#pragma once
#include "core.h"

enum {
    APoolFlag_AutoGrow = (1 << 0)
};
typedef U32 APoolFlags;
typedef union APoolElement APoolElement;
union APoolElement {
    APoolElement *next;       // offset from start to next free block (when not allocated)
};

typedef struct APool APool;
struct APool {
    APoolElement *free_list;  // free list
    U8 *start;                // start of user buffer
    Allocator *allocator;
    APoolFlags flags;
    U32 element_size;         // aligned size of each element
    U32 element_align;        // alignment
    U32 n_elements;           // total elements in the pool
    U32 n_free;               // number of free elements
};
typedef struct APoolCreateOptions APoolCreateOptions;
struct APoolCreateOptions {
    U32 element_size;         // aligned size of each element
    U32 element_align;        // alignment of elements
    U32 n_reserved;           // number of elements reserved
    APoolFlags flags;

};
#define apool_create(arena, n_reserved, type) \
        apool_create_ex(arena, &(APoolCreateOptions){sizeof(type), alignof(type), n_reserved, 0})
APool *apool_create_ex(Allocator *allocator, const APoolCreateOptions *options);
void *apool_alloc(APool *pool);
void apool_free(APool *pool, void *element);