using MrGameEng.Graphics;
using Xunit;

namespace MrGameEng.Graphics.Tests;

public class SpriteBatcherTests
{
    private static SpriteInstance Instance(byte layer) => new() { Layer = layer };

    [Fact]
    public void Sort_OrdersByKey_ReturningOriginalIndices()
    {
        var batcher = new SpriteBatcher(initialCapacity: 2);

        batcher.Submit(Instance(2), SpriteSortKey.Make(2, 0f, 0));
        batcher.Submit(Instance(0), SpriteSortKey.Make(0, 0f, 0));
        batcher.Submit(Instance(1), SpriteSortKey.Make(1, 0f, 0));

        var order = batcher.Sort();

        Assert.Equal(3, order.Length);
        Assert.Equal(0, batcher[order[0]].Layer);
        Assert.Equal(1, batcher[order[1]].Layer);
        Assert.Equal(2, batcher[order[2]].Layer);
    }

    [Fact]
    public void Submit_GrowsBeyondInitialCapacity()
    {
        var batcher = new SpriteBatcher(initialCapacity: 1);

        for (var i = 0; i < 100; i++)
        {
            batcher.Submit(Instance(0), (ulong)(100 - i));
        }

        Assert.Equal(100, batcher.Count);
        var order = batcher.Sort();
        Assert.Equal(99, order[0]); // последний сабмит имеет наименьший ключ
    }

    [Fact]
    public void Clear_ResetsCount_KeepsWorking()
    {
        var batcher = new SpriteBatcher();
        batcher.Submit(Instance(0), 5);
        batcher.Clear();

        Assert.Equal(0, batcher.Count);
        batcher.Submit(Instance(1), 1);
        Assert.Equal(1, batcher.Count);
        Assert.Equal(1, batcher[batcher.Sort()[0]].Layer);
    }
}