Fixed issue where testing the connecting string would fail if local DB was being used

Fixed issue where blacklisting video in with archiving would not work

Cleaned up unused functions in app.js

backend/db.js

@@ -75,7 +75,7 @@ exports.initialize = (input_db, input_users_db, input_logger) => {
 }
 
 exports.connectToDB = async (retries = 5, no_fallback = false, custom_connection_string = null) => {
-    if (using_local_db) return;
+    if (using_local_db && !custom_connection_string) return;
     const success = await exports._connectToDB(custom_connection_string);
     if (success) return true;
 
@@ -1018,4 +1018,16 @@ const applyFilterLocalDB = (db_path, filter_obj, operation) => {
         return filtered;
     });
     return return_val;
-}
+}
+
+// archive helper functions
+
+async function writeToBlacklist(type, line) {
+    const archivePath = path.join(__dirname, 'appdata', 'archives');
+    let blacklistPath = path.join(archivePath, (type === 'audio') ? 'blacklist_audio.txt' : 'blacklist_video.txt');
+    // adds newline to the beginning of the line
+    line.replace('\n', '');
+    line.replace('\r', '');
+    line = '\n' + line;
+    await fs.appendFile(blacklistPath, line);
+}