/*

  * This software is licensed under the Apache License, Version 2.0

  * (the "License") agreement; 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 net.admin4j.ui.filters;

 import java.io.IOException;

 import java.util.List;

 import java.util.Map;

 import java.util.Stack;

 import java.util.concurrent.ConcurrentHashMap;

 import javax.servlet.Filter;

 import javax.servlet.FilterChain;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 import net.admin4j.deps.commons.lang3.StringUtils;

 import net.admin4j.deps.commons.lang3.Validate;

 import net.admin4j.util.Admin4jRuntimeException;

 /**

  * Standard filter chain that implements Admin4J filters with a standard configuration 

  * usable by most.

  * @author D. Ashmore

  *

  */

 public class Admin4JStandardFilterChain implements FilterChain {

     private static Map<String, Filter> filterMap = new ConcurrentHashMap<String, Filter>();

     private static ThreadLocal<Stack<Filter>> localFilterStack = new ThreadLocal<Stack<Filter>>();

     private static Logger logger = LoggerFactory.getLogger(Admin4JStandardFilterChain.class);

     private FilterChain delegateChain;

     public Admin4JStandardFilterChain(List<String> filterKey, FilterChain delegateChain) {

         Validate.notNull(filterKey, "Null filterKey not allowed.");

         Validate.notNull(delegateChain, "Null filterKey not allowed.");

         this.delegateChain = delegateChain;

         Stack<Filter> localStack = new Stack<Filter>();

         Filter localFilter;

         for (int i = filterKey.size() - 1; i>=0; i--) {

             if ( !StringUtils.isEmpty(filterKey.get(i))) {

                 localFilter = filterMap.get(filterKey.get(i));

                 if (localFilter == null) {

                     throw new Admin4jRuntimeException("Filter not recognized")

                         .addContextValue("filterKey", filterKey.get(i));

                 }

                 localStack.push(localFilter);

             }

         }

         localFilterStack.set(localStack);

     }

     public void doFilter(ServletRequest request, ServletResponse response)

             throws IOException, ServletException {

         Filter localFilter = null;

         if (localFilterStack.get().size() > 0) {

             localFilter = localFilterStack.get().pop();

         }

         if (localFilter != null) {

             localFilter.doFilter(request, response, this);

         }

         else this.delegateChain.doFilter(request, response);

     }

     public static void registerFilter(Filter filter) {

         registerFilter(filter, false);

     }

     public static void registerFilter(Filter filter, boolean avoidDuplicateRegistration) {

         Validate.notNull(filter, "Null filter not allowed.");

         synchronized(filterMap) {

             if (avoidDuplicateRegistration && !filterMap.containsKey(filter.getClass().getName())) {                

                 filterMap.put(filter.getClass().getName(), filter);

                 logger.info("Admin4J Filter registered: {}", filter.getClass().getName());

             }

             else if ( !avoidDuplicateRegistration) {

                 filterMap.put(filter.getClass().getName(), filter);

                 logger.info("Admin4J Filter registered: {}", filter.getClass().getName());

             }

         }

     }

     public static boolean isRegistered(String filterClassName) {

         Validate.notEmpty(filterClassName, "Null or blank filterClassName not allowed.");

         return filterMap.containsKey(filterClassName);

     }

     /**

      * This only exists to support unit testing.

      */

     protected static void clearFilterMap() {

         filterMap.clear();

     }

     /**

      * This only exists to support unit testing

      * @param filterClassName

      * @return

      */

     protected static Filter getRegisteredFilter(String filterClassName) {

         return filterMap.get(filterClassName);

     }

 }