/*

  * Copyright 2007 the original author or authors.

  * 

  * Licensed 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.mockftpserver.core.command;

 import org.mockftpserver.core.session.Session;

 import org.mockftpserver.core.util.Assert;

 import org.mockftpserver.core.util.AssertFailedException;

 import java.util.ArrayList;

 import java.util.Iterator;

 import java.util.List;

 import java.util.ResourceBundle;

 /**

  * Composite CommandHandler that manages an internal list of CommandHandlers to which it delegates.

  * The internal CommandHandlers are maintained in an ordered list. Starting with the first 

  * CommandHandler in the list, each invocation of this composite handler will invoke (delegate to) 

  * the current internal CommandHander. Then it moves on the next CommandHandler in the internal list.  

  * <p>

  * The following example replaces the CWD CommandHandler with a <code>SimpleCompositeCommandHandler</code>. 

  * The first invocation of the CWD command will fail (reply code 500). The seconds will succeed.

  * <pre><code>

  * 

  * StubFtpServer stubFtpServer = new StubFtpServer();

  * 

  * CommandHandler commandHandler1 = new StaticReplyCommandHandler(500);

  * CommandHandler commandHandler2 = new CwdCommandHandler();

  * 

  * SimpleCompositeCommandHandler simpleCompositeCommandHandler = new SimpleCompositeCommandHandler();

  * simpleCompositeCommandHandler.addCommandHandler(commandHandler1);

  * simpleCompositeCommandHandler.addCommandHandler(commandHandler2);

  * 

  * stubFtpServer.setCommandHandler("CWD", simpleCompositeCommandHandler);

  * </code></pre>

  * 

  * @version $Revision: 184 $ - $Date: 2008-12-03 17:52:39 -0500 (Wed, 03 Dec 2008) $

  * 

  * @author Chris Mair

  */

 public final class SimpleCompositeCommandHandler implements CommandHandler, ReplyTextBundleAware {

     private List commandHandlers = new ArrayList();

     private int invocationIndex = 0;

     /**

      * Add a CommandHandler to the internal list of handlers.

      * 

      * @param commandHandler - the CommandHandler

      *      

      * @throws AssertFailedException - if the commandHandler is null      

      */

     public void addCommandHandler(CommandHandler commandHandler) {

         Assert.notNull(commandHandler, "commandHandler");

         commandHandlers.add(commandHandler);

     }

     /**

      * Set the List of CommandHandlers to which to delegate. This replaces any CommandHandlers that

      * have been defined previously.

      * @param commandHandlers - the complete List of CommandHandlers to which invocations are delegated

      */

     public void setCommandHandlers(List commandHandlers) {

         Assert.notNull(commandHandlers, "commandHandlers");

         this.commandHandlers = new ArrayList(commandHandlers);

     }

     /**

      * Return the CommandHandler corresponding to the specified invocation index. In other words, return

      * the CommandHandler instance to which the Nth {@link #handleCommand(Command, Session)} has been or will

      * be delegated (where N=index).

      * @param index - the index of the desired invocation (zero-based).

      * @return the CommandHandler

      * 

      * @throws AssertFailedException - if no CommandHandler is defined for the index or the index is not valid

      */

     public CommandHandler getCommandHandler(int index) {

         Assert.isTrue(index < commandHandlers.size(), "No CommandHandler defined for index " + index);

         Assert.isTrue(index >= 0, "The index cannot be less than zero: " + index);

         return (CommandHandler) commandHandlers.get(index);

     }

     /**

      * @see org.mockftpserver.core.command.CommandHandler#handleCommand(org.mockftpserver.core.command.Command, org.mockftpserver.core.session.Session)

      */

     public void handleCommand(Command command, Session session) throws Exception {

         Assert.notNull(command, "command");

         Assert.notNull(session, "session");

         Assert.isTrue(commandHandlers.size() > invocationIndex, "No CommandHandler defined for invocation #" + invocationIndex);

         CommandHandler commandHandler = (CommandHandler) commandHandlers.get(invocationIndex);

         invocationIndex++;

         commandHandler.handleCommand(command, session);

     }

     /**

      * Returns null. This is a composite, and has no reply text bundle.

      * 

      * @see org.mockftpserver.core.command.ReplyTextBundleAware#getReplyTextBundle()

      */

     public ResourceBundle getReplyTextBundle() {

         return null;

     }

     /**

      * Call <code>setReplyTextBundle()</code> on each of the command handlers within the internal list.

      * 

      * @see org.mockftpserver.core.command.ReplyTextBundleAware#setReplyTextBundle(java.util.ResourceBundle)

      */

     public void setReplyTextBundle(ResourceBundle replyTextBundle) {

         for (Iterator iter = commandHandlers.iterator(); iter.hasNext();) {

             CommandHandler commandHandler = (CommandHandler) iter.next();

             ReplyTextBundleUtil.setReplyTextBundleIfAppropriate(commandHandler, replyTextBundle);

         }

     }

 }