using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.IO;
using System.IO.MemoryMappedFiles;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;


namespace IPCLib
{
    // MmfCommunication.cs
    // MmfCommunication.cs - 完整修复版（包含 Disconnected 事件触发）
    public class MmfCommunication : IDisposable
    {
        const string kepId = "KEP";
        private MemoryMappedFile _mmf;
        private MemoryMappedViewAccessor _accessor;

        // ✅ 修复：使用两个独立的 Mutex
        private Mutex _heartbeatMutex;    // 心跳专用锁
        private Mutex _dataMutex;         // 数据专用锁

        private CancellationTokenSource _cts;
        private Task _heartbeatTask;
        private Task _receiveTask;

        private readonly string _mapName;
        private readonly bool _isServer;
        private readonly string _identity;

        private int _heartbeatInterval = 1000;
        private int _heartbeatTimeout = 20000;

        private bool _isConnected = false;
        private bool _isDisconnected = false;
        private bool _isPeerFrozen = false;
        private long _sessionId;
        private long _sequenceId = 0;
        private ConnectionStatus _currentStatus = ConnectionStatus.Connecting;

        public event Action<string> DataReceived;
        public event Action Connected;
        public event Action<string> Disconnected;
        public event Action<string> PeerFrozen;
        public event Action<string> PeerRecovered;
        public event Action<string> ErrorOccurred;
        public event Action<string> StatusChanged;
        public event Action ConnectionRecovered;

        public bool IsConnected => _isConnected;
        public bool IsDisconnected => _isDisconnected;
        public long SessionId => _sessionId;

        public MmfCommunication(string mapName, bool isServer, string identity)
        {
            _mapName = mapName;
            _isServer = isServer;
            _identity = identity;
            _sessionId = DateTime.Now.Ticks;
        }

        public async Task StartAsync()
        {
            try
            {
                if (_isServer)
                {
                    CleanupExistingMemory();
                    _mmf = MemoryMappedFile.CreateNew(_mapName, MemoryLayout.TotalSize);
                    InitializeMemory();
                    Log($"共享内存已创建 (SessionId: {_sessionId})");
                }
                else
                {
                    for (int i = 0; i < 50; i++)
                    {
                        try
                        {
                            _mmf = MemoryMappedFile.OpenExisting(_mapName);
                            break;
                        }
                        catch (FileNotFoundException)
                        {
                            await Task.Delay(100);
                        }
                    }

                    if (_mmf == null)
                        throw new TimeoutException("等待共享内存创建超时");

                    Log($"共享内存已打开 (SessionId: {_sessionId})");
                }

                _accessor = _mmf.CreateViewAccessor();

                // ✅ 修复：创建两个独立的 Mutex
                _heartbeatMutex = new Mutex(false, _mapName + "_HeartbeatMutex");
                _dataMutex = new Mutex(false, _mapName + "_DataMutex");

                await RegisterSessionIdAsync();

                _isConnected = true;
                _isDisconnected = false;

                _cts = new CancellationTokenSource();
                _heartbeatTask = HeartbeatLoopAsync(_cts.Token);
                _receiveTask = ReceiveLoopAsync(_cts.Token);

                Connected?.Invoke();
                Log("通讯模块已启动");
            }
            catch (Exception ex)
            {
                _isConnected = false;
                _isDisconnected = true;
                ErrorOccurred?.Invoke($"启动失败：{ex.Message}");
                throw;
            }
        }

        /// <summary>
        /// ✅ 心跳循环（使用独立的心跳锁）
        /// </summary>
        private async Task HeartbeatLoopAsync(CancellationToken ct)
        {
            Log($"❤️ 心跳任务启动");

            while (!ct.IsCancellationRequested && _isConnected)
            {
                try
                {
                    await Task.Delay(_heartbeatInterval, ct);

                    // ✅ 使用心跳专用锁，不与数据操作竞争
                    if (_heartbeatMutex?.WaitOne(500) == true)
                    {
                        try
                        {
                            SendHeartbeatInternal();
                        }
                        finally
                        {
                            try { _heartbeatMutex?.ReleaseMutex(); } catch { }
                        }
                    }
                    else
                    {
                        Log($"⚠️ 心跳锁超时（可忽略）");
                    }

                    CheckHeartbeatTimeout();
                }
                catch (OperationCanceledException) { break; }
                catch (Exception ex)
                {
                    ErrorOccurred?.Invoke($"心跳错误：{ex.Message}");
                }
            }

            Log($"❤️ 心跳任务退出");
        }

        /// <summary>
        /// ✅ 内部心跳发送（不获取锁，调用者负责）
        /// </summary>
        private void SendHeartbeatInternal()
        {
            if (_accessor == null) return;

            try
            {
                var header = ReadHeader();
                long now = DateTime.Now.Ticks;

                if (_identity == kepId)
                {
                    header.A_LastHeartbeat = now;
                    header.A_SequenceId++;
                }
                else
                {
                    header.B_LastHeartbeat = now;
                    header.B_SequenceId++;
                }

                header.ConnectionStatus = (int)_currentStatus;
                WriteHeader(header);
            }
            catch (Exception ex)
            {
                ErrorOccurred?.Invoke($"发送心跳失败：{ex.Message}");
            }
        }

        /// <summary>
        /// ✅ 检查心跳超时（使用心跳锁）
        /// </summary>
        private void CheckHeartbeatTimeout()
        {
            if (_accessor == null) return;

            try
            {
                if (_heartbeatMutex?.WaitOne(500) != true) return;

                try
                {
                    var header = ReadHeader();
                    long peerHeartbeatTicks = _identity == kepId ? header.B_LastHeartbeat : header.A_LastHeartbeat;

                    if (peerHeartbeatTicks == 0) return;

                    DateTime peerHeartbeat = new DateTime(peerHeartbeatTicks);
                    var timeSincePeer = DateTime.Now - peerHeartbeat;
                    double seconds = timeSincePeer.TotalSeconds;

                    if (seconds > _heartbeatTimeout * 3)
                    {
                        if (_currentStatus != ConnectionStatus.Disconnected)
                        {
                            Log($"❌ 硬断开：对端 {seconds:F0} 秒无心跳");
                            TriggerHardDisconnect($"硬断开：对端 {seconds:F0} 秒无心跳");
                        }
                    }
                    else if (seconds > _heartbeatTimeout * 2)
                    {
                        if (_currentStatus != ConnectionStatus.SoftDisconnected)
                        {
                            _currentStatus = ConnectionStatus.SoftDisconnected;
                            Log($"🔄 软断开：对端 {seconds:F0} 秒无心跳（可恢复）");
                            StatusChanged?.Invoke($"软断开：{seconds:F0}秒");
                        }
                    }
                    else if (seconds > _heartbeatTimeout)
                    {
                        if (_currentStatus == ConnectionStatus.Connected)
                        {
                            _currentStatus = ConnectionStatus.Warning;
                            Log($"⚠️ 心跳警告：对端 {seconds:F0} 秒无心跳");
                            StatusChanged?.Invoke($"警告：{seconds:F0}秒");
                        }
                    }
                    else
                    {
                        if (_currentStatus != ConnectionStatus.Connected)
                        {
                            Log($"✅ 心跳恢复：对端恢复正常 ({seconds:F1}秒)");
                            var previousStatus = _currentStatus;
                            _currentStatus = ConnectionStatus.Connected;

                            if (previousStatus == ConnectionStatus.SoftDisconnected)
                            {
                                ConnectionRecovered?.Invoke();
                                StatusChanged?.Invoke("连接已恢复");
                            }

                            header.ConnectionStatus = (int)ConnectionStatus.Connected;
                            WriteHeader(header);
                        }
                    }
                }
                finally
                {
                    try { _heartbeatMutex?.ReleaseMutex(); } catch { }
                }
            }
            catch (Exception ex)
            {
                ErrorOccurred?.Invoke($"心跳检查失败：{ex.Message}");
            }
        }

        /// <summary>
        /// ✅ 接收数据循环（使用独立的数据锁）
        /// </summary>
        private async Task ReceiveLoopAsync(CancellationToken ct)
        {
            Log($"📥 接收任务启动");

            int lockSuccessCount = 0;
            int lockTimeoutCount = 0;
            DateTime lastLogTime = DateTime.Now;

            while (!ct.IsCancellationRequested && _isConnected)
            {
                try
                {
                    await Task.Delay(100, ct);

                    if (_accessor == null || _dataMutex == null) continue;

                    // ✅ 使用数据专用锁，不与心跳竞争
                    if (_dataMutex.WaitOne(1000))
                    {
                        lockSuccessCount++;

                        try
                        {
                            var header = ReadHeader();
                            bool hasData = _identity == kepId ? header.B_HasData == 1 : header.A_HasData == 1;

                            if (hasData)
                            {
                                int offset = _identity == kepId ? MemoryLayout.BToAOffset : MemoryLayout.AToBOffset;
                                int dataLength = _identity == kepId ? header.B_DataLength : header.A_DataLength;

                                if (dataLength > 0 && dataLength <= 1000)
                                {
                                    string data = ReadPacketData(offset, dataLength);

                                    if (_identity == kepId)
                                        header.B_HasData = 0;
                                    else
                                        header.A_HasData = 0;

                                    WriteHeader(header);
                                    DataReceived?.Invoke(data);
                                    Log($"📥 收到数据：{data}");
                                }
                            }
                        }
                        catch (Exception ex)
                        {
                            Log($"❌ 读取数据异常：{ex.Message}");
                        }
                        finally
                        {
                            try { _dataMutex?.ReleaseMutex(); } catch { }
                        }
                    }
                    else
                    {
                        lockTimeoutCount++;

                        if ((DateTime.Now - lastLogTime).TotalSeconds > 2)
                        {
                            Log($"⚠️ 数据锁超时 (成功:{lockSuccessCount}, 超时:{lockTimeoutCount})");
                            lastLogTime = DateTime.Now;
                        }

                        await Task.Delay(50, ct);
                    }
                }
                catch (OperationCanceledException) { break; }
                catch (IOException ex)
                {
                    Log($"IO 异常：{ex.Message}");
                    TriggerDisconnect($"共享内存访问错误：{ex.Message}");
                    break;
                }
                catch (Exception ex)
                {
                    ErrorOccurred?.Invoke($"接收错误：{ex.Message}");
                }
            }

            Log($"📊 接收任务结束 (成功:{lockSuccessCount}, 超时:{lockTimeoutCount})");
        }

        private void TriggerDisconnect(string reason)
        {
            if (_isDisconnected) return;  // 避免重复触发

            _isDisconnected = true;
            _isConnected = false;
            _isPeerFrozen = false;

            Log($"触发断开事件：{reason}");
            Disconnected?.Invoke(reason);

            // 更新共享内存状态
            //UpdateConnectionStatus(0);
            Task.Run(() => UpdateConnectionStatus(0));
        }
        /// <summary>
        /// ✅ 发送数据（使用数据锁）
        /// </summary>
        public unsafe void SendData(string data)
        {
            if (_accessor == null || _dataMutex == null || !_isConnected)
                throw new InvalidOperationException("未连接");

            if (!_dataMutex.WaitOne(2000))
            {
                ErrorOccurred?.Invoke("获取数据锁超时（2 秒）");
                TriggerDisconnect("获取数据锁超时");
                return;
            }

            try
            {
                var header = ReadHeader();
                bool peerRead = _identity == kepId ? header.B_HasData == 0 : header.A_HasData == 0;

                if (!peerRead)
                {
                    ErrorOccurred?.Invoke("对端未读取上一条数据");
                    return;
                }

                int offset = _identity == kepId ? MemoryLayout.AToBOffset : MemoryLayout.BToAOffset;

                DataPacket packet = new DataPacket
                {
                    Timestamp = DateTime.Now.Ticks,
                    DataType = 2,
                    DataLength = Math.Min(data.Length, 1000),
                    SequenceId = ++_sequenceId
                };

                SharedMemoryHelper.WriteToFixedBuffer(packet.Data, data, 1000);
                WritePacket(offset, packet);

                if (_identity == kepId)
                {
                    header.A_HasData = 1;
                    header.A_DataLength = packet.DataLength;
                }
                else
                {
                    header.B_HasData = 1;
                    header.B_DataLength = packet.DataLength;
                }

                WriteHeader(header);
                Log($"📤 发送数据：{data}");
            }
            catch (IOException ex)
            {
                TriggerDisconnect($"发送数据失败：{ex.Message}");
            }
            catch (Exception ex)
            {
                ErrorOccurred?.Invoke($"发送失败：{ex.Message}");
            }
            finally
            {
                try { _dataMutex?.ReleaseMutex(); } catch { }
            }
        }

        private void TriggerHardDisconnect(string reason)
        {
            if (_currentStatus == ConnectionStatus.Disconnected) return;

            _currentStatus = ConnectionStatus.Disconnected;
            _isConnected = false;
            _isDisconnected = true;
            _isPeerFrozen = false;

            Log($"❌ 硬断开：{reason}");
            Disconnected?.Invoke(reason);
            UpdateConnectionStatus(0);
        }

        private void UpdateConnectionStatus(int status)
        {
            if (_accessor == null || _heartbeatMutex == null) return;

            try
            {
                if (_heartbeatMutex.WaitOne(500))
                {
                    try
                    {
                        var header = ReadHeader();
                        header.ConnectionStatus = status;
                        WriteHeader(header);
                    }
                    finally
                    {
                        try { _heartbeatMutex?.ReleaseMutex(); } catch { }
                    }
                }
            }
            catch { }
        }

        private unsafe string ReadPacketData(int offset, int dataLength)
        {
            DataPacket packet = new DataPacket();
            if(_accessor != null)
                _accessor.Read(offset, out packet);
            return SharedMemoryHelper.ReadFromFixedBuffer(packet.Data, dataLength);
        }

        private SharedMemoryHeader ReadHeader()
        {
            SharedMemoryHeader header = new SharedMemoryHeader();
            if (_accessor != null)
                _accessor.Read(0, out header);
            return header;
        }

        private void WriteHeader(SharedMemoryHeader header)
        {
            if (_accessor != null)
                _accessor.Write(0, ref header);
        }

        private unsafe void WritePacket(int offset, DataPacket packet)
        {
            if (_accessor != null)
                _accessor.Write(offset, ref packet);
        }

        private void CleanupExistingMemory()
        {
            try
            {
                var existing = MemoryMappedFile.OpenExisting(_mapName);
                Log("⚠️ 发现残留共享内存，已清理");
                existing.Dispose();
                GC.Collect();
                GC.WaitForPendingFinalizers();
                Thread.Sleep(100);
            }
            catch (FileNotFoundException) { }
        }

        private void InitializeMemory()
        {
            if (_accessor == null) return;

            var header = new SharedMemoryHeader
            {
                IsLocked = 0,
                A_LastHeartbeat = DateTime.Now.Ticks,
                B_LastHeartbeat = 0,
                A_SessionId = _sessionId,
                B_SessionId = 0,
                A_HasData = 0,
                B_HasData = 0,
                ConnectionStatus = 1,
                Reserved1 = 0,
                Reserved2 = 0,
                Reserved3 = 0,
                Reserved4 = 0
            };

            _accessor.Write(0, ref header);
        }

        private async Task RegisterSessionIdAsync()
        {
            if (_accessor == null || _heartbeatMutex == null) return;

            try
            {
                if (_heartbeatMutex.WaitOne(1000))
                {
                    try
                    {
                        var header = ReadHeader();

                        if (_identity == kepId)
                        {
                            header.A_SessionId = _sessionId;
                            header.A_LastHeartbeat = DateTime.Now.Ticks;
                        }
                        else
                        {
                            header.B_SessionId = _sessionId;
                            header.B_LastHeartbeat = DateTime.Now.Ticks;
                        }

                        WriteHeader(header);
                    }
                    finally
                    {
                        try { _heartbeatMutex?.ReleaseMutex(); } catch { }
                    }
                }
            }
            catch (Exception ex)
            {
                ErrorOccurred?.Invoke($"注册会话 ID 失败：{ex.Message}");
            }
        }

        private void Log(string msg) => System.Diagnostics.Debug.WriteLine($"[{_identity}] {msg}");

        public void Dispose()
        {
            if (!_isDisconnected)
            {
                TriggerHardDisconnect("本地关闭");
            }

            _cts?.Cancel();
            _heartbeatTask?.Wait(1000);
            _receiveTask?.Wait(1000);
            _accessor?.Dispose();
            _mmf?.Dispose();
            _heartbeatMutex?.Dispose();
            _dataMutex?.Dispose();
            _cts?.Dispose();
        }

    }

}