#ifndef BBUFFER_H__
#define BBUFFER_H__
#include <stdlib.h>
#include <stdbool.h>

/*
 * types for bounded buffer for bounded-buffer simulation
 *
 * items in buffer are structs with producer ID and number,
 * stored as circular queue.
 */

/* ---- types ---- */

typedef struct bbuffer_item {
    int producer;
    int number;
} bbuffer_item_t;

typedef struct bbuffer {
    int size;
    int head;
    int count;
    bbuffer_item_t *items;
} bbuffer_t;

/* ---- function declarations ---- */

/* 
 * create bounded buffer of size 'size'.
 * dynamically allocates space for it.
 * returns success/failure
 */
bool bbuffer_create(bbuffer_t * bb, int size);

/* 
 * sets size of buffer back to 0 and frees
 * dynmically-allocated space.
 */
void bbuffer_free(bbuffer_t * bb);

/*
 * inserts item into buffer.
 * no safety check to prevent overflow.
 */
void bbuffer_insert(bbuffer_t *bb, bbuffer_item_t item);

/*
 * removes item from buffer and returns it.
 *
 * no safety check to prevent removing from 
 * empty buffer.
 */
bbuffer_item_t bbuffer_remove(bbuffer_t *bb);

/* ---- function definitions ---- */

bool bbuffer_create(bbuffer_t * bb, const int size) {
    bb->size = size;
    bb->head = 0;
    bb->count = 0;
    bb->items = malloc(sizeof(bb->items[0]) * size);
    return (bb->items != NULL);
}

void bbuffer_destroy(bbuffer_t * bb) {
    free(bb->items);
}

void bbuffer_insert(bbuffer_t *bb, const bbuffer_item_t item) {
    int next_free = (bb->head + bb->count) % bb->size;
    bb->items[next_free] = item;
    ++bb->count;
}

bbuffer_item_t bbuffer_remove(bbuffer_t *bb) {
    int save_head = bb->head;
    bb->head = (save_head + 1) % bb->size;
    --bb->count;
    return bb->items[save_head];
}

#endif