using FluentAssertions;
using PerfectNumbers.Core.Cpu;
using PerfectNumbers.Core.Gpu.Accelerators;
using Xunit;
using UInt128 = System.UInt128;

namespace PerfectNumbers.Core.Tests;

public class MersenneNumberOrderCpuTesterTests
{
	private static LastDigit GetLastDigit(ulong exponent) => (exponent & 3UL) == 3UL ? LastDigit.Seven : LastDigit.One;

	[Theory]
	[InlineData(GpuKernelType.Incremental)]
	[InlineData(GpuKernelType.Pow2Mod)]
	[Trait("Category", "Fast")]
	public void Scan_handles_various_prime_exponents(GpuKernelType type)
	{
		var tester = new MersenneNumberOrderCpuTester(type);

		if (type == GpuKernelType.Pow2Mod)
		{
			RunCase(tester, 23UL, 1UL, expectedPrime: false);
			RunCase(tester, 29UL, 36UL, expectedPrime: false);
		}

		RunCase(tester, 89UL, 1_000UL, expectedPrime: true);
		RunCase(tester, 127UL, 1_000UL, expectedPrime: true);
	}

	private static void RunCase(MersenneNumberOrderCpuTester tester, ulong exponent, ulong maxK, bool expectedPrime)
	{
		bool isPrime = true;
		var gpu = PrimeOrderCalculatorAccelerator.Rent(1);
		try
		{
			tester.Scan(gpu, exponent, (UInt128)exponent << 1, GetLastDigit(exponent), (UInt128)maxK, ref isPrime);
			isPrime.Should().Be(expectedPrime);
		}
		finally
		{
			PrimeOrderCalculatorAccelerator.Return(gpu);
		}
	}
}