#include <voxula/internals/utility/allocation.h>
#include <voxula/internals/utility/math.h>

#include <stdlib.h>

void vx_reset_pool_allocation(vx_pool_s *pool, uint32_t slot_size)
{
    uint32_t slot_index = 0;
    while(slot_index < pool->capacity)
    {
        vx_pool_slot_header_s *header = (void *)
            ((uint8_t *) pool->allocation) + (slot_index * slot_size);
        header->next = header + slot_size;
        header->pool = pool;
        ++slot_index;
    }
    vx_pool_slot_header_s *last_header = (void *)
        ( ((uint8_t *) pool->allocation) + (slot_size * (pool->capacity - 1)) );
    last_header->next = NULL;
}

vx_pool_s * vx_new_pool(uint32_t unit_size, uint32_t capacity)
{
    uint32_t len_header = vx_ceil_to(sizeof(vx_pool_slot_header_s), 16);
    uint32_t slot_size = vx_ceil_to(unit_size + len_header, 16);

    vx_pool_s *pool = malloc(64 + (slot_size * capacity));
    pool->allocation = (void *) vx_ceil_to(((uint64_t) pool + 64), 64);
    pool->unit_size = unit_size;
    pool->capacity = capacity - 1;
    pool->first_free = pool->allocation;
    pool->continuation = NULL;

    vx_reset_pool_allocation(pool, slot_size);
    return pool;
}

void vx_free_pool(vx_pool_s *pool)
{
    if(pool->continuation)
    {
        vx_free_pool(pool->continuation);
    }
    free(pool);
}

void * vx_pool(vx_pool_s *pool)
{
    vx_pool_slot_header_s *item =  pool->first_free;
    if(item == NULL)
    {
        if( ! pool->continuation)
        {
            uint32_t new_pool_size = pool->capacity * 2;
            if(new_pool_size > 262144)
            {
                new_pool_size = 262144;
            }
            pool->continuation = vx_new_pool(pool->unit_size, new_pool_size);
        }
        return vx_pool(pool->continuation);
    }
    pool->first_free = item->next;
    return ((uint8_t *) item + 16);
}

void vx_unpool(void *allocation)
{
    vx_pool_slot_header_s *slot_header = (void *)
        ((uint8_t *) allocation - 16);
    slot_header->next = slot_header->pool->first_free;
    slot_header->pool->first_free = slot_header;
}