Cleanup POP3 keywords

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

@@ -488,6 +488,9 @@ public interface DaoMessage {
             " OR (NOT :hash IS NULL AND message.hash IS :hash))")
     List<EntityMessage> getMessagesBySimilarity(long account, long id, String msgid, String hash);
 
+    @Query("SELECT DISTINCT keywords FROM message WHERE folder = :folder")
+    List<String[]> getKeywords(long folder);
+
     @Query("SELECT COUNT(*) FROM message" +
             " WHERE folder = :folder" +
             " AND msgid = :msgid" +

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

@@ -205,6 +205,24 @@ public class EntityOperation {
                         db.folder().setFolderKeywords(folder.id,
                                 DB.Converters.fromStringArray(fkeywords.toArray(new String[0])));
                     }
+                } else {
+                    EntityAccount account = db.account().getAccount(message.account);
+                    if (account != null && account.protocol == EntityAccount.TYPE_POP) {
+                        EntityFolder folder = db.folder().getFolder(message.folder);
+                        if (folder != null) {
+                            List<String> fkeywords = new ArrayList<>();
+                            List<String[]> mkeywords = db.message().getKeywords(folder.id);
+                            if (mkeywords != null)
+                                for (String[] kws : mkeywords) {
+                                    for (String kw : kws)
+                                        if (!fkeywords.contains(kw))
+                                            fkeywords.add(kw);
+                                }
+                            Collections.sort(fkeywords);
+                            db.folder().setFolderKeywords(folder.id,
+                                    DB.Converters.fromStringArray(fkeywords.toArray(new String[0])));
+                        }
+                    }
                 }
 
             } else if (LABEL.equals(name)) {