using System;

public class StackArray
{
private int[] array;
private int top; // Index of the top element
private int capacity;

// Public property to expose the current number of elements
public int CurrentStackSize => top + 1;

public StackArray(int size)
{
capacity = size;
array = new int[capacity];
top = -1;
}

public void Push(int element)
{
if (IsFull())
{
Console.WriteLine("Stack Overflow! Cannot push element. Stack is full.");
return;
}
array[++top] = element;
Console.WriteLine($"Pushed element: {element}");
}

public int Pop()
{
if (IsEmpty())
{
Console.WriteLine("Stack Underflow! Cannot pop element. Stack is empty.");
return -1;
}
int element = array[top--];
Console.WriteLine($"Popped element: {element}");
return element;
}

public int Peek()
{
if (IsEmpty())
{
Console.WriteLine("Stack is empty. Cannot peek.");
return -1;
}
Console.WriteLine($"Top element is: {array[top]}");
return array[top];
}

public bool IsEmpty()
{
return top == -1;
}

public bool IsFull()
{
return top == capacity - 1;
}

public void Display()
{
if (IsEmpty())
{
Console.WriteLine("Stack is empty. Nothing to display.");
return;
}
Console.Write("Stack elements (Top -> Bottom): ");
for (int i = top; i >= 0; i--)
{
Console.Write(array[i] + (i == 0 ? "" : ", "));
}
Console.WriteLine();
}
}

public class QueueArray
{
private int[] array;
private int front;
private int rear;
private int size;
private int capacity;

// Public method to expose the current number of elements
public int GetCurrentQueueSize() => size;

public QueueArray(int capacity)
{
this.capacity = capacity;
array = new int[this.capacity];
front = 0;
rear = -1;
size = 0;
}

public void Enqueue(int element)
{
if (IsFull())
{
Console.WriteLine("Queue Overflow! Cannot enqueue element. Queue is full.");
return;
}
rear = (rear + 1) % capacity;
array[rear] = element;
size++;
Console.WriteLine($"Enqueued element: {element}");
}

public int Dequeue()
{
if (IsEmpty())
{
Console.WriteLine("Queue Underflow! Cannot dequeue element. Queue is empty.");
return -1;
}
int element = array[front];
front = (front + 1) % capacity;
size--;
Console.WriteLine($"Dequeued element: {element}");
return element;
}

public int Peek()
{
if (IsEmpty())
{
Console.WriteLine("Queue is empty. Cannot peek.");
return -1;
}
Console.WriteLine($"Front element is: {array[front]}");
return array[front];
}

public bool IsEmpty()
{
return size == 0;
}

public bool IsFull()
{
return size == capacity;
}

public void Display()
{
if (IsEmpty())
{
Console.WriteLine("Queue is empty. Nothing to display.");
return;
}

Console.Write("Queue elements (Front -> Rear): ");
for (int i = 0; i < size; i++)
{
int index = (front + i) % capacity;
Console.Write(array[index] + (i == size - 1 ? "" : ", "));
}
Console.WriteLine();
}
}

public class Program
{
private static int arraySize = 0;
private static StackArray stack = null;
private static QueueArray queue = null;

public static void Main(string[] args)
{
GetArraySize();
stack = new StackArray(arraySize);
queue = new QueueArray(arraySize);

MainMenu();
}

private static void GetArraySize()
{
Console.Title = "Data Structures: Stack & Queue Implementation";

while (arraySize <= 0)
{
Console.Write("Enter the size of the array for Stack and Queue: ");
if (int.TryParse(Console.ReadLine(), out int size) && size > 0)
{
arraySize = size;
}
else
{
Console.WriteLine("Invalid input. Please enter a positive integer for the size.");
}
}
}

private static void MainMenu()
{
bool running = true;
while (running)
{
Console.WriteLine("\n==================================");
Console.WriteLine("Main Menu 🏠");
Console.WriteLine("==================================");
Console.WriteLine("1. STACK Operations (LIFO)");
Console.WriteLine("2. QUEUE Operations (FIFO)");
Console.WriteLine("3. EXIT");
Console.Write("Enter your choice (1-3): ");

string choice = Console.ReadLine();
Console.WriteLine();

switch (choice)
{
case "1":
StackSubMenu();
break;
case "2":
QueueSubMenu();
break;
case "3":
running = false;
Console.WriteLine("Exiting program. Goodbye! 👋");
break;
default:
Console.WriteLine("Invalid choice. Please enter 1, 2, or 3.");
break;
}
}
}

private static void StackSubMenu()
{
bool back = false;
while (!back)
{
// FIX: Use the public property CurrentStackSize instead of the private field 'top'
Console.WriteLine("\n----------------------------------");
Console.WriteLine($"STACK Menu (Size: {arraySize}, Elements: {stack.CurrentStackSize}) 📚");
Console.WriteLine("----------------------------------");
Console.WriteLine("1. Push (Add element)");
Console.WriteLine("2. Pop (Remove element)");
Console.WriteLine("3. Peek (View top element)");
Console.WriteLine("4. IsEmpty (Check if empty)");
Console.WriteLine("5. IsFull (Check if full)");
Console.WriteLine("6. View Elements");
Console.WriteLine("7. Back to Main Menu");
Console.Write("Enter your choice (1-7): ");

string choice = Console.ReadLine();
Console.WriteLine();

switch (choice)
{
case "1":
Console.Write("Enter integer to Push: ");
if (int.TryParse(Console.ReadLine(), out int element))
{
stack.Push(element);
}
else
{
Console.WriteLine("Invalid input. Please enter an integer.");
}
break;
case "2":
stack.Pop();
break;
case "3":
stack.Peek();
break;
case "4":
Console.WriteLine($"Stack is Empty: {stack.IsEmpty()}");
break;
case "5":
Console.WriteLine($"Stack is Full: {stack.IsFull()}");
break;
case "6":
stack.Display();
break;
case "7":
back = true;
break;
default:
Console.WriteLine("Invalid choice. Please enter a number from 1 to 7.");
break;
}
}
}

private static void QueueSubMenu()
{
bool back = false;
while (!back)
{
// FIX: Use the public method GetCurrentQueueSize() instead of the private field 'size'
Console.WriteLine("\n----------------------------------");
Console.WriteLine($"QUEUE Menu (Size: {arraySize}, Elements: {queue.GetCurrentQueueSize()}) 🚌");
Console.WriteLine("----------------------------------");
Console.WriteLine("1. Enqueue (Add element)");
Console.WriteLine("2. Dequeue (Remove element)");
Console.WriteLine("3. Peek (View front element)");
Console.WriteLine("4. IsEmpty (Check if empty)");
Console.WriteLine("5. IsFull (Check if full)");
Console.WriteLine("6. View Elements");
Console.WriteLine("7. Back to Main Menu");
Console.Write("Enter your choice (1-7): ");

string choice = Console.ReadLine();
Console.WriteLine();

switch (choice)
{
case "1":
Console.Write("Enter integer to Enqueue: ");
if (int.TryParse(Console.ReadLine(), out int element))
{
queue.Enqueue(element);
}
else
{
Console.WriteLine("Invalid input. Please enter an integer.");
}
break;
case "2":
queue.Dequeue();
break;
case "3":
queue.Peek();
break;
case "4":
Console.WriteLine($"Queue is Empty: {queue.IsEmpty()}");
break;
case "5":
Console.WriteLine($"Queue is Full: {queue.IsFull()}");
break;
case "6":
queue.Display();
break;
case "7":
back = true;
break;
default:
Console.WriteLine("Invalid choice. Please enter a number from 1 to 7.");
break;
}
}
}
}