Allow moving trash / POP3 / leave deleted

app/src/main/java/eu/faircode/email/AdapterMessage.java

@@ -1959,7 +1959,8 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
                     boolean archive = (move && (hasArchive && !inArchive && !inSent && !inTrash && !inJunk));
                     boolean trash = (move || outbox || debug ||
                             message.accountProtocol == EntityAccount.TYPE_POP);
-                    boolean inbox = (move && hasInbox && (inArchive || inTrash || inJunk));
+                    boolean inbox = (move && hasInbox && (inArchive || inTrash || inJunk)) ||
+                            (message.accountProtocol == EntityAccount.TYPE_POP && message.accountLeaveDeleted && inTrash);
                     boolean keywords = (message.uid != null &&
                             message.accountProtocol == EntityAccount.TYPE_IMAP);
                     boolean labels = (data.isGmail && move && !inTrash && !inJunk && !outbox);

app/src/main/java/eu/faircode/email/Core.java

@@ -358,7 +358,7 @@ class Core {
                                     break;
 
                                 case EntityOperation.MOVE:
-                                    onMove(context, jargs, folder, message);
+                                    onMove(context, jargs, account, folder, message);
                                     break;
 
                                 case EntityOperation.DELETE:
@@ -1496,7 +1496,7 @@ class Core {
             }
     }
 
-    private static void onMove(Context context, JSONArray jargs, EntityFolder folder, EntityMessage message) throws JSONException, FolderNotFoundException {
+    private static void onMove(Context context, JSONArray jargs, EntityAccount account, EntityFolder folder, EntityMessage message) throws JSONException, FolderNotFoundException {
         // Move message
         DB db = DB.getInstance(context);
 
@@ -1513,10 +1513,11 @@ class Core {
             throw new IllegalArgumentException("self");
 
         // Move from trash/drafts only
-        if (!EntityFolder.TRASH.equals(folder.type) &&
-                !EntityFolder.DRAFTS.equals(folder.type))
+        if (!EntityFolder.DRAFTS.equals(folder.type) &&
+                !(EntityFolder.TRASH.equals(folder.type) && account.leave_deleted))
             throw new IllegalArgumentException("Invalid POP3 folder" +
-                    " source=" + folder.type + " target=" + target.type);
+                    " source=" + folder.type + " target=" + target.type +
+                    " leave deleted=" + account.leave_deleted);
 
         message.folder = target.id;
         if (seen)

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -3292,7 +3292,8 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                             .setIcon(R.drawable.twotone_attachment_24);
 
                 if (!result.read_only) {
-                    if (result.hasInbox && !result.isInbox) // not is inbox
+                    if ((result.hasInbox && !result.isInbox) ||
+                            (result.leave_deleted != null && result.leave_deleted && result.isTrash)) // not is inbox
                         popupMenu.getMenu().add(Menu.FIRST, R.string.title_folder_inbox, order++, R.string.title_folder_inbox)
                                 .setIcon(R.drawable.twotone_move_to_inbox_24);