// =====================================================================================================================
//	glw, an open-source library that wraps OpenGL structures into classes.
//	Copyright (C) 2024  Medusa Slockbower
//
//	This program is free software: you can redistribute it and/or modify
//	it under the terms of the GNU 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 General Public License for more details.
//
//	You should have received a copy of the GNU General Public License
//	along with this program.  If not, see <https://www.gnu.org/licenses/>.
// =====================================================================================================================

#ifndef GLW_VERTEX_DESCRIPTOR_H
#define GLW_VERTEX_DESCRIPTOR_H

#include "common.h"

#include <open-cpp-utils/dynarray.h>

namespace ocu = open_cpp_utils;

namespace glw
{

// =====================================================================================================================
// Definitions
// =====================================================================================================================

class vertex_descriptor
{
// Functions ===========================================================================================================

private:
    struct attribute
    {
        size_t  size;
        enum_t  type;
        bool    normalized;
        index_t offset;
    };
    
    
// Functions ===========================================================================================================

public:
    vertex_descriptor();
    vertex_descriptor(const vertex_descriptor&);
    vertex_descriptor(vertex_descriptor&&) = default;
    ~vertex_descriptor();

    void add_attribute(enum_t type, size_t size, bool normalized);

    void bind();
    
// Variables ===========================================================================================================

private:
    handle_t handle_;
    ocu::dynarray<attribute> attributes_;
};

inline vertex_descriptor::vertex_descriptor()
    : handle_(NULL)
{
    glCreateVertexArrays(1, &handle_);
}

inline vertex_descriptor::vertex_descriptor(const vertex_descriptor& other)
    : handle_(NULL)
{
    glCreateVertexArrays(1, &handle_);
    attributes_.reserve(other.attributes_.size());

    for(const attribute& attrib : other.attributes_)
    {
        add_attribute(attrib.type, attrib.size, attrib.normalized);
    }
}

inline vertex_descriptor::~vertex_descriptor()
{
    glDeleteVertexArrays(1, &handle_);
}

inline void vertex_descriptor::add_attribute(enum_t type, size_t size, bool normalized)
{
    index_t offset = 0;

    if(attributes_.empty() == false)
    {
        const attribute& prev = attributes_.back();
        offset = prev.offset + prev.size * size_of(prev.type);
    }

    glEnableVertexArrayAttrib(handle_, attributes_.size());
    glVertexArrayAttribFormat(handle_, attributes_.size(), size, type, normalized, offset);

    attributes_.push_back(attribute(size, type, normalized, offset));
}

inline void vertex_descriptor::bind()
{
    glBindVertexArray(handle_);
}
    
}

#endif //VERTEX_DESCRIPTOR_H