Migrate to singbox

lib/utils/custom_log_printer.dart

@@ -0,0 +1,31 @@
+import 'dart:io';
+
+import 'package:loggy/loggy.dart';
+
+class MultiLogPrinter extends LoggyPrinter {
+  MultiLogPrinter(this.consolePrinter, this.filePrinter);
+
+  final LoggyPrinter consolePrinter;
+  final LoggyPrinter filePrinter;
+
+  @override
+  void onLog(LogRecord record) {
+    consolePrinter.onLog(record);
+    filePrinter.onLog(record);
+  }
+}
+
+class FileLogPrinter extends LoggyPrinter {
+  FileLogPrinter(String filePath) : _logFile = File(filePath);
+
+  final File _logFile;
+
+  late final _sink = _logFile.openWrite(
+    mode: FileMode.writeOnly,
+  );
+
+  @override
+  void onLog(LogRecord record) {
+    _sink.writeln(record.toString());
+  }
+}