Move Infrastructure.Email into Features.Emails (#288)

web/backend/Features/Features.Emails/Services/EmailDispatcher.cs

@@ -1,6 +1,5 @@
 using Features.Emails.Templates.Rendering;
 using Infrastructure.Configuration;
-using Infrastructure.Email;
 using Microsoft.Extensions.Configuration;
 
 namespace Features.Emails.Services;

web/backend/Features/Features.Emails/Services/IEmailProvider.cs

@@ -0,0 +1,21 @@
+namespace Features.Emails.Services;
+
+/// <summary>
+///     Service for sending emails.
+/// </summary>
+public interface IEmailProvider
+{
+    /// <summary>Sends an email to a single recipient.</summary>
+    /// <param name="to">The recipient's email address.</param>
+    /// <param name="subject">The email subject line.</param>
+    /// <param name="body">The email body content.</param>
+    /// <param name="isHtml">Whether <paramref name="body"/> is HTML; when <see langword="false"/> it is sent as plain text.</param>
+    Task SendAsync(string to, string subject, string body, bool isHtml = true);
+
+    /// <summary>Sends an email to multiple recipients.</summary>
+    /// <param name="to">The recipients' email addresses.</param>
+    /// <param name="subject">The email subject line.</param>
+    /// <param name="body">The email body content.</param>
+    /// <param name="isHtml">Whether <paramref name="body"/> is HTML; when <see langword="false"/> it is sent as plain text.</param>
+    Task SendAsync(IEnumerable<string> to, string subject, string body, bool isHtml = true);
+}

web/backend/Features/Features.Emails/Services/SmtpEmailProvider.cs

@@ -0,0 +1,110 @@
+using Infrastructure.Configuration;
+using MailKit.Net.Smtp;
+using MailKit.Security;
+using Microsoft.Extensions.Configuration;
+using MimeKit;
+
+namespace Features.Emails.Services;
+
+/// <summary>
+///     SMTP email service implementation using MailKit.
+///     Configured via application configuration (backed by environment variables).
+/// </summary>
+public class SmtpEmailProvider : IEmailProvider
+{
+    private readonly string _fromEmail;
+    private readonly string _fromName;
+    private readonly string _host;
+    private readonly string? _password;
+    private readonly int _port;
+    private readonly string? _username;
+    private readonly bool _useSsl;
+
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="SmtpEmailProvider" /> class, reading SMTP configuration
+    ///     (<c>SMTP_HOST</c>, <c>SMTP_PORT</c>, <c>SMTP_USERNAME</c>, <c>SMTP_PASSWORD</c>, <c>SMTP_USE_SSL</c>,
+    ///     <c>SMTP_FROM_EMAIL</c>, <c>SMTP_FROM_NAME</c>) from <paramref name="configuration" />.
+    /// </summary>
+    /// <exception cref="InvalidOperationException">
+    ///     Thrown when <c>SMTP_HOST</c>, <c>SMTP_PORT</c>, or <c>SMTP_FROM_EMAIL</c> is not set,
+    ///     or when <c>SMTP_PORT</c> is not a valid integer.
+    /// </exception>
+    public SmtpEmailProvider(IConfiguration configuration)
+    {
+        _host = ConfigurationHelpers.GetKeyOrThrow(configuration, ConfigurationKeys.SmtpHost);
+
+        _port = ConfigurationHelpers.GetIntKeyOrThrow(configuration, ConfigurationKeys.SmtpPort);
+
+        _username = configuration[ConfigurationKeys.SmtpUsername];
+        _password = configuration[ConfigurationKeys.SmtpPassword];
+
+        string useSslString = configuration[ConfigurationKeys.SmtpUseSsl] ?? "true";
+        _useSsl = bool.Parse(useSslString);
+
+        _fromEmail = ConfigurationHelpers.GetKeyOrThrow(
+            configuration,
+            ConfigurationKeys.SmtpFromEmail
+        );
+
+        _fromName = configuration[ConfigurationKeys.SmtpFromName] ?? "The Biergarten";
+    }
+
+    /// <inheritdoc/>
+    public async Task SendAsync(string to, string subject, string body, bool isHtml = true)
+    {
+        await SendAsync([to], subject, body, isHtml);
+    }
+
+    /// <inheritdoc/>
+    /// <remarks>
+    ///     Connects using StartTls when SSL is enabled (or no encryption otherwise), authenticates
+    ///     if credentials were configured, sends the message, and disconnects.
+    /// </remarks>
+    /// <exception cref="InvalidOperationException">
+    ///     Thrown when connecting, authenticating, or sending via SMTP fails, wrapping the original exception.
+    /// </exception>
+    public async Task SendAsync(
+        IEnumerable<string> to,
+        string subject,
+        string body,
+        bool isHtml = true
+    )
+    {
+        MimeMessage message = new();
+        message.From.Add(new MailboxAddress(_fromName, _fromEmail));
+
+        foreach (string recipient in to)
+            message.To.Add(MailboxAddress.Parse(recipient));
+
+        message.Subject = subject;
+
+        BodyBuilder bodyBuilder = new();
+        if (isHtml)
+            bodyBuilder.HtmlBody = body;
+        else
+            bodyBuilder.TextBody = body;
+
+        message.Body = bodyBuilder.ToMessageBody();
+
+        using SmtpClient client = new();
+
+        try
+        {
+            SecureSocketOptions secureSocketOptions = _useSsl
+                ? SecureSocketOptions.StartTls
+                : SecureSocketOptions.None;
+
+            await client.ConnectAsync(_host, _port, secureSocketOptions);
+
+            if (!string.IsNullOrEmpty(_username) && !string.IsNullOrEmpty(_password))
+                await client.AuthenticateAsync(_username, _password);
+
+            await client.SendAsync(message);
+            await client.DisconnectAsync(true);
+        }
+        catch (Exception ex)
+        {
+            throw new InvalidOperationException($"Failed to send email: {ex.Message}", ex);
+        }
+    }
+}