/*
    * 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.config;
  
  import java.io.File;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import java.util.Map;
  
  import javax.faces.context.ExternalContext;
  
  import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFWebConfigParam;
  import org.apache.myfaces.config.element.ManagedBean;
  import org.apache.myfaces.config.element.NavigationCase;
  import org.apache.myfaces.config.element.NavigationRule;
  import org.apache.myfaces.shared.util.ClassUtils;
  
  public class FacesConfigValidator
  {
  
      /**
       * Validate if the managed beans and navigations rules are correct.
       * 
       * <p>For example, it checks if the managed bean classes really exists, or if the 
       * navigation rules points to existing view files.</p>
       */
      @JSFWebConfigParam(since="2.0", defaultValue="false", expectedValues="true, false")
      public static final String VALIDATE_CONTEXT_PARAM = "org.apache.myfaces.VALIDATE";
      
      private FacesConfigValidator(){
          // hidden 
      }
  
      public static List<String> validate(ExternalContext ctx){
          
          RuntimeConfig runtimeConfig = RuntimeConfig.getCurrentInstance(ctx);
          
          Map<String, ManagedBean> managedBeansMap = runtimeConfig.getManagedBeans();
          
          Collection<? extends ManagedBean> managedBeans = null;
          if (managedBeansMap != null)
          {
              managedBeans = managedBeansMap.values();
          }
          
          Collection<? extends NavigationRule> navRules = runtimeConfig.getNavigationRules();
          
          return validate(managedBeans, navRules, ctx);
          
      }
      
      public static List<String> validate(Collection<? extends ManagedBean> managedBeans, 
                                          Collection<? extends NavigationRule> navRules, ExternalContext ctx)
      {
          
          List<String> list = new ArrayList<String>();
          
          if (managedBeans != null)
          {
              validateManagedBeans(managedBeans, list);
          }
          
          if (navRules != null)
          {
              validateNavRules(navRules, list, ctx);
          }
          
          return list;
      }
  
      private static void validateNavRules(Collection<? extends NavigationRule> navRules, List<String> list, ExternalContext ctx)
      {
          for (NavigationRule navRule : navRules)
          {
              validateNavRule(navRule, list, ctx);
          }
      }
      
      private static void validateNavRule(NavigationRule navRule, List<String> list, ExternalContext ctx){
          
         String fromId = navRule.getFromViewId();
         URL filePath;
         try
         {
             filePath = ctx.getResource(fromId);
 
             if(fromId != null && ! "*".equals(fromId) && filePath == null)
             {
                 list.add("File for navigation 'from id' does not exist " + filePath);
             }            
         }
         catch (MalformedURLException e)
         {
             list.add("File for navigation 'from id' does not exist " + fromId);
         }
         
         for (NavigationCase caze : navRule.getNavigationCases())
         {
             try
             {
                 URL toViewPath = ctx.getResource(caze.getToViewId());
                 
                 if(toViewPath == null)
                 {
                     list.add("File for navigation 'to id' does not exist " + toViewPath);
                 }
             }
             catch (MalformedURLException e)
             {
                 list.add("File for navigation 'from id' does not exist " + caze.getToViewId());
             }
         }
     }
     
     private static void validateManagedBeans(Collection<? extends ManagedBean> managedBeans, List<String> list)
     {
         for (ManagedBean managedBean : managedBeans)
         {
             validateManagedBean(managedBean, list);
         }
     }
 
     private static void validateManagedBean(ManagedBean managedBean, List<String> list)
     {
         String className = managedBean.getManagedBeanClassName();
         
         try
         {
             ClassUtils.classForName(className);
         }
         catch (ClassNotFoundException e)
         { 
             String msg = "Could not locate class " 
                 + className + " for managed bean '" + managedBean.getManagedBeanName() + "'";
             
             list.add(msg);
         }
     }
 }