/**

  * The MIT License (MIT)

  *

  * Copyright (C) 2013 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  *

  * Permission is hereby granted, free of charge, to any person obtaining a copy

  * of this software and associated documentation files (the "Software"), to deal

  * in the Software without restriction, including without limitation the rights

  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

  * copies of the Software, and to permit persons to whom the Software is

  * furnished to do so, subject to the following conditions:

  *

  * The above copyright notice and this permission notice shall be included in

  * all copies or substantial portions of the Software.

  *

  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

  * THE SOFTWARE.

  */

 package org.apidesign.demo.chat.server;

 import java.util.ArrayList;

 import java.util.IdentityHashMap;

 import java.util.List;

 import java.util.Map;

 import java.util.logging.Logger;

 import javax.inject.Singleton;

 import javax.ws.rs.Consumes;

 import javax.ws.rs.DefaultValue;

 import javax.ws.rs.GET;

 import javax.ws.rs.POST;

 import javax.ws.rs.Path;

 import javax.ws.rs.Produces;

 import javax.ws.rs.QueryParam;

 import javax.ws.rs.container.AsyncResponse;

 import javax.ws.rs.container.Suspended;

 import javax.ws.rs.core.MediaType;

 import org.apidesign.demo.chat.shared.Message;

 import org.apidesign.demo.chat.shared.Query;

 /** Server side of the chat application.*/

 @Path("/chat/") @Singleton

 public final class ChatServerResource {

     private static final Logger LOG = Logger.getLogger(ChatServerResource.class.getName());

     private static final long started = System.currentTimeMillis() - 10;

     private List<Message> msgs = new ArrayList<>();

     {

         Message welcome = new Message();

         welcome.setUser("system");

         welcome.setComment("Welcome and enjoy!");

         welcome.setSince(10);

         msgs.add(welcome);

     }

     private final Map<AsyncResponse, Long> awaiting = new IdentityHashMap<>();

     @Produces(MediaType.APPLICATION_JSON)

     @GET public synchronized void getResources(

         @QueryParam("since") @DefaultValue("0") long since,

         @Suspended AsyncResponse ar

     ) {

         Query q = new Query();

         for (Message m : msgs) {

             if (m.getSince()>= since) {

                 q.getMessages().add(m);

             }

         }

         if (!q.getMessages().isEmpty()) {

             ar.resume(q);

         } else {

             awaiting.put(ar, since);

         }

     }

     private void handleAwaiting(long newest) {

         assert Thread.holdsLock(this);

         AGAIN: for (;;) {

             for (Map.Entry<AsyncResponse, Long> entry : awaiting.entrySet()) {

                 AsyncResponse ar = entry.getKey();

                 Long since = entry.getValue();

                 if (since <= newest) {

                     awaiting.remove(ar);

                     getResources(since, ar);

                     continue AGAIN;

                 }

             }

             return;

         }

     }

     @POST @Consumes(value = MediaType.APPLICATION_JSON)

     public synchronized Message publish(Message msg) {

         msg.setSince(System.currentTimeMillis() - started);

         msgs.add(msg);

         handleAwaiting(msg.getSince());

         return msg;

     }

 }