using System.Numerics;
using BenchmarkDotNet.Attributes;
using PerfectNumbers.Core;

namespace EvenPerfectBitScanner.Benchmarks;

[MemoryDiagnoser]
public class Mod10_8_5_3Benchmarks
{
    [Params(3UL, 8191UL, 131071UL, 2147483647UL)]
    public ulong Value { get; set; }

    [Benchmark(Baseline = true)]
    public (ulong Mod10, ulong Mod8, ulong Mod3, ulong Mod5) LegacyModulo()
    {
		ulong mod10, mod8, mod3, mod5;
		UInt128 zero = UInt128.Zero;
		if (Value == zero)
		{
			mod3 = 0UL;
			mod5 = 0UL;
			mod8 = 0UL;
			mod10 = 0UL;
			return (mod10, mod8, mod3, mod5);
		}

		UInt128 high = Value >> 64;
		ulong result = Value;
		mod8 = result & 7UL;
		// 2^64 ≡ 1 (mod 3)
		ulong modRem = (result % 3UL) + ((ulong)high % 3UL);
		mod3 = modRem >= 3UL ? modRem - 3UL : modRem;
		// 2^64 ≡ 1 (mod 5)
		modRem = (result % 5UL) + ((ulong)high % 5UL);
		mod5 = modRem >= 5UL ? modRem - 5UL : modRem;

		while (high != zero)
		{
			// 2^64 ≡ 6 (mod 10)
			result = (result + (ulong)high * 6UL) % 10UL;
			high >>= 64;
		}

		mod10 = result % 10UL;
        return (mod10, mod8, mod3, mod5);
    }

    [Benchmark]
    public (ulong Mod10, ulong Mod8, ulong Mod3, ulong Mod5) ModMethodModulo()
    {
        Value.Mod10_8_5_3(out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3);
        return (mod10, mod8, mod3, mod5);
    }
}