using VoiceCat.Dsp;
using System.Text.Json;

namespace VoiceCat.Tests;

public sealed class DspTests
{
    [Fact]
    public void SuppressesNoiseAndPreservesUnsupportedSampleRates()
    {
        using var processor = new RnnoiseProcessor();
        short[] pcm = new short[960];
        uint random = 0x12345678;
        double inputEnergy = 0, outputEnergy = 0;
        for (int frame = 0; frame < 200; frame++)
        {
            FillNoise(pcm, ref random);
            if (frame >= 60) foreach (short value in pcm) inputEnergy += (double)value * value;
            processor.Process(pcm);
            if (frame >= 60) foreach (short value in pcm) outputEnergy += (double)value * value;
        }
        Assert.True(Math.Sqrt(outputEnergy / inputEnergy) < 0.2);
        using var fixture = JsonDocument.Parse(File.ReadAllText(Path.Combine(AppContext.BaseDirectory, "Fixtures", "rnnoise.json")));
        short[] expected = fixture.RootElement.GetProperty("samples").EnumerateArray().Select(value => value.GetInt16()).ToArray();
        Assert.Equal(pcm.Length, expected.Length);
        for (int i = 0; i < pcm.Length; i++) Assert.InRange(Math.Abs(pcm[i] - expected[i]), 0, 1);
        FillNoise(pcm, ref random);
        short[] original = (short[])pcm.Clone();
        processor.Process(pcm, 16000);
        Assert.Equal(original, pcm);
        Assert.Throws<ArgumentException>(() => processor.Process(new short[481]));
        processor.Dispose();
        Assert.Throws<ObjectDisposedException>(() => processor.Process(pcm));
    }

    [Fact]
    public void VadStartsClosedAndUsesMonotonicHangTime()
    {
        var clock = new ManualTimeProvider();
        var processor = new EnergyVadProcessor(0.02f, TimeSpan.FromMilliseconds(300), clock);
        Assert.False(processor.Process(new short[480]));
        Assert.True(processor.Process(new short[] { 32767 }));
        clock.Advance(299);
        Assert.True(processor.Process([]));
        clock.Advance(1);
        Assert.False(processor.Process(new short[480]));
        processor.Threshold = 0.5f;
        Assert.False(processor.Process(new short[] { 1000 }));
        Assert.Throws<ArgumentOutOfRangeException>(() => processor.Threshold = float.NaN);
    }

    internal static void FillNoise(Span<short> pcm, ref uint random)
    {
        for (int i = 0; i < pcm.Length; i++)
        {
            random ^= random << 13;
            random ^= random >> 17;
            random ^= random << 5;
            pcm[i] = (short)((int)(random % 6001) - 3000);
        }
    }

    private sealed class ManualTimeProvider : TimeProvider
    {
        private long timestamp;
        public override long TimestampFrequency => 1000;
        public override long GetTimestamp() => timestamp;
        public void Advance(int milliseconds) => timestamp += milliseconds;
    }
}