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>
    /// 表示文件分块基本信息。
    /// </summary>
    public struct ChunkBaseInfo
    {
        /// <summary>
        /// 相对文件路径。
        /// </summary>
        public string Filename { get; set; }
        /// <summary>
        /// 文件大小。
        /// </summary>
        public long FileSize { get; set; }
        /// <summary>
        /// 文件分块区间最小值。
        /// </summary>
        public long RangeMin { get; set; }
        /// <summary>
        /// 文件分块区间最大值。
        /// </summary>
        public long RangeMax { get; set; }
    }

    /// <summary>
    /// 表示文件分块数据信息。
    /// </summary>
    public struct ChunkDataInfo
    {
        /// <summary>
        /// 相对文件路径。
        /// </summary>
        public string Filename { get; set; }
        /// <summary>
        /// 文件大小。
        /// </summary>
        public long FileSize { get; set; }
        /// <summary>
        /// 文件分块区间最小值。
        /// </summary>
        public long RangeMin { get; set; }
        /// <summary>
        /// 文件分块区间最大值。
        /// </summary>
        public long RangeMax { get; set; }
        /// <summary>
        /// 文件块数据。
        /// </summary>
        public ArraySegment<byte> Data { get; set; }
    }

    /// <summary>
    /// 表示文件信息。
    /// </summary>
    public struct FileInfo
    {
        /// <summary>
        /// 相对文件路径。
        /// </summary>
        public string Filename { get; set; }
        /// <summary>
        /// 文件大小。
        /// </summary>
        public long FileSize { get; set; }
        /// <summary>
        /// 文件标签，可用作扩展。
        /// </summary>
        public string Tag { get; set; }
    }

    /// <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>
        /// 表示临时的文件名称。
        /// </summary>
        public string TempName;
        /// <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>
        /// 文件大小。
        /// </summary>
        public long FileSize;
        /// <summary>
        /// 表示文件标签。
        /// </summary>
        public string Tag;
        /// <summary>
        /// 表示文件还需传输多少字节。
        /// </summary>
        public long TransferedSize;
        /// <summary>
        /// 表示文件传输过程中的进度变化。
        /// </summary>
        public Action<string, string, float> ProgressChanged;
        /// <summary>
        /// 表示文件传输完毕事件。
        /// </summary>
        public Action<string, string> Completed;
    }

    public static class FileTransfer
    {
        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 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 int ChunkSize = 65536 - 8192;
        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>();

        /// <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(UPLOAD_FILE_INFO_REPLY, OnUploadFileInfoReply);
            NetworkMessageDispatcher.AddListener(UPLOAD_CHUNK_INFO_REPLY, OnUploadChunkInfoReply);
        }

        public static void Dispose()
        {
            NetworkMessageDispatcher.RemoveListener(DOWNLOAD_FILE_INFO_REPLY, OnDownloadFileInfoReply);
            NetworkMessageDispatcher.RemoveListener(DOWNLOAD_CHUNK_INFO_REPLY, OnDownloadChunkInfoReply);
            NetworkMessageDispatcher.RemoveListener(UPLOAD_FILE_INFO_REPLY, OnUploadFileInfoReply);
            NetworkMessageDispatcher.RemoveListener(UPLOAD_CHUNK_INFO_REPLY, OnUploadChunkInfoReply);
        }

        private static void OnUploadChunkInfoReply(BinaryMessage message)
        {
            var reply = message.Body.Deserialize<ChunkBaseInfo>();
            var status = UploadContainer[reply.Filename];

            status.TransferedSize -= reply.RangeMax - reply.RangeMin;

            // 表示文件上传成功
            if (status.TransferedSize == 0)
            {
                // 通知服务器上传文件成功
                var info = new FileInfo()
                {
                    Filename = status.Filename,
                    FileSize = status.FileSize,
                    Tag = status.Tag,
                };

                status.AppSession.SendRequestAsync(UPLOAD_FILE_INFO_REQUEST, info);
            }
            else
            {
                var progress = (float)(1.0f - (double)status.TransferedSize / status.FileSize) * 100.0f;

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

                //Debug.Log(reply.Filename+":["+reply.RangeMin+","+reply.RangeMax+")");

                // 继续上传文件
                UploadFileChunkAsync(status, reply.RangeMax);
            }
        }

        private static void OnUploadFileInfoReply(BinaryMessage message)
        {
            var reply = message.Body.Deserialize<FileInfo>();
            var status = UploadContainer[reply.Filename];

            if (status.ProgressChanged != null)
                status.ProgressChanged(status.FullName, status.Filename, 100.0f);

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

            UploadContainer.Remove(status.Filename);
        }

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

            var status = DownloadContainer[info.Filename];

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

            status.TransferedSize -= info.RangeMax - info.RangeMin;

            // 表示文件下载成功
            if (status.TransferedSize == 0)
            {
                // 重命名
                //File.Move(status.TempName, status.FullName);
                FileMove(status.TempName, status.FullName);

                if (status.ProgressChanged != null)
                    status.ProgressChanged(status.FullName, status.Filename, 100.0f);

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

                DownloadContainer.Remove(status.Filename);
            }
            else
            {
                var progress = (float)(1.0f - (double)status.TransferedSize / status.FileSize) * 100.0f;

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

                // 继续下载文件
                DownloadFileChunkAsync(status, info.RangeMax);
            }
        }

        private static void OnDownloadFileInfoReply(BinaryMessage message)
        {

            var info = message.Body.Deserialize<FileInfo>();
            var status = DownloadContainer[info.Filename];

            status.FileSize = info.FileSize;
            status.TransferedSize = info.FileSize;

            // 预留磁盘空间
            // 注意：这里的操作可能会非常耗时，当文件非常大时
            using (var stream = new FileStream(status.TempName, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite))
            {
                stream.SetLength(info.FileSize);
                stream.Flush();
            }

            // 开始真正下载文件
            DownloadFileChunkAsync(status, 0);
        }

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

            using (var stream = new FileStream(status.FullName, FileMode.Open, FileAccess.Read, FileShare.Read))
            {
                stream.Seek(offset, SeekOrigin.Begin);

                var readCount = stream.Read(buffer, 0, ChunkSize);
                var data = new ArraySegment<byte>(buffer, 0, readCount);

                var info = new ChunkDataInfo
                {
                    Filename = status.Filename,
                    FileSize = status.FileSize,
                    RangeMin = offset,
                    RangeMax = offset + readCount,
                    Data = data
                };

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

            BufferPool.Release(buffer);
        }

        private static void DownloadFileChunkAsync(TransferedFileStatus status, long offset)
        {
            var restSize = status.FileSize - offset;

            var info = new ChunkBaseInfo()
            {
                Filename = status.Filename,
                FileSize = status.FileSize,
                RangeMin = offset,
                RangeMax = restSize >= ChunkSize ? offset + ChunkSize : offset + restSize
            };

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

        /// <summary>
        /// 异步上传文件。
        /// </summary>
        public static void UploadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string fullname, string filename, string tag = null, Action<string, string, float> progress = null, Action<string, string> completed = null)
        {
            var fileinfo = new System.IO.FileInfo(fullname);

            var status = new TransferedFileStatus()
            {
                AppSession = session,
                FullName = fullname,
                Filename = filename,
                FileSize = fileinfo.Length,
                Tag = tag,
                TransferedSize = fileinfo.Length,
                ProgressChanged = progress,
                Completed = completed
            };

            UploadContainer[status.Filename] = status;

            UploadFileChunkAsync(status, 0);
        }

        /// <summary>
        /// 异步下载文件。
        /// </summary>
        public static void DownloadFileAsync(this IAppSession<BinaryProtocol, BinaryMessage> session, string fullname, string filename, string tag = null, Action<string, string, float> progress = null, Action<string, string> completed = null)
        {
            var status = new TransferedFileStatus()
            {
                AppSession = session,
                FullName = fullname,
                TempName = fullname + ".tmp",
                Filename = filename,
                Tag = tag,
                ProgressChanged = progress,
                Completed = completed,
            };

            DownloadContainer[status.Filename] = status;

            var info = new FileInfo()
            {
                Filename = filename,
                Tag = tag
            };

            // 发送下载文件请求
            session.SendRequestAsync(DOWNLOAD_FILE_INFO_REQUEST, info);
        }
        /// <summary>
        /// 文件移动
        /// </summary>
        /// <param name="sourceFile"></param>
        /// <param name="targetFile"></param>
        private static void FileMove(string sourceFile, string targetFile)
        {
            if (File.Exists(targetFile))
            {
                File.Delete(targetFile);
            }
            else
            {
                string directoryName = Path.GetDirectoryName(targetFile);
                if (!Directory.Exists(directoryName) && directoryName != "")
                {
                    Directory.CreateDirectory(directoryName);
                }
            }
            try
            {
                File.Move(sourceFile, targetFile);
            }
            catch (Exception exception)
            {
                Debug.LogError(exception.Message);
            }
        }
    }

}