#include "world.h"

#include <stdlib.h>

void tc_reset_chunk_pool(tc_chunk_pool_s *chunk_pool)
{
    chunk_pool->used_entries        = 0;
    chunk_pool->first_free          = chunk_pool->entries;
    
    uint32_t                entry_index     = 0;
    while(entry_index < chunk_pool->capacity)
    {
        chunk_pool->entries[entry_index].next       = &chunk_pool->entries[entry_index+1];
        chunk_pool->entries[entry_index].previous   = &chunk_pool->entries[entry_index-1];
        ++entry_index;
    }
    
    chunk_pool->entries[0].previous                     = NULL;
    chunk_pool->entries[chunk_pool->capacity-1].next    = NULL;
}

tc_chunk_pool_s * tc_new_chunk_pool(uint32_t capacity)
{
    tc_chunk_pool_s        *pool            = malloc(sizeof(tc_chunk_pool_s));
    pool->capacity              = capacity;
    pool->entries               = calloc(sizeof(tc_chunk_pool_entry_s), pool->capacity);
    tc_reset_chunk_pool(pool);
    
    return pool;
}

tc_chunk_pool_entry_s * tc_allocate_chunk_pool_entry(tc_chunk_pool_s *pool)
{
    if(pool->first_free == NULL)
    {
        pool->continuation          = tc_new_chunk_pool(pool->capacity * 2);
        return tc_allocate_chunk_pool_entry(pool->continuation);
    }
    tc_chunk_pool_entry_s  *allocated       = pool->first_free;
    pool->first_free            = allocated->next;
    
    return allocated;
}

tc_chunk_s * tc_allocate_chunk(tc_world_s *world)
{
    tc_chunk_pool_entry_s *entry = tc_allocate_chunk_pool_entry(world->pool);
    entry->chunk.superstructure  = entry;
    
    return &entry->chunk;
}

void tc_free_chunk(tc_world_s *world, tc_chunk_s *chunk)
{
    tc_chunk_pool_s         *pool       = world->pool;
    
    chunk->superstructure->next = pool->first_free;
    pool->first_free            = chunk->superstructure;
}