#ifndef MATH_UTILS_HPP
#define MATH_UTILS_HPP

#include <array>
#include <utility>
#include <concepts>
#include "math/vector.hpp"

namespace engine::math {

struct Vector2;
struct Vector3;
struct Vector4;

}

namespace engine::math::utils {

template<size_t size> struct Vector;
template<> struct Vector<2> { using type = engine::math::Vector2; };
template<> struct Vector<3> { using type = engine::math::Vector3; };
template<> struct Vector<4> { using type = engine::math::Vector4; };

template<size_t vector_size>
constexpr Vector<vector_size>::type array_to_vec(const std::array<float, vector_size>& coords) {
    return [&]<size_t... i>(std::index_sequence<i...>) constexpr -> Vector<vector_size>::type {
        return { coords[i] ... };
    }(std::make_index_sequence<vector_size>());
}

constexpr float lerp(float a, float b, float t) {
    return a + t * (b - a);
}

constexpr float map(float x, float from1, float from2, float to1, float to2) {
    return to1 + (x - from1) * (to2 - to1) / (from2 - from1);
}

template<typename UInt>
constexpr UInt log2_floored(UInt n) noexcept
requires std::same_as<UInt, unsigned> || std::same_as<UInt, unsigned long> || std::same_as<UInt, unsigned long long>
{
#ifdef __GNUG__
    if constexpr (std::is_same_v<UInt, unsigned>) {
        return static_cast<UInt>(sizeof(UInt) * 8 - 1) - __builtin_clz(n);
    } else if constexpr (std::is_same_v<UInt, unsigned long>) {
        return static_cast<UInt>(sizeof(UInt) * 8 - 1) - __builtin_clzl(n);
    } else { // unsigned long long
        return static_cast<UInt>(sizeof(UInt) * 8 - 1) - __builtin_clzll(n);
    }
#else
    UInt ret = 0;
    while (n & 1) {
        n >>= 1;
        ret++;
    }
    return ret;
#endif
}

}

#endif // MATH_UTILS_HPP