namespace ytLive.Services.Audio;

/// <summary>
/// Computes the smoothed mic level (0..1) from captured samples. Pure —
/// unit-tested; the <see cref="AudioMixer"/> only feeds it and forwards the
/// result. RMS-based so it tracks perceived loudness, smoothed so the meter
/// does not flicker.
/// </summary>
public sealed class AudioLevelMeter
{
    private const float Smoothing = 0.2f;
    private float _level;

    public float Level => _level;

    public float Push(AudioSample sample)
    {
        if (sample.Samples.Length == 0)
            return _level;

        double sumSquares = 0;
        var count = 0;
        foreach (var value in sample.Samples)
        {
            sumSquares += value * value;
            count++;
        }

        var rms = (float)Math.Sqrt(sumSquares / count);
        _level = _level * (1 - Smoothing) + rms * Smoothing;
        return _level;
    }

    public void Reset() => _level = 0;
}