using System.Net.Sockets;
using System.Text;

namespace Housing.Services;

public sealed class TcpScpiClient : IScpiClient
{
    private readonly TcpClient _tcpClient;
    private readonly NetworkStream _stream;
    private readonly int _timeoutMilliseconds;

    private TcpScpiClient(TcpClient tcpClient, int timeoutMilliseconds)
    {
        _tcpClient = tcpClient;
        _stream = _tcpClient.GetStream();
        _timeoutMilliseconds = timeoutMilliseconds;
    }

    public static async Task<TcpScpiClient> ConnectAsync(string host, int port, int timeoutMilliseconds)
    {
        var tcpClient = new TcpClient();
        using var cancellation = new CancellationTokenSource(timeoutMilliseconds);

        try
        {
            await tcpClient.ConnectAsync(host, port, cancellation.Token);
        }
        catch (OperationCanceledException)
        {
            tcpClient.Dispose();
            throw new TimeoutException($"{host}:{port} 장비 연결 시간이 초과되었습니다.");
        }
        catch
        {
            tcpClient.Dispose();
            throw;
        }

        return new TcpScpiClient(tcpClient, timeoutMilliseconds);
    }

    public async Task SendAsync(string command)
    {
        using var cancellation = new CancellationTokenSource(_timeoutMilliseconds);
        var bytes = Encoding.ASCII.GetBytes(command.Trim() + "\n");
        await _stream.WriteAsync(bytes, cancellation.Token);
        await _stream.FlushAsync(cancellation.Token);
    }

    public async Task<string> QueryAsync(string command)
    {
        await SendAsync(command);

        using var cancellation = new CancellationTokenSource(_timeoutMilliseconds);
        var buffer = new byte[1024];
        var response = new StringBuilder();

        while (true)
        {
            int bytesRead;
            try
            {
                bytesRead = await _stream.ReadAsync(buffer, cancellation.Token);
            }
            catch (OperationCanceledException)
            {
                throw new TimeoutException($"{command} 응답 시간이 초과되었습니다.");
            }

            if (bytesRead == 0)
            {
                break;
            }

            var chunk = Encoding.ASCII.GetString(buffer, 0, bytesRead);
            response.Append(chunk);

            if (chunk.Contains('\n'))
            {
                break;
            }
        }

        return response.ToString().Trim();
    }

    public void Dispose()
    {
        _stream.Dispose();
        _tcpClient.Dispose();
    }
}