/**
	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 OUR_DICK_GRAPHICS_OGL_VAO_HPP
#define OUR_DICK_GRAPHICS_OGL_VAO_HPP

#include "gl_include.hpp"
#include "math/math.hpp"
#include "vbo.hpp"

namespace gfx::ogl{
	using namespace math;

	class vertex_attribute;

	//class representing a vertex array object
	class vao
	{
	private:
		GLuint m_buffer; //handle to the vertex array

	public:
		//create a default initialized opengl vao
		vao();
		vao(const vao&) = delete;
		vao(vao&&);
		~vao();

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

		GLuint raw()const;

		//Set the instanced divisor of this binding point. Used with instanced rendering.
		void set_instance_divisor(GLuint binding, GLuint divisor);
		void bind_buffer(const vbo& buffer, GLuint bind_point, GLuint offset, GLuint stride);
		void bind_element_buffer(const vbo& buffer);

		//Get access to a generic vertex attribute within this vao
		vertex_attribute get_attribute(int index);

		//bind this vao for use with rendering program
		void bind();
		//unbind this vao and rebind state machine to 0
		void unbind();
	};

	//class representing a generic vertex attribute in a vao
	class vertex_attribute
	{
	private:
		GLuint m_vao; //handle to vertex array object
		int m_index;  //index of this attribute
	public:
		constexpr vertex_attribute(GLuint vao, int index):
			m_vao(vao),
			m_index(index){}
		constexpr vertex_attribute(const vertex_attribute&) = default;
		constexpr vertex_attribute(vertex_attribute&&) = default;
		~vertex_attribute() = default;

		constexpr vertex_attribute& operator=(const vertex_attribute&) = default;
		constexpr vertex_attribute& operator=(vertex_attribute&&) = default;

		//enable use as an array attribute (most likely what is desired)
		void enable();
		//disable use as an array attribute. used for static data in attributes during rendering
		void disable();

		//Associate this attribute's location with the given buffer binding location
		void associate_with(GLuint buffer_binding);
		//setters for use in array mode. Same arguments as glVertexAttribPointer but these take arguments
		//as object counts rather than bytes. a valid vbo must be bound to buffers::array_buffer before these are called.
		void set_float_array(GLint size, GLsizei offset);
		void set_double_array(GLint size, GLsizei offset);
		void set_byte_array(GLint size, GLsizei offset);
		void set_ubyte_array(GLint size, GLsizei offset);
		void set_short_array(GLint size, GLsizei offset);
		void set_ushort_array(GLint size, GLsizei offset);
		void set_int_array(GLint size, GLsizei offset);
		void set_uint_array(GLint size, GLsizei offset);
	};

}

#endif