using System;

using System.Collections.Generic;

​

public class Product

{   

    public string Name { get; set; }

    public decimal Price { get; set; }

    public int StockQuantity { get; set; }

    public Product(string name, decimal price, int stockQuantity)

    {

        Name = name;

        Price = price;

        StockQuantity = stockQuantity;

    }

}

public class Program

{

    // Store products in a static list here.

    static List<Product> products = new List<Product>();

    public static void Main()

    {

        bool exit = false;

        // Main application loop

        while(!exit) {

            Console.WriteLine("=====================================");

            Console.WriteLine("       Inventory Management");

            Console.WriteLine("=====================================");

            Console.WriteLine("1. Add Product");

            Console.WriteLine("2. Update Stock");

            Console.WriteLine("3. View Products");

            Console.WriteLine("4. Remove Product");

            Console.WriteLine("5. Exit");

            Console.Write("Please choose an option (1-5): ");

            // Read the user choice

            string userInput = Console.ReadLine();

            Console.WriteLine();

             // We can use a switch statement to handle menu selection

            switch (userInput)

            {

                case "1":

                    AddProduct();

                    break;

​

                case "2":

                    UpdateStock();

                    break;

​

                case "3":

                    ViewProducts();

                    break;

​

                case "4":

                    RemoveProduct();

                    break;

​

                case "5":

                    // Exit application

                    exit = true;

                    Console.WriteLine("Exiting the application. Goodbye!");

                    Environment.Exit(0);

                    break;

                default:

                    Console.WriteLine("Invalid option. Please try again.\n");

                    break;

            }

        }

        // 1. Method to add a product

        static void AddProduct()

        {

            Console.WriteLine("--- Add New Product ---");

            // Get product name

            Console.Write("\nEnter product name: ");

            string name = Console.ReadLine() ?? "";

             // Get product price

            decimal price = 0;

            bool validPrice = false;

            while (!validPrice)

            {

                Console.Write("Enter price: $");

                validPrice = decimal.TryParse(Console.ReadLine(), out price) && price >= 0;

                if (!validPrice)

                {

                    Console.WriteLine("Invalid price. Please enter a non-negative number.");

                }

        }

            // Get product stock quantity

            int quantity = 0;

            bool validQuantity = false;

            while (!validQuantity)

            {

                Console.Write("Enter initial stock quantity: ");

                validQuantity = int.TryParse(Console.ReadLine(), out quantity) && quantity >= 0;

                if (!validQuantity)

                {

                    Console.WriteLine("Invalid quantity. Please enter a non-negative integer.");

                }

            }

            // Create and add the product to the list

            Product newProduct = new Product(name, price, quantity);

            products.Add(newProduct);

            Console.WriteLine($"Product '{name}' added successfully!\n");

        }

        // 2. Method to update stock

        static void UpdateStock()

        {

            Console.WriteLine("--- Update Product Stock ---");

​

            // If there are no products, let the user know

            if (products.Count == 0)

            {

                Console.WriteLine("No products available in inventory.\n");

                return;

            }

            // Show products first so user can pick id

            ViewProducts(); 

​

            Console.Write("Enter the Product Index (0-based) to update: ");

            string indexInput = Console.ReadLine();

​

            int index;

            if (int.TryParse(indexInput, out index) && index >= 0 && index < products.Count)

            {

                Product productToUpdate = products[index];

                Console.WriteLine($"Current stock for '{productToUpdate.Name}': {productToUpdate.StockQuantity}");

​

                Console.Write("Enter new stock quantity: ");

                string newStockInput = Console.ReadLine();

                int newStock;

​

                if (int.TryParse(newStockInput, out newStock) && newStock >= 0)

                {

                    productToUpdate.StockQuantity = newStock;

                    Console.WriteLine($"Stock updated for '{productToUpdate.Name}'. New Stock: {productToUpdate.StockQuantity}\n");

                }

                else

                {

                    Console.WriteLine("Invalid stock quantity.\n");

                }

            }

            else

            {

                Console.WriteLine("Invalid product index.\n");

            }

        }

        // 3. Method to view products

        static void ViewProducts()

        {

            Console.WriteLine("--- View All Products ---");

​

            // If there are no products, let the user know

            if (products.Count == 0)

            {

                Console.WriteLine("No products available in inventory.\n");

                return;

            }

​

            // Use a for loop to list products

            for (int i = 0; i < products.Count; i++)

            {

                Product product = products[i];

                Console.WriteLine($"{i}. Name: {product.Name}, Price: {product.Price}, Stock: {product.StockQuantity}");

            }

            Console.WriteLine();

        }

        // 4. Method to remove product

        static void RemoveProduct()

        {

            Console.WriteLine("--- Remove Product ---");

            // If there are no products, let the user know

            if (products.Count == 0)

            {

                Console.WriteLine("No products available in inventory.\n");

                return;

            }

            // Show products first so user can pick id

            ViewProducts(); 

​

            Console.Write("Enter the Product Index (0-based) to remove: ");

            string indexInput = Console.ReadLine();

            int index;

            if (int.TryParse(indexInput, out index) && index >= 0 && index < products.Count)

            {

                string removedProductName = products[index].Name;

                products.RemoveAt(index);

                Console.WriteLine($"Product '{removedProductName}' removed successfully!\n");

            }

            else

            {

                Console.WriteLine("Invalid product index.\n");

            }

        }

    }

}