using System.Device.Gpio;

namespace GPIORaspberryPI4;

public sealed class RelayOutput : IRelayOutput
{
    private readonly GpioController _gpio;
    private readonly int _pin;
    private readonly bool _activeLow;
    private bool _disposed;

    public bool IsOn { get; private set; }

    public RelayOutput(int pin, bool activeLow = false)
    {
        _pin = pin;
        _activeLow = activeLow;

        _gpio = new GpioController();
        _gpio.OpenPin(_pin, PinMode.Output);

        // Safe default state
        WriteInternal(false);
    }

    public void On()
    {
        ThrowIfDisposed();
        WriteInternal(true);
    }

    public void Off()
    {
        ThrowIfDisposed();
        WriteInternal(false);
    }

    public void Set(bool on)
    {
        ThrowIfDisposed();
        WriteInternal(on);
    }

    private void WriteInternal(bool on)
    {
        var pinValue = _activeLow
            ? (on ? PinValue.Low : PinValue.High)
            : (on ? PinValue.High : PinValue.Low);

        _gpio.Write(_pin, pinValue);
        IsOn = on;
    }

    private void ThrowIfDisposed()
    {
        if (_disposed)
            throw new ObjectDisposedException(nameof(RelayOutput));
    }

    public void Dispose()
    {
        if (_disposed)
            return;

        try
        {
            // Fail-safe: relay OFF on dispose
            WriteInternal(false);
        }
        catch
        {
            // Ignore cleanup errors
        }

        if (_gpio.IsPinOpen(_pin))
            _gpio.ClosePin(_pin);

        _gpio.Dispose();
        _disposed = true;
    }
}