using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}

​

public class MessageService

{

    private readonly IEnumerable<IPreProcessor> _preProcessors;

    private readonly IEnumerable<IPostProcessor> _postProcessors;

    public MessageService(

        IEnumerable<IPreProcessor> preProcessors,

        IEnumerable<IPostProcessor> postProcessors

    )

    {

        _preProcessors = preProcessors;

        _postProcessors = postProcessors;

    }

    public async ResultOrError<SendEmailResponse, SendEmailError> SendEmail(SendEmailRequest request)

    {

        var preProcessor = _preProcessors.Single(x => x.Type == request.Type);

        var postProcessor = _postProcessors.Single(x => x.Type == request.Type);

​

        if (preProcessor is not null)

        {

            var internalRequest = request.ToInternal();

            await preProcessor.Run(ref internalRequest);

            request = internalRequest.ToExternal();

        }

​

        var response = await Send(request);

​

        if (postProcessor is not null)

        {

            var internalResponse = request.ToInternal();

            await postProcessor.Run(ref internalResponse);

            response = internalResponse.ToExternal();

        }

​

        return response;

    }

​

    public interface IPreProcessor

    {

        ProcessorType Type { get; } 

        Task Run(InternalSendEmailRequest request);

    }

​

    public interface IPostProcessor

    {

        ProcessorType Type { get; } 

        Task Run(InternalSendEmailResponse response);

    }

​

    public enum ProcessorType

    {

        Contact,

        Deal,

        CustomerCare,

        InsuranceCustomerCare,

        InsuranceProfiler,

        InsuranceQuote,

    }

}

​

public static class MessageModule

{

    public static void Load(IServiceCollection services, IConfiguration configuration)

    {

        services.AddScoped<IPreProcessor, InsurancePolicyPreProcessor>();

        services.AddScoped<IPreProcessor, InsuranceQuotePreProcessor>();

        services.AddScoped<IPostProcessor, CustomerCarePostProcessor>();

    }

}

​