feat(infrastructure): add OAuth2 auth support and SendAndAppend capability to LimilabsEmailService and LimilabsImapEmailService

src/infrastructure/DigitalData.MessagingService.Infrastructure/Services/LimilabsEmailService.cs

@@ -12,14 +12,10 @@ namespace DigitalData.MessagingService.Infrastructure.Services;
 
 /// <summary>
 /// Email service using Limilabs Mail.dll for SMTP operations (send-only).
-/// Commercial-grade library with superior Exchange support.
+/// Supports both plain/STARTTLS and OAuth2 (XOAUTH2) authentication.
-/// SMTP configuration is injected via IOptions&lt;EmailAccountsOptions&gt; from appsettings.json.
-/// Uses the first account in the list whose <see cref="EmailAccount.Name"/> equals <c>"default"</c>,
-/// or falls back to the first account if none is named "default".
 /// </summary>
-public class LimilabsEmailService() : IEmailService
+public class LimilabsEmailService(IOAuth2TokenService oauth2TokenService) : IEmailService
 {
-    // Register encoding provider for Limilabs (requires windows-1252 and other code pages)
     static LimilabsEmailService()
     {
         Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
@@ -31,7 +27,7 @@ public class LimilabsEmailService() : IEmailService
         ISendMessageResult? result = null;
         try
         {
-            await ConnectAndAuthenticateSmtpAsync(smtp, context.Sender);
+            await ConnectAndAuthenticateSmtpAsync(smtp, context.Sender, cancellationToken);
 
             var builder = new MailBuilder();
             builder.From.Add(new MailBox(context.Sender.Username));
@@ -62,37 +58,43 @@ public class LimilabsEmailService() : IEmailService
         catch (Limilabs.Client.ServerException ex)
         {
             await smtp.CloseSafelyAsync();
-            throw new AuthenticationFailedException($"SMTP authentication failed. Check credentials or OAuth2 configuration. {ErrorMessageBuilder(result)}", ex);
+            throw new AuthenticationFailedException($"SMTP authentication failed. {ErrorMessageBuilder(result)}", ex);
         }
-        catch (Exception ex)
+        catch (Exception ex) when (ex is not AuthenticationFailedException && ex is not InvalidOperationException)
         {
             await smtp.CloseSafelyAsync();
             throw new InvalidOperationException($"Failed to send email via SMTP server. {ErrorMessageBuilder(result)}", ex);
         }
+        catch
+        {
+            await smtp.CloseSafelyAsync();
+            throw;
+        }
     }
 
-    private static async Task ConnectAndAuthenticateSmtpAsync(Smtp smtp, EmailAccount smtpAccount)
+    internal async Task ConnectAndAuthenticateSmtpAsync(Smtp smtp, EmailAccount smtpAccount, CancellationToken cancellationToken = default)
     {
         if (smtpAccount.SmtpUseSsl)
         {
-            await smtp.ConnectSSLAsync(smtpAccount.SmtpServer, smtpAccount.SmtpPort);
+            await smtp.ConnectSSLAsync(smtpAccount.SmtpServer, smtpAccount.SmtpPort, cancellationToken);
         }
         else
         {
-            await smtp.ConnectAsync(smtpAccount.SmtpServer, smtpAccount.SmtpPort);
+            await smtp.ConnectAsync(smtpAccount.SmtpServer, smtpAccount.SmtpPort, cancellationToken);
         }
 
         if (smtpAccount.UseOAuth2)
         {
-            throw new NotSupportedException("OAuth2 is not configured for this SMTP account. UseOAuth2 must be false.");
+            var token = await oauth2TokenService.GetAccessTokenAsync(smtpAccount, cancellationToken);
+            await smtp.LoginOAUTH2Async(smtpAccount.Username, token, cancellationToken);
         }
         else
         {
-            await smtp.LoginAsync(smtpAccount.Username, smtpAccount.Password);
+            await smtp.LoginAsync(smtpAccount.Username, smtpAccount.Password, cancellationToken);
         }
     }
 
-    private static string ErrorMessageBuilder(ISendMessageResult? result = null)
+    internal static string ErrorMessageBuilder(ISendMessageResult? result = null)
     {
         if(result is null || result.GeneralErrors.Count == 0)
             return string.Empty;
@@ -109,7 +111,7 @@ public class LimilabsEmailService() : IEmailService
         return message.ToString();
     }
 
-    private static void AddAttachments(MailBuilder builder, IEnumerable<EmailAttachmentDto> attachments)
+    internal static void AddAttachments(MailBuilder builder, IEnumerable<EmailAttachmentDto> attachments)
     {
         foreach (var attachment in attachments)
         {

src/infrastructure/DigitalData.MessagingService.Infrastructure/Services/LimilabsImapEmailService.cs

@@ -14,8 +14,13 @@ namespace DigitalData.MessagingService.Infrastructure.Services;
 /// <summary>
 /// IMAP email service using Limilabs Mail.dll.
 /// Opens a fresh connection per call — stateless and thread-safe.
+/// Supports both password and OAuth2 (XOAUTH2) authentication.
 /// </summary>
-public class LimilabsImapEmailService(ILogger<LimilabsImapEmailService> Logger, IRepository<ReceivedEmail> Repository) : IImapEmailService
+public class LimilabsImapEmailService(
+    ILogger<LimilabsImapEmailService> Logger,
+    IRepository<ReceivedEmail> Repository,
+    IOAuth2TokenService oauth2TokenService,
+    LimilabsEmailService smtpService) : IImapEmailService
 {
     private static readonly string CacheKeyPrefix = Guid.NewGuid().ToString();
 
@@ -27,7 +32,7 @@ public class LimilabsImapEmailService(ILogger<LimilabsImapEmailService> Logger,
     // Public API
     public async Task<EmailSyncResult> SyncEmailsAsync(EmailAccount account, string folder = "INBOX", CancellationToken cancel = default)
     {
-        using var imap = await OpenAsync(account, folder, cancel);
+        using var imap = await OpenAsync(account, folder, cancel: cancel);
         try
         {
             #region Find UIDs
@@ -138,7 +143,7 @@ public class LimilabsImapEmailService(ILogger<LimilabsImapEmailService> Logger,
 
     public async Task MarkAsSeenAsync(EmailAccount account, long uid, string folder = "INBOX", CancellationToken cancel = default)
     {
-        using var imap = await OpenAsync(account, folder, cancel);
+        using var imap = await OpenAsync(account, folder, cancel: cancel);
         try
         {
             await imap.MarkMessageSeenByUIDAsync(uid, cancel);
@@ -151,7 +156,48 @@ public class LimilabsImapEmailService(ILogger<LimilabsImapEmailService> Logger,
         }
     }
 
-    private static async Task<Imap> OpenAsync(EmailAccount account, string folder = "INBOX", CancellationToken cancel = default)
+    public async Task SendAndAppendAsync(EmailContext context, string sentFolder = "Sent", CancellationToken cancellationToken = default)
+    {
+        // Send via SMTP first
+        await smtpService.SendEmailAsync(context, cancellationToken);
+
+        // Then upload a copy to the IMAP Sent folder (no need to SELECT first)
+        using var imap = await OpenAsync(context.Sender, "INBOX", cancel: cancellationToken);
+        try
+        {
+            var builder = new MailBuilder();
+            builder.From.Add(new Limilabs.Mail.Headers.MailBox(context.Sender.Username));
+
+            foreach (var recipient in context.Recipients)
+                builder.To.Add(new Limilabs.Mail.Headers.MailBox(recipient));
+
+            builder.Subject = context.Subject;
+
+            if (context.IsHtml)
+                builder.Html = context.Body;
+            else
+                builder.Text = context.Body;
+
+            LimilabsEmailService.AddAttachments(builder, context.Attachments);
+
+            var mail = builder.Create();
+
+            var uploadInfo = new Limilabs.Client.IMAP.UploadMessageInfo
+            {
+                Flags = [Limilabs.Client.IMAP.Flag.Seen]
+            };
+
+            await imap.UploadMessageAsync(sentFolder, mail, uploadInfo, cancellationToken);
+            await imap.CloseAsync(cancellationToken);
+        }
+        catch
+        {
+            await imap.CloseSafelyAsync();
+            throw;
+        }
+    }
+
+    private async Task<Imap> OpenAsync(EmailAccount account, string folder = "INBOX", bool createIfMissing = false, CancellationToken cancel = default)
     {
         var imap = new Imap();
 
@@ -160,12 +206,27 @@ public class LimilabsImapEmailService(ILogger<LimilabsImapEmailService> Logger,
         else
             await imap.ConnectAsync(account.ImapServer!, account.ImapPort, cancel: cancel);
 
-        await imap.LoginAsync(account.Username, account.Password, cancel);
+        if (account.UseOAuth2)
+        {
+            var token = await oauth2TokenService.GetAccessTokenAsync(account, cancel);
+            await imap.LoginOAUTH2Async(account.Username, token, cancel);
+        }
+        else
+            await imap.LoginAsync(account.Username, account.Password, cancel);
 
         if (string.Equals(folder, "INBOX", StringComparison.OrdinalIgnoreCase))
             await imap.SelectInboxAsync(cancel);
         else
+        {
+            if (createIfMissing)
+            {
+                var folders = await imap.GetFoldersAsync(cancel);
+                if (!folders.Any(f => string.Equals(f.Name, folder, StringComparison.OrdinalIgnoreCase)))
+                    await imap.CreateFolderAsync(folder, cancel);
+            }
+
             await imap.SelectAsync(folder, cancel);
+        }
 
         return imap;
     }