SerialPortConnectionListener.cs

using System;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
 
namespace OSDP.Net.Connections;

public class SerialPortConnectionListener : OsdpConnectionListener
{
    private readonly string _portName;

    public SerialPortConnectionListener(
        string portName, int baudRate, ILoggerFactory loggerFactory = null) : base(baudRate, loggerFactory)
    {
        _portName = portName;
    }

    public override async Task Start(Func<IOsdpConnection, Task> newConnectionHandler)
    {
        IsRunning = true;
 
        Logger?.LogInformation("Starting serial port listener on {Port} @ {BaudRate} baud", _portName, BaudRate);
 
        await OpenSerialPort(newConnectionHandler);
    }

    private async Task OpenSerialPort(Func<IOsdpConnection, Task> newConnectionHandler)
    {
        try
        {
            var connection = new SerialPortOsdpConnection(_portName, BaudRate)
            {
                // An ACU discards its buffers before each command because it drives a strict
                // command/reply cycle. A PD must not: this listener serves devices that reply to an
                // incoming stream, and DiscardInBuffer throws away bytes of a command that is
                // already arriving. Those bytes are dropped below the tracing layer, so the loss is
                // invisible in a packet capture.
                DiscardBuffersBeforeWrite = false
            };
            await connection.Open();
 
            Logger?.LogDebug("Serial port {Port} opened successfully", _portName);
 
            var task = Task.Run(async () =>
            {
                try
                {
                    await newConnectionHandler(connection);
                }
                catch (Exception ex)
                {
                    Logger?.LogError(ex, "Error in serial connection handler");
                }
                finally
                {
                    // If still running, reopen the serial port after a brief delay
                    if (IsRunning)
                    {
                        Logger?.LogDebug("Serial connection closed, reopening port {Port}", _portName);
                        await Task.Delay(1000); // Brief delay before reopening
                        await OpenSerialPort(newConnectionHandler);
                    }
                }
            });
            
            RegisterConnection(connection, task);
        }
        catch (Exception ex)
        {
            Logger?.LogError(ex, "Failed to open serial port {Port}", _portName);
            
            // Retry after delay if still running
            if (IsRunning)
            {
                await Task.Delay(5000); // Longer delay on error
                await OpenSerialPort(newConnectionHandler);
            }
        }
    }
}