feat: consume transactional email notifications

Add contract validation, SMTP delivery results, terminal failure context, neutral development seeding, and local Docker setup. Ref: IT-1033
2026-08-04 12:32:28 +03:00
parent b8435ac07b
commit 2757869176
37 changed files with 1465 additions and 122 deletions
@@ -8,6 +8,18 @@ internal sealed class EmailTemplateRenderingService : IEmailTemplateRenderingSer
 {
    public RenderedEmail Render(EmailTemplate template, SendEmailMessageData data)
    {
+        string[] missingVariables = template.Variables
+            .Where(variable => variable.Required)
+            .Select(variable => variable.Name)
+            .Where(name => !data.Variables.TryGetValue(name, out string? value) || string.IsNullOrWhiteSpace(value))
+            .ToArray();
+
+        if (missingVariables.Length > 0)
+        {
+            throw new InvalidDataException(
+                $"Required template variables are missing: {string.Join(", ", missingVariables)}.");
+        }
+
        return new RenderedEmail(
            Interpolate(template.Subject, data.Variables),
            Interpolate(template.HtmlBody, data.Variables),
@@ -18,11 +18,15 @@ internal sealed class EmailTemplateService : IEmailTemplateService
        string? languageCode,
        CancellationToken cancellationToken)
    {
-        var lang = string.IsNullOrWhiteSpace(languageCode) ? "en" : languageCode;
-        var template = await _templateRepository.GetAsync(serviceName, templateKey, lang, cancellationToken);
+        if (string.IsNullOrWhiteSpace(languageCode))
+            throw new InvalidDataException("LanguageCode is required.");

-        if (template is null && lang != "en")
-            template = await _templateRepository.GetAsync(serviceName, templateKey, "en", cancellationToken);
+        string lang = languageCode.Trim().ToLowerInvariant();
+        EmailTemplate? template = await _templateRepository.GetAsync(
+            serviceName,
+            templateKey,
+            lang,
+            cancellationToken);

        return template
            ?? throw new InvalidOperationException(
@@ -0,0 +1,11 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using HrynCo.NotificationService.Contracts.Messages;
+
+public interface INotificationResultPublisher
+{
+    Task PublishAsync(
+        SendEmailMessage message,
+        string? deliveryError,
+        CancellationToken cancellationToken);
+}
@@ -0,0 +1,13 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using HrynCo.NotificationService.DAL.Abstract.Providers;
+
+internal interface ISmtpEmailSender
+{
+    Task SendAsync(
+        SmtpChannelSettings settings,
+        RenderedEmail email,
+        string recipientEmail,
+        string recipientName,
+        CancellationToken cancellationToken);
+}
@@ -0,0 +1,80 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using System.Net.Mail;
+using System.Net.Sockets;
+
+public static class NotificationDeliveryErrorFormatter
+{
+    private const int MaximumErrorLength = 2000;
+    private const string FallbackError = "Notification delivery failed after all retry attempts.";
+
+    public static string Format(Exception exception)
+    {
+        string technicalMessage = Normalize(exception.GetBaseException().Message);
+        if (string.IsNullOrWhiteSpace(technicalMessage))
+        {
+            return FallbackError;
+        }
+
+        string contextualMessage = CreateContextualMessage(exception, technicalMessage);
+        return contextualMessage.Length <= MaximumErrorLength
+            ? contextualMessage
+            : contextualMessage[..MaximumErrorLength];
+    }
+
+    private static string CreateContextualMessage(Exception exception, string technicalMessage)
+    {
+        if (FindException<SmtpFailedRecipientException>(exception) is not null)
+        {
+            return "SMTP delivery failed after all retry attempts: " +
+                   "the SMTP server rejected the recipient address.";
+        }
+
+        SocketException? socketException = FindException<SocketException>(exception);
+        if (socketException is not null)
+        {
+            string reason = socketException.SocketErrorCode switch
+            {
+                SocketError.HostNotFound or SocketError.NoData =>
+                    "the configured SMTP server host could not be resolved",
+                SocketError.ConnectionRefused =>
+                    "the configured SMTP server refused the connection",
+                SocketError.TimedOut =>
+                    "the connection to the configured SMTP server timed out",
+                _ when technicalMessage.Contains(
+                    "Name or service not known",
+                    StringComparison.OrdinalIgnoreCase) =>
+                    "the configured SMTP server host could not be resolved",
+                _ => "the configured SMTP server could not be reached"
+            };
+
+            return $"SMTP delivery failed after all retry attempts: {reason} ({technicalMessage}).";
+        }
+
+        if (FindException<SmtpException>(exception) is not null)
+        {
+            return $"SMTP delivery failed after all retry attempts ({technicalMessage}).";
+        }
+
+        return $"Notification delivery failed after all retry attempts ({technicalMessage}).";
+    }
+
+    private static TException? FindException<TException>(Exception exception)
+        where TException : Exception
+    {
+        for (Exception? current = exception; current is not null; current = current.InnerException)
+        {
+            if (current is TException typedException)
+            {
+                return typedException;
+            }
+        }
+
+        return null;
+    }
+
+    private static string Normalize(string message)
+    {
+        return message.ReplaceLineEndings(" ").Trim();
+    }
+}
@@ -0,0 +1,63 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using HrynCo.NotificationService.Contracts.Messages;
+using Hrynco.RabbitMq;
+using Microsoft.Extensions.Logging;
+
+internal sealed class NotificationResultPublisher : INotificationResultPublisher
+{
+    private readonly ILogger<NotificationResultPublisher> _logger;
+    private readonly IRabbitMqPublisher _publisher;
+
+    public NotificationResultPublisher(
+        IRabbitMqPublisher publisher,
+        ILogger<NotificationResultPublisher> logger)
+    {
+        _publisher = publisher;
+        _logger = logger;
+    }
+
+    public async Task PublishAsync(
+        SendEmailMessage message,
+        string? deliveryError,
+        CancellationToken cancellationToken)
+    {
+        CorrelationContext correlationContext = message.CorrelationContext;
+        string? replyTo = correlationContext.ReplyTo;
+        if (string.IsNullOrWhiteSpace(replyTo))
+        {
+            return;
+        }
+
+        try
+        {
+            var result = new NotificationResultMessage
+            {
+                CorrelationContext = correlationContext with { ReplyTo = null },
+                Data = new NotificationResultData
+                {
+                    ServiceName = message.Data.ServiceName,
+                    RecipientEmail = message.Data.RecipientEmail,
+                    TemplateKey = message.Data.TemplateKey,
+                    Timestamp = DateTimeOffset.UtcNow,
+                    ErrorMessage = deliveryError
+                }
+            };
+
+            await _publisher.PublishAsync(replyTo, result, cancellationToken);
+
+            _logger.LogDebug(
+                "Notification result published to reply queue {Queue} [CorrelationId={CorrelationId}]",
+                replyTo,
+                correlationContext.CorrelationId);
+        }
+        catch (Exception exception)
+        {
+            _logger.LogWarning(
+                exception,
+                "Failed to publish notification result to reply queue {Queue} [CorrelationId={CorrelationId}]",
+                replyTo,
+                correlationContext.CorrelationId);
+        }
+    }
+}
@@ -0,0 +1,22 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+public static class RecipientAddressRedactor
+{
+    public static string Redact(string? address)
+    {
+        if (string.IsNullOrWhiteSpace(address))
+            return "<missing>";
+
+        int separator = address.LastIndexOf('@');
+        if (separator <= 0 || separator == address.Length - 1)
+            return "***";
+
+        string local = address[..separator];
+        string domain = address[(separator + 1)..];
+        int dot = domain.LastIndexOf('.');
+        string domainName = dot > 0 ? domain[..dot] : domain;
+        string suffix = dot > 0 ? domain[dot..] : string.Empty;
+
+        return $"{local[0]}***@{domainName[0]}***{suffix}";
+    }
+}
@@ -0,0 +1,36 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using System.Net.Mail;
+using HrynCo.NotificationService.Contracts.Messages;
+
+public static class SendEmailMessageValidator
+{
+    public static void Validate(SendEmailMessage message)
+    {
+        ArgumentNullException.ThrowIfNull(message);
+
+        if (message.CorrelationContext is null)
+            throw new InvalidDataException("CorrelationContext is required.");
+        if (string.IsNullOrWhiteSpace(message.CorrelationContext.CorrelationId))
+            throw new InvalidDataException("CorrelationContext.CorrelationId is required.");
+        if (message.Data is null)
+            throw new InvalidDataException("Data is required.");
+
+        Require(message.Data.ServiceName, nameof(message.Data.ServiceName));
+        Require(message.Data.TemplateKey, nameof(message.Data.TemplateKey));
+        Require(message.Data.RecipientEmail, nameof(message.Data.RecipientEmail));
+        Require(message.Data.RecipientName, nameof(message.Data.RecipientName));
+        Require(message.Data.LanguageCode, nameof(message.Data.LanguageCode));
+
+        if (!MailAddress.TryCreate(message.Data.RecipientEmail, out _))
+            throw new InvalidDataException("RecipientEmail is not a valid email address.");
+        if (message.Data.Variables is null)
+            throw new InvalidDataException("Variables is required.");
+    }
+
+    private static void Require(string? value, string fieldName)
+    {
+        if (string.IsNullOrWhiteSpace(value))
+            throw new InvalidDataException($"{fieldName} is required.");
+    }
+}
@@ -1,13 +1,9 @@
 namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;

-using System.Net;
-using System.Net.Mail;
-using System.Text;
 using HrynCo.NotificationService.Contracts.Messages;
 using HrynCo.NotificationService.DAL.Abstract.Providers;
 using HrynCo.NotificationService.DAL.Abstract.Repositories;
 using HrynCo.NotificationService.DAL.Abstract.Templates;
-using Hrynco.RabbitMq;
 using Microsoft.Extensions.Logging;

 internal sealed class SendEmailService : ISendEmailService
@@ -16,7 +12,8 @@ internal sealed class SendEmailService : ISendEmailService
    private readonly IEmailChannelUsageRepository _usageRepository;
    private readonly IEmailTemplateService _templateService;
    private readonly IEmailTemplateRenderingService _templateRenderingService;
-    private readonly IRabbitMqPublisher _publisher;
+    private readonly ISmtpEmailSender _smtpEmailSender;
+    private readonly INotificationResultPublisher _resultPublisher;
    private readonly ILogger<SendEmailService> _logger;

    public SendEmailService(
@@ -24,24 +21,28 @@ internal sealed class SendEmailService : ISendEmailService
        IEmailChannelUsageRepository usageRepository,
        IEmailTemplateService templateService,
        IEmailTemplateRenderingService templateRenderingService,
-        IRabbitMqPublisher publisher,
+        ISmtpEmailSender smtpEmailSender,
+        INotificationResultPublisher resultPublisher,
        ILogger<SendEmailService> logger)
    {
        _channelRepository = channelRepository;
        _usageRepository = usageRepository;
        _templateService = templateService;
        _templateRenderingService = templateRenderingService;
-        _publisher = publisher;
+        _smtpEmailSender = smtpEmailSender;
+        _resultPublisher = resultPublisher;
        _logger = logger;
    }

    public async Task ProcessAsync(SendEmailMessage message, CancellationToken cancellationToken)
    {
+        SendEmailMessageValidator.Validate(message);
        SendEmailMessageData data = message.Data;
+        string redactedRecipient = RecipientAddressRedactor.Redact(data.RecipientEmail);

        _logger.LogInformation(
            "Processing SendEmail for service={Service} template={Template} recipient={Recipient} [CorrelationId={CorrelationId}]",
-            data.ServiceName, data.TemplateKey, data.RecipientEmail, message.CorrelationContext?.CorrelationId);
+            data.ServiceName, data.TemplateKey, redactedRecipient, message.CorrelationContext?.CorrelationId);

        EmailChannel channel = await ResolveChannelAsync(data.ServiceName, cancellationToken);
        EmailTemplate template = await GetTemplateAsync(data, cancellationToken);
@@ -56,34 +57,12 @@ internal sealed class SendEmailService : ISendEmailService

        try
        {
-            using var client = new SmtpClient(smtpChannel.Host, smtpChannel.Port)
-            {
-                EnableSsl = smtpChannel.UseSsl,
-                Credentials = string.IsNullOrWhiteSpace(smtpChannel.Username)
-                    ? null
-                    : new NetworkCredential(smtpChannel.Username, smtpChannel.Password)
-            };
-
-            using var mail = new MailMessage
-            {
-                From = new MailAddress(smtpChannel.FromEmail, smtpChannel.FromName),
-                Subject = rendered.Subject,
-                Body = rendered.TextBody,
-                IsBodyHtml = false,
-                BodyEncoding = Encoding.UTF8,
-                SubjectEncoding = Encoding.UTF8
-            };
-
-            if (!string.IsNullOrWhiteSpace(rendered.HtmlBody))
-            {
-                var html = AlternateView.CreateAlternateViewFromString(
-                    rendered.HtmlBody, Encoding.UTF8, "text/html");
-                mail.AlternateViews.Add(html);
-            }
-
-            mail.To.Add(new MailAddress(data.RecipientEmail, data.RecipientName));
-
-            await client.SendMailAsync(mail, cancellationToken);
+            await _smtpEmailSender.SendAsync(
+                smtpChannel,
+                rendered,
+                data.RecipientEmail,
+                data.RecipientName,
+                cancellationToken);
        }
        catch (Exception ex)
        {
@@ -98,9 +77,9 @@ internal sealed class SendEmailService : ISendEmailService

        _logger.LogInformation(
            "Email sent successfully service={Service} template={Template} recipient={Recipient}",
-            data.ServiceName, data.TemplateKey, data.RecipientEmail);
+            data.ServiceName, data.TemplateKey, redactedRecipient);

-        await PublishResultAsync(message.CorrelationContext, data, null, cancellationToken);
+        await _resultPublisher.PublishAsync(message, null, cancellationToken);
    }

    private async Task<EmailTemplate> GetTemplateAsync(SendEmailMessageData data, CancellationToken cancellationToken)
@@ -151,48 +130,4 @@ internal sealed class SendEmailService : ISendEmailService
        }
    }

-    private async Task PublishResultAsync(
-        CorrelationContext? correlationContext,
-        SendEmailMessageData data,
-        string? errorMessage,
-        CancellationToken ct)
-    {
-        string? replyTo = correlationContext?.ReplyTo;
-
-        if (string.IsNullOrWhiteSpace(replyTo))
-        {
-            return;
-        }
-
-        try
-        {
-            var result = new NotificationResultMessage
-            {
-                CorrelationContext = (correlationContext ?? new CorrelationContext
-                    {
-                        CorrelationId = Guid.NewGuid().ToString()
-                    }) with
-                    {
-                        ReplyTo = null
-                    },
-                Data = new NotificationResultData
-                {
-                    ServiceName = data.ServiceName,
-                    RecipientEmail = data.RecipientEmail,
-                    TemplateKey = data.TemplateKey,
-                    Timestamp = DateTimeOffset.UtcNow,
-                    ErrorMessage = errorMessage
-                }
-            };
-
-            await _publisher.PublishAsync(replyTo, result, ct);
-
-            _logger.LogDebug("Result published to reply queue '{Queue}' [CorrelationId={CorrelationId}]",
-                replyTo, correlationContext?.CorrelationId);
-        }
-        catch (Exception ex)
-        {
-            _logger.LogWarning(ex, "Failed to publish notification result to reply queue '{Queue}'", replyTo);
-        }
-    }
 }
@@ -0,0 +1,47 @@
+namespace HrynCo.NotificationService.Worker.Services.EmailProcessing;
+
+using System.Net;
+using System.Net.Mail;
+using System.Text;
+using HrynCo.NotificationService.DAL.Abstract.Providers;
+
+internal sealed class SmtpEmailSender : ISmtpEmailSender
+{
+    public async Task SendAsync(
+        SmtpChannelSettings settings,
+        RenderedEmail email,
+        string recipientEmail,
+        string recipientName,
+        CancellationToken cancellationToken)
+    {
+        using var client = new SmtpClient(settings.Host, settings.Port)
+        {
+            EnableSsl = settings.UseSsl,
+            Credentials = string.IsNullOrWhiteSpace(settings.Username)
+                ? null
+                : new NetworkCredential(settings.Username, settings.Password)
+        };
+
+        using var mail = new MailMessage
+        {
+            From = new MailAddress(settings.FromEmail, settings.FromName),
+            Subject = email.Subject,
+            Body = email.TextBody,
+            IsBodyHtml = false,
+            BodyEncoding = Encoding.UTF8,
+            SubjectEncoding = Encoding.UTF8
+        };
+
+        if (!string.IsNullOrWhiteSpace(email.HtmlBody))
+        {
+            AlternateView html = AlternateView.CreateAlternateViewFromString(
+                email.HtmlBody,
+                Encoding.UTF8,
+                "text/html");
+            mail.AlternateViews.Add(html);
+        }
+
+        mail.To.Add(new MailAddress(recipientEmail, recipientName));
+        await client.SendMailAsync(mail, cancellationToken);
+    }
+}
@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("HrynCo.NotificationService.Services.Tests")]
@@ -11,6 +11,8 @@ public static class ServiceCollectionExtensions
        services.AddSingleton<IRabbitMqPublisher, RabbitMqPublisher>();
        services.AddScoped<IEmailTemplateService, EmailTemplateService>();
        services.AddScoped<IEmailTemplateRenderingService, EmailTemplateRenderingService>();
+        services.AddScoped<ISmtpEmailSender, SmtpEmailSender>();
+        services.AddScoped<INotificationResultPublisher, NotificationResultPublisher>();
        services.AddScoped<ISendEmailService, SendEmailService>();
        return services;
    }