using KeyOverlay.Core;
using Xunit;

namespace KeyOverlay.Core.Tests;

public class LayerProtocolTests
{
    [Fact]
    public void BuildRequest_Is32BytesWithCommandAndVersion()
    {
        var request = LayerProtocol.BuildRequest();
        Assert.Equal(32, request.Length);
        Assert.Equal(0xE0, request[0]);
        Assert.Equal(0x01, request[1]);
    }

    [Fact]
    public void TryParse_ReadsLayerAndMasks()
    {
        var payload = new byte[32];
        payload[0] = 0xE0;
        payload[1] = 0x01;
        payload[2] = 2;
        payload[3] = 0b0000_0101; // layer_state = layers 0 and 2
        payload[7] = 0b0000_0001; // default_layer_state = layer 0

        Assert.True(LayerProtocol.TryParse(payload, out var report));
        Assert.Equal(2, report.HighestLayer);
        Assert.Equal(5u, report.LayerState);
        Assert.Equal(1u, report.DefaultLayerState);
    }

    [Fact]
    public void TryParse_ReadsLittleEndianMask()
    {
        var payload = new byte[32];
        payload[0] = 0xE0;
        payload[1] = 0x01;
        payload[4] = 0x01; // bit 8 of layer_state

        Assert.True(LayerProtocol.TryParse(payload, out var report));
        Assert.Equal(0x100u, report.LayerState);
    }

    [Fact]
    public void TryParse_RejectsUnhandledResponse()
    {
        var payload = new byte[32];
        payload[0] = 0xFF; // old firmware: "unhandled"
        Assert.False(LayerProtocol.TryParse(payload, out _));
    }

    [Fact]
    public void TryParse_RejectsUnknownProtocolVersion()
    {
        var payload = new byte[32];
        payload[0] = 0xE0;
        payload[1] = 0x7F;
        Assert.False(LayerProtocol.TryParse(payload, out _));
    }

    [Fact]
    public void TryParse_RejectsShortPayload() =>
        Assert.False(LayerProtocol.TryParse(new byte[5], out _));
}