namespace Nonemm.Recorder.Tests;

/// A sound system with no hardware: the test lists devices and pushes samples.
internal sealed class FakeBackend : AudioBackend
{
    private readonly Dictionary<string, CaptureHandler> handlers = [];

    public List<AudioDeviceInfo> Devices { get; } = [];

    public int PlaybackOpened { get; private set; }

    public IReadOnlyList<AudioDeviceInfo> ListDevices() => [.. Devices];

    public IDisposable OpenCapture(AudioDeviceInfo device, CaptureHandler handler)
    {
        handlers[device.Name] = handler;
        return new Closer(() => handlers.Remove(device.Name));
    }

    public IDisposable OpenPlayback(PlaybackHandler handler)
    {
        PlaybackOpened++;
        return new Closer(() => { });
    }

    public bool IsOpen(string name) => handlers.ContainsKey(name);

    /// Delivers `frames` of interleaved samples, `value` in each channel `channel`.
    public void Push(string name, int channels, int frames, int channel, float value)
    {
        float[] samples = new float[frames * channels];
        for (int frame = 0; frame < frames; frame++)
        {
            samples[frame * channels + channel] = value;
        }
        handlers[name](samples);
    }

    public void Dispose()
    {
    }

    private sealed class Closer(Action close) : IDisposable
    {
        public void Dispose() => close();
    }
}