/**
	This file is a part of our_dick
	Copyright (C) 2020-2022 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 OUR_DICK_GRAPHICS_OGL_BUFFER_MAP_HPP
#define OUR_DICK_GRAPHICS_OGL_BUFFER_MAP_HPP

#include "gl_include.hpp"

#include <cstdlib> //size_t, ptrdiff_t

namespace gfx::ogl{

	namespace buffer{
		//strongly typed enum for different mapping styles
		enum class maptype : GLenum{
			READ = GL_READ_ONLY,
			WRITE = GL_WRITE_ONLY,
			RW = GL_READ_WRITE,
		};
		//strongly typed enum for different usages
		enum class usage : GLenum{
			STATIC_DRAW = GL_STATIC_DRAW,
			DYNAMIC_DRAW = GL_DYNAMIC_DRAW,
			STREAM_DRAW = GL_STREAM_DRAW,
			STATIC_READ = GL_STATIC_READ,
			DYNAMIC_READ = GL_DYNAMIC_READ,
			STREAM_READ = GL_STREAM_READ,
			STATIC_COPY = GL_STATIC_COPY,
			DYNAMIC_COPY = GL_DYNAMIC_COPY,
			STREAM_COPY = GL_STREAM_COPY,
		};
	}

	//RAII wrapper for mapping vbo's
	template<typename T>
	class scoped_buffer_map
	{
	public:
		using value_type = T;
		using size_type = size_t;
		using difference_type = ptrdiff_t;
		using reference = T&;
		using const_reference = const T&;
		using pointer = T*;
		using const_pointer = const T*;

	private:
		pointer m_data = nullptr; //pointer to the mapped region
		GLuint m_buffer;

	public:
		//create a mapping for 'v' on 'targ' with map style 'm'
		explicit scoped_buffer_map(GLuint bid, buffer::maptype m);
		scoped_buffer_map(const scoped_buffer_map&) = delete;
		scoped_buffer_map(scoped_buffer_map&&);
		~scoped_buffer_map(void);

		scoped_buffer_map& operator=(const scoped_buffer_map&) = delete;
		scoped_buffer_map& operator=(scoped_buffer_map&&);

		//size of the mapped region as reported by glGetBufferParameteriv
		size_type length(void)const;

		//release ownership of the mapping. unsafe
		pointer release(void);

		//direct access to the underlaying data region
		operator pointer(void);
		operator const_pointer(void)const;
		pointer raw(void);
		const_pointer raw(void)const;

		bool valid(void)const;

		//indexed access to the data region
		reference operator[](size_type i);
		const_reference operator[](size_type i)const;
	};

	//specialization for void pointers. The same in every way except no subscript operators
	template<>
	class scoped_buffer_map<void>
	{
	public:
		using value_type = void;
		using size_type = size_t;
		using difference_type = ptrdiff_t;
		using reference = void;
		using const_reference = void;
		using pointer = void*;
		using const_pointer = const void*;

	private:
		pointer m_data = nullptr;
		GLuint m_buffer;

	public:
		explicit scoped_buffer_map(GLuint bid, buffer::maptype m);
		scoped_buffer_map(const scoped_buffer_map&) = delete;
		scoped_buffer_map(scoped_buffer_map&&);
		~scoped_buffer_map(void);

		scoped_buffer_map& operator=(const scoped_buffer_map&) = delete;
		scoped_buffer_map& operator=(scoped_buffer_map&&);

		size_type length(void)const;

		pointer release(void);
		operator pointer(void);
		operator const_pointer(void)const;
		pointer raw(void);
		const_pointer raw(void)const;

		bool valid(void)const;
	};

}

#include "buffer_map.tpp"

#endif