using Nonemm.Core;

namespace Nonemm.Spotting.Tests;

public class BandmapSliceTests
{
    private static Frequency Khz(double kilohertz) => Frequency.FromHertz((long)(kilohertz * 1000));

    [Fact]
    public void ACentredSliceHasTheReceiverInTheMiddleEvenPastTheBandEdge()
    {
        (Frequency low, Frequency high) = BandmapSlice.Choose(
            Bands.Band20M, Khz(14_348), 20_000, centred: true, previousLow: null);

        Assert.Equal(Khz(14_338), low);
        Assert.Equal(Khz(14_358), high);
    }

    [Fact]
    public void ASliceThatDoesNotFollowKeepsItsPlaceWhileTheReceiverIsInside()
    {
        (Frequency low, _) = BandmapSlice.Choose(
            Bands.Band20M, Khz(14_025), 20_000, centred: false, previousLow: Khz(14_010));

        Assert.Equal(Khz(14_010), low);
    }

    [Fact]
    public void ASliceThatDoesNotFollowMovesWhenTheReceiverLeaves()
    {
        (Frequency low, _) = BandmapSlice.Choose(
            Bands.Band20M, Khz(14_100), 20_000, centred: false, previousLow: Khz(14_010));

        Assert.Equal(Khz(14_090), low);
    }

    [Fact]
    public void AMovedSliceStaysInsideTheBand()
    {
        (Frequency low, _) = BandmapSlice.Choose(
            Bands.Band20M, Bands.Band20M.Low, 20_000, centred: false, previousLow: null);

        Assert.Equal(Bands.Band20M.Low, low);
    }

    [Fact]
    public void ASpanOfZeroShowsTheWholeBand()
    {
        (Frequency low, Frequency high) = BandmapSlice.Choose(
            Bands.Band20M, Khz(14_025), 0, centred: true, previousLow: null);

        Assert.Equal(Bands.Band20M.Low, low);
        Assert.Equal(Bands.Band20M.High, high);
    }

    [Fact]
    public void ZoomingKeepsTheFrequencyUnderThePointerAtTheSameHeight()
    {
        // the pointer is a quarter of the way down a 40 kHz slice
        Frequency low = BandmapSlice.Zoom(Khz(14_000), 40_000, 20_000, Khz(14_010));

        Assert.Equal(Khz(14_005), low);
    }
}