using Xunit;

namespace MrGameEng.Mods.Tests;

public sealed class DefDatabaseTests : IDisposable
{
    private sealed class AnimalDef : Def
    {
        public float Speed { get; init; }

        public int Legs { get; init; } = 4;

        public List<string> Tags { get; init; } = [];
    }

    private readonly string _root = Directory.CreateTempSubdirectory("mrge-defs-tests-").FullName;
    private int _modCounter;

    public void Dispose() => Directory.Delete(_root, recursive: true);

    /// <summary>Создаёт мод с одним файлом дефов и возвращает его (порядок загрузки = порядок создания).</summary>
    private Mod WriteDefsMod(string defsJson)
    {
        var id = $"mod{_modCounter++:D2}";
        var modDir = Path.Combine(_root, id);
        Directory.CreateDirectory(Path.Combine(modDir, "Defs"));
        File.WriteAllText(Path.Combine(modDir, "Defs", "animals.json"), defsJson);
        return new Mod(new ModInfo { Id = id }, modDir);
    }

    private DefDatabase LoadAnimals(params Mod[] mods)
    {
        var database = new DefDatabase();
        database.RegisterType<AnimalDef>("Animal");
        database.Load(mods);
        return database;
    }

    [Fact]
    public void Load_ParsesDefs_AndAllIsSortedByName()
    {
        var mod = WriteDefsMod(
            """
            { "type": "Animal", "defs": [
                { "defName": "Wolf", "label": "волк", "speed": 9 },
                { "defName": "Bear", "speed": 6 }
            ]}
            """);

        var database = LoadAnimals(mod);

        Assert.Equal(["Bear", "Wolf"], database.All<AnimalDef>().Select(d => d.DefName));
        Assert.Equal(9f, database.Get<AnimalDef>("Wolf").Speed);
        Assert.Equal("волк", database.Get<AnimalDef>("Wolf").Label);
        Assert.Equal(4, database.Get<AnimalDef>("Bear").Legs); // значение по умолчанию
    }

    [Fact]
    public void Load_ParentChain_MergesFields_ChildWins()
    {
        var mod = WriteDefsMod(
            """
            { "type": "Animal", "defs": [
                { "defName": "BaseAnimal", "abstract": true, "speed": 5, "tags": ["wild"] },
                { "defName": "Hare", "parent": "BaseAnimal", "speed": 12 },
                { "defName": "Snail", "parent": "BaseAnimal", "legs": 0, "tags": ["slow", "slimy"] }
            ]}
            """);

        var database = LoadAnimals(mod);

        var hare = database.Get<AnimalDef>("Hare");
        Assert.Equal(12f, hare.Speed);            // своё поле победило
        Assert.Equal(["wild"], hare.Tags);        // унаследовано
        var snail = database.Get<AnimalDef>("Snail");
        Assert.Equal(5f, snail.Speed);            // унаследовано
        Assert.Equal(0, snail.Legs);
        Assert.Equal(["slow", "slimy"], snail.Tags); // массив заменён целиком
        Assert.False(database.TryGet<AnimalDef>("BaseAnimal", out _)); // абстрактный не эмитится
    }

    [Fact]
    public void Load_LaterMod_ReplacesSameDefName()
    {
        var core = WriteDefsMod(
            """{ "type": "Animal", "defs": [ { "defName": "Wolf", "speed": 9, "tags": ["wild"] } ] }""");
        var patch = WriteDefsMod(
            """{ "type": "Animal", "defs": [ { "defName": "Wolf", "speed": 20 } ] }""");

        var database = LoadAnimals(core, patch);

        var wolf = database.Get<AnimalDef>("Wolf");
        Assert.Equal(20f, wolf.Speed);
        Assert.Empty(wolf.Tags); // полная замена, не слияние с дефом раннего мода
    }

    [Fact]
    public void Load_CyclicParents_Throws()
    {
        var mod = WriteDefsMod(
            """
            { "type": "Animal", "defs": [
                { "defName": "A", "parent": "B" },
                { "defName": "B", "parent": "A" }
            ]}
            """);

        var exception = Assert.Throws<InvalidDataException>(() => LoadAnimals(mod));
        Assert.Contains("Cyclic", exception.Message);
    }

    [Fact]
    public void Load_UnknownParent_Throws()
    {
        var mod = WriteDefsMod("""{ "type": "Animal", "defs": [ { "defName": "X", "parent": "Ghost" } ] }""");

        var exception = Assert.Throws<InvalidDataException>(() => LoadAnimals(mod));
        Assert.Contains("Ghost", exception.Message);
    }

    [Fact]
    public void Load_UnknownDefType_ThrowsWithFileAndMod()
    {
        var mod = WriteDefsMod("""{ "type": "Vehicle", "defs": [] }""");

        var exception = Assert.Throws<InvalidDataException>(() => LoadAnimals(mod));
        Assert.Contains("Vehicle", exception.Message);
        Assert.Contains(mod.Id, exception.Message);
    }

    [Fact]
    public void Get_UnknownDef_Throws_TryGetReturnsFalse()
    {
        var database = LoadAnimals(WriteDefsMod("""{ "type": "Animal", "defs": [] }"""));

        Assert.Throws<KeyNotFoundException>(() => database.Get<AnimalDef>("Dodo"));
        Assert.False(database.TryGet<AnimalDef>("Dodo", out _));
    }
}