#include "CoreMinimal.h"
#include "UnrealPerlinHelpers.inl"

float FMath::PerlinNoise2D(const FVector2D& Location)
{
    using namespace FMathPerlinHelpers;
    const float Xfl = FMath::FloorToFloat(static_cast<float>(Location.X));
    const float Yfl = FMath::FloorToFloat(static_cast<float>(Location.Y));
    const int32 Xi = static_cast<int32>(Xfl) & 255;
    const int32 Yi = static_cast<int32>(Yfl) & 255;
    const float X = static_cast<float>(Location.X) - Xfl;
    const float Y = static_cast<float>(Location.Y) - Yfl;
    const float Xm1 = X - 1.0f;
    const float Ym1 = Y - 1.0f;
    const int32* P = Permutation;
    const int32 AA = P[Xi] + Yi;
    const int32 AB = AA + 1;
    const int32 BA = P[Xi + 1] + Yi;
    const int32 BB = BA + 1;
    const float U = SmoothCurve(X);
    const float V = SmoothCurve(Y);
    return FMath::Lerp(
        FMath::Lerp(Grad2(P[AA], X, Y), Grad2(P[BA], Xm1, Y), U),
        FMath::Lerp(Grad2(P[AB], X, Ym1), Grad2(P[BB], Xm1, Ym1), U),
        V);
}

float FMath::PerlinNoise3D(const FVector& Location)
{
    using namespace FMathPerlinHelpers;
    const float Xfl = FMath::FloorToFloat(static_cast<float>(Location.X));
    const float Yfl = FMath::FloorToFloat(static_cast<float>(Location.Y));
    const float Zfl = FMath::FloorToFloat(static_cast<float>(Location.Z));
    const int32 Xi = static_cast<int32>(Xfl) & 255;
    const int32 Yi = static_cast<int32>(Yfl) & 255;
    const int32 Zi = static_cast<int32>(Zfl) & 255;
    const float X = static_cast<float>(Location.X) - Xfl;
    const float Y = static_cast<float>(Location.Y) - Yfl;
    const float Z = static_cast<float>(Location.Z) - Zfl;
    const float Xm1 = X - 1.0f;
    const float Ym1 = Y - 1.0f;
    const float Zm1 = Z - 1.0f;
    const int32* P = Permutation;
    const int32 A = P[Xi] + Yi;
    const int32 AA = P[A] + Zi;
    const int32 AB = P[A + 1] + Zi;
    const int32 B = P[Xi + 1] + Yi;
    const int32 BA = P[B] + Zi;
    const int32 BB = P[B + 1] + Zi;
    const float U = SmoothCurve(X);
    const float V = SmoothCurve(Y);
    const float W = SmoothCurve(Z);
    const float Value = 0.97f * FMath::Lerp(
        FMath::Lerp(
            FMath::Lerp(Grad3(P[AA], X, Y, Z), Grad3(P[BA], Xm1, Y, Z), U),
            FMath::Lerp(Grad3(P[AB], X, Ym1, Z), Grad3(P[BB], Xm1, Ym1, Z), U),
            V),
        FMath::Lerp(
            FMath::Lerp(Grad3(P[AA + 1], X, Y, Zm1), Grad3(P[BA + 1], Xm1, Y, Zm1), U),
            FMath::Lerp(Grad3(P[AB + 1], X, Ym1, Zm1), Grad3(P[BB + 1], Xm1, Ym1, Zm1), U),
            V),
        W);
    return FMath::Clamp(Value, -1.0f, 1.0f);
}