/**
	This file is a part of our_dick
	Copyright (C) 2020 rexy712

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Affero General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Affero General Public License for more details.

	You should have received a copy of the GNU Affero General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef REXY_QUAT_HPP
#define REXY_QUAT_HPP

#include <cstdlib> //size_t
#include <utility> //pair
#include <type_traits> //is_same, is_arithmetic, integral_constant

#include "math_common.hpp"
#include "fwd_declare.hpp"

namespace math{

	//( ͡° ͜ʖ ͡°)
	template<Scalar T>
	class quaternion
	{
	public:
		using value_type = T;
		using size_type = size_t;
		using pointer = value_type*;
		using const_pointer = const value_type*;
		using reference = value_type&;
		using const_reference = const value_type&;

	private:
		value_type m_data[4];

	public:
		constexpr quaternion(void);
		//Construct from Euler angles
		constexpr quaternion(detail::zero_initialize_t);
		constexpr quaternion(detail::id_initialize_t);
		constexpr quaternion(detail::no_initialize_t);
		constexpr quaternion(detail::manual_initialize_t,
		                     value_type w, value_type x,
		                     value_type y, value_type z);
		quaternion(const mat3<T>& rotmat);
		quaternion(const mat4<T>& rotmat);
		quaternion(value_type bank, value_type heading, value_type attitude);
		quaternion(const vec3<value_type>& angles);
		//Construct from axis-angle
		quaternion(value_type angle, const vec3<value_type>& axis);
		quaternion(value_type angle, value_type x, value_type y, value_type z);
		//Copy ctor
		constexpr quaternion(const quaternion&) = default;
		constexpr quaternion(quaternion&&) = default;
		~quaternion(void) = default;

		//Assignment
		constexpr quaternion& operator=(const quaternion&) = default;
		constexpr quaternion& operator=(quaternion&&) = default;

		//Direct array access
		constexpr operator pointer(void);
		constexpr operator const_pointer(void)const;
		constexpr reference operator[](size_type i);
		constexpr const_reference operator[](size_type i)const;
		constexpr reference get(size_type i);
		constexpr const_reference get(size_type i)const;

		constexpr reference w(void);
		constexpr const_reference w(void)const;
		constexpr reference x(void);
		constexpr const_reference x(void)const;
		constexpr reference y(void);
		constexpr const_reference y(void)const;
		constexpr reference z(void);
		constexpr const_reference z(void)const;

		//Assign axis from angle-axis
		void set_axis(value_type x, value_type y, value_type z);
		void set_axis(const vec3<value_type>& axis);
		vec3<value_type> get_axis(void)const;

		void set_angle(value_type a);
		value_type get_angle(void)const;
		value_type norm(void)const;
		quaternion conjugate(void)const;
		quaternion inverse(void)const;
		value_type magnitude(void)const;
		quaternion normalize(void)const;

		vec3<value_type> get_right(void)const;
		vec3<value_type> get_up(void)const;
		vec3<value_type> get_forward(void)const;

		//Explicit Conversion1
		vec3<value_type> to_vec3(void)const;
		vec4<value_type> to_vec4(void)const;
		mat3<value_type> to_mat3(void)const;
		mat4<value_type> to_mat4(void)const;
		vec3<value_type> to_euler_angles(void)const;
		std::pair<value_type,vec3<value_type>> to_axis_angle(void)const;
	};

	template<Scalar T, Scalar U>
	bool operator==(const quaternion<T>& left, const quaternion<U>& right);
	template<Scalar T, Scalar U>
	bool operator!=(const quaternion<T>& left, const quaternion<U>& right);
	template<Scalar T>
	auto operator-(const quaternion<T>& left);
	template<Scalar T, Scalar U>
	auto operator-(const quaternion<T>& left, const quaternion<U>& right);
	template<Scalar T, Scalar U>
	auto operator+(const quaternion<T>& left, const quaternion<U>& right);
	template<Scalar T, Scalar U>
	auto operator*(const quaternion<T>& left, const quaternion<U>& right);
	template<Scalar T, Scalar U>
	auto operator*(const quaternion<T>& left, const vec3<U>& right);
	template<Scalar T, Scalar U>
	auto operator*(const quaternion<T>& left, U&& right);
	template<Scalar T, Scalar U>
	auto operator/(const quaternion<T>& left, U&& right);

	template<Scalar T, Scalar U>
	decltype(auto) operator+=(quaternion<T>& left, const quaternion<U>& right);
	template<Scalar T, Scalar U>
	decltype(auto) operator-=(quaternion<T>& left, const quaternion<U>& right);
	template<Scalar T, Scalar U>
	decltype(auto) operator*=(quaternion<T>& left, const quaternion<U>& right);
	template<Scalar T, Scalar U>
	decltype(auto) operator*=(quaternion<T>& left, U&& right);
	template<Scalar T, Scalar U>
	decltype(auto) operator/=(quaternion<T>& left, U&& right);

}

#include "quat.tpp"

#endif