#include <stdio.h>
#include <stdbool.h>

#define MAX 5     // change size if needed

typedef struct {
    int data[MAX];
    int front;
    int rear;
    int count;
} Queue;

void initialize(Queue *q) {
    q->front = 0;
    q->rear = -1;
    q->count = 0;
}

bool isFull(Queue *q) {
    return q->count == MAX;
}

bool isEmpty(Queue *q) {
    return q->count == 0;
}

void push_back(Queue *q, int value) {
    if (isFull(q)) {
        printf("Queue is FULL! Cannot insert %d\n", value);
        return;
    }
    q->rear = (q->rear + 1) % MAX;
    q->data[q->rear] = value;
    q->count++;
}

int pop_front(Queue *q) {
    if (isEmpty(q)) {
        printf("Queue is EMPTY! Cannot pop.\n");
        return -1;  // return invalid value
    }
    int removed = q->data[q->front];
    q->front = (q->front + 1) % MAX;
    q->count--;
    return removed;
}

int size(Queue *q) {
    return q->count;
}

void display(Queue *q) {
    if (isEmpty(q)) {
        printf("Queue is EMPTY\n");
        return;
    }

    printf("Queue: ");
    int i, index;
    for (i = 0; i < q->count; i++) {
        index = (q->front + i) % MAX;
        printf("%d ", q->data[index]);
    }
    printf("\n");
}

/* ---------------- DRIVER MAIN ---------------- */

int main() {
    Queue q;
    initialize(&q);

    printf("Pushing 10, 20, 30...\n");
    push_back(&q, 10);
    push_back(&q, 20);
    push_back(&q, 30);
    display(&q);

    printf("\nPop two elements:\n");
    printf("Popped: %d\n", pop_front(&q));
    printf("Popped: %d\n", pop_front(&q));
    display(&q);

    printf("\nPushing 40, 50, 60...\n");
    push_back(&q, 40);
    push_back(&q, 50);
    push_back(&q, 60);
    display(&q);

    printf("\nQueue size: %d\n", size(&q));
    printf("Is full? %s\n", isFull(&q) ? "YES" : "NO");
    printf("Is empty? %s\n", isEmpty(&q) ? "YES" : "NO");

    printf("\nPopping all elements:\n");
    while (!isEmpty(&q)) {
        printf("Popped: %d\n", pop_front(&q));
    }

    printf("Is queue empty now? %s\n", isEmpty(&q) ? "YES" : "NO");

    return 0;
}