/**

 * 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;

    }

}