Refactor IMAP initialization with OpenAsync helper

Refactored IMAP object initialization and folder selection into a new `OpenAsync` helper method to reduce code duplication and improve maintainability.

- Replaced repetitive connection, authentication, and folder selection logic in multiple methods (`FetchEmailsAsync`, `FetchEmailUidsAsync`, etc.) with `OpenAsync`.
- Removed `ConnectAndAuthenticateAsync` and `SelectFolderAsync` methods, as their functionality is now encapsulated in `OpenAsync`.
- Updated `FetchEmailUidsAsync` to remove the `EmailAccountDto account` parameter, delegating connection logic to `OpenAsync`.
- Ensured all methods now use `OpenAsync` to obtain a fully prepared `Imap` instance, improving clarity and reducing error risk.

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

@@ -33,10 +33,10 @@ public class LimilabsImapEmailService(
         MailSearchFilter filter,
         CancellationToken cancellationToken = default)
     {
-        using var imap = new Imap();
+        using var imap = await OpenAsync(account, filter.Folder);
         try
         {
-            var uids = await FetchEmailUidsAsync(imap, account, filter, cancellationToken);
+            var uids = await FetchEmailUidsAsync(imap, filter, cancellationToken);
 
             if (uids.Count == 0)
                 return [];
@@ -84,13 +84,10 @@ public class LimilabsImapEmailService(
         MailSearchFilter filter,
         CancellationToken cancellationToken = default)
     {
-        using var imap = new Imap();
+        using var imap = await OpenAsync(account, filter.Folder);
         try
         {
-            await ConnectAndAuthenticateAsync(imap, account);
-            await SelectFolderAsync(imap, filter.Folder);
-
-            List<long> uids = await FetchEmailUidsAsync(imap, account, filter, cancellationToken);
+            List<long> uids = await FetchEmailUidsAsync(imap, filter, cancellationToken);
 
             await imap.CloseAsync(cancellationToken);
             return uids;
@@ -116,12 +113,9 @@ public class LimilabsImapEmailService(
         bool withAttachments = false,
         CancellationToken cancellationToken = default)
     {
-        using var imap = new Imap();
+        using var imap = await OpenAsync(account, folder);
         try
         {
-            await ConnectAndAuthenticateAsync(imap, account);
-            await SelectFolderAsync(imap, folder);
-
             var mail = await FetchEmailByUidAsync(imap, uid, withAttachments, cancellationToken);
 
             await imap.CloseAsync(cancellationToken);
@@ -147,11 +141,9 @@ public class LimilabsImapEmailService(
         string folder = "INBOX",
         CancellationToken cancellationToken = default)
     {
-        using var imap = new Imap();
+        using var imap = await OpenAsync(account, folder);
         try
         {
-            await ConnectAndAuthenticateAsync(imap, account);
-            await SelectFolderAsync(imap, folder);
             await imap.MarkMessageSeenByUIDAsync(uid, cancellationToken);
             await imap.CloseAsync(cancellationToken);
         }
@@ -172,13 +164,9 @@ public class LimilabsImapEmailService(
     // Private helpers
     private async Task<List<long>> FetchEmailUidsAsync(
         Imap imap,
-        EmailAccountDto account,
         MailSearchFilter filter,
         CancellationToken cancellationToken = default)
     {
-        await ConnectAndAuthenticateAsync(imap, account);
-        await SelectFolderAsync(imap, filter.Folder);
-
         List<ICriterion> criterions = [];
 
         if (filter.UnseenOnly)
@@ -286,8 +274,10 @@ public class LimilabsImapEmailService(
         return withAttachments || email is null ? email : email with { Attachments = [] };
     }
 
-    private async Task ConnectAndAuthenticateAsync(Imap imap, EmailAccountDto account)
+    private async Task<Imap> OpenAsync(EmailAccountDto account, string folder)
     {
+        var imap = new Imap();
+
         if (account.ImapUseSsl)
             await imap.ConnectSSLAsync(account.ImapServer!, account.ImapPort);
         else
@@ -298,13 +288,12 @@ public class LimilabsImapEmailService(
             : account.Password;
 
         await imap.LoginAsync(account.Username, password);
-    }
 
-    private static async Task SelectFolderAsync(Imap imap, string folder)
-    {
         if (string.Equals(folder, "INBOX", StringComparison.OrdinalIgnoreCase))
             await imap.SelectInboxAsync();
         else
             await imap.SelectAsync(folder);
+
+        return imap;
     }
 }