/**
 * @file engine.h
 * @author Travis Vroman (travis@kohiengine.com)
 * @brief This file contains structures and logic pertaining to the
 * overall engine itself.
 * The engine is responsible for managing both the platform layers
 * as well as all systems within the engine.
 * @version 1.0
 * @date 2022-01-10
 *
 * @copyright Kohi Game Engine is Copyright (c) Travis Vroman 2021-2024
 *
 */

#pragma once

#include "defines.h"

#include "identifiers/khandle.h"
#include "platform/vfs.h"

struct application;
struct frame_data;
struct platform_state;
struct console_state;
struct kvar_state;
struct event_state;
struct input_state;
struct timeline_state;
struct resource_state;
struct shader_system_state;
struct renderer_system_state;
struct job_system_state;
struct kaudio_system_state;
struct ktransform_system_state;
struct texture_system_state;
struct font_system_state;
struct kmaterial_system_state;
struct static_mesh_system_state;
struct kmodel_system_state;
struct light_system_state;
struct camera_system_state;
struct plugin_system_state;
struct rendergraph_system_state;
struct asset_system_state;
struct kmatrix_system_state;
struct vfs_state;
struct kwindow;

typedef struct engine_system_states {
	u64 platform_memory_requirement;
	struct platform_state *platform_system;

	u64 console_memory_requirement;
	struct console_state *console_system;

	u64 kvar_system_memory_requirement;
	struct kvar_state *kvar_system;

	u64 event_system_memory_requirement;
	struct event_state *event_system;

	u64 input_system_memory_requirement;
	struct input_state *input_system;

	u64 timeline_system_memory_requirement;
	struct ktimeline_system_state *timeline_system;

	u64 shader_system_memory_requirement;
	struct shader_system_state *shader_system;

	u64 renderer_system_memory_requirement;
	struct renderer_system_state *renderer_system;

	u64 job_system_memory_requirement;
	struct job_system_state *job_system;

	u64 kaudio_system_memory_requirement;
	struct kaudio_system_state *audio_system;

	u64 ktransform_system_memory_requirement;
	struct ktransform_system_state *ktransform_system;

	u64 texture_system_memory_requirement;
	struct texture_system_state *texture_system;

	u64 font_system_memory_requirement;
	struct font_system_state *font_system;

	u64 material_system_memory_requirement;
	struct kmaterial_system_state *material_system;
	struct kmaterial_renderer *material_renderer;

	u64 static_mesh_system_memory_requirement;
	struct static_mesh_system_state *static_mesh_system;

	u64 light_system_memory_requirement;
	struct light_system_state *light_system;

	u64 model_system_memory_requirement;
	struct kmodel_system_state *model_system;

	u64 camera_system_memory_requirement;
	struct camera_system_state *camera_system;

	u64 plugin_system_memory_requirement;
	struct plugin_system_state *plugin_system;

	u64 rendergraph_system_memory_requirement;
	struct rendergraph_system_state *rendergraph_system;

	u64 vfs_system_memory_requirement;
	struct vfs_state *vfs_system_state;

	u64 asset_system_memory_requirement;
	struct asset_system_state *asset_state;

	u64 kmatrix_system_memory_requirement;
	struct kmatrix_system_state *matrix_system;
} engine_system_states;

/**
 * @brief Creates the engine, standing up the platform layer and all
 * underlying subsystems.
 * @param app A pointer to the application instance associated with the engine
 * @param app_config_path A string containing the relative or absolute path of the application config file.
 * @param game_lib_name The name of the library containing the game's code.
 * @returns True on success; otherwise false.
 */
KAPI b8 engine_create (struct application *app, const char *app_config_path, const char *game_lib_name);

/**
 * @brief Starts the main engine loop.
 * @param app A pointer to the application instance associated with the engine
 * @returns True on success; otherwise false.
 */
KAPI b8 engine_run (struct application *app);

/**
 * @brief A callback made when the event system is initialized,
 * which internally allows the engine to begin listening for events
 * required for initialization.
 */
void engine_on_event_system_initialized (void);

/**
 * @brief Obtains a constant pointer to the current frame data.
 *
 * @return A constant pointer to the current frame data.
 */
KAPI const struct frame_data *engine_frame_data_get (void);

/**
 * @brief Obtains a constant pointer to the collection of system states from the engine.
 */
KAPI const engine_system_states *engine_systems_get (void);

KAPI struct application *engine_app_state_get (void);

KAPI khandle engine_external_system_register (u64 system_state_memory_requirement);

KAPI void *engine_external_system_state_get (khandle system_handle);

KAPI struct kwindow *engine_active_window_get (void);