(FacesContext context, String message)
     {
         HttpServletResponse response = (HttpServletResponse) context.getExternalContext().getResponse();
         try
         {
             context.responseComplete();
             response.sendError(HttpServletResponse.SC_NOT_FOUND, message);
         }
         catch (IOException ioe)
         {
             throw new FacesException(ioe);
         }
     }
     
     public void setViewHandlerSupport(ViewHandlerSupport viewHandlerSupport)
     {
         _viewHandlerSupport = viewHandlerSupport;
     }    
     
     protected ViewHandlerSupport getViewHandlerSupport()
     {
         return getViewHandlerSupport(FacesContext.getCurrentInstance());
     }
 
     protected ViewHandlerSupport getViewHandlerSupport(FacesContext context)
     {
         if (_viewHandlerSupport == null)
         {
             _viewHandlerSupport = new DefaultViewHandlerSupport(context);
         }
         return _viewHandlerSupport;
     }
 
     @Override
     public Stream<String> getViews(FacesContext facesContext, String path, int maxDepth, ViewVisitOption... options)
     {
         Stream concatenatedStream = null;
         for (ViewDeclarationLanguage vdl : _vdlFactory.getAllViewDeclarationLanguages())
         {
             Stream stream = vdl.getViews(facesContext, path, maxDepth, options);
             if (concatenatedStream == null)
             {
                 concatenatedStream = stream;
             }
             else
             {
                 concatenatedStream = Stream.concat(concatenatedStream, stream);
             }
         }
         return concatenatedStream == null ? Stream.empty() : concatenatedStream;
     }
     
     @Override
     public String getWebsocketURL(FacesContext context, String channelAndToken)
     {
         String url = context.getExternalContext().getRequestContextPath() + 
                 "/javax.faces.push/"+channelAndToken;
         return url;
     }
     
 }