// 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_H
#define _RK_ENGINE_RENDER_H

#include "types.hpp"
#include "math.hpp"

typedef rk_handle_t rk_shader_t;
typedef rk_handle_t rk_input_t;
typedef rk_handle_t rk_param_t;
typedef rk_handle_t rk_texture_t;
typedef rk_handle_t rk_triangles_t;
typedef rk_handle_t rk_vertices_t;
typedef rk_handle_t rk_batch_t;

typedef rk_uint rk_texture_format;

enum : rk_uint {
    RK_TEXTURE_FORMAT_SRGB8_A8 = 0,
    RK_TEXTURE_FORMAT_RGBA8 = 1,
    RK_TEXTURE_FORMAT_RGB10_A2 = 2,
    RK_TEXTURE_FORMAT_FLOAT_32 = 3
};

typedef rk_uint rk_texture_flags;

enum : rk_uint {
    RK_TEXTURE_FLAG_3D = RK_FLAG(0),
    RK_TEXTURE_FLAG_MIPMAPS = RK_FLAG(1),
    RK_TEXTURE_FLAG_MIN_NEAREST = 0,
    RK_TEXTURE_FLAG_MIN_LINEAR = RK_FLAG(2),
    RK_TEXTURE_FLAG_MAG_NEAREST = 0,
    RK_TEXTURE_FLAG_MAG_LINEAR = RK_FLAG(3),
};

typedef rk_ubyte rk_vertex_format;

enum : rk_ubyte {
    RK_VERTEX_FORMAT_VEC3_FLOAT = 1,
    RK_VERTEX_FORMAT_VEC3_INT10 = 2,
    RK_VERTEX_FORMAT_VEC3_UINT10 = 3,
    RK_VERTEX_FORMAT_NORMALIZE = RK_FLAG(7),
    RK_VERTEX_FORMAT_MASK = RK_VERTEX_FORMAT_NORMALIZE - 1
};

typedef rk_ubyte rk_param_format;

enum : rk_ubyte {
    RK_PARAM_FORMAT_VEC3_FLOAT = 1,
    RK_PARAM_FORMAT_VEC3_SHORT = 2,
    RK_PARAM_FORMAT_VEC3_INT10 = 3,
    RK_PARAM_FORMAT_MAT3_FLOAT = 4,
    RK_PARAM_FORMAT_MAT3_INT10 = 5,
    RK_PARAM_FORMAT_NORMALIZE = RK_FLAG(7),
    RK_PARAM_FORMAT_MASK = RK_PARAM_FORMAT_NORMALIZE - 1
};

typedef rk_ubyte rk_instance_flags;

enum : rk_ubyte {
    RK_INSTANCE_FLAG_SPAWNED = RK_FLAG(0),
    RK_INSTANCE_FLAG_VISIBLE = RK_FLAG(1),
    RK_INSTANCE_FLAGS_SPAWNED_VISIBLE = RK_INSTANCE_FLAG_SPAWNED | RK_INSTANCE_FLAG_VISIBLE
};

typedef rk_ushort rk_instance_index;

enum : rk_uint {
    RK_BATCH_MAX_SIZE = 1 << (sizeof(rk_instance_index) * 8)
};

typedef rk_ushort rk_vertex_index;
typedef rk_ushort rk_mesh_index;

struct rk_mesh {
    rk_uint base_index;
    rk_uint ntriangles;
};

// param input types must be size compatible with an array of rk_param_input
typedef rk_uint rk_param_input;

template<typename _input_type>
void rk_param_get_input_size(unsigned & _size, unsigned & _len) {
    static_assert((sizeof(_input_type) % sizeof(rk_param_input)) == 0);
    _size = sizeof(_input_type);
    _len = sizeof(_input_type) / sizeof(rk_param_input);
}

RK_EXPORT void rk_render_initialize(
    rk_bool debug);

RK_EXPORT void rk_render_terminate();

RK_EXPORT rk_shader_t rk_create_shader(
    rk_uint const vert_nlines,
    rk_char const * const * vert_lines,
    rk_uint const frag_nlines,
    rk_char const * const * frag_lines);

RK_EXPORT rk_input_t rk_resolve_input(
    rk_shader_t shader,
    rk_char const * name);

RK_EXPORT rk_param_t rk_resolve_param(
    rk_shader_t shader,
    rk_char const * name);

RK_EXPORT rk_texture_t rk_create_texture(
    rk_texture_format format,
    rk_uint width,
    rk_uint height,
    rk_uint nlevels,
    rk_texture_flags flags,
    rk_ubyte const * pixels);

RK_EXPORT rk_triangles_t rk_create_triangles(
    rk_uint nvertices,
    rk_vec3 const * vertices);

RK_EXPORT rk_vertices_t rk_create_vertices(
    rk_vertex_format const * format,
    rk_uint nvertices,
    rk_ubyte const * vertices,
    rk_uint nindices,
    rk_vertex_index const * indices,
    rk_uint nmeshes,
    rk_mesh const * meshes);

RK_EXPORT rk_batch_t rk_create_batch(
    rk_vertices_t vertices,
    rk_uint max_size,
    rk_param_format const * params_format);

RK_EXPORT void rk_fill_batch(
    rk_batch_t batch,
    rk_uint count,
    rk_instance_flags const * flags,
    rk_mesh_index const * meshes,
    rk_param_input const * const * params);

RK_EXPORT void rk_clear_buffer(
    rk_bool pixels,
    rk_bool depth,
    rk_bool stencil);

RK_EXPORT void rk_select_shader(
    rk_shader_t _shader);

RK_EXPORT void rk_set_input_float(
    rk_input_t input,
    float value);

RK_EXPORT void rk_set_input_vec3(
    rk_input_t input,
    rk_vec3 const & value);

RK_EXPORT void rk_set_input_mat3(
    rk_input_t input,
    rk_mat3 const & value);

RK_EXPORT void rk_set_input_mat4(
    rk_input_t input,
    rk_mat4 const & value);

RK_EXPORT void rk_set_param_vec3(
    rk_param_t param,
    rk_vec3 const & value);

RK_EXPORT void rk_set_param_mat3(
    rk_param_t param,
    rk_mat3 const & value);

RK_EXPORT void rk_select_texture(
    rk_uint slot,
    rk_texture_t texture);

RK_EXPORT void rk_draw_triangles(
    rk_triangles_t triangles);

RK_EXPORT void rk_draw_batch(
    rk_batch_t batch);

RK_EXPORT void rk_unselect_texture(
    rk_uint slot,
    rk_texture_t texture);

RK_EXPORT void rk_unselect_shader(
    rk_shader_t shader);

RK_EXPORT void rk_destroy_batch(
    rk_batch_t batch);

RK_EXPORT void rk_destroy_triangles(
    rk_triangles_t triangles);

RK_EXPORT void rk_destroy_vertices(
    rk_vertices_t vertices);

RK_EXPORT void rk_destroy_texture(
    rk_texture_t texture);

RK_EXPORT void rk_destroy_shader(
    rk_shader_t shader);

#endif // _RK_ENGINE_RENDER_H