////////////////////////////////////////////////////////////////////////////////
//
//  Licensed to the Apache Software Foundation (ASF) under one or more
//  contributor license agreements.  See the NOTICE file distributed with
//  this work for additional information regarding copyright ownership.
//  The ASF licenses this file to You 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 mx.messaging.config
{

import flash.utils.getDefinitionByName;
import flash.utils.getQualifiedClassName;

import mx.collections.ArrayCollection;
import mx.core.mx_internal;
import mx.messaging.Channel;
import mx.messaging.ChannelSet;
import mx.messaging.MessageAgent;
import mx.messaging.errors.InvalidChannelError;
import mx.messaging.errors.InvalidDestinationError;
import mx.resources.IResourceManager;
import mx.resources.ResourceManager;
import mx.utils.ObjectUtil;

use namespace mx_internal;

[ResourceBundle("messaging")]

/**
 *  This class provides access to the server messaging configuration information.
 *  This class encapsulates information from the services-config.xml file on the client
 *  and is used by the messaging system to provide configured ChannelSets and Channels
 *  to the messaging framework.
 *
 *  <p>The XML source is provided during the compilation process.
 *  However, there is currently no internal restriction preventing the
 *  acquisition of this XML data by other means, such as network, local file
 *  system, or shared object at runtime.</p>
 *  
 *  @langversion 3.0
 *  @playerversion Flash 9
 *  @playerversion AIR 1.1
 *  @productversion BlazeDS 4
 *  @productversion LCDS 3 
 */
public class ServerConfig
{
    //--------------------------------------------------------------------------
    //
    // Static Constants
    //
    //--------------------------------------------------------------------------

    /**
     *  @private
     *  Channel config parsing constant.
     */
    public static const CLASS_ATTR:String = "type";

    /**
     *  @private
     *  Channel config parsing constant.
     */
    public static const URI_ATTR:String = "uri";

    //--------------------------------------------------------------------------
    //
    // Class variables
    //
    //--------------------------------------------------------------------------

    /**
     *  @private
     *  Storage for the resourceManager getter.
     *  This gets initialized on first access,
     *  not at static initialization time, in order to ensure
     *  that the Singleton registry has already been initialized.
     */
    private static var _resourceManager:IResourceManager;

    /**
     *  @private
     *  A reference to the object which manages
     *  all of the application's localized resources.
     *  This is a singleton instance which implements
     *  the IResourceManager interface.
     */
    private static function get resourceManager():IResourceManager
    {
        if (!_resourceManager)
            _resourceManager = ResourceManager.getInstance();

        return _resourceManager;
    }

    //--------------------------------------------------------------------------
    //
    // Static Variables
    //
    //--------------------------------------------------------------------------

    /**
     *  @private
     *  The server configuration data.
     */
    public static var serverConfigData:XML;

    /**
     *  @private
     *  Caches shared ChannelSets, keyed by strings having the format:
     *  <list of comma delimited channel ids>:[true|false] - where the final
     *  flag indicates whether the ChannelSet should be used for clustered
     *  destinations or not.
     */
    private static var _channelSets:Object = {};

    /**
     *  @private
     *  Caches shared clustered Channel instances keyed by Channel id.
     */
    private static var _clusteredChannels:Object = {};

    /**
     *  @private
     *  Caches shared unclustered Channel instances keyed by Channel id.
     */
    private static var _unclusteredChannels:Object = {};

    /**
     * @private
     * Keeps track of Channel endpoint uris whose configuration has been fetched
     * from the server.
     */
    private static var _configFetchedChannels:Object;

    //--------------------------------------------------------------------------
    //
    // Static Properties
    //
    //--------------------------------------------------------------------------

    //----------------------------------
    //  xml
    //----------------------------------

    /**
     *  The XML configuration; this value must contain the relevant portions of
     *  the &lt;services&gt; tag from the services-config.xml file.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion BlazeDS 4
     *  @productversion LCDS 3 
     */
    public static function get xml():XML
    {
        if (serverConfigData == null)
            serverConfigData = <services/>;
        return serverConfigData;
    }

    /**
     *  @private
     */
    public static function set xml(value:XML):void
    {
        serverConfigData = value;
        // Reset cached Channels and ChannelSets.
        _channelSets = {};
        _clusteredChannels = {};
        _unclusteredChannels = {};
    }

    //----------------------------------
    //  channelSetFactory
    //----------------------------------

    /**
     *  @private
     *  A Class factory to use to generate auto-instantiated ChannelSet instances
     *  as is done in getChannelSet(String).
     *  Default factory is the base ChannelSet class.
     */
    public static var channelSetFactory:Class = ChannelSet;

    //--------------------------------------------------------------------------
    //
    // Static Methods
    //
    //--------------------------------------------------------------------------

    /**
     *  This method ensures that the destinations specified contain identical
     *  channel definitions.
     *  If the channel definitions between the two destinations specified are
     *  not identical this method will throw an ArgumentError.
     *
     *  @param   destinationA:String first destination to compare against
     *  @param   destinationB:String second destination to compare channels with
     *  @throw   ArgumentError if the channel definitions of the specified
     *           destinations aren't identical.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion BlazeDS 4
     *  @productversion LCDS 3 
     */
    public static function checkChannelConsistency(destinationA:String,
                                                   destinationB:String):void
    {
        var channelIdsA:Array = getChannelIdList(destinationA);
        var channelIdsB:Array = getChannelIdList(destinationB);
        if (ObjectUtil.compare(channelIdsA, channelIdsB) != 0)
            throw new ArgumentError("Specified destinations are not channel consistent");
    }

    /**
     *  Returns a shared instance of the configured Channel.
     *
     *  @param id The id of the desired Channel.
     *
     *  @param clustered True if the Channel will be used in a clustered
     *                   fashion; otherwise false.
     *
     *  @return The Channel instance.
     *
     *  @throws mx.messaging.errors.InvalidChannelError If no Channel has the specified id.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion BlazeDS 4
     *  @productversion LCDS 3 
     */
    public static function getChannel(id:String,
                                      clustered:Boolean = false):Channel
    {
        var channel:Channel;

        if (!clustered)
        {
            if (id in _unclusteredChannels)
            {
                return _unclusteredChannels[id];
            }
            else
            {
                 channel = createChannel(id);
                _unclusteredChannels[id] = channel;
                return channel;
            }
        }
        else
        {
            if (id in _clusteredChannels)
            {
                return _clusteredChannels[id];
            }
            else
            {
                channel = createChannel(id);
                _clusteredChannels[id] = channel;
                return channel;
            }
        }
    }

    /**
     *  Returns a shared ChannelSet for use with the specified destination
     *  belonging to the service that handles the specified message type.
     *
     *  @param destinationId The target destination id.
     *
     *  @return The ChannelSet.
     *
     *  @throws mx.messaging.errors.InvalidDestinationError If the specified destination
     *                                  does not have channels and the application
     *                                  did not define default channels.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion BlazeDS 4
     *  @productversion LCDS 3 
     */
    public static function getChannelSet(destinationId:String):ChannelSet
    {
        var destinationConfig:XML = getDestinationConfig(destinationId);
        return internalGetChannelSet(destinationConfig, destinationId);
    }

    /**
     *  Returns the property information for the specified destination
     *
     *  @param destinationId The id of the desired destination.
     *
     *  @return XMLList containing the &lt;property&gt; tag information.
     *
     *  @throws mx.messaging.errors.InvalidDestinationError If the specified destination is not found.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion BlazeDS 4
     *  @productversion LCDS 3 
     */
    public static function getProperties(destinationId:String):XMLList
    {
        var destination:XMLList = xml..destination.(@id == destinationId);

        if (destination.length() > 0)
        {
            return destination.properties;
        }
        else
        {
            var message:String = resourceManager.getString(
                "messaging", "unknownDestination", [ destinationId ]);
            throw new InvalidDestinationError(message);
        }

        return destination;
    }

    //--------------------------------------------------------------------------
    //
    // Static Internal Methods
    //
    //--------------------------------------------------------------------------

    /**
     *  This method returns true iff the channelset specified has channels with
     *  ids or uris that match those found in the destination specified.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion BlazeDS 4
     *  @productversion LCDS 3 
     */
    mx_internal static function channelSetMatchesDestinationConfig(channelSet:ChannelSet,
                                                                   destination:String):Boolean
    {
        if (channelSet != null)
        {
            if (ObjectUtil.compare(channelSet.channelIds, getChannelIdList(destination)) == 0)
                return true;

            // if any of the specified channelset channelIds do not match then
            // we have to move to comparing the uris, as the ids could be null
            // in the specified channelset.
            var csUris:Array = [];
            var csChannels:Array = channelSet.channels;
            for (var i:uint = 0; i<csChannels.length; i++)
                csUris.push(csChannels[i].uri);

            var ids:Array = getChannelIdList(destination);
            var dsUris:Array = [];
            var dsChannels:XMLList;
            var channelConfig:XML;
            var endpoint:XML;
            var dsUri:String;
            for (var j:uint = 0; j<ids.length; j++)
            {
                dsChannels = xml.channels.channel.(@id == ids[j]);
                channelConfig = dsChannels[0];
                endpoint = channelConfig.endpoint;
                // uri might be undefined when client-load-balancing urls are specified.
                dsUri = endpoint.length() > 0? endpoint[0].attribute(URI_ATTR).toString() : null;
                if (dsUri != null)
                    dsUris.push(dsUri);
            }

            return ObjectUtil.compare(csUris, dsUris) == 0;

        }
        return false;
    }

    /**
     * @private
     * returns if the specified endpoint has been fetched already
     */
    mx_internal static function fetchedConfig(endpoint:String):Boolean
    {
        return _configFetchedChannels != null && _configFetchedChannels[endpoint] != null;
    }

    /**
     *  @private
     *  This method returns a list of the channel ids for the given destination
     *  configuration. If no channels exist for the destination, it returns a
     *  list of default channel ids for the applcation
     */
    mx_internal static function getChannelIdList(destination:String):Array
    {
         var destinationConfig:XML = getDestinationConfig(destination);
        return destinationConfig? getChannelIds(destinationConfig)
                                        : getDefaultChannelIds();
    }

    /**
     *  @private
     *  Used by the Channels to determine whether the Channel should request
     *  dynamic configuration from the server for its MessageAgents.
     */
    mx_internal static function needsConfig(channel:Channel):Boolean
    {
        // Configuration for the endpoint has not been fetched by some other channel.
        if (_configFetchedChannels == null || _configFetchedChannels[channel.endpoint] == null)
        {
            var channelSets:Array = channel.channelSets;
            var m:int = channelSets.length;
            for (var i:int = 0; i < m; i++)
            {
                // If the channel belongs to an advanced ChannelSet, always fetch runtime config.
                if (getQualifiedClassName(channelSets[i]).indexOf("Advanced") != -1)
                    return true;

                // Otherwise, only fetch if a connected MessageAgent requires it.
                var messageAgents:Array = ChannelSet(channelSets[i]).messageAgents;
                var n:int = messageAgents.length;
                for (var j:int = 0; j < n; j++)
                {
                    if (MessageAgent(messageAgents[j]).needsConfig)
                        return true;
                }
            }
        }
        return false;
    }

    /**
     *  @private
     *  This method updates the xml with serverConfig object returned from the
     *  server during initial client connect
     */
     mx_internal static function updateServerConfigData(serverConfig:ConfigMap, endpoint:String = null):void
     {
        if (serverConfig != null)
        {
            if (endpoint != null)
            {
                // Add the endpoint uri to the list of uris whose configuration
                // has been fetched.
                if (_configFetchedChannels == null)
                    _configFetchedChannels = {};

                _configFetchedChannels[endpoint] = true;
            }

            var newServices:XML = <services></services>;
            convertToXML(serverConfig, newServices);

            // Update default-channels of the application.
            xml["default-channels"] = newServices["default-channels"];

            // Update the service destinations.
            for each (var newService:XML in newServices..service)
            {
                var oldServices:XMLList = xml.service.(@id == newService.@id);
                var oldDestinations:XMLList;
                var newDestination:XML;
                // The service already exists, update its destinations.
                if (oldServices.length() != 0)
                {
                    var oldService:XML = oldServices[0]; // Service ids are unique.
                    for each (newDestination in newService..destination)
                    {
                        oldDestinations = oldService.destination.(@id == newDestination.@id);
                        if (oldDestinations.length() != 0)
                            delete oldDestinations[0]; // Destination ids are unique.
                        oldService.appendChild(newDestination.copy());
                    }
                }
                // The service does not exist which means that this is either a new
                // service with its destinations, or a proxy service (eg. GatewayService)
                // with configuration for existing destinations for other services.
                else
                {
                    for each (newDestination in newService..destination)
                    {
                        oldDestinations = xml..destination.(@id == newDestination.@id);
                        if (oldDestinations.length() != 0) // Replace the existing destination.
                        {
                            oldDestinations[0] = newDestination[0].copy(); // Destination ids are unique.
                            delete newService..destination.(@id == newDestination.@id)[0];
                        }
                    }

                    if (newService.children().length() > 0) // Add the new service.
                        xml.appendChild(newService);
                }
            }

            // Update the channels
            var newChannels:XMLList = newServices.channels;
            if (newChannels.length() > 0)
            {
                var oldChannels:XML = xml.channels[0];
                if (oldChannels == null || oldChannels.length() == 0)
                {
                    xml.appendChild(newChannels);
                }
                // Commenting this section out as there is no real use case
                // for updating channel definitions.
                /*
                else
                {
                    for each (var newChannel:XML in newChannels.channel)
                    {
                        var oldChannel:XMLList = oldChannels.channel.(@id == newChannel.@id);
                        if (oldChannel.length() > 0)
                        {
                            // Assuming only one channel exists with the same id.
                            delete oldChannel[0];
                        }
                        oldChannels.appendChild(newChannel);
                    }
                }
                */
            }
        }
     }

    //--------------------------------------------------------------------------
    //
    // Static Private Methods
    //
    //--------------------------------------------------------------------------

    /**
     *  Helper method that builds a new Channel instance based on the
     *  configuration for the specified id.
     *
     *  @param id The id for the configured Channel to build.
     *
     *  @return The Channel instance.
     *
     *  @throws mx.messaging.errors.InvalidChannelError If no configuration data for the specified
     *                             id exists.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion BlazeDS 4
     *  @productversion LCDS 3 
     */
    private static function createChannel(channelId:String):Channel
    {
        var message:String;

        var channels:XMLList = xml.channels.channel.(@id == channelId);
        if (channels.length() == 0)
        {
            message = resourceManager.getString(
                "messaging", "unknownChannelWithId", [ channelId ]);
            throw new InvalidChannelError(message);
        }

        var channelConfig:XML = channels[0];
        var className:String = channelConfig.attribute(CLASS_ATTR).toString();
        var endpoint:XMLList = channelConfig.endpoint;
        /// uri might be undefined when client-load-balancing urls are specified.
        var uri:String = endpoint.length() > 0? endpoint[0].attribute(URI_ATTR).toString() : null;
        var channel:Channel = null;
        try
        {
            var channelClass:Class = getDefinitionByName(className) as Class;
            channel = new channelClass(channelId, uri);
            channel.applySettings(channelConfig);

            // If we have an WSRP_ENCODED_CHANNEL in FlashVars,
            // use that instead of uri configured in the config file
            if (LoaderConfig.parameters != null && LoaderConfig.parameters.WSRP_ENCODED_CHANNEL != null)
                channel.url = LoaderConfig.parameters.WSRP_ENCODED_CHANNEL;
        }
        catch(e:ReferenceError)
        {
            message = resourceManager.getString(
                "messaging", "unknownChannelClass", [ className ]);
            throw new InvalidChannelError(message);
        }
        return channel;
    }

       /**
        * Converts the ConfigMap of properties into XML
        *  
        *  @langversion 3.0
        *  @playerversion Flash 9
        *  @playerversion AIR 1.1
        *  @productversion BlazeDS 4
        *  @productversion LCDS 3 
        */
    private static function convertToXML(config:ConfigMap, configXML:XML):void
    {
        for (var propertyKey:Object in config)
        {
            var propertyValue:Object = config[propertyKey];

            if (propertyValue is String)
            {
                if (propertyKey == "")
                {
                    // Add as a value
                    configXML.appendChild(propertyValue);
                }
                else
                {
                    // Add as an attribute
                    configXML.@[propertyKey] = propertyValue;
                }
            }
            else if (propertyValue is ArrayCollection || propertyValue is Array)
            {
                var propertyValueList:Array;
                if (propertyValue is ArrayCollection)
                    propertyValueList = ArrayCollection(propertyValue).toArray();
                else
                    propertyValueList = propertyValue as Array;

                for (var i:int = 0; i < propertyValueList.length; i++)
                {
                    var propertyXML1:XML = <{propertyKey}></{propertyKey}>
                    configXML.appendChild(propertyXML1);
                    convertToXML(propertyValueList[i] as ConfigMap, propertyXML1);
                }
            }
            else // assuming that it is ConfigMap
            {
                var propertyXML2:XML = <{propertyKey}></{propertyKey}>
                configXML.appendChild(propertyXML2);
                convertToXML(propertyValue as ConfigMap, propertyXML2);
            }
        }
    }

    private static function getChannelIds(destinationConfig:XML):Array
    {
        var result:Array = [];
        var channels:XMLList = destinationConfig.channels.channel;
        var n:int = channels.length();
        for (var i:int = 0; i < n; i++)
        {
            result.push(channels[i].@ref.toString());
        }
        return result;
    }

    /**
     * @private
     * This method returns a list of default channel ids for the application
     */
    private static function getDefaultChannelIds():Array
    {
        var result:Array = [];
        var channels:XMLList = xml["default-channels"].channel;
        var n:int = channels.length();
        for (var i:int = 0; i < n; i++)
        {
            result.push(channels[i].@ref.toString());
        }
        return result;
    }

    /**
     *  Returns the destination XML data specific to the destination and message
     *  type specified. Returns null if the destination is not found.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion BlazeDS 4
     *  @productversion LCDS 3 
     */
    private static function getDestinationConfig(destinationId:String):XML
    {
        var destinations:XMLList = xml..destination.(@id == destinationId);
        var destinationCount:int = destinations.length();
        if (destinationCount == 0)
        {
            return null;
        }
        else
        {
            // Destination ids are unique among services
            return destinations[0];
        }
    }

    /**
     *  Helper method to look up and return a cached ChannelSet (and build and
     *  cache an instance if necessary).
     *
     *  @param destinationConfig The configuration for the target destination.
     *  @param destinatonId The id of the target destination.
     *
     *  @return The ChannelSet.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion BlazeDS 4
     *  @productversion LCDS 3 
     */
    private static function internalGetChannelSet(
                                        destinationConfig:XML,
                                        destinationId:String):ChannelSet
    {
        var channelIds:Array;
        var clustered:Boolean;

        if (destinationConfig == null)
        {
            channelIds = getDefaultChannelIds();
            if (channelIds.length == 0)
            {
                var message:String = resourceManager.getString(
                    "messaging", "noChannelForDestination", [ destinationId ]);
                throw new InvalidDestinationError(message);
            }
            clustered = false;
        }
        else
        {
            channelIds = getChannelIds(destinationConfig);
            clustered = (destinationConfig.properties.network.cluster.length() > 0) ? true : false;
        }       

        var channelSetId:String = channelIds.join(",") + ":" + clustered;

        if (channelSetId in _channelSets)
        {
            return _channelSets[channelSetId];
        }
        else
        {
            var channelSet:ChannelSet = new channelSetFactory(channelIds, clustered);
            var heartbeatMillis:int = serverConfigData["flex-client"]["heartbeat-interval-millis"];
            if (heartbeatMillis > 0) channelSet.heartbeatInterval = heartbeatMillis;
            if (clustered) channelSet.initialDestinationId = destinationId;
            _channelSets[channelSetId] = channelSet;           
            return channelSet;
        }
    }

}

}