using VoxelEngine.World.Blocks;
using VoxelEngine.World.WorldGen;
using Xunit;

namespace VoxelEngine.Tests.WorldGen;

public class BiomeMapTests
{
    private static (BiomeMap map, BiomeRegistry biomes) Build(int seed = 42)
    {
        var blocks = new BlockRegistry();
        var biomes = new BiomeRegistry(seed, blocks);
        var noise = new NoiseSource(seed);
        var cells = new VoronoiCells(seed, 96f);
        return (new BiomeMap(noise, cells, biomes), biomes);
    }

    [Fact]
    public void Classify_HighElevation_IsMountains()
    {
        var (_, biomes) = Build();
        Assert.Same(biomes.Mountains, BiomeMap.Classify(0f, 0.5f, 0f, biomes));
    }

    [Fact]
    public void Classify_HotLowElevation_IsDesert()
    {
        var (_, biomes) = Build();
        Assert.Same(biomes.Desert, BiomeMap.Classify(0.5f, 0f, 0f, biomes));
    }

    [Fact]
    public void Classify_TemperateWooded_IsForest()
    {
        var (_, biomes) = Build();
        Assert.Same(biomes.Forest, BiomeMap.Classify(0f, 0f, 0.5f, biomes));
    }

    [Fact]
    public void Classify_ColdLow_IsPlains()
    {
        var (_, biomes) = Build();
        Assert.Same(biomes.Plains, BiomeMap.Classify(-0.9f, 0f, 0f, biomes));
    }

    [Fact]
    public void BiomeAt_IsConstantWithinACell()
    {
        var (map, _) = Build();
        IBiome a = map.BiomeAt(500f, 500f);
        IBiome b = map.BiomeAt(500.01f, 500.01f); // same cell
        Assert.Same(a, b);
    }
}