Design Pattern - Structural - Facade

   

Scenario:

Create a e-Retail Checkout.

Solution:

This pattern hides the complexities of the larger system and provides a simpler interface to the client. 

Example: The Checkout, involves multiple steps to move the Order ahead, but through Facade we expose only Checkout.TryProcess method to the client and hiding the complexity.

1. Checkout 



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namespace TestProject
{
    public class Shopper
    {
        public int Id { get; set; }
        public string? Name { get; set; }
        public string? Address { get; set; }
    }

    public class OrderService
    {
        public bool TryCreateOrder(string order, out Guid? orderId)
        {
            orderId = Guid.NewGuid();
            return true;
        }
    }

    public class ValidationService
    {
        public bool IsAddressValid(string? address)
        {
            return true;
        }
    }

    public class FraudService
    {
        public bool IsShopperLegit(Shopper shopper)
        {
            return true;
        }
    }

    public class Checkout
    {
        public bool TryProcess(string order, Shopper shopper, out Guid? orderId)
        {
            var orderService = new OrderService();
            var fraudService = new FraudService();
            var validationService = new ValidationService();
            if (validationService.IsAddressValid(shopper.Address))
            {
                Console.WriteLine("Shopper address is valid");

                if (fraudService.IsShopperLegit(shopper))
                {
                    Console.WriteLine("Shopper passed Fraud");
                }

                if (orderService.TryCreateOrder(order, out orderId))
                {
                    Console.WriteLine($"Order created. Order ID: {orderId}");

                    return true;
                }
            }

            orderId = null;
            return false;
        }
    }
}



2. Call Checkout/TrProcess which internally does validation, fraud check and order creation and if all successful returns the orderId.

var checkout = new Checkout(); Console.WriteLine(checkout.TryProcess("order details", new Shopper { Address = "Test", Name = "Ram" }, out var orderId) ? $"Order Created Successfully" : $"Order Creation Failed"); Console.ReadLine();