logging framework

lib/util/logger.dart

@@ -0,0 +1,48 @@
+import 'package:logger/logger.dart';
+
+class LogLevelFilter extends LogFilter {
+  @override
+  bool shouldLog(LogEvent event) {
+    return event.level >= level!;
+  }
+}
+
+class SubtracksLogger extends Logger {
+  SubtracksLogger({
+    super.filter,
+    super.printer,
+    super.output,
+    required Level level,
+  }) : _level = level,
+       super(level: level);
+
+  final Level _level;
+  Level get level => _level;
+}
+
+SubtracksLogger createLogger() {
+  var isDebug = false;
+  assert(() {
+    isDebug = true;
+    return true;
+  }());
+
+  if (isDebug) {
+    return SubtracksLogger(
+      filter: DevelopmentFilter(),
+      printer: PrettyPrinter(),
+      output: ConsoleOutput(),
+      level: Level.debug,
+    );
+  }
+
+  // TODO: production logger
+  return SubtracksLogger(
+    filter: DevelopmentFilter(),
+    printer: PrettyPrinter(),
+    output: ConsoleOutput(),
+    level: Level.debug,
+  );
+}
+
+final logger = createLogger();