using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using UnityEngine;
using AX.Network.Common;
using AX.Network.Protocols;
using AX.Serialization;

namespace AX.NetworkSystem
{
    /// <summary>
    /// 表示传输的文件信息。
    /// </summary>
    public struct TransferedFileInfo
    {
        /// <summary>
        /// 表示传输的文件名。只包含文件名和扩展名，不包含路径。
        /// </summary>
        /// <remarks>文件名必须保证唯一。</remarks>
        public string Filename;
        /// <summary>
        /// 表示传输的文件大小，最大支持 2G。
        /// </summary>
        public int FileSize;

        /// <summary>
        /// 表示文件附加信息。
        /// </summary>
        public ArraySegment<byte> Tag;
    }

    /// <summary>
    /// 表示传输的文件块信息。
    /// </summary>
    public struct TransferedChunkInfo
    {
        /// <summary>
        /// 表示文件块对应的文件。
        /// </summary>
        public string Filename;

        /// <summary>
        /// 表示文件块总数。
        /// </summary>
        public int ChunkCount;

        /// <summary>
        /// 表示文件块的 ID。
        /// </summary>
        public int ChunkId;

        /// <summary>
        /// 表示文件块划分的标准。
        /// </summary>
        public int ChunkSize;

        /// <summary>
        /// 表示文件块的数据。
        /// </summary>
        public ArraySegment<byte> Data;
    }

    /// <summary>
    /// 表示传输文件块时的回复。
    /// </summary>
    public struct TransferedChunkInfoReply
    {
        /// <summary>
        /// 表示文件名。
        /// </summary>
        public string Filename;
        /// <summary>
        /// 表示文件块 Id。
        /// </summary>
        public int ChunkId;
    }

    /// <summary>
    /// 表示传输文件块时的请求。
    /// </summary>
    public struct TransferedChunkInfoRequest
    {
        /// <summary>
        /// 表示文件名。
        /// </summary>
        public string Filename;
        /// <summary>
        /// 表示文件块 Id。
        /// </summary>
        public int ChunkId;
        /// <summary>
        /// 表示文件块划分的标准。
        /// </summary>
        public int ChunkSize;
    }

    /// <summary>
    /// 表示错误消息。
    /// </summary>
    public struct ErrorInfo
    {
        /// <summary>
        /// 表示出错的文件名。
        /// </summary>
        public string Filename;
        /// <summary>
        /// 表示错误码。
        /// </summary>
        public int ErrorCode;
        /// <summary>
        /// 表示错误详细信息。
        /// </summary>
        public string ErrorMessage;
    }

    /// <summary>
    /// 表示文件传输过程中的状态。
    /// </summary>
    internal class TransferedFileStatus
    {
        /// <summary>
        /// 表示传输文件会话。
        /// </summary>
        public IAppSession<BinaryProtocol, BinaryMessage> AppSession;
        /// <summary>
        /// 表示要传输的文件路径。相对路径和绝对路径均可。
        /// </summary>
        public string FullName;
        /// <summary>
        /// 表示文件名。只包含文件名和扩展名，不包含路径。
        /// </summary>
        public string Filename;
        /// <summary>
        /// 表示文件总共划分了多少块。
        /// </summary>
        public int TotalChunkCount;
        /// <summary>
        /// 表示当前传输到哪块了。
        /// </summary>
        public int CurrentChunkIndex;
        /// <summary>
        /// 表示当前已经传输了多少块了。
        /// </summary>
        public int TransferedChunkCount;
        /// <summary>
        /// 表示文件传输过程中的进度变化。
        /// </summary>
        public Action<string, float> ProgressChanged;
        /// <summary>
        /// 表示文件传输完毕事件。
        /// </summary>
        public Action<string> Completed;
        /// <summary>
        /// 表示文件传输时发生错误，当前只针对下载。
        /// </summary>
        public Action<ErrorInfo> Error;
    }

    public static class FileTransfer
    {
        internal class FileSyncStatus
        {
            public BitArray BitArray;
            public ArraySegment<byte> Tag;
            public int TotalChunkCount;
            public int TransferedChunkCount;
        }

        private const string DOWNLOAD_FILE_INFO_REQUEST = "DOWNLOAD_FILE_INFO_REQUEST";
        private const string DOWNLOAD_CHUNK_INFO_REQUEST = "DOWNLOAD_CHUNK_INFO_REQUEST";

        private const string DOWNLOAD_FILE_INFO_REPLY = "DOWNLOAD_FILE_INFO_REPLY";
        private const string DOWNLOAD_CHUNK_INFO_REPLY = "DOWNLOAD_CHUNK_INFO_REPLY";

        private const string DOWNLOAD_ERROR = "DOWNLOAD_ERROR";

        private const string UPLOAD_FILE_INFO_REQUEST = "UPLOAD_FILE_INFO_REQUEST";
        private const string UPLOAD_CHUNK_INFO_REQUEST = "UPLOAD_CHUNK_INFO_REQUEST";

        private const string UPLOAD_FILE_INFO_REPLY = "UPLOAD_FILE_INFO_REPLY";
        private const string UPLOAD_CHUNK_INFO_REPLY = "UPLOAD_CHUNK_INFO_REPLY";

        private const string FORWARD_FILE_INFO_REQUEST = "FORWARD_FILE_INFO_REQUEST";
        private const string FORWARD_CHUNK_INFO_REQUEST = "FORWARD_CHUNK_INFO_REQUEST";

        private const string FORWARD_FILE_INFO_REPLY = "FORWARD_FILE_INFO_REPLY";
        private const string FORWARD_CHUNK_INFO_REPLY = "FORWARD_CHUNK_INFO_REPLY";

        private const string FORWARD_FILE_INFO_SYNC = "FORWARD_FILE_INFO_SYNC";
        private const string FORWARD_CHUNK_INFO_SYNC = "FORWARD_CHUNK_INFO_SYNC";

        private const string PULL_CHUNK_INFO_REQUEST = "PULL_CHUNK_INFO_REQUEST";
        private const string PULL_CHUNK_INFO_REPLY = "PULL_CHUNK_INFO_REQUEST";

        private const string PULL_FILE_INFO_REQUEST = "PULL_FILE_INFO_REQUEST";
        private const string PULL_FILE_INFO_REPLY = "PULL_FILE_INFO_REPLY";

        private const string SEND_FILE_SYNC = "SEND_FILE_SYNC";

        private static string BaseTempFolder = Application.dataPath + Path.DirectorySeparatorChar + "Temp" + Path.DirectorySeparatorChar;
        private static string BaseUploadFolder = Application.dataPath + Path.DirectorySeparatorChar + "Upload" + Path.DirectorySeparatorChar;
        private static string TempFolder = BaseTempFolder;
        private static string UploadFolder = BaseUploadFolder;
        private static string DirectorySeparator = new string(new char[] { Path.DirectorySeparatorChar });

        private const int ChunkSize = 65536 - 4096;
        private const int TransferedChunkCount = 1024 * 1024 / ChunkSize;

        private static readonly BufferPool BufferPool = new BufferPool(1, ChunkSize);

        private static Dictionary<string, TransferedFileStatus> UploadContainer = new Dictionary<string, TransferedFileStatus>();
        private static Dictionary<string, TransferedFileStatus> DownloadContainer = new Dictionary<string, TransferedFileStatus>();
        private static Dictionary<string, TransferedFileStatus> ForwardContainer = new Dictionary<string, TransferedFileStatus>();
        private static Dictionary<string, FileSyncStatus> FileSyncContainer = new Dictionary<string, FileSyncStatus>();

        /// <summary>
        /// 表示文件传输初始化。
        /// </summary>
        public static void Initialize()
        {
            NetworkMessageDispatcher.AddListener(DOWNLOAD_FILE_INFO_REPLY, OnDownloadFileInfoReply);
            NetworkMessageDispatcher.AddListener(DOWNLOAD_CHUNK_INFO_REPLY, OnDownloadChunkInfoReply);
            NetworkMessageDispatcher.AddListener(DOWNLOAD_ERROR, OnDownloadError);
            NetworkMessageDispatcher.AddListener(UPLOAD_FILE_INFO_REPLY, OnUploadFileInfoReply);
            NetworkMessageDispatcher.AddListener(UPLOAD_CHUNK_INFO_REPLY, OnUploadChunkInfoReply);
            NetworkMessageDispatcher.AddListener(FORWARD_FILE_INFO_REPLY, OnForwardFileInfoReply);
            NetworkMessageDispatcher.AddListener(FORWARD_CHUNK_INFO_REPLY, OnForwardChunkInfoReply);
            NetworkMessageDispatcher.AddListener(FORWARD_FILE_INFO_SYNC, OnForwardFileInfoSync);
            NetworkMessageDispatcher.AddListener(FORWARD_CHUNK_INFO_SYNC, OnForwardChunkInfoSync);
            NetworkMessageDispatcher.AddListener(PULL_FILE_INFO_REPLY, OnPullFileInfoReply);
            NetworkMessageDispatcher.AddListener(PULL_CHUNK_INFO_REPLY, OnPullChunkInfoReply);
        }

        public static void Dispose()
        {
            NetworkMessageDispatcher.RemoveListener(DOWNLOAD_FILE_INFO_REPLY, OnDownloadFileInfoReply);
            NetworkMessageDispatcher.RemoveListener(DOWNLOAD_CHUNK_INFO_REPLY, OnDownloadChunkInfoReply);
            NetworkMessageDispatcher.RemoveListener(DOWNLOAD_ERROR, OnDownloadError);
            NetworkMessageDispatcher.RemoveListener(UPLOAD_FILE_INFO_REPLY, OnUploadFileInfoReply);
            NetworkMessageDispatcher.RemoveListener(UPLOAD_CHUNK_INFO_REPLY, OnUploadChunkInfoReply);
            NetworkMessageDispatcher.RemoveListener(FORWARD_FILE_INFO_REPLY, OnForwardFileInfoReply);
            NetworkMessageDispatcher.RemoveListener(FORWARD_CHUNK_INFO_REPLY, OnForwardChunkInfoReply);
            NetworkMessageDispatcher.RemoveListener(FORWARD_FILE_INFO_SYNC, OnForwardFileInfoSync);
            NetworkMessageDispatcher.RemoveListener(FORWARD_CHUNK_INFO_SYNC, OnForwardChunkInfoSync);
            NetworkMessageDispatcher.RemoveListener(PULL_FILE_INFO_REPLY, OnPullFileInfoReply);
            NetworkMessageDispatcher.RemoveListener(PULL_CHUNK_INFO_REPLY, OnPullChunkInfoReply);
        }

        /// <summary>
        /// 设置文件下载时的临时目录。
        /// </summary>
        /// <param name="temp">用户指定的临时目录</param>
        /// <remarks>注意：最好在登录成功之后进行设置。用户指定的临时完整路径是 Application.dataPath/Temp/temp/。</remarks>
        public static void SetTempPath(string temp)
        {
            if (temp.EndsWith(DirectorySeparator))
                TempFolder = BaseTempFolder + temp;
            else
                TempFolder = BaseTempFolder + temp + DirectorySeparator;
        }

        /// <summary>
        /// 获得文件下载时的临时目录。
        /// </summary>
        public static string GetTempPath()
        {
            return TempFolder;
        }

        /// <summary>
        /// 设置文件上传目录。
        /// </summary>
        /// <param name="upload">用户指定的文件上传目录</param>
        /// <remarks>注意：最好在登录成功之后进行设置。</remarks>
        public static void SetUploadPath(string upload)
        {
            if (upload.EndsWith(DirectorySeparator))
                UploadFolder = upload;
            else
                UploadFolder = upload + DirectorySeparator;
        }

        /// <summary>
        /// 获得文件上传目录。
        /// </summary>
        public static string GetUploadPath()
        {
            return UploadFolder;
        }

        private static void OnPullFileInfoReply(BinaryMessage message)
        {
            var info = message.Body.Deserialize<TransferedFileInfo>();
            var status = default(FileSyncStatus);

            if (!FileSyncContainer.TryGetValue(info.Filename, out status))
            {
                status = new FileSyncStatus();
                status.Tag = info.Tag;

                FileSyncContainer.Add(info.Filename, status);
            }
            else
                status.Tag = info.Tag;
        }

        private static void OnPullChunkInfoReply(BinaryMessage message)
        {
            var status = default(FileSyncStatus);
            var info = message.Body.Deserialize<TransferedChunkInfo>();

            using (var stream = new FileStream(TempFolder + info.Filename, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite))
            {
                var position = info.ChunkId * info.ChunkSize;
                stream.Seek(position, SeekOrigin.Begin);
                stream.Write(info.Data.Array, info.Data.Offset, info.Data.Count);
                stream.Flush();
            }

            status.BitArray[info.ChunkId] = true;
            ++status.TransferedChunkCount;


            // 确实同步完成
            if (status.TransferedChunkCount == info.ChunkCount)
            {
                FileSyncContainer.Remove(info.Filename);
                ForwardContainer.Remove(info.Filename);

                var tag = status.Tag.Deserialize<KeyValuePair<string, ArraySegment<byte>>>();
                NetworkMessageDispatcher.SendMessage(tag.Key, tag.Value, TempFolder + info.Filename);
            }
            else
            {
                // 拉取未完成的文件块
                var chunkId = GetChunkId(status.BitArray);

                if (chunkId > 0)
                {
                    var request = new TransferedChunkInfoRequest();

                    request.Filename = info.Filename;
                    request.ChunkId = chunkId;
                    request.ChunkSize = ChunkSize;

                    var session = ForwardContainer[info.Filename].AppSession;
                    session.SendRequestAsync(PULL_CHUNK_INFO_REQUEST, request);
                }
            }
        }

        private static void OnForwardChunkInfoSync(BinaryMessage message)
        {
            var info = message.Body.Deserialize<TransferedChunkInfo>();
            var status = default(FileSyncStatus);

            if (!FileSyncContainer.TryGetValue(info.Filename, out status))
            {
                status = new FileSyncStatus();
                FileSyncContainer.Add(info.Filename, status);

                // 拉取文件信息
                var session = ForwardContainer[info.Filename].AppSession;
                session.SendRequestAsync(PULL_FILE_INFO_REQUEST, info.Filename);
            }

            if (status.BitArray == null)
            {
                status.BitArray = new BitArray(info.ChunkCount);
                status.TotalChunkCount = info.ChunkCount;
            }

            using (var stream = new FileStream(TempFolder + info.Filename, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite))
            {
                var position = info.ChunkId * info.ChunkSize;
                stream.Seek(position, SeekOrigin.Begin);
                stream.Write(info.Data.Array, info.Data.Offset, info.Data.Count);
                stream.Flush();
            }

            status.BitArray[info.ChunkId] = true;
            status.TransferedChunkCount += 1;

            // 同步到了最后一个文件块
            if (info.ChunkId == info.ChunkCount - 1)
            {
                // 确实同步完成
                if (status.TransferedChunkCount == info.ChunkCount)
                {
                    FileSyncContainer.Remove(info.Filename);
                    ForwardContainer.Remove(info.Filename);

                    var tag = status.Tag.Deserialize<KeyValuePair<string, ArraySegment<byte>>>();
                    NetworkMessageDispatcher.SendMessage(tag.Key, tag.Value, TempFolder + info.Filename);
                }
                else
                {
                    // 拉取未完成的文件块
                    var chunkId = GetChunkId(status.BitArray);

                    if (chunkId > 0)
                    {
                        var request = new TransferedChunkInfoRequest();

                        request.Filename = info.Filename;
                        request.ChunkId = chunkId;
                        request.ChunkSize = ChunkSize;

                        var session = ForwardContainer[info.Filename].AppSession;
                        session.SendRequestAsync(PULL_CHUNK_INFO_REQUEST, request);
                    }
                }
            }
        }

        private static void OnForwardFileInfoSync(BinaryMessage message)
        {
            var info = message.Body.Deserialize<TransferedFileInfo>();
            var fullname = TempFolder + info.Filename;

            if (!Directory.Exists(TempFolder))
                Directory.CreateDirectory(TempFolder);

            if (!File.Exists(fullname))
            {
                using (var stream = new FileStream(fullname, FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite))
                {
                    stream.SetLength(info.FileSize);
                    stream.Flush();
                }
            }

            var status = default(FileSyncStatus);

            if (!FileSyncContainer.TryGetValue(info.Filename, out status))
            {
                status = new FileSyncStatus();
                status.Tag = info.Tag;

                FileSyncContainer.Add(info.Filename, status);
            }
        }

        private static void OnForwardChunkInfoReply(BinaryMessage message)
        {
            // 传输文件块
            var reply = message.Body.Deserialize<TransferedChunkInfoReply>();
            var status = default(TransferedFileStatus);

            if (!ForwardContainer.TryGetValue(reply.Filename, out status))
                return;

            ++status.TransferedChunkCount;

            // 表示文件上传成功
            if (status.TransferedChunkCount == status.TotalChunkCount)
            {
                if (status.ProgressChanged != null)
                    status.ProgressChanged(status.FullName, 100.0f);

                if (status.Completed != null)
                    status.Completed(status.FullName);

                //ForwardContainer.Remove(status.Filename);
            }
            else
            {
                var progress = ((float)status.TransferedChunkCount / status.TotalChunkCount) * 100.0f;

                if (status.ProgressChanged != null)
                    status.ProgressChanged(status.FullName, progress);

                ++status.CurrentChunkIndex;

                // 继续上传文件
                if (status.CurrentChunkIndex < status.TotalChunkCount)
                    ForwardFileChunkAsync(status, status.CurrentChunkIndex);
            }
        }

        private static void OnForwardFileInfoReply(BinaryMessage message)
        {
            var pair = message.Body.Deserialize<KeyValuePair<string, ArraySegment<byte>>>();
            var filename = pair.Key;
            var body = pair.Value.Deserialize<KeyValuePair<string, ArraySegment<byte>>>();

            // 通知客户端收到回复了
            NetworkMessageDispatcher.SendMessage(body.Key, body.Value, filename);

            // 开始真正上传文件
            var status = ForwardContainer[filename];

            var count = Math.Min(status.TotalChunkCount, TransferedChunkCount);

            status.CurrentChunkIndex = count - 1;

            for (var i = 0; i < count; ++i)
                ForwardFileChunkAsync(status, i);
        }

        private static void OnUploadChunkInfoReply(BinaryMessage message)
        {
            // 传输文件块
            var reply = message.Body.Deserialize<TransferedChunkInfoReply>();
            var status = default(TransferedFileStatus);

            if (!UploadContainer.TryGetValue(reply.Filename, out status))
                return;

            ++status.TransferedChunkCount;

            // 表示文件上传成功
            if (status.TransferedChunkCount == status.TotalChunkCount)
            {
                if (status.ProgressChanged != null)
                    status.ProgressChanged(status.FullName, 100.0f);

                if (status.Completed != null)
                    status.Completed(status.FullName);

                UploadContainer.Remove(status.Filename);
            }
            else
            {
                var progress = ((float)status.TransferedChunkCount / status.TotalChunkCount) * 100.0f;

                if (status.ProgressChanged != null)
                    status.ProgressChanged(status.FullName, progress);

                ++status.CurrentChunkIndex;

                // 继续上传文件
                if (status.CurrentChunkIndex < status.TotalChunkCount)
                    UploadFileChunkAsync(status, status.CurrentChunkIndex);
            }
        }

        private static void OnUploadFileInfoReply(BinaryMessage message)
        {
            // 开始真正上传文件
            var filename = message.Body.Deserialize<string>();
            var status = UploadContainer[filename];
            var count = Math.Min(status.TotalChunkCount, TransferedChunkCount);

            status.CurrentChunkIndex = count - 1;

            for (var i = 0; i < count; ++i)
                UploadFileChunkAsync(status, i);
        }

        private static void OnDownloadError(BinaryMessage message)
        {
            var error = message.Body.Deserialize<ErrorInfo>();
            var status = DownloadContainer[error.Filename];

            if (status.Error != null)
                status.Error(error);

            DownloadContainer.Remove(error.Filename);
        }

        private static void OnDownloadChunkInfoReply(BinaryMessage message)
        {
            var info = message.Body.Deserialize<TransferedChunkInfo>();

            var status = DownloadContainer[info.Filename];

            using (var stream = new FileStream(status.FullName, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite))
            {
                stream.Seek(info.ChunkId * info.ChunkSize, SeekOrigin.Begin);
                stream.Write(info.Data.Array, info.Data.Offset, info.Data.Count);
                stream.Flush();
            }

            status.TotalChunkCount = info.ChunkCount;
            ++status.TransferedChunkCount;

            // 表示文件下载成功
            if (status.TransferedChunkCount == status.TotalChunkCount)
            {
                if (status.ProgressChanged != null)
                    status.ProgressChanged(status.FullName, 100.0f);

                if (status.Completed != null)
                    status.Completed(status.FullName);

                DownloadContainer.Remove(status.Filename);
            }
            else
            {
                var progress = ((float)status.TransferedChunkCount / status.TotalChunkCount) * 100.0f;

                if (status.ProgressChanged != null)
                    status.ProgressChanged(status.FullName, progress);

                // 继续下载文件
                if (status.CurrentChunkIndex == 0)
                {
                    var count = Math.Min(info.ChunkCount, TransferedChunkCount);

                    for (var i = 1; i < count; ++i)
                        DownloadFileChunkAsync(status, i);

                    status.CurrentChunkIndex += count;
                }
                else
                {
                    if (status.CurrentChunkIndex < status.TotalChunkCount)
                    {
                        DownloadFileChunkAsync(status, status.CurrentChunkIndex);
                        ++status.CurrentChunkIndex;
                    }
                }
            }
        }

        private static void OnDownloadFileInfoReply(BinaryMessage message)
        {
            // 开始真正下载文件
            var info = message.Body.Deserialize<TransferedFileInfo>();
            var status = DownloadContainer[info.Filename];

            using (var stream = new FileStream(status.FullName, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite))
            {
                stream.SetLength(info.FileSize);
                stream.Flush();
            }

            status.CurrentChunkIndex = 0;

            // 下载第一块
            DownloadFileChunkAsync(status, 0);
        }

        private static void UploadFileChunkAsync(TransferedFileStatus status, int chunkId)
        {
            var buffer = BufferPool.Acquire();

            using (var stream = new FileStream(status.FullName, FileMode.Open, FileAccess.Read, FileShare.Read))
            {
                stream.Seek(chunkId * ChunkSize, SeekOrigin.Begin);
                var readCount = stream.Read(buffer, 0, ChunkSize);
                var data = new ArraySegment<byte>(buffer, 0, readCount);

                var info = new TransferedChunkInfo();

                info.Filename = status.Filename;
                info.ChunkCount = status.TotalChunkCount;
                info.ChunkId = chunkId;
                info.ChunkSize = ChunkSize;
                info.Data = data;

                status.AppSession.SendRequestAsync(UPLOAD_CHUNK_INFO_REQUEST, info);
            }

            BufferPool.Release(buffer);
        }

        private static void ForwardFileChunkAsync(TransferedFileStatus status, int chunkId)
        {
            var buffer = BufferPool.Acquire();

            using (var stream = new FileStream(status.FullName, FileMode.Open, FileAccess.Read, FileShare.Read))
            {
                stream.Seek(chunkId * ChunkSize, SeekOrigin.Begin);
                var readCount = stream.Read(buffer, 0, ChunkSize);
                var data = new ArraySegment<byte>(buffer, 0, readCount);

                var info = new TransferedChunkInfo();

                info.Filename = status.Filename;
                info.ChunkCount = status.TotalChunkCount;
                info.ChunkId = chunkId;
                info.ChunkSize = ChunkSize;
                info.Data = data;

                status.AppSession.SendRequestAsync(FORWARD_CHUNK_INFO_REQUEST, info);
            }

            BufferPool.Release(buffer);
        }

        private static void DownloadFileChunkAsync(TransferedFileStatus status, int chunkId)
        {
            var request = new TransferedChunkInfoRequest();

            request.Filename = status.Filename;
            request.ChunkId = chunkId;

            status.AppSession.SendRequestAsync(DOWNLOAD_CHUNK_INFO_REQUEST, request);
        }

        // 获得未完成的文件块索引
        private static int GetChunkId(BitArray array)
        {
            for (var i = 0; i < array.Length; ++i)
                if (!array[i])
                    return i;

            return -1;
        }

        public static void UploadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string filename)
        {
            UploadFileAsync(session, filename, null, null);
        }

        public static void UploadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string filename, Action<string, float> progress)
        {
            UploadFileAsync(session, filename, progress, null);
        }

        public static void UploadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string filename, Action<string> completed)
        {
            UploadFileAsync(session, filename, null, completed);
        }

        /// <summary>
        /// 异步上传文件。
        /// </summary>
        public static void UploadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string filename, Action<string, float> progress, Action<string> completed)
        {
            var fullname = UploadFolder + filename;

            if (!File.Exists(fullname))
                throw new ArgumentException("filename");

            var fileinfo = new FileInfo(fullname);

            var fileSize = (int)fileinfo.Length;
            var chunkCount = fileSize % ChunkSize == 0 ? fileSize / ChunkSize : fileSize / ChunkSize + 1;

            var info = new TransferedFileInfo();

            info.Filename = filename;
            info.FileSize = fileSize;

            var status = new TransferedFileStatus();

            status.AppSession = session;
            status.FullName = fullname;
            status.Filename = filename;
            status.TotalChunkCount = chunkCount;
            status.ProgressChanged = progress;
            status.Completed = completed;

            UploadContainer.Add(status.Filename, status);

            // 发送上传文件请求
            session.SendRequestAsync(UPLOAD_FILE_INFO_REQUEST, info);
        }

        public static void SendFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string header, string filename)
        {
            SendFileAsync(session, header, filename, (Action<string, float>)null);
        }

        public static void SendFileAsync<T>(this IAppSession<BinaryProtocol, BinaryMessage> session, string header, T body, string filename)
        {
            SendFileAsync(session, header, body, filename, null, null);
        }

        public static void SendFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string header, string filename, Action<string, float> progress)
        {
            SendFileAsync(session, header, filename, progress, null);
        }

        public static void SendFileAsync<T>(this IAppSession<BinaryProtocol, BinaryMessage> session, string header, T body, string filename, Action<string, float> progress)
        {
            SendFileAsync(session, header, body, filename, progress, null);
        }

        public static void SendFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string header, string filename, Action<string, float> progress, Action<string> completed)
        {
            var pair = new KeyValuePair<string, ArraySegment<byte>>(header, default(ArraySegment<byte>));

            SendFileAsync(session, filename, pair, progress, completed);
        }

        public static void SendFileAsync<T>(this IAppSession<BinaryProtocol, BinaryMessage> session, string header, T body, string filename, Action<string, float> progress, Action<string> completed)
        {
            var buffer = BufferPool.Acquire();
            var segment = body.Serialize();

            Buffer.BlockCopy(segment.Array, segment.Offset, buffer, 0, segment.Count);

            var rawBody = new ArraySegment<byte>(buffer, 0, segment.Count);
            var pair = new KeyValuePair<string, ArraySegment<byte>>(header, rawBody);

            SendFileAsync(session, filename, pair, progress, completed);

            BufferPool.Release(buffer);
        }

        /// <summary>
        /// 异步转发文件。
        /// </summary>
        /// <remarks>注意，调用此方法传输的文件应该都是小文件（不大于 1M 的文件）。传输大文件可能会比较低效。</remarks>
        public static void SendFileAsync<T>(this IAppSession<BinaryProtocol, BinaryMessage> session, string filename, T tag, Action<string, float> progress, Action<string> completed)
        {
            if (!File.Exists(filename))
                throw new ArgumentException("filename");

            var fileinfo = new FileInfo(filename);

            var fileSize = (int)fileinfo.Length;
            var chunkCount = fileSize % ChunkSize == 0 ? fileSize / ChunkSize : fileSize / ChunkSize + 1;

            var info = new TransferedFileInfo();

            info.Filename = fileinfo.Name;
            info.FileSize = fileSize;

            var buffer = BufferPool.Acquire();
            var segment = tag.Serialize();

            Buffer.BlockCopy(segment.Array, segment.Offset, buffer, 0, segment.Count);

            info.Tag = new ArraySegment<byte>(buffer, 0, segment.Count);

            var status = new TransferedFileStatus();

            status.AppSession = session;
            status.FullName = filename;
            status.Filename = fileinfo.Name;
            status.TotalChunkCount = chunkCount;
            status.ProgressChanged = progress;
            status.Completed = completed;

            ForwardContainer.Add(status.Filename, status);

            // 发送转发文件请求
            session.SendRequestAsync(FORWARD_FILE_INFO_REQUEST, info);

            BufferPool.Release(buffer);
        }

        public static void DownloadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string filename)
        {
            DownloadFileAsync(session, filename, null, null);
        }

        public static void DownloadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string filename, Action<string> completed)
        {
            DownloadFileAsync(session, filename, null, completed);
        }

        public static void DownloadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string filename, Action<string, float> progress)
        {
            DownloadFileAsync(session, filename, progress, null);
        }

        /// <summary>
        /// 异步下载文件。
        /// </summary>
        public static void DownloadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string fullname, Action<string, float> progress, Action<string> completed)
        {
            DownloadFileAsync(session, fullname, progress, completed, null);
        }

        /// <summary>
        /// 异步下载文件。
        /// </summary>
        public static void DownloadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string fullname, Action<string, float> progress, Action<string> completed, Action<ErrorInfo> error)
        {
            if (string.IsNullOrEmpty(fullname))
                throw new ArgumentException("fullname 不能为空！");

            var actualName = TempFolder + fullname;
            var directory = Path.GetDirectoryName(TempFolder + fullname);

            if (!Directory.Exists(directory))
                Directory.CreateDirectory(directory);

            var status = new TransferedFileStatus();

            status.AppSession = session;
            status.FullName = actualName;
            status.Filename = fullname;
            status.ProgressChanged = progress;
            status.Completed = completed;
            status.Error = error;

            DownloadContainer.Add(status.Filename, status);

            var info = new TransferedFileInfo();

            info.Filename = fullname;
            info.FileSize = 0;

            // 发送下载文件请求
            session.SendRequestAsync(DOWNLOAD_FILE_INFO_REQUEST, info);
        }
    }
}