#ifndef BUF_H
#define BUF_H

#include <stddef.h>
#include <stdio.h>

/*
 * Growable byte buffer (Milestone 2). Holds arbitrary bytes; buf_cstr() always
 * returns a NUL-terminated view so the buffer can be used as a string.
 * Opaque: callers only see buf_t *.
 */
typedef struct buf buf_t;

buf_t *buf_new(void);                            /* empty buffer; NULL on OOM */
int buf_append(buf_t *b, const char *s, size_t n); /* append n bytes; 0 ok, -1 OOM */
int buf_appendc(buf_t *b, char c);               /* append one byte; 0 ok, -1 OOM */
const char *buf_cstr(const buf_t *b);            /* NUL-terminated view; "" if empty */
size_t buf_len(const buf_t *b);                  /* bytes currently held */
void buf_reset(buf_t *b);                        /* drop contents, keep allocation */
void buf_free(buf_t *b);                         /* free buffer + storage */

/*
 * Read one full line (including the trailing newline) from f into b.
 * Returns the line length (>= 0), -1 at EOF with nothing read, or -2 on error.
 */
long buf_readline(buf_t *b, FILE *f);

#endif /* BUF_H */