#include "world.h"
#include "entity.h"

#include <stdlib.h>
#include <stdio.h>

void tc_add_chunk_to_loader(tc_chunkloader_s *chunkloader, tc_entity_s *entity)
{
    if(chunkloader->num_chunks >= chunkloader->chunks_capacity)
    {
        chunkloader->chunks_capacity           *= 2;
        chunkloader->chunks                     = realloc(chunkloader->chunks, sizeof(tc_entity_s *) * chunkloader->chunks_capacity);
    }
    chunkloader->chunks[chunkloader->num_chunks] = entity;
    ++chunkloader->num_chunks;
}

bool tc_coord_is_within_loaders_range(tc_chunkloader_s *loader, tc_vec3i_s coord)
{
    if(coord.x < (loader->center.x - loader->extent.x / 2))     return false;
    if(coord.y < (loader->center.y - loader->extent.y / 2))     return false;
    if(coord.z < (loader->center.z - loader->extent.z / 2))     return false;
    
    if(coord.x > (loader->center.x + loader->extent.x / 2))     return false;
    if(coord.y > (loader->center.y + loader->extent.y / 2))     return false;
    if(coord.z > (loader->center.z + loader->extent.z / 2))     return false;
    
    return true;
}

tc_chunkloader_s * tc_get_corresponding_loader(tc_world_s *world, tc_vec3i_s coord)
{
    for(uint32_t loader_index = 0; loader_index < world->num_loaders; ++loader_index)
        if(tc_coord_is_within_loaders_range(&world->loaders[loader_index], coord))
            return &world->loaders[loader_index];
    
    return NULL;
}

tc_entity_s * tc_get_chunk_of_loader(tc_chunkloader_s *loader, tc_vec3i_s coord)
{
    for(uint32_t chunk_index = 0; chunk_index < loader->num_chunks; ++chunk_index)
    {
        tc_chunk_s         *chunk       = loader->chunks[chunk_index]->specific;
        if(tc_vec3i_equ(chunk->position, coord))
            return loader->chunks[chunk_index];
    }
    
    return NULL;
}

tc_entity_s * tc_get_loaded_chunk(tc_world_s *world, tc_vec3i_s coord)
{
    tc_chunkloader_s *loader = tc_get_corresponding_loader(world, coord);
    if(loader == NULL) return NULL;
    
    return tc_get_chunk_of_loader(loader, coord);
}

tc_entity_s * tc_load_chunk_of_loader(tc_chunkloader_s *loader, tc_vec3i_s coord)
{
    tc_entity_s        *entity          = tc_get_chunk_of_loader(loader, coord);
    
    if(entity == NULL)
    {
        tc_entity_s            *entity             = tc_create_entity("chunk"); // TODO: FURTHER RESTRUCTUING FOR ENTITIES
        tc_chunk_s             *chunk           = entity->specific;
        chunk                   = entity->specific;
        chunk->position         = coord;
        
        loader->world->worldgen->fn_generate_chunk(loader->world->worldgen, chunk);
        tc_upload_chunk(chunk);
        
        tc_add_chunk_to_loader(loader, entity);
   }
    return entity;
}

void tc_reload_chunk_of_loader(tc_chunkloader_s *loader, tc_vec3i_s coord)
{
    tc_entity_s *entity = tc_get_chunk_of_loader(loader, coord);
    tc_chunk_s  *chunk  = entity->specific;
    if(chunk == NULL) return;
    
    tc_meshize_chunk(chunk);
    tc_upload_chunk(chunk);
}

void tc_reload_chunk(tc_world_s *world, tc_vec3i_s coord)
{
    tc_chunkloader_s *loader = tc_get_corresponding_loader(world, coord);
    if(loader == NULL) return;
    
    tc_reload_chunk_of_loader(loader, coord);
}

void tc_remove_loaders_chunk(tc_chunkloader_s *loader, uint32_t index)
{
    tc_delete_entity(loader->chunks[index]);
    
    if(loader->num_chunks != 0)
    {
        // This is is NOT last element
        if((index+1) < loader->num_chunks)
        {
                loader->chunks[index] = loader->chunks[loader->num_chunks-1]; // move last chunk into gap
        }
        
        --loader->num_chunks;
    }
}

void tc_remove_unnecessary_chunks_of_loader(tc_chunkloader_s *loader)
{
    for(uint32_t chunk_index = 0; chunk_index < loader->num_chunks; ++chunk_index)
    {
        tc_entity_s *entity = loader->chunks[chunk_index];
        tc_chunk_s  *chunk  = entity->specific;
        
        if(!tc_coord_is_within_loaders_range(loader, chunk->position))
        {
            tc_remove_loaders_chunk(loader, chunk_index);
        }
    }
}

void tc_load_all_chunks_of_chunkloader(tc_chunkloader_s *loader)
{
    for(int32_t x = 0; x < loader->extent.x; ++x)
    {
        for(int32_t y = 0; y < loader->extent.y; ++y)
        {
            for(int32_t z = 0; z < loader->extent.z; ++z)
            {
                tc_vec3i_s      coords;
                coords.x = (loader->center.x - (x - ((int32_t) loader->extent.x)))-1;
                coords.y = (loader->center.y - (y - ((int32_t) loader->extent.y)))-1;
                coords.z = (loader->center.z - (z - ((int32_t) loader->extent.z)))-1;
                
                tc_load_chunk_of_loader(loader, coords);
            }
        }
    }
}

void tc_reload_chunkloader_zone(tc_chunkloader_s *loader)
{
    tc_remove_unnecessary_chunks_of_loader(loader);
    tc_load_all_chunks_of_chunkloader(loader);
}

uint64_t world_update_tick = 0;

void tc_update_world(tc_world_s *world)
{
    if((world_update_tick % 512) == 0)
    {
        uint32_t chunkloader_index = 0;
        while(chunkloader_index < world->num_loaders)
        {
            if(world->loaders[chunkloader_index].needs_reload)
            {
                tc_reload_chunkloader_zone(&world->loaders[chunkloader_index]);
            }
            ++chunkloader_index;
        }
    }
    ++world_update_tick;
}