public class Global : HttpApplication
    {
        protected void Application_Start(object sender, EventArgs e)
        {
            new AppHost().Init();
        }
    }

    public class AppHost : AppHostBase
    {
        public AppHost() : base("Verification Code Service", Assembly.GetExecutingAssembly())
        {
        }

        public override void Configure(Container container)
        {
            container.Register<IVerificationCode>(new GeneralVerificationCode());
            container.RegisterAs<ImageVerificationCodeProvider, IImageVerificationCodeFactory>()
                .InitializedBy((c, f) =>
                {
                    f.Width = 80;
                    f.Height = 32;
                    f.ImageDrawCompletedHandler = text =>
                    {
                        // store in session
                    };
                })
                .ReusedWithin(ReuseScope.Container);
        }
    }

    public class VerificationCodeService : Service
    {
        public IImageVerificationCodeFactory Factory { get; set; }

        public object Get(GetVcodeRequest request)
        {
            var bytes = Factory.Draw();

            return new HttpResult(bytes, MimeTypes.ImageJpg);
        }
    }

    [Route("/vcode")]
    public class GetVcodeRequest
    {
    }

    public class VcodeController : Controller
    {
        public ActionResult GetGeneralVerificationCode(GeneralCodeFlags flags, int length = 4)
        {
            IImageVerificationCodeFactory factory = new ImageVerificationCodeProvider(
                    new GeneralVerificationCode(flags, length)
                )
            {
                Width = 89,
                Height = 32
            };
            return File(factory.Draw(), "image/jpg");
        }
    }

    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
            var server = Configuration.GetValue<string>("MailSmtp:SmtpServer");
            var port = Configuration.GetValue<int>("MailSmtp:SmtpPort");
            var username = Configuration.GetValue<string>("MailSmtp:SmtpUsername");
            var password = Configuration.GetValue<string>("MailSmtp:SmtpPassword");
            var useSsl = Configuration.GetValue<bool>("MailSmtp:UseSsl");

            services.AddSingleton<IMailSmtpConfiguration>(new MailSmtpConfiguration
            {
                SmtpServer = server,
                SmtpPort = port,
                SmtpUsername = username,
                SmtpPassword = password,
                UseSsl = useSsl
            });

            services.AddSingleton<IVerificationCode>(new GeneralVerificationCode(
                GeneralCodeFlags.Number, 6
            ));
            services.AddSingleton<ITemplateParser>(new DefaultTemplateParser
            {
                Template = "【吾乐购】{{Code}} 是您的验证码，非本人操作请忽略"
            });
            services.AddSingleton<IMessageVerificationCodeFactory>(provider =>
            {
                return new MailVerificationCodeProvider(
                    provider.GetService<IMailSmtpConfiguration>(),
                    provider.GetService<IVerificationCode>(),
                    provider.GetService<ITemplateParser>()
                )
                {
                    From = "postmaster@wulegou.top",
                    MessageSentHandler = (text, message) =>
                    {
                        // store code in session and log the message
                    }
                };
            });
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseBrowserLink();
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }

            app.UseStaticFiles();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    "default",
                    "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }

    [Produces("application/json")]
    [Route("api/[controller]")]
    public class MessageController : Controller
    {
        private readonly IMessageVerificationCodeFactory _factory;

        public MessageController(IMessageVerificationCodeFactory factory)
        {
            _factory = factory;
        }

        public void Post(MessageRequest request)
        {
            _factory.Send(request.To);
        }
    }

    public class MessageRequest
    {
        public string To { get; set; }
    }