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

namespace VoxelEngine.Tests.WorldGen;

public class BiomeTests
{
    [Fact]
    public void Desert_TopAndFiller_AreSand()
    {
        var blocks = new BlockRegistry();
        var biomes = new BiomeRegistry(42, blocks);
        Assert.Equal("Sand", biomes.Desert.Surface.Top.Name);
        Assert.Equal("Sand", biomes.Desert.Surface.Filler.Name);
    }

    [Fact]
    public void Mountains_UseSnowAboveSnowLine_StoneBelow()
    {
        var blocks = new BlockRegistry();
        var biomes = new BiomeRegistry(42, blocks);
        Assert.Equal("Stone", biomes.Mountains.TopBlock(200).Name);       // below snow line
        Assert.Equal("Snow Block", biomes.Mountains.TopBlock(420).Name);  // above snow line (384)
    }

    [Fact]
    public void Plains_TopBlock_IsGrass_RegardlessOfHeight()
    {
        var blocks = new BlockRegistry();
        var biomes = new BiomeRegistry(42, blocks);
        Assert.Equal("Grass", biomes.Plains.TopBlock(40).Name);
        Assert.Equal("Grass", biomes.Plains.TopBlock(120).Name);
    }

    [Fact]
    public void SampleHeight_IsDeterministic()
    {
        var blocks = new BlockRegistry();
        var biomes = new BiomeRegistry(42, blocks);
        var noise = new NoiseSource(42);
        float h1 = biomes.Mountains.SampleHeight(noise, 100f, 200f);
        float h2 = biomes.Mountains.SampleHeight(noise, 100f, 200f);
        Assert.Equal(h1, h2);
    }
}