using System.IO.Ports;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using Microsoft.Extensions.Options;
using YD_TrainingCompetition_Api.Options;

namespace YD_TrainingCompetition_Api.Serial;

public sealed class SerialGateway : ISerialGateway
{
    private static readonly HttpClient DebugClient = new();
    private readonly SerialPort _serialPort;

    public SerialGateway(IOptions<Serial24GOptions> options)
    {
        var cfg = options.Value;
        _serialPort = new SerialPort
        {
            PortName = cfg.PortName,
            BaudRate = cfg.BaudRate,
            DataBits = cfg.DataBits,
            StopBits = StopBits.One,
            Parity = Parity.None,
            ReadBufferSize = cfg.ReadBufferSize,
            WriteBufferSize = cfg.WriteBufferSize
        };

        _serialPort.DataReceived += (_, _) =>
        {
            try
            {
                var len = _serialPort.BytesToRead;
                if (len <= 0)
                {
                    return;
                }

                var buf = new byte[len];
                _serialPort.Read(buf, 0, len);
                #region debug-point A:serial-receive
                _ = DebugReportAsync("A", "SerialGateway.DataReceived", "[DEBUG] serial bytes received", new
                {
                    port = _serialPort.PortName,
                    length = len,
                    hex = Convert.ToHexString(buf)
                });
                #endregion
                DataReceived?.Invoke(this, buf);
            }
            catch
            {
            }
        };
    }

    public event EventHandler<byte[]>? DataReceived;
    public bool IsOpen => _serialPort.IsOpen;
    public string? CurrentPort => _serialPort.IsOpen ? _serialPort.PortName : null;

    public string[] GetAvailablePorts() => SerialPort.GetPortNames().OrderBy(x => x, StringComparer.OrdinalIgnoreCase).ToArray();

    public Task OpenAsync(string portName, CancellationToken cancellationToken = default)
    {
        if (_serialPort.IsOpen)
        {
            _serialPort.Close();
        }

        _serialPort.PortName = portName;
        _serialPort.Open();
        #region debug-point A:serial-open
        _ = DebugReportAsync("A", "SerialGateway.OpenAsync", "[DEBUG] serial opened", new
        {
            port = _serialPort.PortName,
            baudRate = _serialPort.BaudRate,
            dataBits = _serialPort.DataBits,
            readBufferSize = _serialPort.ReadBufferSize,
            writeBufferSize = _serialPort.WriteBufferSize
        });
        #endregion
        return Task.CompletedTask;
    }

    public Task CloseAsync(CancellationToken cancellationToken = default)
    {
        if (_serialPort.IsOpen)
        {
            _serialPort.Close();
        }

        return Task.CompletedTask;
    }

    public void ClearInputBuffer()
    {
        if (_serialPort.IsOpen)
        {
            _serialPort.DiscardInBuffer();
        }
    }

    public Task SendAsync(byte[] data, CancellationToken cancellationToken = default)
    {
        if (!_serialPort.IsOpen)
        {
            throw new InvalidOperationException("Serial port is not open");
        }

        #region debug-point B:serial-send
        _ = DebugReportAsync("B", "SerialGateway.SendAsync", "[DEBUG] serial bytes sent", new
        {
            port = _serialPort.PortName,
            length = data.Length,
            hex = Convert.ToHexString(data)
        });
        #endregion
        _serialPort.Write(data, 0, data.Length);
        return Task.CompletedTask;
    }

    private static async Task DebugReportAsync(string hypothesisId, string location, string msg, object data)
    {
        try
        {
            var url = "http://127.0.0.1:7777/event";
            var sessionId = "serial-gateway-download";
            var envPath = Path.Combine(Directory.GetCurrentDirectory(), ".dbg", "serial-gateway-download.env");
            if (File.Exists(envPath))
            {
                foreach (var line in await File.ReadAllLinesAsync(envPath))
                {
                    if (line.StartsWith("DEBUG_SERVER_URL=", StringComparison.Ordinal))
                    {
                        url = line["DEBUG_SERVER_URL=".Length..].Trim();
                    }
                    else if (line.StartsWith("DEBUG_SESSION_ID=", StringComparison.Ordinal))
                    {
                        sessionId = line["DEBUG_SESSION_ID=".Length..].Trim();
                    }
                }
            }

            var payload = JsonSerializer.Serialize(new
            {
                sessionId,
                runId = "pre-fix",
                hypothesisId,
                location,
                msg,
                data,
                ts = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()
            });
            using var content = new StringContent(payload, Encoding.UTF8, "application/json");
            await DebugClient.PostAsync(url, content);
        }
        catch
        {
        }
    }
}