/* storage.h — file backend mapping the torrent's flat byte space to files.
 *
 * A torrent is one contiguous byte space [0, total_length); this layer splits a
 * read/write at any global offset across the underlying files (a single block
 * write can straddle a file boundary). Phase 3 uses positional pread/pwrite for
 * correctness; the io_uring O_DIRECT fast path is a Phase 6 swap behind this
 * same interface. The backend is a vtable so a memory/object-store backend can
 * be registered later (the "extensible" goal).
 */
#ifndef NAUT_STORAGE_H
#define NAUT_STORAGE_H

#include "naut/common.h"
#include "naut/metainfo.h"

typedef struct naut_storage naut_storage;

typedef struct {
    bool direct_io;
    bool preallocate;
} naut_storage_opts;

/* Open (creating + preallocating) all files under `root`. */
naut_storage *naut_storage_open(const naut_file *files, size_t nfiles,
                                const char *root, naut_err *err);
naut_storage *naut_storage_open_opts(const naut_file *files, size_t nfiles,
                                     const char *root,
                                     const naut_storage_opts *opts,
                                     naut_err *err);
void naut_storage_close(naut_storage *s);

naut_err naut_storage_write(naut_storage *s, int64_t offset, const void *buf, size_t len);
naut_err naut_storage_read(naut_storage *s, int64_t offset, void *buf, size_t len);
naut_err naut_storage_sync(naut_storage *s);

/* Move one completed file out to `dest` (rename, or copy+unlink across file
 * systems). The caller must guarantee the file is complete — every piece
 * overlapping it verified — so no further writes target it. After this the slot
 * is "externalized": subsequent I/O to its region returns NAUT_ERR_RANGE. This
 * is the storage half of the "move files as they finish" feature. */
naut_err naut_storage_relocate(naut_storage *s, size_t file_index, const char *dest);

int64_t naut_storage_total(const naut_storage *s);
bool    naut_storage_direct_enabled(const naut_storage *s);

#endif /* NAUT_STORAGE_H */