using KeyOverlay.Core;
using Xunit;

namespace KeyOverlay.Core.Tests;

public class KeymapTests
{
    // 2 layers, 10 matrix rows x 6 cols. Layer 1 is mostly transparent.
    private static string Vil(string layer0Row0, string layer1Row0, string layer0Row5 = "[\"KC_BSPACE\",\"KC_0\",\"KC_9\",\"KC_8\",\"KC_7\",\"KC_6\"]")
    {
        string Layer(string row0, string row5)
        {
            var rows = new List<string>();
            for (var r = 0; r < 10; r++)
            {
                rows.Add(r switch
                {
                    0 => row0,
                    5 => row5,
                    4 or 9 => "[-1,-1,-1,\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\"]",
                    _ => "[\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\"]",
                });
            }
            return "[" + string.Join(",", rows) + "]";
        }
        var tr = "[\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\"]";
        return "{\"layout\":[" + Layer(layer0Row0, layer0Row5) + "," + Layer(layer1Row0, tr) + "]}";
    }

    private static readonly string Row0L0 = "[\"KC_ESCAPE\",\"KC_1\",\"KC_2\",\"KC_3\",\"KC_4\",\"KC_5\"]";
    private static readonly string Row0L1 = "[\"KC_GRAVE\",\"KC_F1\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"MO(2)\"]";

    [Fact]
    public void Parse_ReadsLayerCount()
    {
        var km = Keymap.Parse(Vil(Row0L0, Row0L1));
        Assert.Equal(2, km.LayerCount);
    }

    [Fact]
    public void Parse_MapsLeftHalfRowsAndCols()
    {
        var km = Keymap.Parse(Vil(Row0L0, Row0L1));
        Assert.Equal("KC_ESCAPE", km.GetRaw(0, new KeyId(Side.Left, 0, 0)));
        Assert.Equal("KC_5", km.GetRaw(0, new KeyId(Side.Left, 0, 5)));
    }

    [Fact]
    public void Parse_MapsRightHalfFromMatrixRows5To9()
    {
        var km = Keymap.Parse(Vil(Row0L0, Row0L1));
        Assert.Equal("KC_BSPACE", km.GetRaw(0, new KeyId(Side.Right, 0, 0)));
        Assert.Equal("KC_6", km.GetRaw(0, new KeyId(Side.Right, 0, 5)));
    }

    [Fact]
    public void Parse_SkipsMinusOnePositions()
    {
        var km = Keymap.Parse(Vil(Row0L0, Row0L1));
        Assert.Null(km.GetRaw(0, new KeyId(Side.Left, 4, 0)));
        Assert.NotNull(km.GetRaw(0, new KeyId(Side.Left, 4, 3)));
    }

    [Fact]
    public void Describe_TransparentFallsThroughToLowerLayer()
    {
        var km = Keymap.Parse(Vil(Row0L0, Row0L1));
        var d = km.Describe(1, new KeyId(Side.Left, 0, 2));
        Assert.Equal("2", d.Main);
        Assert.True(d.FromLowerLayer);
    }

    [Fact]
    public void Describe_OwnKeyIsNotFromLowerLayer()
    {
        var km = Keymap.Parse(Vil(Row0L0, Row0L1));
        var d = km.Describe(1, new KeyId(Side.Left, 0, 1));
        Assert.Equal("F1", d.Main);
        Assert.False(d.FromLowerLayer);
    }

    [Fact]
    public void UsedLayers_SkipsLayersWithoutOwnKeys()
    {
        var allTransparent = "[\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\",\"KC_TRNS\"]";
        var km = Keymap.Parse(Vil(Row0L0, allTransparent));
        Assert.Equal(new[] { 0 }, km.UsedLayers);
    }

    [Fact]
    public void UsedLayers_IncludesLayersWithOwnKeys()
    {
        var km = Keymap.Parse(Vil(Row0L0, Row0L1));
        Assert.Equal(new[] { 0, 1 }, km.UsedLayers);
    }

    [Theory]
    [InlineData("{}")]
    [InlineData("{\"layout\":[]}")]
    [InlineData("{\"layout\":[[[\"KC_A\"]]]}")]
    [InlineData("not json")]
    public void Parse_RejectsInvalidInput(string json) =>
        Assert.Throws<FormatException>(() => Keymap.Parse(json));

    [Fact]
    public void IsLit_RequiresBaseKeyDown()
    {
        var pressed = new PressedKeys();
        var a = Keycodes.Describe("KC_A");
        Assert.False(Keymap.IsLit(a, pressed));
        pressed.Apply(0x1E, false, true);
        Assert.True(Keymap.IsLit(a, pressed));
    }

    [Fact]
    public void IsLit_ShiftWrappedKeyNeedsShift()
    {
        var pressed = new PressedKeys();
        var bang = Keycodes.Describe("LSFT(KC_1)");
        pressed.Apply(0x02, false, true);
        Assert.False(Keymap.IsLit(bang, pressed));
        pressed.Apply(0x2A, false, true);
        Assert.True(Keymap.IsLit(bang, pressed));
    }
}