#ifndef TC_WORLD_H
#define TC_WORLD_H

#include <stdbool.h>
#include <stdint.h>

#include "blocks.h"
#include "utility.h"


#define UPDATE_DISTANCE 2


typedef struct  tc_worldgen             tc_worldgen_s;
typedef struct  tc_block                tc_block_s;
typedef struct  tc_chunk                tc_chunk_s;
typedef struct  tc_world                tc_world_s;

typedef struct  tc_chunk_pool           tc_chunk_pool_s;
typedef struct  tc_chunk_pool_entry     tc_chunk_pool_entry_s;

struct tc_worldgen
{
    char               *name;
    bool              (*fn_generate_chunk)              (tc_worldgen_s *gen, tc_chunk_s *chunk);
    
};

struct tc_block
{
    uint32_t            type_identifier;
    tc_vec3_s           position;
    tc_vec3_s           rotation;
    tc_object_s         drawing;
    
};

struct tc_chunk
{
    tc_chunk_pool_entry_s      *pool_entry;
    
    tc_vec3i_s                  position;
    uint32_t                    blocks[32][32][32];
    
    uint32_t                    num_vertices;
    float                      *vertex_positions;
    float                      *vertex_uvs;
    
    uint32_t                    vao;
    uint32_t                    vertex_data;
};

struct tc_chunk_pool_entry
{
    tc_chunk_pool_entry_s      *next;
    tc_chunk_pool_entry_s      *previous;
    
    tc_chunk_s                  chunk;
};

typedef struct tc_chunkloader
{
    tc_vec3i_s                  center;
    tc_vec3i_s                  extent;
    
    uint32_t                    chunks_capacity;
    uint32_t                    num_chunks;
    tc_chunk_s                **chunks;
    tc_world_s                 *world;
    
    bool                        needs_reload;
    
} tc_chunkloader_s;

struct tc_chunk_pool
{
    uint32_t                    capacity;
    uint32_t                    used_entries;
    tc_chunk_pool_entry_s      *entries;
    tc_chunk_pool_entry_s      *first_free;
    
    tc_chunk_pool_s            *continuation;
};

struct tc_world
{
    // tc_chunk_s                 *center_chunk;
    
    tc_chunk_pool_s            *pool;
    tc_worldgen_s              *worldgen;
    
    uint32_t                    num_loaders;
    tc_chunkloader_s           *loaders;
    
    // chunk_loading_center: The center of loading ON THE CHUNK GRID COORDINATES
    tc_chunkloader_s           *spawn_loader;
};

extern tc_worldgen_s tc_default_terrain_generator_g;

void                tc_init_worlds          ();
void                tc_draw_world           (tc_world_s *world);

tc_world_s *        tc_new_world            (tc_worldgen_s *generator);
tc_chunk_s *        tc_new_chunk            (tc_world_s *world, int32_t x, int32_t y, int32_t z); // must be integers

void tc_set_block_in_chunk(
    tc_chunk_s *chunk,
    uint8_t x, uint8_t y, uint8_t z,
    tc_block_s block
);

uint32_t            tc_count_chunk_vertices                 (tc_chunk_s *chunk);
void                tc_meshize_chunk                        (tc_chunk_s *chunk);
void                tc_upload_chunk                         (tc_chunk_s *chunk);

bool                tc_generate_default_terrain_chunk       (tc_worldgen_s *gen, tc_chunk_s *chunk);

void                tc_add_chunk_to_loader                  (tc_chunkloader_s *chunkloader, tc_chunk_s *chunk);
tc_chunk_s *        tc_load_chunk_at                        (tc_world_s *world, int32_t x, int32_t y, int32_t z);
tc_chunk_s *        tc_get_loaded_chunk_at                  (tc_world_s *world, int32_t x, int32_t y, int32_t z);
bool                tc_chunk_is_loaded                      (tc_world_s *world, int32_t x, int32_t y, int32_t z);

void                tc_update_world                         (tc_world_s *world);

void                tc_on_each_loaded_chunk                 (
    tc_world_s *world,
    bool (*fn_do)(tc_chunk_s *chunk, void *userdata),
    void *userdata
);

tc_chunk_pool_s *   tc_new_chunk_pool                       (uint32_t capacity);
tc_chunk_s *        tc_allocate_chunk                       (tc_world_s *world);
void                tc_free_chunk                           (tc_world_s *world, tc_chunk_s *chunk);

#endif