ofbapi/OFBButte.Application/Users/SendEmailValidation.cs

using Microsoft.EntityFrameworkCore;
using OFBButte.Application.Codes;
using OFBButte.Application.Database;
using OFBButte.Application.Email;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace OFBButte.Application.Users
{
    public class SendEmailValidation
    {
        private readonly IOFBContext context;
        private readonly IEmailSender emailSender;
        private readonly ICodeGenerator codes;
        public SendEmailValidation(IOFBContext context, IEmailSender emailSender, ICodeGenerator codes)
        {
            this.context = context;
            this.emailSender = emailSender;
            this.codes = codes;
        }

        public async Task Handle(string email)
        {
            var user = context.Users.Include(u => u.EmailVerificationCode).FirstOrDefault(u => u.Email == email);
            if (user == null)
                throw new Exception($"Could not find user with email: {email}");

            if (user.EmailVerificationCode != null)
            {
                context.EmailVerificationCodes.Remove(user.EmailVerificationCode);
            }

            // Generate verification code
            user.EmailVerificationCode = new Entities.EmailVerificationCode()
            {
                Code = codes.Generate(),
                CreatedDate = DateTime.Now
            };            

            context.SaveChanges();

            // Create the email
            var emailMessage = new VerifyEmailMessage()
            {
                To = email,
                From = "donotreply@ofbbutte.com",
                VerificationUrl = $"https://ofbbutte.com/user/emailverification?c={user.EmailVerificationCode.Id}&code={user.EmailVerificationCode.Code}"
            };

            await emailSender.Send(emailMessage);
        }
    }
}