namespace QWERTYkez.Mensura.Tests;

public class CollectionsPowNExtensions
{
    private const double BaseVal = 3.0;
    private const double Expected = 9.0; // 3^2 = 9

    [Fact]
    public void Test_PowN()
    {
        Length[] arr = [new(BaseVal)];
        Length?[] arrNull = [new(BaseVal), null];
        List<Length> list = [new(BaseVal)];
        List<Length?> listNull = [new(BaseVal), null];
        IReadOnlyCollection<Length> roc = list;
        IEnumerable<Length> en = list;
        IEnumerable<Length?> enNull = listNull;

        // --- 1. Целые степени (int) ---
        // Span-based Core
        Span<Length> dstSpan = new Length[1];
        arr.AsSpan().PowCore(2, 1, dstSpan);
        Assert.Equal(Expected, dstSpan[0]._Value);

        arrNull.AsSpan().PowCore(2, 2, new Length?[2]); // Проверка nullable span

        arr.AsSpan().Pow(2, dstSpan);
        Assert.Equal(Expected, dstSpan[0]._Value);

        // Arrays
        Assert.Equal(Expected, arr.Pow<Length, Length>(2)[0]._Value);
        Assert.Equal(Expected, arrNull.Pow<Length, Length>(2)[0]?._Value);

        // Lists
        Assert.Equal(Expected, list.Pow<Length, Length>(2)[0]._Value);
        Assert.Equal(Expected, listNull.Pow<Length, Length>(2)[0]?._Value);

        // ReadOnlyCollection
        roc.Pow(2, dstSpan);
        Assert.Equal(Expected, dstSpan[0]._Value);

        // IEnumerable / Iterators
        Assert.Equal(Expected, en.Pow<Length, Length>(2).First()._Value);
        Assert.Equal(Expected, enNull.Pow<Length, Length>(2).First(x => x.HasValue)?._Value);


        // --- 2. Дробные степени (double) ---
        // Span-based Core
        arr.AsSpan().PowCore(2.0, 1, dstSpan);
        Assert.Equal(Expected, dstSpan[0]._Value);

        arr.AsSpan().Pow(2.0, dstSpan);
        Assert.Equal(Expected, dstSpan[0]._Value);

        // Arrays
        Assert.Equal(Expected, arr.Pow<Length, Length>(2.0)[0]._Value);
        Assert.Equal(Expected, arrNull.Pow<Length, Length>(2.0)[0]?._Value);

        // Lists
        Assert.Equal(Expected, list.Pow<Length, Length>(2.0)[0]._Value);
        Assert.Equal(Expected, listNull.Pow<Length, Length>(2.0)[0]?._Value);

        // ReadOnlyCollection
        roc.Pow(2.0, dstSpan);
        Assert.Equal(Expected, dstSpan[0]._Value);

        // IEnumerable / Iterators
        Assert.Equal(Expected, en.Pow<Length, Length>(2.0).First()._Value);
        Assert.Equal(Expected, enNull.Pow<Length, Length>(2.0).First(x => x.HasValue)?._Value);

        // Дополнительные итераторы
        Assert.Equal(Expected, en.PowIterator<Length, Length>(2.0).First()._Value);
        Assert.Equal(Expected, enNull.PowNullableIterator<Length, Length>(2.0).First(x => x.HasValue)?._Value);
    }
}