using MrGameEng.Genetics;
using Xunit;

namespace MrGameEng.Genetics.Tests;

public class GenomeTemplateTests
{
    private static GeneDef Numeric(string name, float min, float max) =>
        new()
        {
            DefName = name,
            Kind = GeneKind.Numeric,
            Min = min,
            Max = max,
        };

    private static GeneDef Discrete(string name, int variants = 2) =>
        new()
        {
            DefName = name,
            Kind = GeneKind.Discrete,
            Variants = variants,
        };

    [Fact]
    public void Generate_UsesPerEntryBaseAndSpread_NotGeneDefault()
    {
        var gene = Numeric("opt", min: 0f, max: 100f); // GeneDef.Default is 0
        var template = new GenomeTemplate([
            new GenomeTemplate.Entry(gene, Base: 50f, Spread: 0.1f),
        ]);
        var random = new Random(3);

        for (var i = 0; i < 200; i++)
        {
            var allele = template.Generate(random)["opt"];
            Assert.InRange(allele.A, 45f, 55f); // around the template base, not 0
            Assert.InRange(allele.B, 45f, 55f);
        }
    }

    [Fact]
    public void Generate_TwoSpecies_DifferInCentre()
    {
        var gene = Numeric("opt", 0f, 100f);
        var oak = new GenomeTemplate([new GenomeTemplate.Entry(gene, 20f, 0f)]);
        var grass = new GenomeTemplate([new GenomeTemplate.Entry(gene, 80f, 0f)]);

        Assert.Equal(20f, oak.Generate(new Random(1)).Express(gene), 3);
        Assert.Equal(80f, grass.Generate(new Random(1)).Express(gene), 3);
    }

    [Fact]
    public void Registry_CoversEntries_AndDrivesBreeding()
    {
        var template = new GenomeTemplate([
            new GenomeTemplate.Entry(Numeric("a", 0f, 10f), 5f, 0.1f),
            new GenomeTemplate.Entry(Discrete("morph"), 0f, 0f),
        ]);
        var random = new Random(9);
        var a = template.Generate(random);
        var b = template.Generate(random);

        var child = Genome.Breed(a, b, template.Registry, random);

        Assert.True(child.Has("a"));
        Assert.True(child.Has("morph"));
    }

    [Fact]
    public void Breed_MutationChanceOverride_ForcesMutation()
    {
        var gene = Numeric("a", min: -100f, max: 100f);
        var registry = new Dictionary<string, GeneDef> { ["a"] = gene };
        var parent = new Genome { ["a"] = new Allele(10f, 10f) };

        // Override chance to 1 → every inherited allele mutates away from 10.
        var moved = false;
        for (var seed = 0; seed < 30 && !moved; seed++)
        {
            var child = Genome.Breed(
                parent,
                parent,
                registry,
                new Random(seed),
                mutationChance: 1f
            );
            moved = child["a"].A != 10f || child["a"].B != 10f;
        }

        Assert.True(moved, "with overridden mutationChance=1 the allele should mutate");
    }

    [Fact]
    public void Breed_MutationChanceZero_KeepsAlleles()
    {
        var gene = Numeric("a", -100f, 100f);
        var registry = new Dictionary<string, GeneDef> { ["a"] = gene };
        var parent = new Genome { ["a"] = new Allele(10f, 10f) };

        var child = Genome.Breed(parent, parent, registry, new Random(5), mutationChance: 0f);

        Assert.Equal(10f, child["a"].A);
        Assert.Equal(10f, child["a"].B);
    }
}