#pragma once

#include "EHS.h"
#include "Math.h"
#include "Mat3.h"
#include "Vec4.h"
#include "Vec3.h"

namespace ehs
{
	template <typename T = float>
	class Mat4
	{
	private:
		friend class GpuUniform;

		T data[16];

	public:
		Mat4()
		{
			for (UInt_8 i = 0; i < 16; ++i)
				data[i] = 0;
		}

		explicit Mat4(const T* data)
		{
			for (UInt_8 i = 0; i < 16; ++i)
				this->data[i] = data[i];
		}

		template<typename C>
		Mat4(const Mat3<C>& mat)
		{
			for (UInt_8 i = 0; i < 9; ++i)
			{
				UInt_8 row = i / 3;
				UInt_8 column = i % 3;
				UInt_8 dst = row * 4 + column;

				data[dst] = (T)mat[i];
			}

			data[3] = 0;
			data[7] = 0;
			data[11] = 0;
			data[12] = 0;
			data[13] = 0;
			data[14] = 0;
			data[15] = 1;
		}

		template<typename C>
		Mat4(const Mat4<C>& mat)
		{
			for (UInt_8 i = 0; i < 16; ++i)
				data[i] = (T)mat.data[i];
		}

		template<typename C>
		Mat4<T>& operator=(const Mat4<C>& mat)
		{
			if (this == &mat)
				return *this;

			for (UInt_8 i = 0; i < 16; ++i)
				data[i] = (T)mat.data[i];

			return *this;
		}

		Vec4<T> operator*(Vec4<T> vec) const
		{
			Vec4<T> result;
			result.x = vec.x * data[0] + vec.y * data[4] + vec.z * data[8] + vec.w * data[12];
			result.y = vec.x * data[1] + vec.y * data[5] + vec.z * data[9] + vec.w * data[13];
			result.z = vec.x * data[2] + vec.y * data[6] + vec.z * data[10] + vec.w * data[14];
			result.w = vec.x * data[3] + vec.y * data[7] + vec.z * data[11] + vec.w * data[15];

			return result;
		}

		Mat4<T>& operator*=(const T scalar)
		{
			for (UInt_8 i = 0; i < 16; ++i)
				data[i] *= scalar;

			return *this;
		}

		Mat4<T> operator*(const T scalar) const
		{
			Mat4<T> result;
			for (UInt_8 i = 0; i < 16; ++i)
				result.data[i] = data[i] * scalar;

			return result;
		}

		Mat4<T>& operator*=(const Mat4<T>& mat)
		{
			Mat4 transposed = GetTranspose();

			for (UInt_8 i = 0; i < 16; i++)
			{
				UInt_8 row = i / 4 * 4;
				UInt_8 column = i % 4 * 4;
				data[i] += transposed.data[column] * mat.data[row];
				data[i] += transposed.data[column + 1] * mat.data[row + 1];
				data[i] += transposed.data[column + 2] * mat.data[row + 2];
				data[i] += transposed.data[column + 3] * mat.data[row + 3];
			}

			return *this;
		}

		Mat4<T> operator*(const Mat4<T>& mat) const
		{
			Mat4 transposed = GetTranspose();

			Mat4<T> result;
			for (UInt_8 i = 0; i < 16; i++)
			{
				UInt_8 row = i / 4 * 4;
				UInt_8 column = i % 4 * 4;
				result.data[i] += transposed.data[column] * mat.data[row];
				result.data[i] += transposed.data[column + 1] * mat.data[row + 1];
				result.data[i] += transposed.data[column + 2] * mat.data[row + 2];
				result.data[i] += transposed.data[column + 3] * mat.data[row + 3];
			}

			return result;
		}

		operator const T*() const
		{
			return data;
		}

		operator T*()
		{
			return data;
		}

		Vec3<T> GetRight() const
		{
			return Vec3<T>(data[0], data[4], data[8]);
		}

		Vec3<T> GetUp() const
		{
			return Vec3<T>(data[1], data[5], data[9]);
		}

		Vec3<T> GetForward() const
		{
			return Vec3<T>(data[2], data[6], data[10]);
		}

		Mat4<T> GetTranspose() const
		{
			Mat4<T> result;
			for (UInt_8 i = 0; i < 16; ++i)
				result.data[i] = data[i % 4 * 4 + i / 4];

			return result;
		}

		void Transpose()
		{
			Mat4<T> old = *this;
			for (UInt_8 i = 0; i < 16; ++i)
				data[i] = old.data[4 * (i % 4) + i / 4];
		}

		Mat3<T> Cut(const UInt_8 row, const UInt_8 column) const
		{
			Mat3<T> result;
			UInt_8 index = 0;

			for (UInt_8 r = 0; r < 4; ++r)
			{
				for (UInt_8 c = 0; c < 4; ++c)
				{
					if (r == row || c == column)
						continue;

					result[index++] = data[4 * r + c];
				}
			}

			return result;
		}

		Mat4<T> GetMinor() const
		{
			Mat4<T> result;

			for (UInt_8 r = 0; r < 4; ++r)
				for (UInt_8 c = 0; c < 4; ++c)
					result.data[4 * r + c] = Cut(r, c).GetDeterminant();

			return result;
		}

		void Minor()
		{
			Mat4<T> old = *this;

			for (UInt_8 r = 0; r < 4; ++r)
				for (UInt_8 c = 0; c < 4; ++c)
					data[4 * r + c] = old.Cut(r, c).GetDeterminant();
		}

		Mat4<T> GetCofactor() const
		{
			Mat4<T> minor = GetMinor();
			Mat4<T> result;

			for (UInt_8 r = 0; r < 4; ++r)
			{
				for (UInt_8 c = 0; c < 4; ++c)
				{
					UInt_8 i = 4 * c + r;
					result.data[i] = minor.data[i] * Math::Pow<T>(-1, r + c);
				}
			}

			return result;
		}

		void Cofactor()
		{
			Mat4<T> minor = GetMinor();

			for (UInt_8 r = 0; r < 4; ++r)
			{
				for (UInt_8 c = 0; c < 4; ++c)
				{
					UInt_8 i = 4 * c + r;
					data[i] = minor.data[i] * Math::Pow<T>(-1, r + c);
				}
			}
		}

		T GetDeterminant() const
		{
			Mat4<T> cofactor = GetCofactor();
			T result = 0;

			for (UInt_8 c = 0; c < 4; ++c)
				result += data[c] * cofactor[c];

			return result;
		}

		Mat4<T> GetAdjugate() const
		{
			return GetCofactor().GetTranspose();
		}

		void Adjugate()
		{
			Cofactor();
			Transpose();
		}

		Mat4<T> GetInverse() const
		{
			T det = GetDeterminant();
			if (Math::ComCmp(det, 0))
				return {};

			return GetAdjugate() * (1 / det);
		}

		void Inverse()
		{
			T det = GetDeterminant();
			if (Math::ComCmp(det, 0))
				return;

			Adjugate();
			operator*=(1 / det);
		}

		static Mat4<T> Identity()
		{
			Mat4<T> result;
			result.data[0] = 1;
			result.data[5] = 1;
			result.data[10] = 1;
			result.data[15] = 1;
			return result;
		}

		static Mat4<T> Scale(const Vec3<T>& scale)
		{
			Mat4<T> result;
			result.data[0] = scale.x;
			result.data[5] = scale.y;
			result.data[10] = scale.z;
			result.data[15] = 1;

			return result;
		}

		static Mat4<T> Translate(const Vec3<T>& pos)
		{
			Mat4<T> result = Identity();
			result.data[12] = pos.x;
			result.data[13] = pos.y;
			result.data[14] = pos.z;

			return result;
		}

		static Mat4<T> PitchRotate(const T angle)
		{
			T radians = Math::Rads(angle);

			Mat4<T> result;
			result.data[0] = 1;
			result.data[5] = Math::Cos(radians);
			result.data[6] = Math::Sin(radians);
			result.data[9] = -Math::Sin(radians);
			result.data[10] = Math::Cos(radians);
			result.data[15] = 1;

			return result;
		}

		static Mat4<T> YawRotate(const T angle)
		{
			T radians = Math::Rads(angle);

			Mat4<T> result;
			result.data[0] = Math::Cos(radians);
			result.data[2] = -Math::Sin(radians);
			result.data[5] = 1;
			result.data[8] = Math::Sin(radians);
			result.data[10] = Math::Cos(radians);
			result.data[15] = 1;

			return result;
		}

		static Mat4<T> RollRotate(const T angle)
		{
			T radians = Math::Rads(angle);

			Mat4<T> result;
			result.data[0] = Math::Cos(radians);
			result.data[1] = Math::Sin(radians);
			result.data[4] = -Math::Sin(radians);
			result.data[5] = Math::Cos(radians);
			result.data[10] = 1;
			result.data[15] = 1;

			return result;
		}

		static Mat4<T> Rotate(const Vec3<T>& vec)
		{
			return YawRotate(vec.y) * RollRotate(vec.z) * PitchRotate(vec.x);
		}

		static Mat4<T> RH_Perspective(const T fov, const T aspect, const T zNear, const T zFar)
		{
			const float tanHalfFovy = tan(Math::Rads(fov) / 2.0f);

			Mat4<T> result;
			result[0] = 1.0f / (aspect * tanHalfFovy);
			result[5] = -1.0f / tanHalfFovy;
			result[10] = zFar / (zFar - zNear);
			result[14] = -(zFar * zNear) / (zFar - zNear);

			return result;
		}

		static Mat4<T> LH_Perspective(const T fov, const T aspect, const T zNear, const T zFar)
		{
			const float tanHalfFovy = Math::Tan(Math::Rads(fov) / 2.0f);

			Mat4<T> result;
			result[0] = 1.0f / (aspect * tanHalfFovy);
			result[5] = -1.0f / tanHalfFovy;
			result[10] = zFar / (zFar - zNear);
			result[11] = 1.0f;
			result[14] = -(zFar * zNear) / (zFar - zNear);
			result[15] = 0.0f;

			return result;
		}

		static Mat4<T> LH_Orthographic(const T left, const T right, const T top, const T bottom, const T zNear, const T zFar)
		{
			Mat4<T> result;
			result[0] = 2.0f / (right - left); // 0,0 entry
			result[5] = 2.0f / (bottom - top); // 1,1 entry
			result[10] = 1.0f / (zFar - zNear); // 2,2 entry
			result[12] = -(right + left) / (right - left); // 3,0 entry
			result[13] = -(bottom + top) / (bottom - top); // 3,1 entry
			result[14] = -zNear / (zFar - zNear); // 3,2 entry
			result[15] = 1.0f; // 3,3 entry

			return result;

			/*
			Mat4<T> result;
			result.data[0] = 2 / (right - left);
			result.data[5] = 2 / (top - bottom);
			result.data[10] = 1 / (zFar - zNear);
			result.data[12] = (left + right) / (left - right);
			result.data[13] = (top + bottom) / (bottom - top);
			result.data[14] = zNear / (zNear - zFar);
			result.data[15] = 1;

			return result;
			*/
		}
	};

	template class EHS_LIB_IO Mat4<float>;
	template class EHS_LIB_IO Mat4<double>;

	typedef Mat4<float> Mat4_f;
	typedef Mat4<double> Mat4_d;
}