/*

  * 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.mc.test.core.mock;

 import java.util.regex.Pattern;

 import javax.faces.application.ViewHandler;

 import javax.faces.context.ExternalContext;

 import javax.faces.context.FacesContext;

 import javax.faces.view.ViewDeclarationLanguage;

 import org.apache.myfaces.view.ViewDeclarationLanguageStrategy;

 /**

  * @author Leonardo Uribe 

  * @since 2.0

  */

 public class MockMyFacesFaceletViewDeclarationLanguageStrategy implements ViewDeclarationLanguageStrategy

 {

     private Pattern _acceptPatterns;

     private String _extension;

     private ViewDeclarationLanguage _language;

     public MockMyFacesFaceletViewDeclarationLanguageStrategy()

     {

         FacesContext context = FacesContext.getCurrentInstance();

         ExternalContext eContext = context.getExternalContext();

         _acceptPatterns = loadAcceptPattern(eContext);

         _extension = loadFaceletExtension(eContext);

         _language = new MockMyFacesFaceletViewDeclarationLanguage(context, this);

     }

     /**

      * {@inheritDoc}

      */

     public ViewDeclarationLanguage getViewDeclarationLanguage()

     {

         return _language;

     }

     /**

      * {@inheritDoc}

      */

     public boolean handles(String viewId)

     {

         if (viewId == null)

         {

             return false;

         }

         // Check extension first as it's faster than mappings

         if (viewId.endsWith(_extension))

         {

             // If the extension matches, it's a Facelet viewId.

             return true;

         }

         // Otherwise, try to match the view identifier with the facelet mappings

         return _acceptPatterns != null && _acceptPatterns.matcher(viewId).matches();

     }

     /**

      * Load and compile a regular expression pattern built from the Facelet view mapping parameters.

      * 

      * @param context

      *            the application's external context

      * 

      * @return the compiled regular expression

      */

     private Pattern loadAcceptPattern(ExternalContext context)

     {

         assert context != null;

         String mappings = context.getInitParameter(ViewHandler.FACELETS_VIEW_MAPPINGS_PARAM_NAME);

         if(mappings == null)    //consider alias facelets.VIEW_MAPPINGS

         {

             mappings = context.getInitParameter("facelets.VIEW_MAPPINGS");

         }

         if (mappings == null)

         {

             return null;

         }

         // Make sure the mappings contain something

         mappings = mappings.trim();

         if (mappings.length() == 0)

         {

             return null;

         }

         return Pattern.compile(toRegex(mappings));

     }

     private String loadFaceletExtension(ExternalContext context)

     {

         assert context != null;

         String suffix = context.getInitParameter(ViewHandler.FACELETS_SUFFIX_PARAM_NAME);

         if (suffix == null)

         {

             suffix = ViewHandler.DEFAULT_FACELETS_SUFFIX;

         }

         else

         {

             suffix = suffix.trim();

             if (suffix.length() == 0)

             {

                 suffix = ViewHandler.DEFAULT_FACELETS_SUFFIX;

             }

         }

         return suffix;

     }

     /**

      * Convert the specified mapping string to an equivalent regular expression.

      * 

      * @param mappings

      *            le mapping string

      * 

      * @return an uncompiled regular expression representing the mappings

      */

     private String toRegex(String mappings)

     {

         assert mappings != null;

         // Get rid of spaces

         mappings = mappings.replaceAll("\\s", "");

         // Escape '.'

         mappings = mappings.replaceAll("\\.", "\\\\.");

         // Change '*' to '.*' to represent any match

         mappings = mappings.replaceAll("\\*", ".*");

         // Split the mappings by changing ';' to '|'

         mappings = mappings.replaceAll(";", "|");

         return mappings;

     }

 }