refactor

mobile/lib/domain/models/metadata_key.dart

@@ -1,3 +1,4 @@
+import 'package:collection/collection.dart';
 import 'package:flutter/material.dart';
 import 'package:immich_mobile/domain/models/config/app_config.dart';
 import 'package:immich_mobile/domain/models/config/system_config.dart';
@@ -12,17 +13,89 @@ enum MetadataDomain<T extends Object> {
 }
 
 enum MetadataKey<T extends Object> {
-  themeMode<ThemeMode>(.appConfig, 'theme.mode', .system, ThemeMode.values),
-  logLevel<LogLevel>(.systemConfig, 'log.level', .info, LogLevel.values);
+  themeMode<ThemeMode>(.appConfig, 'theme.mode', .system, _EnumCodec(ThemeMode.values)),
+  logLevel<LogLevel>(.systemConfig, 'log.level', .info, _EnumCodec(LogLevel.values));
 
   final MetadataDomain domain;
   final String name;
   final T defaultValue;
-  final List<T>? enumValues;
+  final _MetadataCodec<T>? _codecOverride;
 
-  const MetadataKey(this.domain, this.name, this.defaultValue, [this.enumValues]);
+  const MetadataKey(this.domain, this.name, this.defaultValue, [this._codecOverride]);
 
   String get key => '${domain.prefix}.$name';
 
+  _MetadataCodec<T> get _codec => _codecOverride ?? _MetadataCodec.forPrimitive(defaultValue);
+
+  String encode(T value) => _codec.encode(value);
+
+  T decode(String raw) => _codec.decode(raw) ?? defaultValue;
+
   static Map<String, MetadataKey<Object>> asKeyMap() => {for (var value in MetadataKey.values) value.key: value};
 }
+
+sealed class _MetadataCodec<T extends Object> {
+  const _MetadataCodec();
+
+  String encode(T value);
+  T? decode(String raw);
+
+  static const Map<Type, _MetadataCodec<Object>> _primitives = {
+    int: _PrimitiveCodec.integer,
+    double: _PrimitiveCodec.real,
+    bool: _PrimitiveCodec.boolean,
+    String: _PrimitiveCodec.string,
+    DateTime: _DateTimeCodec(),
+  };
+
+  static _MetadataCodec<T> forPrimitive<T extends Object>(T sample) {
+    final codec = _primitives[sample.runtimeType];
+    if (codec == null) {
+      throw StateError(
+        'No primitive codec for ${sample.runtimeType}. Provide an explicit codec when defining the MetadataKey.',
+      );
+    }
+    return codec as _MetadataCodec<T>;
+  }
+}
+
+final class _EnumCodec<T extends Enum> extends _MetadataCodec<T> {
+  final List<T> values;
+
+  const _EnumCodec(this.values);
+
+  @override
+  String encode(T value) => value.name;
+
+  @override
+  T? decode(String raw) => values.firstWhereOrNull((v) => v.name == raw);
+}
+
+final class _DateTimeCodec extends _MetadataCodec<DateTime> {
+  const _DateTimeCodec();
+
+  @override
+  String encode(DateTime value) => value.toIso8601String();
+
+  @override
+  DateTime? decode(String raw) => DateTime.tryParse(raw);
+}
+
+final class _PrimitiveCodec<T extends Object> extends _MetadataCodec<T> {
+  final T? Function(String) _parse;
+
+  const _PrimitiveCodec._(this._parse);
+
+  @override
+  String encode(T value) => value.toString();
+
+  @override
+  T? decode(String raw) => _parse(raw);
+
+  static const integer = _PrimitiveCodec<int>._(int.tryParse);
+  static const real = _PrimitiveCodec<double>._(double.tryParse);
+  static const boolean = _PrimitiveCodec<bool>._(bool.tryParse);
+  static const string = _PrimitiveCodec<String>._(_identity);
+
+  static String? _identity(String s) => s;
+}