fix: Don't try to do fetch_move_delete() if Trash is needed but not yet configured

This fixes things for Gmail f.e. Before, `Imap::fetch_move_delete()` was called before looking for
Trash and returned an error because of that failing the whole `fetch_idle()` which prevented
configuring Trash in turn.

python/tests/test_1_online.py

@@ -2128,17 +2128,21 @@ def test_delete_multiple_messages(acfactory, lp):
 
 def test_trash_multiple_messages(acfactory, lp):
     ac1, ac2 = acfactory.get_online_accounts(2)
+    ac2.stop_io()
 
-    # Create the Trash folder on IMAP server
-    # and recreate the account so Trash folder is configured.
+    # Create the Trash folder on IMAP server and configure deletion to it. There was a bug that if
+    # Trash wasn't configured initially, it can't be configured later, let's check this.
     lp.sec("Creating trash folder")
     ac2.direct_imap.create_folder("Trash")
-    lp.sec("Creating new accounts")
-    ac2 = acfactory.new_online_configuring_account(cloned_from=ac2)
-    acfactory.bring_accounts_online()
-
     ac2.set_config("delete_to_trash", "1")
-    assert ac2.get_config("configured_trash_folder")
+
+    lp.sec("Check that Trash can be configured initially as well")
+    ac3 = acfactory.new_online_configuring_account(cloned_from=ac2)
+    acfactory.bring_accounts_online()
+    assert ac3.get_config("configured_trash_folder")
+    ac3.stop_io()
+
+    ac2.start_io()
     chat12 = acfactory.get_accepted_chat(ac1, ac2)
 
     lp.sec("ac1: sending 3 messages")
@@ -2153,6 +2157,9 @@ def test_trash_multiple_messages(acfactory, lp):
         assert msg.text in texts
         if text != "second":
             to_delete.append(msg)
+    # ac2 has received some messages, this is impossible w/o the trash folder configured, let's
+    # check the configuration.
+    assert ac2.get_config("configured_trash_folder") == "Trash"
 
     lp.sec("ac2: deleting all messages except second")
     assert len(to_delete) == len(texts) - 1

src/imap/scan_folders.rs

@@ -89,9 +89,16 @@ impl Imap {
             Config::ConfiguredSentboxFolder,
             Config::ConfiguredTrashFolder,
         ] {
-            context
-                .set_config_internal(conf, folder_configs.get(&conf).map(|s| s.as_str()))
-                .await?;
+            let val = folder_configs.get(&conf).map(|s| s.as_str());
+            let interrupt = conf == Config::ConfiguredTrashFolder
+                && val.is_some()
+                && context.get_config(conf).await?.is_none();
+            context.set_config_internal(conf, val).await?;
+            if interrupt {
+                // `Imap::fetch_move_delete()` is possible now for other folders (NB: we are in the
+                // Inbox loop).
+                context.scheduler.interrupt_oboxes().await;
+            }
         }
 
         last_scan.replace(tools::Time::now());

src/scheduler.rs

@@ -247,6 +247,14 @@ impl SchedulerState {
         }
     }
 
+    /// Interrupt optional boxes (mvbox, sentbox) loops.
+    pub(crate) async fn interrupt_oboxes(&self) {
+        let inner = self.inner.read().await;
+        if let InnerSchedulerState::Started(ref scheduler) = *inner {
+            scheduler.interrupt_oboxes();
+        }
+    }
+
     pub(crate) async fn interrupt_smtp(&self) {
         let inner = self.inner.read().await;
         if let InnerSchedulerState::Started(ref scheduler) = *inner {
@@ -565,19 +573,28 @@ async fn fetch_idle(
             .context("store_seen_flags_on_imap")?;
     }
 
-    // Fetch the watched folder.
-    connection
-        .fetch_move_delete(ctx, &mut session, &watch_folder, folder_meaning)
-        .await
-        .context("fetch_move_delete")?;
+    if !ctx.should_delete_to_trash().await?
+        || ctx
+            .get_config(Config::ConfiguredTrashFolder)
+            .await?
+            .is_some()
+    {
+        // Fetch the watched folder.
+        connection
+            .fetch_move_delete(ctx, &mut session, &watch_folder, folder_meaning)
+            .await
+            .context("fetch_move_delete")?;
 
-    // Mark expired messages for deletion. Marked messages will be deleted from the server
-    // on the next iteration of `fetch_move_delete`. `delete_expired_imap_messages` is not
-    // called right before `fetch_move_delete` because it is not well optimized and would
-    // otherwise slow down message fetching.
-    delete_expired_imap_messages(ctx)
-        .await
-        .context("delete_expired_imap_messages")?;
+        // Mark expired messages for deletion. Marked messages will be deleted from the server
+        // on the next iteration of `fetch_move_delete`. `delete_expired_imap_messages` is not
+        // called right before `fetch_move_delete` because it is not well optimized and would
+        // otherwise slow down message fetching.
+        delete_expired_imap_messages(ctx)
+            .await
+            .context("delete_expired_imap_messages")?;
+    } else if folder_config == Config::ConfiguredInboxFolder {
+        ctx.last_full_folder_scan.lock().await.take();
+    }
 
     // Scan additional folders only after finishing fetching the watched folder.
     //
@@ -911,6 +928,12 @@ impl Scheduler {
         self.inbox.conn_state.interrupt();
     }
 
+    fn interrupt_oboxes(&self) {
+        for b in &self.oboxes {
+            b.conn_state.interrupt();
+        }
+    }
+
     fn interrupt_smtp(&self) {
         self.smtp.interrupt();
     }