#ifndef RESERVOIR_H_MZSA8WJ3
#define RESERVOIR_H_MZSA8WJ3

#include <stdlib.h>

#include "buf.h"

#ifndef NDEBUG
#include "notify.h"
#endif /* NDEBUG */

/*
	A size-limited pool of buf_t entries.  When the reservoir is filled with
	more entries than there is room for, some spill away and are lost.
*/

typedef struct reservoir_ {
	size_t reservoir_sz; /* allocated slots */
	size_t reservoir_used; /* slots filled */
	unsigned long reservoir_tally; /* total number of items remembered */
	buf_t reservoir[];
} *reservoir_t;

#ifndef NDEBUG
/*	For debugging, dump an entire reservoir's contents. */
#define D_RESERVOIR(__r__) do {\
	size_t i;\
		NOTIFY_DEBUG("reservoir:%p sz: %zu used:%zu tally:%zu", (__r__), (__r__)->reservoir_sz, (__r__)->reservoir_used, (__r__)->reservoir_tally);\
		for (i = 0; i < (__r__)->reservoir_sz; i++) {\
			D_BUF("reservoir[%zu] ", (__r__)->reservoir[i], i);\
		}\
} while (0)
#else /* NDEBUG */
#define D_RESERVOIR(...)
#endif /* NDEBUG */

/*	reservoir_new
		Allocate and return a new reservoir capable of holding #sz buf_t
	entries.
*/
reservoir_t reservoir_new(size_t sz);

/*	reservoir_del
		Deallocate the reservoir pointed to by #preservoir.
*/
void reservoir_del(reservoir_t *preservoir);

/*	reservoir_grow
		Increase the storage capacity of the reservoir pointed to by
	#preservoir by #growby entries.
*/
int reservoir_grow(reservoir_t *preservoir, size_t growby);

/*	reservoir_remember
		Remember #buf, forgetting (and freeing) another buf_t chosen at random
	if the reservoir pointed to by #preservoir is already full to capacity.
*/
void reservoir_remember(reservoir_t reservoir, buf_t buf);

/*	reservoir_write
		Write the contents of the buf_t entries within #reservoir to #fd, each
	with a trailing #delim character.
*/
int reservoir_write(int fd, reservoir_t reservoir, char delim);

/*	reservoir_write_meta
		Write metadata about #reservoir and #samples to fd.
*/
int reservoir_write_meta(int fd, reservoir_t reservoir, unsigned long samples, char delim);

#endif /* RESERVOIR_H_MZSA8WJ3 */