Domain Service Example

CustomerRegistrationService.cs

using System;
using Website.Domain;

namespace Website.Domain.Customers
{
    public class ContactRegistrationService : IRegisterContactCommandHandler, IActivateExistingContactCommandHandler
    {
        private readonly ITransactionProvider _transactor;
        private readonly ISelfRegistrationValidator _validator;
        private readonly ICompanyRepository _companyRepo;
        private readonly ICompanyNotifier _notifier;

        public ContactRegistrationService(ITransactionProvider transactor, ISelfRegistrationValidator validator,
            ICompanyRepository companyRepo, ICompanyNotifier notifier)
        {
            if (transactor == null) throw new ArgumentNullException("transactor");
            if (validator == null) throw new ArgumentNullException("validator");
            if (companyRepo == null) throw new ArgumentNullException("companyRepo");
            if (notifier == null) throw new ArgumentNullException("notifier");

            _transactor = transactor;
            _validator = validator;
            _companyRepo = companyRepo;
            _notifier = notifier;
        }


        /// <summary>
        /// Registers and activates a new contact
        /// </summary>
        /// <param name="command"></param>
        public void RegisterContact(RegisterContactCommand command)
        {
            if (command == null) throw new ArgumentNullException("command");

            using (var transaction = _transactor.NewTransaction())
            {
                var company = GetValidCompanyId(command.CompanyAgreementCode);
                AssertEmailIsAvailable(command.Email);
                int createdContactId = _companyRepo.CreateOnlineActiveContact(
                    new ContactCreationDTO
                    {
                        FirstName = command.FirstName, 
                        Surname = command.Surname,
                        Mobile = command.Mobile,
                        Email = command.Email,
                        CompanyCustomerId = company.CustomerNumber,
                        CompanyName = company.Name});
                                
                _notifier.OnContactOnlineRegistered(command.Email, createdContactId, company.CustomerNumber);
                transaction.Complete();
            }            
        }

        /// <summary>
        /// Activates specified contact which belongs to Corporate structure identified by companyAgreementCode
        /// </summary>
        /// <param name="contactCustomerNumber"></param>
        /// <param name="companyAgreementCode"></param>
        public void ActivateExistingContact(int contactCustomerNumber, string companyAgreementCode)
        {
            using (var transaction = _transactor.NewTransaction())
            {
                var activation = _companyRepo.ActivateExistingContact(contactCustomerNumber, companyAgreementCode);
                _notifier.OnContactOnlineActivated(activation.Email, contactCustomerNumber, activation.CompanyCustomerNumber);
            }
        }

        private CompanyInfo GetValidCompanyId(string code)
        {
            var result = _validator.VerifyCompanyAgreementCode(code);
            if(!result.HasMatch)
            {
                throw new DomainConstraintViolatedException("InvalidCompanyAgreementCode", "The specified company agreement code is not valid");
            }
            return new CompanyInfo
            {
                Name = result.MatchedCompany,
                CustomerNumber = result.CompanyCustomerId.Value
            };
        }

        private void AssertEmailIsAvailable(string email)
        {
            if(_companyRepo.ContactEmailIsInUse(email))
            { 
                throw new DomainConstraintViolatedException("EmailIsNotAvailable", "The specified email is already in use");
            }
        }

        private class CompanyInfo
        {
            public string Name;
            public int CustomerNumber;
        }
    }
}