#pragma once

//#include <OpenGL wrapper headers>
#include <GL/gl.h>
#include <tuple>


namespace std140
{
    inline GLsizeiptr constexpr scal = sizeof(GLfloat);
    inline GLsizeiptr constexpr vec2 = 2 * scal;
    inline GLsizeiptr constexpr vec3 = 4 * scal;
    inline GLsizeiptr constexpr vec4 = 4 * scal;
    inline GLsizeiptr constexpr mat3 = 3 * vec4;
    inline GLsizeiptr constexpr mat4 = 4 * vec4;
}


template<GLuint Bind, GLsizeiptr... Size>
class UBO
{
public:

    UBO()
    {
        glGenBuffers(1, &buffer_id_);
        glBindBuffer(GL_UNIFORM_BUFFER, buffer_id_);
        glBufferData(GL_UNIFORM_BUFFER, (Size + ...), nullptr, GL_STATIC_DRAW);
        glBindBufferRange(GL_UNIFORM_BUFFER, Bind, buffer_id_, 0, (Size + ...));
    }

    ~UBO()
    {
        glDeleteBuffers(1, &buffer_id_);
    }

    template<std::size_t I>
    requires (I < sizeof...(Size))
    void write(void const* data) const
    {
        glBindBuffer(GL_UNIFORM_BUFFER, buffer_id_);
        glBufferSubData(GL_UNIFORM_BUFFER, offset<I>(), size<I>(), data);
    }

private:

    template<std::size_t I>
    requires (I < sizeof...(Size))
    static constexpr GLintptr offset()
    {
        if constexpr (I == 0)
            return 0;
        else
            return size<I - 1>() + offset<I - 1>();
    }

    template<std::size_t I>
    requires (I < sizeof...(Size))
    static constexpr GLsizeiptr size()
    {
        return std::get<I>(std::make_tuple(Size...));
    }

private:

    GLuint buffer_id_ = 0;
};