#ifndef __NICKEL_VM_H
#define __NICKEL_VM_H

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

#ifdef __cplusplus
extern "C" {
#endif

/* VM layer: portable-ish page allocation based on mmap/munmap (Linux + macOS). */

typedef struct ni_vm_stats {
    size_t page_size;

    /* cumulative counters */
    uint64_t reserves;      /* number of reserve calls */
    uint64_t releases;      /* number of release calls */
    uint64_t commits;       /* if supported by impl (optional), else 0 */
    uint64_t decommits;     /* if supported by impl (optional), else 0 */

    size_t bytes_reserved;  /* current bytes reserved */
    size_t bytes_peak;      /* peak reserved */
} ni_vm_stats;

/* Returns OS page size (usually sysconf(_SC_PAGESIZE)). Never returns 0. */
size_t ni_vm_page_size(void);

/* Reserve anonymous virtual memory.
   - bytes will be rounded up to a page multiple.
   - returns NULL on failure.
*/
void* ni_vm_reserve(size_t bytes);

/* Release a region previously returned by ni_vm_reserve (page-multiple size). */
bool ni_vm_release(void* addr, size_t bytes);

/* Optional: “commit/decommit” for platforms where it’s meaningful.
   On many Unix systems, reserve implies commit; implementations may no-op.
*/
bool ni_vm_commit(void* addr, size_t bytes);
bool ni_vm_decommit(void* addr, size_t bytes);

/* Optional: set guard pages (mprotect) for debug.
   Returns false if unsupported or fails.
*/
bool ni_vm_protect_none(void* addr, size_t bytes);
bool ni_vm_protect_rw(void* addr, size_t bytes);

/* Stats are optional but very useful for tests/tools. */
void ni_vm_get_stats(ni_vm_stats* out_stats);
void ni_vm_reset_stats(void);

#ifdef __cplusplus
}
#endif

#endif /* __NICKEL_VM_H */