DependencyInjection/DependencyInjection.cs

using Microsoft.Extensions.DependencyInjection;

namespace DependencyInjections
{
    public class ImplementDependencyInjections
    {
        public void Implement()
        {
            ServiceCollection serviceCollection = new ServiceCollection();

            serviceCollection.AddTransient<ILogger, ConsoleLogger>();
            serviceCollection.AddTransient<ILogger, FileLogger>();
            serviceCollection.AddTransient<UserService>();


            // Byt de 2 udkommentering for at skrifte processor

            bool usePaypal = false;

            if (usePaypal)
            {
                serviceCollection.AddTransient<IPaymentProcessor, PayPalPaymentProcessor>();
            }
            else
            {
                serviceCollection.AddTransient<IPaymentProcessor, StripePaymentProcessor>();
            }

            serviceCollection.AddTransient<CheckoutService>();

            serviceCollection.AddTransient<IEmailSender, SmtpEmailSender>();
            serviceCollection.AddTransient<IEmailSender, ConsoleEmailSender>();

            serviceCollection.AddTransient<NotificationService>();

            var sp = serviceCollection.BuildServiceProvider();

            sp.GetRequiredService<UserService>().Log();
            sp.GetRequiredService<CheckoutService>().process();
            sp.GetRequiredService<NotificationService>().SendNotification("Hello, There");

        }
    }

    public interface ILogger
    {
        void Log(string message);
    }

    public class ConsoleLogger : ILogger
    {
        public void Log(string message)
        {
            Console.WriteLine(message);
        }
    }

    public class FileLogger : ILogger
    {
        public void Log(string message)
        {
            var currentPath = Directory.GetCurrentDirectory();

            var path = Path.Combine(currentPath, "test.txt");

            using (StreamWriter sw = File.AppendText(path))
            {
                sw.WriteLine(message);
            }
        }
    }

    public class UserService
    {
        private readonly IEnumerable<ILogger> logger;

        public UserService(IEnumerable<ILogger> logger)
        {
            this.logger = logger;
        }

        public void Log()
        {
            foreach (var log in logger)
            {
                log.Log("Hello from user service");
            }
        }
    }

    public interface IPaymentProcessor
    {
        void Process(decimal amount);
    }

    public class StripePaymentProcessor : IPaymentProcessor
    {
        public void Process(decimal amount)
        {
            Console.WriteLine($"Stripe processing for {amount}...");
        }
    }

    public class PayPalPaymentProcessor : IPaymentProcessor
    {
        public void Process(decimal amount)
        {
            Console.WriteLine($"Paypal processing for {amount}...");
        }
    }

    public class CheckoutService
    {
        private readonly IPaymentProcessor paymentProcessor;

        public CheckoutService(IPaymentProcessor paymentProcessor)
        {
            this.paymentProcessor = paymentProcessor;
        }

        public void process()
        {
            paymentProcessor.Process(5);
        }
    }

    public interface IEmailSender
    {
        void SendEmail(string to, string subject, string body);
    }

    public class ConsoleEmailSender : IEmailSender
    {
        public void SendEmail(string to, string subject, string body)
        {
            Console.WriteLine($"To: {to} subject: {subject} body: {body}");
        }
    }

    public class SmtpEmailSender : IEmailSender
    {
        public void SendEmail(string to, string subject, string body)
        {
            Console.WriteLine($"SENDING EMAIL:: To: {to} subject: {subject} body: {body}");
        }
    }

    public class NotificationService
    {
        private readonly IEnumerable<IEmailSender> emailSender;

        public NotificationService(IEnumerable<IEmailSender> emailSender)
        {
            this.emailSender = emailSender;
        }

        public void SendNotification(string message)
        {
            foreach (var sender in emailSender)
            {
                sender.SendEmail("test", "Notification", message);
            }
        }
    }
}