ДЗ Магазин

using System;
using System.Collections.Generic;

namespace CSLight
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Shop shop = new Shop(new Buyer());
            shop.Trade();
        }
    }

    class Shop
    {
        private Seller _seller = new Seller();
        private Buyer _buyer;

        public Shop(Buyer buyer)
        {
            _buyer = buyer;
        }

        public void Trade()
        {
            const string CommandEndTrade = "Да";

            bool isTrading = true;

            while (isTrading)
            {
                ShowSellerInventory();
                TryExchangeProduct();
                ShowBuyerInventory();

                Console.WriteLine("Закончить торговлю?");

                string userInput = Console.ReadLine();

                if(userInput == CommandEndTrade)
                {
                    isTrading = false;
                }
            }

            Console.ReadKey();
        }

        public void ShowSellerInventory()
        {
            Console.WriteLine("Товары на прилавке:");

            _seller.ShowProducts();
        }

        public void ShowBuyerInventory()
        {
            Console.WriteLine("У покупателя " + _buyer.Money + " денег");
            Console.WriteLine("Инвентарь покупателя:");

            _buyer.ShowProducts();
        }

        public void TryExchangeProduct()
        {
            Console.WriteLine("Выберите продукт для покупки");

            if (int.TryParse(Console.ReadLine(), out int id) && id < _seller.GetProductsCount())
            {
                Product product = _seller.GetProduct(id);
                int price = product.Price;

                if (_buyer.TryBuyProduct(product))
                {
                    _buyer.Buy(product);
                    _seller.SellProduct(product);
                    _buyer.DecreaseMoney(price);
                    Console.WriteLine("Покупка завершена");
                }
                else
                {
                    Console.WriteLine("У покупателя не хватает денег");
                }
            }
        }
    }


    class Buyer : Person
    {
        public Buyer()
        {
            int startingMoney = 50;
            IncreaseMoney(startingMoney);
        }

        public bool TryBuyProduct(Product product)
        {
            return product.Price <= Money;
        }

        public void Buy(Product product)
        {
            Bag.AddProduct(product);
            DecreaseMoney(product.Price);
        }
    }

    class Seller : Person
    {
        public Seller()
        {
            int fruitsPrice = 10;
            int breadPrice = 5;
            int vegetablePrice = 10;
            int meatPrice = 30;

            Bag.AddProduct(new Product("Яблоки", fruitsPrice));
            Bag.AddProduct(new Product("Черешня", fruitsPrice));
            Bag.AddProduct(new Product("Апельсин", fruitsPrice));
            Bag.AddProduct(new Product("Хлеб", breadPrice));
            Bag.AddProduct(new Product("Булочка", breadPrice));
            Bag.AddProduct(new Product("Пирожок", breadPrice));
            Bag.AddProduct(new Product("Помидоры", vegetablePrice));
            Bag.AddProduct(new Product("Огурцы", vegetablePrice));
            Bag.AddProduct(new Product("Мясо", meatPrice));

            Console.WriteLine("На прилавке" + Bag.ProductsCount);
        }

        public void SellProduct(Product product)
        {
            Bag.RemoveProduct(product);
            IncreaseMoney(product.Price);
        }
    }

    class Person
    {
        protected Inventory Bag = new Inventory();

        public int Money { get; private set; }

        public int GetProductsCount()
        {
            return Bag.ProductsCount;
        }

        public void ShowProducts()
        {
            for (int i = 0; i < Bag.ProductsCount; i++)
            {
                Console.WriteLine($"{i} - {Bag.GetProduct(i).Name} - {Bag.GetProduct(i).Price}");
            }
        }

        public void IncreaseMoney(int value)
        {
            if (value > 0)
            {
                Money += value;
            }
        }

        public void DecreaseMoney(int value)
        {
            if (value > 0)
            {
                Money -= value;

                if (Money < 0)
                {
                    Money = 0;
                }
            }
        }

        public Product GetProduct(int id)
        {
            return Bag.GetProduct(id);
        }
    }

    class Inventory
    {
        private List<Product> _products = new List<Product>();

        public int ProductsCount
        {
            get { return _products.Count; }
        }

        public void AddProduct(Product product)
        {
            _products.Add(product);
        }

        public void RemoveProduct(Product product)
        {
            _products.Remove(product);
        }

        public Product GetProduct(int id)
        {
            return _products[id];
        }
    }

    class Product
    {
        public Product(string name, int price)
        {
            Name = name;
            Price = price;
        }

        public string Name { get; private set; }
        public int Price { get; private set; }
    }
}