using System;
using System.IO.Ports;
using System.Threading;
using System.Threading.Tasks;

namespace ERVSimulator.Protocol
{
    // 공용 시리얼 채널 - byte 단위 수신 콜백 + 송신 helper
    public class SerialChannel : IDisposable
    {
        private SerialPort? _port;
        private CancellationTokenSource? _cts;
        private bool _disposed;

        public string ChannelName { get; }
        public event Action<byte>? ByteReceived;
        public event Action<string>? Log;
        public event Action<bool>? ConnectionChanged;
        public bool IsConnected => _port?.IsOpen == true;

        public SerialChannel(string channelName) { ChannelName = channelName; }

        public static string[] GetAvailablePorts() => SerialPort.GetPortNames();

        public bool Connect(string portName, int baudRate)
        {
            try
            {
                Disconnect();
                _port = new SerialPort(portName, baudRate, Parity.None, 8, StopBits.One)
                {
                    ReadTimeout = 100,
                    WriteTimeout = 200,
                    Handshake = Handshake.None,
                    DtrEnable = false,
                    RtsEnable = false,
                };
                _port.Open();
                _cts = new CancellationTokenSource();
                _ = Task.Run(() => ReadLoop(_cts.Token));
                Log?.Invoke($"[{ChannelName}] Connected {portName} @ {baudRate}");
                ConnectionChanged?.Invoke(true);
                return true;
            }
            catch (Exception ex)
            {
                Log?.Invoke($"[{ChannelName}] Connect FAIL: {ex.Message}");
                return false;
            }
        }

        public void Disconnect()
        {
            try { _cts?.Cancel(); } catch { }
            try { _port?.Close(); } catch { }
            _port?.Dispose();
            _port = null;
            ConnectionChanged?.Invoke(false);
        }

        void ReadLoop(CancellationToken ct)
        {
            var buf = new byte[64];
            while (!ct.IsCancellationRequested && _port != null && _port.IsOpen)
            {
                try
                {
                    int n = _port.Read(buf, 0, buf.Length);
                    for (int i = 0; i < n; i++) ByteReceived?.Invoke(buf[i]);
                }
                catch (TimeoutException) { /* expected */ }
                catch (Exception ex)
                {
                    Log?.Invoke($"[{ChannelName}] ReadLoop error: {ex.Message}");
                    break;
                }
            }
        }

        public bool Send(byte[] data, int length)
        {
            if (_port == null || !_port.IsOpen) return false;
            try
            {
                _port.Write(data, 0, length);
                return true;
            }
            catch (Exception ex)
            {
                Log?.Invoke($"[{ChannelName}] Send FAIL: {ex.Message}");
                return false;
            }
        }

        public void Dispose()
        {
            if (_disposed) return;
            _disposed = true;
            Disconnect();
        }
    }

    public static class HexFormat
    {
        public static string Bytes(byte[] data, int length)
        {
            var sb = new System.Text.StringBuilder(length * 3);
            for (int i = 0; i < length; i++)
            {
                if (i > 0) sb.Append(' ');
                sb.Append(data[i].ToString("X2"));
            }
            return sb.ToString();
        }
    }
}