import java.util.*;

public class Queues {
    private static Scanner sc = new Scanner(System.in);
    private static int max = 5, size = 0, front = 0, rear = 0;
    private static int[] arr = new int[max];

    public static void main(String[] args) {
        Loop();
    }

    private static void Enqueue() {
        if (!isFull()) {
            System.out.print("Enter a number to enqueue: ");
            arr[rear] = sc.nextInt();
            rear++;

            if (rear == max)
                rear = 0;

            size++;
            System.out.println("Value enqueued");
        }
        else
            System.out.println("Array is full");
    }

    private static void Dequeue() {
        if (!isEmpty()) {
            arr[front] = -1;
            front++;

            if (front == max)
                front = 0;
            size--;
            System.out.println("Value dequeued");
        }
        else
            System.out.println("Array is empty");
    }

    private static void Peek() {
        if (!isEmpty()) {
            System.out.println("============================");
            for (int i = front; i < max; i++) {
                if (arr[i] == -1 || arr[i] == 0) continue;
                System.out.println("Number: " + arr[i]);
            }

            for (int i = 0; i < front; i++) {
                if (arr[i] == -1 || arr[i] == 0) continue;
                System.out.println("Number: " + arr[i]);
            }
            System.out.println("============================");
        }
        else
            System.out.println("Array is empty");
    }

    private static void Clear() {
        rear = size = front = 0;
        arr = new int[max];
    }

    private static boolean isFull() {
        return max == size;
    }

    private static boolean isEmpty() {
        return size == 0;
    }

    private static void Loop() {
        while (true) {
            System.out.println("What do you want to do?");
            System.out.println("1 - Enqueue / Add");
            System.out.println("2 - Dequeue / Remove");
            System.out.println("3 - Peek / Show");
            System.out.println("4 - Clear");
            System.out.println("5 - Quit");
            System.out.print("Choose one: ");
            int choice = sc.nextInt();

            if (choice == 1)
                Enqueue();
            else if (choice == 2)
                Dequeue();
            else if (choice == 3)
                Peek();
            else if (choice == 4)
                Clear();
            else if (choice == 5)
                break;
        }
    }
}