// Copyright (C) 2022 RozK
//
// 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 _RK_ENGINE_RENDER_OPENGLES_H
#define _RK_ENGINE_RENDER_OPENGLES_H

#include "../render.hpp"
#include "render_context.hpp"
#include <GLES3/gl32.h>
#include <GLES3/gl3ext.h>
#include <GLES3/gl3platform.h>

enum : rk_uint {
    RK_VERTICES_BINDING = 0,
    RK_PARAMS_BINDING = 1
};

struct rk_uniforms {
    GLint view;
    GLint view_km;
    GLint projection;
};

struct rk_shader {
    GLuint vertex;
    GLuint fragment;
    GLuint program;
    rk_uniforms uniforms;
};

struct rk_texture {
    rk_uint slot;
    rk_uint nlevels;
    GLint sampler;
    GLuint texture;
};

struct rk_triangles {
    rk_uint size;
    GLuint array;
    GLuint vertices;
};

struct rk_vertices {
    rk_uint vertex_size;
    rk_uint layout;
    GLuint array;
    GLuint vertices;
    GLuint indices;
};

struct rk_command {
    GLuint count;
    GLuint ninstances;
    GLuint base_index;
    GLint base_vertex;
    GLuint base_instance;
};

struct rk_batch {
    rk_uint size;
    rk_batch_translation_format translation_format;
    rk_batch_orientation_format orientation_format;
    rk_uint params_size;
    rk_ushort * indices;
    rk_ubyte * params;
    rk_command * commands;
    GLuint params_buffer;
    GLuint commands_buffer;
};

struct rk_translation_float {
    rk_vec3 xyz;
    float l;

    inline void set(rk_vec3 const & translation, rk_ushort const texlevel) {
        xyz = translation;
        l = static_cast<float>(texlevel);
    }
};

struct rk_translation_short {
    rk_short x;
    rk_short y;
    rk_short z;
    rk_ushort l;

    inline void set(rk_vec3 const & translation, rk_ushort const texlevel) {
        x = static_cast<rk_short>(translation.x);
        y = static_cast<rk_short>(translation.y);
        z = static_cast<rk_short>(translation.z);
        l = texlevel;
    }
};

struct rk_orientation_float {
    rk_vec3 xyz;

    inline void set(rk_vec3 const & orientation) {
        xyz = orientation;
    }
};


struct rk_orientation_int10 {
    rk_uint xyz;

    inline void set(rk_vec3 const & orientation) {
        #define _pack_10(x) static_cast<rk_uint>(static_cast<rk_int>((x) * ((x) < 0.f ? 512.f : 511.f)) & 1023)
        xyz = _pack_10(orientation.x) << 20 | _pack_10(orientation.y) << 10 | _pack_10(orientation.z);
        #undef _pack_10
    }
};

template < typename _translation_t, typename _orientation_t >
struct rk_params {
    _translation_t translation;
    _orientation_t orientation;

    inline void set(rk_vec3 const & translation, rk_ushort const texlevel, rk_vec3 const & orientation) {
        this->translation.set(translation, texlevel);
        this->orientation.set(orientation);
    }
};

typedef rk_params<rk_translation_float, rk_orientation_float> rk_params_float_float;
typedef rk_params<rk_translation_float, rk_orientation_int10> rk_params_float_int10;
typedef rk_params<rk_translation_short, rk_orientation_float> rk_params_short_float;
typedef rk_params<rk_translation_short, rk_orientation_int10> rk_params_short_int10;

#endif // _RK_ENGINE_RENDER_OPENGLES_H