using Xunit;
using ytLive.Helpers;

namespace ytLive.Tests;

/// <summary>The mono output exists because single-sided audio is inaudible to this creator, not
/// merely unbalanced. The fold has to move content to BOTH sides — a "fold" that keeps a channel
/// empty would leave the exact problem in place — and it must not touch mono buffers.</summary>
public class AudioFoldTests
{
    [Fact]
    public void Folding_to_mono_puts_a_one_sided_signal_on_both_sides()
    {
        // Hard LEFT content becomes audible on the right at half amplitude.
        var left = new[] { 0.5f, 0f, 0.5f, 0f };
        AudioFold.ToMono(left, 2);
        Assert.Equal(new[] { 0.25f, 0.25f, 0.25f, 0.25f }, left);

        // Hard RIGHT — the inaudible case — becomes audible on the left.
        var right = new[] { 0f, 0.6f };
        AudioFold.ToMono(right, 2);
        Assert.Equal(0.3f, right[0], 4);
        Assert.Equal(0.3f, right[1], 4);

        // Centred material keeps its level (the mic case): no quietening.
        var centred = new[] { 0.4f, 0.4f };
        AudioFold.ToMono(centred, 2);
        Assert.Equal(0.4f, centred[0], 4);

        // Mono buffers are untouched — folding is about pairs.
        var mono = new[] { 0.7f, 0.2f };
        AudioFold.ToMono(mono, 1);
        Assert.Equal(new[] { 0.7f, 0.2f }, mono);
    }
}