//
// 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.
//

//======================================================================================================
// Code originally contributed by Microsoft Corporation.
// This contribution to the Stonehenge project is limited strictly 
// to the source code that is submitted in this submission.  
// Any technology, including underlying platform technology, 
// that is referenced or required by the submitted source code 
// is not a part of the contribution.  
// For example and not by way of limitation, 
// any systems/Windows libraries (WPF, WCF, ASP.NET etc.) 
// required to run the submitted source code is not a part of the contribution
//======================================================================================================

using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.Runtime.Serialization;
using System.Configuration;
using System.Diagnostics;
using System.Reflection;
using Trade.Utility;
using Trade.BusinessServiceContract;
using Trade.OrderProcessorContract;


namespace Trade.Client
{
    public sealed class ClientList
    {
        public Connection _connection;
        private Type _type;
        private string _clientConfig;
        private string _userName;
        private string _password;

        /// <summary>
        /// Constructor logic.
        /// </summary>
        /// <param name="serviceFriendlyName">Friendly name of the virtual endpoint this ClientList instance will initialize.</param>
        public ClientList(Type clientContractType, string clientConfig)
        {
            _clientConfig = clientConfig;
            _type = clientContractType;
            _connection = new Connection(_type, null, _clientConfig, null);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="clientContractType"></param>
        /// <param name="clientConfig"></param>
        public ClientList(Type clientContractType, string clientConfig, string userName, string password)
        {
            _clientConfig = clientConfig;
            _type = clientContractType;
            _userName = userName;
            _password = password;
            _connection = new Connection(_type, null, _clientConfig, null,userName,password);
        }

        public class Connection
        {
            private IChannel _channel;
            private string _clientConfig;
            private ChannelFactory _factory;
            private object _channelLock = new object();
            public Type _type;
            string _userName;
            string _password;


            /// <summary>
            /// Creates a new Connection instance, which stores all the information for a cached Channel instance
            /// </summary>
            /// <param name="channel"></param>
            /// <param name="endpointAddress"></param>
            /// <param name="clientConfig"></param>
            /// <param name="friendlyName"></param>
            /// <param name="factory"></param>
            public Connection(Type type, IChannel channel, string clientConfig, ChannelFactory factory)
            {
                _type = type;
                _channel = channel;
                _clientConfig = clientConfig;
                _factory = factory;
            }

            public Connection(Type type, IChannel channel, string clientConfig, ChannelFactory factory, string userName, string password)
            {
                _type = type;
                _channel = channel;
                _clientConfig = clientConfig;
                _factory = factory;
                _userName = userName;
                _password = password;
            }

            /// <summary>
            /// Uses reflection to create a typed generic object.
            /// </summary>
            /// <param name="settingsInstance"></param>
            /// <param name="generic"></param>
            /// <param name="innerType"></param>
            /// <param name="args"></param>
            /// <returns></returns>
            public static object CreateGeneric(Type generic, Type innerType, params object[] args)
            {
                try
                {
                    System.Type specificType = generic.MakeGenericType(new System.Type[] { innerType });
                    return Activator.CreateInstance(specificType, args);
                }
                catch
                {
                    throw;
                }
            }

            /// <summary>
            /// Returns a channel factory as an object type. The channel factory will be created as type "theType"
            /// </summary>
            /// <param name="theType">The type representing the service contract type.</param>
            /// <param name="clientConfiguration">The name of the binding configuration to be used when creating the factory.</param>
            /// <param name="remoteNodeEndPointAddress">The endpoint address to be used when creating the channel factory.</param>
            /// <returns>object representing a channel factory</returns>
            public static object createChannelFactory(Type theType, string clientConfiguration, string userName, string password)
            {
                object channelFactory = CreateGeneric(typeof(ChannelFactory<>), theType, new object[] { clientConfiguration});
                ((ChannelFactory)channelFactory).Credentials.UserName.UserName = userName;
                ((ChannelFactory)channelFactory).Credentials.UserName.Password = password;
                return channelFactory;
            }

            public string ClientConfig
            {
                get
                {
                    return _clientConfig;
                }
                set
                {
                    this._clientConfig = value;
                }
            }

            /// <summary>
            /// Returns a channel as an IChannel type. The channel will be created using a channel factory.
            /// </summary>
            /// <param name="channelFactory">The channel factory that will be used to create the channel instance.</param>
            /// <returns>IChannel representing a WCF service channel</returns>
            public static IChannel createChannel(object channelFactory)
            {
                if (channelFactory == null)
                    return null;
                IChannel returnChannel = null;
                try
                {
                    returnChannel = (IChannel)channelFactory.GetType().InvokeMember("CreateChannel", BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.Public, null, channelFactory, null);
                }
                catch
                {
                    throw;
                }
                return returnChannel;
            }

            public IChannel Channel
            {

                get
                {

                    IChannel localChannel = _channel;
                    if (localChannel == null)
                    {
                        lock (_channelLock)
                        {
                            if (_factory == null)
                            {
                                _factory = (ChannelFactory)createChannelFactory(_type, ClientConfig,_userName,_password);
                            }
                            if (_channel == null)
                            {
                                _channel = createChannel(_factory);
                            }
                            return _channel;
                        }
                    }
                    return localChannel;
                }

                set
                {
                    lock (_channelLock)
                    {
                        if (_channel!=null && ((IChannel)_channel).State != CommunicationState.Opened)
                        {
                            ((IChannel)_channel).Abort();
                            _channel = null;
                        }

                        if (_factory!=null && _factory.State != CommunicationState.Opened)
                        {
                            _factory.Abort();
                            _factory = null;
                        }
                    }
                }
            }

            public ChannelFactory Factory
            {
                get
                {
                    return _factory;
                }
                set
                {
                    this._factory = value;
                }
            }
        }
    }

    /// <summary>
    /// This is the WCF master Client class.  It will be instantiated once per remote operation (web service call) request,
    /// but uses a static Dictionary (connectionList) of type ClientList to ensure channels are chached and not instanced on a pre-request basis.
    /// The connecitonList will contain one entry per type of service connected to from an app/service client.  The connection ClientList entry
    /// will in turn contain the list of all service nodes for this specific service type. 
    /// </summary>
    public class Client
    {
        private static Dictionary<string, ClientList> connectionDictionary;
        public ClientList connection;
        private string _clientConfig;
        private Type _type;

        /// <summary>
        /// 
        /// </summary>
        /// <param name="clientContractType"></param>
        /// <param name="clientConfig"></param>
        public Client(Type clientContractType, string clientConfig)
        {
            _type = clientContractType;
            _clientConfig = clientConfig;
            if (connectionDictionary == null)
                connectionDictionary = new Dictionary<string, ClientList>();
            try
            {
                connection = connectionDictionary[_type.FullName];
            }
            catch
            {
                //No entry!
                connection = new ClientList(clientContractType,clientConfig);
                connectionDictionary.Add(_type.FullName, connection);
            }
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="clientContractType"></param>
        /// <param name="clientConfig"></param>
        public Client(Type clientContractType, string clientConfig, string userName, string password)
        {
            _type = clientContractType;
            _clientConfig = clientConfig;
            if (connectionDictionary == null)
                connectionDictionary = new Dictionary<string, ClientList>();
            try
            {
                connection = connectionDictionary[_type.FullName];
            }
            catch
            {
                //No entry!
                connection = new ClientList(clientContractType, clientConfig, userName, password);
                connectionDictionary.Add(_type.FullName, connection);
            }
        }

        /// <summary>
        /// Property that is referenced in custom client code to get a channel from the connection list.  Hence, when
        /// getting a channel via this property, load balancing and failover will occur.
        /// </summary>
        /// <returns></returns>
        public IChannel Channel
        {
            get
            {
                return connection._connection.Channel;
            }
            set
            {
                connection._connection.Channel = value;
            }
        }

        public static void ClearCache()
        {
            connectionDictionary = null;
        }
    }
}