Home work - trader

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Home_Work
{
    class Program
    {
        static void Main(string[] args)
        {
            Player player = new Player(200);
            Trader seller = new Trader(5000);
            string userInput;
            bool isWorking = true;

            while (isWorking)
            {
                Console.WriteLine("Приветсвуем вас в торговом доме Виндсома.\n" +
                  "1. Посмотреть свой инвентарь.\n" +
                  "2. Посмотреть товары продовца.\n" +
                  "3. Выйти.");
                userInput = Console.ReadLine();
                Console.Clear();

                switch (userInput)
                {
                    case "1":
                        player.ShowInventory();
                        Console.ReadKey();
                        break;

                    case "2":
                        seller.OfferToSell(player);
                        break;

                    case "3":
                        isWorking = false;
                        break;
                }

                Console.Clear();
            }
        }
    }

    class Person
    {
        protected Inventory Inventory;
        protected int Money;

        public Person(int money = 0)
        {
            Inventory = new Inventory();
            Money = money;
        }

        public void ShowInventory()
        {
            Console.WriteLine($"Золота в наличии {Money}.");
            Inventory.ShowAll();
        }
    }

    class Player : Person
    {
        public Player(int money) : base(money)
        {
            Inventory.AddProduct(new Product("Тренировочный одноручный меч", 20), 1);
            Inventory.AddProduct(new Product("Тренировочный щит", 15), 1);
            Inventory.AddProduct(new Product("Форма рыцаря - новичка", 40), 1);
            Inventory.AddProduct(new Product("Бинт", 4), 2);
            Inventory.AddProduct(new Product("Железная сабля стражи", 50), 1);
        }

        public void Buy(Product product, int quantity)
        {
            Inventory.AddProduct(product, quantity);
            Money -= product.Price * quantity;
        }

        public bool IsSolvent(int purchase)
        {
            return Money >= purchase;
        }
    }

    class Trader : Person
    {
        public Trader(int money) : base(money)
        {
            Inventory.AddProduct(new Product("Меч короля Лича", 2000), 1);
            Inventory.AddProduct(new Product("Одноручный железный клинок рыцарей серебрянного авангарда", 150), 2);
            Inventory.AddProduct(new Product("Щит солнечного колодца", 200), 2);
            Inventory.AddProduct(new Product("Одноручный меч воина клана Ястреба", 70), 10);
            Inventory.AddProduct(new Product("Двухручный меч Кромсатель Драконов", 2000), 1);
            Inventory.AddProduct(new Product("Броня Берсерка", 1500), 1);
            Inventory.AddProduct(new Product("Железный щит стражи", 40), 20);
            Inventory.AddProduct(new Product("Железная сабля стражи", 50), 20);
        }

        public void OfferToSell(Player player)
        {
            ConsoleKeyInfo userKey;
            bool isShowing = true;

            while (isShowing)
            {
                ShowInventory();

                Console.WriteLine("\n1. Если хотите что-то купить.\n" +
                    "2. Выйти.");
                userKey = Console.ReadKey(true);

                switch (userKey.Key)
                {
                    case ConsoleKey.D1:
                        TrySell(player);
                        break;

                    case ConsoleKey.D2:
                        isShowing = false;
                        break;

                    default:
                        Console.WriteLine("Такой команды нет.");
                        Console.ReadKey();
                        break;
                }

                Console.Clear();
            }
        }

        private void TrySell(Player player)
        {
            Product product;
            int quantity;

            product = Inventory.GetProduct();
            quantity = Inventory.GetQuantity(product.Name);

            if (player.IsSolvent(product.Price * quantity))
            {
                player.Buy(product, quantity);
                Sell(product, quantity);

                Console.WriteLine("Сделка совершена.");
            }
            else
            {
                Console.WriteLine("Нужно больше золота.");
            }

            Console.ReadKey();
        }

        private void Sell(Product product, int quantity)
        {
            Inventory.ReduceProduct(product, quantity);
            Money += product.Price * quantity;
        }
    }

    class Inventory
    {
        private Dictionary<string, StackOfProduct> _products;

        public Inventory()
        {
            _products = new Dictionary<string, StackOfProduct>();
        }

        public int StacksCount => _products.Count();

        public void AddProduct(Product product, int quantity)
        {
            if (_products.ContainsKey(product.Name))
            {
                _products[product.Name].AddQuantity(quantity);
            }
            else
            {
                _products.Add(product.Name, new StackOfProduct(product, quantity));
            }
        }

        public void ShowAll()
        {
            int index = 1;

            Console.WriteLine($"В наличии: ");

            foreach (var product in _products)
            {
                Console.Write($"\n№{index}. ");
                product.Value.ShowInfo();

                index++;
            }
        }

        public void ReduceProduct(Product product, int quantity)
        {
            _products[product.Name].ReduceAmount(quantity);

            if (_products[product.Name].IsEmpty)
            {
                _products.Remove(product.Name);
            }
        }

        public Product GetProduct()
        {
            Product product = null;
            bool isGetIndex = false;

            int index;
            string userInput;

            while (isGetIndex == false)
            {
                Console.Write("Введите индекс товара: ");
                userInput = Console.ReadLine();

                if (Int32.TryParse(userInput, out index) && index > 0 && index <= StacksCount)
                {
                    string productName = _products.ElementAt(index - 1).Value.Name;
                    int productPrice = _products.ElementAt(index - 1).Value.PriceForOne;

                    product = new (productName, productPrice);
                    isGetIndex = true;
                }
                else
                {
                    Console.WriteLine("Такого индекса нет.");
                }
            }

            return product;
        }

        public int GetQuantity(string productName)
        {
            bool isGetQuaintity = false;
            int quantity = 0;

            string userInput;

            while (isGetQuaintity == false)
            {
                Console.Write("Введите кол-во товара: ");
                userInput = Console.ReadLine();

                if (Int32.TryParse(userInput, out quantity))
                {
                    if (quantity >= 0 && _products[productName].HaveQuanity(quantity))
                    {
                        isGetQuaintity = true;
                    }
                    else
                    {
                        Console.WriteLine("Такого кол-ва нет.");
                    }
                }
                else
                {
                    Console.WriteLine("Это даже не число.");
                }
            }

            return quantity;
        }
    }

    class StackOfProduct
    {
        private Product _product;
        private int _quantity;

        public StackOfProduct(Product product, int quantity)
        {
            _product = product;
            _quantity = quantity;
        }

        public string Name => _product.Name;
        public int PriceForOne => _product.Price;
        public int Quantity => _quantity;
        public bool IsEmpty => _quantity <= 0;

        public void AddQuantity(int quantity)
        {
            _quantity += quantity;
        }

        public void ReduceAmount(int quantity)
        {
            _quantity -= quantity;

        }

        public void ShowInfo()
        {
            Console.Write($"{Name} | Стоит {PriceForOne} золота/шт | Кол-во: {Quantity}");
        }

        public bool HaveQuanity(int quanity)
        {
            return _quantity >= quanity;
        }
    }

    class Product
    {
        private string _name;
        private int _price;

        public Product(string name, int price)
        {
            _name = name;
            _price = price;
        }

        public string Name => _name;
        public int Price => _price;
    }
}