/*
  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.clustering;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import javax.servlet.http.HttpSession;

import flex.messaging.messages.AsyncMessage;
import flex.messaging.messages.CommandMessage;

/**
 * @author Franck WOLFF
 */
public class SessionDistributedData implements DistributedData {

        private static final String KEY_PREFIX = "__GDD__";
        private static final String CREDENTIALS_KEY = KEY_PREFIX + "CREDENTIALS";
        private static final String CREDENTIALS_CHARSET_KEY = KEY_PREFIX + "CREDENTIALS_CHARSET";
        private static final String CHANNELID_KEY_PREFIX = KEY_PREFIX + "CHANNELID.";
        private static final String SUBSCRIPTION_KEY_PREFIX = KEY_PREFIX + "SUBSCRIPTION.";
        private static final String DESTINATION_CLIENTID_KEY_PREFIX = "org.granite.gravity.channel.clientId.";
        private static final String DESTINATION_SUBSCRIPTIONID_KEY_PREFIX = "org.granite.gravity.channel.subscriptionId.";
        private static final String DESTINATION_SELECTOR_KEY_PREFIX = KEY_PREFIX + "org.granite.gravity.selector.";
        private static final String DESTINATION_DATA_SELECTORS_KEY_PREFIX = KEY_PREFIX + "org.granite.gravity.dataSelectors.";
        
        private final HttpSession session;

        public SessionDistributedData(HttpSession session) {
                if (session == null)
                        throw new NullPointerException("HTTP session cannot be null");
                this.session = session;
        }
        
        public Object getCredentials() {
                return session.getAttribute(CREDENTIALS_KEY);
        }

        public boolean hasCredentials() {
                return (getCredentials() != null);
        }

        public void setCredentials(Object credentials) {
                if (credentials != null)
                        session.setAttribute(CREDENTIALS_KEY, credentials);
                else
                        removeCredentials();
        }

        public void removeCredentials() {
                session.removeAttribute(CREDENTIALS_KEY);
        }

        public String getCredentialsCharset() {
                return (String)session.getAttribute(CREDENTIALS_CHARSET_KEY);
        }

        public boolean hasCredentialsCharset() {
                return (getCredentialsCharset() != null);
        }

        public void setCredentialsCharset(String credentialsCharset) {
                if (credentialsCharset != null)
                        session.setAttribute(CREDENTIALS_CHARSET_KEY, credentialsCharset);
                else
                        removeCredentialsCharset();
        }

        public void removeCredentialsCharset() {
                session.removeAttribute(CREDENTIALS_CHARSET_KEY);
        }

        public void addChannelId(String channelId, String channelFactoryClassName) {
                if (channelId == null)
                        throw new NullPointerException("channelId cannot be null");
                session.setAttribute(CHANNELID_KEY_PREFIX + channelId, channelFactoryClassName);
        }

        public boolean hasChannelId(String channelId) {
                if (channelId == null)
                        return false;
                return session.getAttribute(CHANNELID_KEY_PREFIX + channelId) != null;
        }
        
        public String getChannelFactoryClassName(String channelId) {
                if (channelId == null)
                        return null;
                return (String)session.getAttribute(CHANNELID_KEY_PREFIX + channelId);
        }

        public void removeChannelId(String channelId) {
                if (channelId == null)
                        return;
                session.removeAttribute(CHANNELID_KEY_PREFIX + channelId);
                clearSubscriptions(channelId);
        }

        public Set<String> getChannelIds() {
                Set<String> channelIds = new HashSet<String>();
                for (Enumeration<String> e = session.getAttributeNames(); e.hasMoreElements(); ) {
                        String key = e.nextElement();
                        if (key.startsWith(CHANNELID_KEY_PREFIX))
                                channelIds.add(key.substring(CHANNELID_KEY_PREFIX.length()));
                }
                return channelIds;
        }

        public void clearChannelIds() {
                Set<String> channelIds = getChannelIds();
                for (String channelId : channelIds)
                        removeChannelId(channelId);
        }

        public void addSubcription(String channelId, CommandMessage message) {
                if (channelId == null || message == null)
                        throw new IllegalArgumentException("channelId and message cannot be null");
                if (!hasChannelId(channelId))
                        throw new IllegalArgumentException("Unknown channelId: " + channelId);
                if (channelId.indexOf('.') != -1)
                        throw new IllegalArgumentException("Invalid channelId (should not contain '.' characters): " + channelId);
                String subscriptionId = (String)message.getHeader(AsyncMessage.DESTINATION_CLIENT_ID_HEADER);
                if (subscriptionId == null)
                        throw new IllegalArgumentException("Subscription id cannot be null: " + message);
                session.setAttribute(SUBSCRIPTION_KEY_PREFIX + channelId + '.' + subscriptionId, message);
        }

        public boolean hasSubcription(String channelId, String subscriptionId) {
                if (channelId == null || subscriptionId == null)
                        return false;
                return (session.getAttribute(SUBSCRIPTION_KEY_PREFIX + channelId + '.' + subscriptionId) != null);
        }

        public void removeSubcription(String channelId, String subscriptionId) {
                if (channelId == null || subscriptionId == null)
                        return;
                session.removeAttribute(SUBSCRIPTION_KEY_PREFIX + channelId + '.' + subscriptionId);
        }

        public List<CommandMessage> getSubscriptions(String channelId) {
                if (channelId == null)
                        return Collections.emptyList();
                String channelSubscriptionKeyPrefix = SUBSCRIPTION_KEY_PREFIX + channelId + '.';
                List<CommandMessage> subscriptions = new ArrayList<CommandMessage>();
                for (Enumeration<String> e = session.getAttributeNames(); e.hasMoreElements(); ) {
                        String key = e.nextElement();
                        if (key.startsWith(channelSubscriptionKeyPrefix)) {
                                CommandMessage subscription = (CommandMessage)session.getAttribute(key);
                                subscriptions.add(subscription);
                        }
                }
                return subscriptions;
        }

        public void clearSubscriptions(String channelId) {
                if (channelId == null)
                        return;
                String channelSubscriptionKeyPrefix = SUBSCRIPTION_KEY_PREFIX + channelId + '.';
                for (Enumeration<String> e = session.getAttributeNames(); e.hasMoreElements(); ) {
                        String key = e.nextElement();
                        if (key.startsWith(channelSubscriptionKeyPrefix))
                                session.removeAttribute(key);
                }
        }
        
        
        public String getDestinationClientId(String destination) {
                return (String)session.getAttribute(DESTINATION_CLIENTID_KEY_PREFIX + destination);
        }
        
        public void setDestinationClientId(String destination, String clientId) {
                session.setAttribute(DESTINATION_CLIENTID_KEY_PREFIX + destination, clientId);
        }
        
        public String getDestinationSubscriptionId(String destination) {
                return (String)session.getAttribute(DESTINATION_SUBSCRIPTIONID_KEY_PREFIX + destination);
        }
        
        public void setDestinationSubscriptionId(String destination, String subscriptionId) {
                session.setAttribute(DESTINATION_SUBSCRIPTIONID_KEY_PREFIX + destination, subscriptionId);
        }
        
        public String getDestinationSelector(String destination) {
                return (String)session.getAttribute(DESTINATION_SELECTOR_KEY_PREFIX + destination);
        }
        
        public void setDestinationSelector(String destination, String selector) {
                session.setAttribute(DESTINATION_SELECTOR_KEY_PREFIX + destination, selector);
        }
        
        public Object[] getDestinationDataSelectors(String destination) {
                return (Object[])session.getAttribute(DESTINATION_DATA_SELECTORS_KEY_PREFIX + destination);
        }
        
        public void setDestinationDataSelectors(String destination, Object[] selectors) {
                session.setAttribute(DESTINATION_DATA_SELECTORS_KEY_PREFIX + destination, selectors);
        }
}