/*
  GRANITE DATA SERVICES
  Copyright (C) 2011 GRANITE DATA SERVICES S.A.S.

  This file is part of Granite Data Services.

  Granite Data Services is free software; you can redistribute it and/or modify
  it under the terms of the GNU Library General Public License as published by
  the Free Software Foundation; either version 2 of the License, or (at your
  option) any later version.

  Granite Data Services is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
  for more details.

  You should have received a copy of the GNU Library General Public License
  along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

package org.granite.gravity.gae;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.granite.gravity.AsyncHttpContext;
import org.granite.gravity.AsyncPublishedMessage;
import org.granite.gravity.Channel;
import org.granite.gravity.MessagePublishingException;
import org.granite.gravity.MessageReceivingException;
import org.granite.gravity.Subscription;
import org.granite.logging.Logger;

import com.google.appengine.api.memcache.Expiration;
import com.google.appengine.api.memcache.MemcacheService;
import com.google.appengine.api.memcache.MemcacheServiceFactory;

import flex.messaging.messages.AsyncMessage;
import flex.messaging.messages.Message;

/**
 * @author William DRAI
 */
public class GAEChannel implements Channel, Serializable {

        private static final long serialVersionUID = 5129029435795219401L;
        
        private static final Logger log = Logger.getLogger(GAEChannel.class);
    
    static final String MSG_COUNT_PREFIX = "org.granite.gravity.channel.msgCount.";
    static final String MSG_PREFIX = "org.granite.gravity.channel.msg.";
    
    private static MemcacheService gaeCache = MemcacheServiceFactory.getMemcacheService();

    protected final String id;
    protected final String clientType;
    protected final GAEGravity gravity;
    protected final GAEChannelFactory factory;

    private final Map<String, Subscription> subscriptions = new HashMap<String, Subscription>();
    private final long expiration;


    GAEChannel(GAEGravity gravity, String id, GAEChannelFactory factory, String clientType) {
        if (id == null)
                throw new NullPointerException("id cannot be null");
        
        this.id = id;
        this.clientType = clientType;
        this.factory = factory;
        this.gravity = gravity;
        this.expiration = gravity.getGravityConfig().getChannelIdleTimeoutMillis();
    }

        public String getId() {
                return id;
        }
        
        public String getClientType() {
                return clientType;
        }
        
        public GAEChannelFactory getFactory() {
                return factory;
        }
        
        public GAEGravity getGravity() {
                return gravity;
        }
    
    private Long msgCount() {
        return (Long)gaeCache.get(MSG_COUNT_PREFIX + id);
    }
    
    
    public void close() {
    }
    
        public void destroy() {
        Long msgCount = msgCount();
        if (msgCount != null) {
                List<Object> list = new ArrayList<Object>();
                list.add(MSG_COUNT_PREFIX + id);
                for (long i = 0; i < msgCount; i++)
                        list.add(MSG_PREFIX + id + "#" + i);
                gaeCache.deleteAll(list);
        }
        this.subscriptions.clear();
    }

    
        public void publish(AsyncPublishedMessage message) throws MessagePublishingException {
                message.publish(this);
    }

        public void receive(AsyncMessage message) throws MessageReceivingException {
        log.debug("Publish message to channel %s", id);
//        System.err.println("Publish messages to channel " + id);
        synchronized (this) {
                Long msgCount = msgCount();
                gaeCache.put(MSG_PREFIX + id + "#" + msgCount, message, Expiration.byDeltaMillis((int)expiration));
                gaeCache.increment(MSG_COUNT_PREFIX + id, 1);
        }
        }
    
    public List<Message> takeMessages() {
        log.debug("Try to take messages for channel %s", id);
//        System.err.println("Try to take messages for channel " + id);
        synchronized (this) {
                Long msgCount = msgCount();
                if (msgCount == null || msgCount == 0)
                return null;

            log.debug("Taking %s messages", msgCount);
//            System.err.println("Taking " + msgCount + " messages");
                List<Object> list = new ArrayList<Object>();
                for (int i = 0; i < msgCount; i++)
                        list.add(MSG_PREFIX + id + "#" + i);
                Map<Object, Object> msgs = gaeCache.getAll(list);
            List<Message> messages = new ArrayList<Message>();
                for (int i = 0; i < msgCount; i++) {
                        Message msg = (Message)msgs.get(list.get(i));
                        if (msg != null)
                                messages.add(msg);
                }
                
                gaeCache.deleteAll(list);
                gaeCache.put(MSG_COUNT_PREFIX + id, 0L, Expiration.byDeltaMillis((int)expiration));
                
            return messages.isEmpty() ? null : messages;
        }
    }


    public Subscription addSubscription(String destination, String subTopicId, String subscriptionId, boolean noLocal) {
        Subscription subscription = new Subscription(this, destination, subTopicId, subscriptionId, noLocal);
        subscriptions.put(subscriptionId, subscription);
        return subscription;
    }

    public Collection<Subscription> getSubscriptions() {
        return subscriptions.values();
    }
    
    public Subscription removeSubscription(String subscriptionId) {
        return subscriptions.remove(subscriptionId);
    }

    
    @Override
    public boolean equals(Object obj) {
        return (obj instanceof GAEChannel && id.equals(((GAEChannel)obj).id));
    }

    @Override
    public int hashCode() {
        return id.hashCode();
    }

        @Override
    public String toString() {
        return getClass().getName() + " {id=" + id + ", subscriptions=" + subscriptions + "}";
    }


        public boolean hasPublishedMessage() {
                return false;
        }

        public boolean runPublish() {
                return false;
        }

        public boolean hasReceivedMessage() {
                return false;
        }

        public boolean runReceive() {
                return false;
        }

        public boolean runReceived(AsyncHttpContext asyncHttpContext) {
                return false;
        }

        public void run() {
        }
}