#include <iostream>
#include "queue.h"

using namespace std;

void InitQueue(QueueT & q) {
    q.size = 0;
    q.front = 0;
    q.back = 0;

    return;
}

int Next(int i) {
    i++;
    if (i >= QUEUE_MAX) {
       i = 0;
    }

    return i;
}

void Enqueue(QueueT & q,  ItemT item){
    if (q.size < QUEUE_MAX) {
       q.data[q.back] = item;
       q.back =Next(q.back);
       q.size++;
    } else {
       cout << "Error, enqueue to a full queue!" << endl;
    }
    return;
}

ItemT Dequeue(QueueT & q){
    ItemT i = ITEM_DEFAULT;
    if (q.size > 0) {
       i = q.data[q.front];

       // fix front
       q.front = Next(q.front);

       // fix size if queue is empty
       q.size --;
       if (q.size == 0) {
          q.front =0;
	  q.back = 0;
       }
    } else {
       cout <<"Error,  dequeue from an empty queue" << endl;
    }

    return i;
}

ItemT Front(const QueueT & q){
    ItemT i = ITEM_DEFAULT;
    if (q.size > 0) {
       i = q.data[q.front];
    } else {
       cout <<"Error,  front of an empty queue" << endl;
    }

    return i;
}

bool IsEmpty(const QueueT & q){
   return q.size==0;
}

bool IsFull(const QueueT & q){
    return q.size==QUEUE_MAX;
}

int Size(const QueueT & q){
    return q.size;
}