#ifndef RT_GFX_BACKEND_H
#define RT_GFX_BACKEND_H

/* Backend functions and types. */

#include <stddef.h>

#include "gfx.h"
#include "runtime.h"
#include "resources.h"

#ifdef __cplusplus
extern "C" {
#endif

#ifdef _WIN32
struct HINSTANCE__;
struct HWND__;
#elif defined(RT_USE_XLIB)
struct _XDisplay;
#endif

struct rt_renderer_init_info_s {
#ifdef _WIN32
    struct HINSTANCE__ *hInstance;
    struct HWND__ *hWnd;
#elif defined(RT_USE_XLIB)
    struct _XDisplay *display;
    unsigned long window;
#endif
};

typedef struct {
    rt_resource_id vertex_shader;
    rt_resource_id fragment_shader;
    rt_resource_id compute_shader;

    rt_relptr texture_bindings;
    rt_relptr uniform_bindings;
    rt_relptr storage_bindings;

    uint16_t texture_binding_count;
    uint16_t uniform_binding_count;
    uint16_t storage_binding_count;
} rt_pipeline_info;

/* Attributes are used to bind buffers (or textures) to symbolic values.
 * For example, an attribute might be bound to "CELL_GRID", which would be
 * replaced with the (at the time of the invoke) grid buffer of the current
 * world cell.
 */

typedef enum {
    RT_ATTRIBUTE_VALUE_UNDEFINED,

    RT_ATTRIBUTE_VALUE_MATERIAL_ALBEDO,
    RT_ATTRIBUTE_VALUE_MATERIAL_NORMAL,

    RT_ATTRIBUTE_VALUE_count
} rt_attribute_value;

typedef struct {
    uint32_t index;
    rt_attribute_value value;
} rt_attribute_binding;

typedef enum {
    RT_SHADER_TYPE_INVALID,
    RT_SHADER_TYPE_VULKAN,

    RT_SHADER_TYPE_count,
} rt_shader_type;

typedef enum {
    RT_SHADER_STAGE_VERTEX,
    RT_SHADER_STAGE_FRAGMENT,
    RT_SHADER_STAGE_COMPUTE,

    RT_SHADER_STAGE_count,
} rt_shader_stage;

typedef struct {
    rt_shader_type type;
    rt_shader_stage stage;
    rt_relptr bytecode;
    size_t bytecode_length;
} rt_shader_info;


/* Handles for backend objects */

#define RT_GFX_HANDLE_MAX_VERSION 255

typedef struct {
    uint32_t version : 8;
    uint32_t index : 24;
} rt_pipeline_handle;

typedef void rt_register_renderer_cvars_fn(void);
typedef rt_result rt_init_renderer_fn(const rt_renderer_init_info *info);
typedef void rt_shutdown_renderer_fn(void);
typedef rt_pipeline_handle rt_compile_pipeline_fn(const rt_pipeline_info *info);
typedef void rt_destroy_pipeline_fn(rt_pipeline_handle handle);

typedef struct {
    rt_register_renderer_cvars_fn *RegisterCVars;
    rt_init_renderer_fn *Init;
    rt_shutdown_renderer_fn *Shutdown;
    rt_compile_pipeline_fn *CompilePipeline;
    rt_destroy_pipeline_fn *DestroyPipeline;
} rt_renderer_api;

#define RT_RENDERER_API_FN(name) RT_DLLEXPORT rtRen##name

#ifndef RT_DONT_DEFINE_RENDERER_GLOBAL
extern rt_renderer_api g_renderer;
#endif

#ifdef __cplusplus
}
#endif

#endif