#pragma once

#include "Defines.h"
#include <cmath>

namespace td {
namespace maths {

//////////////////////////////////////////////////////////////////
// 							Vectors								//
//////////////////////////////////////////////////////////////////

template<typename T>
Vec3<T> operator- (const Vec3<T>& vect) {
	return { -vect.x, -vect.y, -vect.z };
}

template<typename T>
Vec3<T> operator+ (const Vec3<T>& vect, const Vec3<T>& other) {
	return { vect.x + other.x, vect.y + other.y, vect.z + other.y };
}

template<typename T>
Vec3<T> operator- (const Vec3<T>& vect, const Vec3<T>& other) {
	return vect + (-other);
}

template<typename T>
Vec3<T> Normalize(const Vec3<T>& vect) {
	T length = std::sqrt(vect.x * vect.x + vect.y * vect.y + vect.z * vect.z);

	return { vect.x / length, vect.y / length, vect.z / length };
}

template<typename T>
T Dot(const Vec3<T>& vect, const Vec3<T>& other) {
	return vect.x * other.x + vect.y * other.y + vect.z * other.z;
}

template<typename T>
Vec3<T> Cross(const Vec3<T>& vect, const Vec3<T>& other) {
	return {
		vect.y * other.z - vect.z * other.y,
		vect.z * other.x - vect.x * other.z,
		vect.x * other.y - vect.y * other.x,
	};
}

template<typename T>
T Dot(const Vec4<T>& vect, const Vec4<T>& other) {
	return vect.x * other.x + vect.y * other.y + vect.z * other.z + vect.w * other.w;
}

//////////////////////////////////////////////////////////////////
// 						    Matricies							//
//////////////////////////////////////////////////////////////////

template<typename T>
struct Mat4 {
	static const std::size_t MATRIX_SIZE = 4;

	T x0, x1, x2, x3;
	T y0, y1, y2, y3;
	T z0, z1, z2, z3;
	T w0, w1, w2, w3;

	T operator[] (std::size_t offset) const {
		return reinterpret_cast<const T*>(this)[offset];
	}

	T& operator[] (std::size_t offset) {
		return reinterpret_cast<T*>(this)[offset];
	}

	T at(std::size_t row, std::size_t column) const {
		return operator[](row * MATRIX_SIZE + column);
	}

	T& at(std::size_t row, std::size_t column) {
		return operator[](row * MATRIX_SIZE + column);
	}
};

typedef Mat4<float> Mat4f;
typedef Mat4<int> Mat4i;
typedef Mat4<double> Mat4d;

template<typename T>
Vec4<T> Dot(const Mat4<T>& mat, const Vec4<T>& vect) {
	return {
		Dot(*reinterpret_cast<const Vec4<T>*>(&mat), vect),
		Dot(*reinterpret_cast<const Vec4<T>*>(&mat[Mat4<T>::MATRIX_SIZE]), vect),
		Dot(*reinterpret_cast<const Vec4<T>*>(&mat[2 * Mat4<T>::MATRIX_SIZE]), vect),
		Dot(*reinterpret_cast<const Vec4<T>*>(&mat[3 * Mat4<T>::MATRIX_SIZE]), vect),
	};
}

template<typename T>
Mat4<T> Dot(const Mat4<T>& mat, const Mat4<T>& other) {
	Mat4<T> result {};

	for (std::size_t i = 0; i < Mat4<T>::MATRIX_SIZE; i++) {
		for (std::size_t j = 0; j < Mat4<T>::MATRIX_SIZE; j++) {
			for (std::size_t k = 0; k < Mat4<T>::MATRIX_SIZE; k++) {
				result.at(i, j) = mat.at(i, k) * other.at(k, j);
			}
		}
	}

	return result;
}

template<typename T>
Mat4<T> Identity() {
	Mat4<T> result{};

	result.x0 = static_cast<T>(1);
	result.y1 = static_cast<T>(1);
	result.z2 = static_cast<T>(1);
	result.w3 = static_cast<T>(1);

	return result;
}

template<typename T>
Mat4<T> Transpose(const Mat4<T>& mat) {
	Mat4<T> result;

	result.x1 = mat.y0;
	result.x2 = mat.z0;
	result.x3 = mat.w0;
	result.y0 = mat.x1;
	result.y2 = mat.z1;
	result.y3 = mat.w1;
	result.z0 = mat.x2;
	result.z1 = mat.y2;
	result.z3 = mat.w2;
	result.w0 = mat.x3;
	result.w1 = mat.y3;
	result.w2 = mat.z3;

	return result;
}

Mat4f Perspective(float fovY, float aspectRatio, float zNear, float zFar);
Mat4f Look(const Vec3f& eye, const Vec3f& center, const Vec3f& up);

Mat4f Inverse(const Mat4f& mat);

} // namespace maths
} // namespace td