#54 snippet group

lib/data/provider/snippet.dart

@@ -5,25 +5,44 @@ import 'package:toolbox/data/model/server/snippet.dart';
 import 'package:toolbox/data/store/snippet.dart';
 import 'package:toolbox/locator.dart';
 
+import '../../core/extension/order.dart';
+
 class SnippetProvider extends BusyProvider {
-  List<Snippet> get snippets => _snippets;
+  late Order<Snippet> _snippets;
+  Order<Snippet> get snippets => _snippets;
+
+  final _tags = <String>[];
+  List<String> get tags => _tags;
+
   final _store = locator<SnippetStore>();
-  late List<Snippet> _snippets;
 
   void loadData() {
     _snippets = _store.fetch();
   }
 
+  void _updateTags() {
+    _tags.clear();
+    for (final s in _snippets) {
+      if (s.tags?.isEmpty ?? true) {
+        continue;
+      }
+      _tags.addAll(s.tags!);
+    }
+    _tags.toSet().toList();
+  }
+
   void add(Snippet snippet) {
     _snippets.add(snippet);
     _store.put(snippet);
     notifyListeners();
+    _updateTags();
   }
 
   void del(Snippet snippet) {
     _snippets.remove(snippet);
     _store.delete(snippet);
     notifyListeners();
+    _updateTags();
   }
 
   void update(Snippet old, Snippet newOne) {
@@ -32,6 +51,21 @@ class SnippetProvider extends BusyProvider {
     _snippets.remove(old);
     _snippets.add(newOne);
     notifyListeners();
+    _updateTags();
+  }
+
+  void renameTag(String old, String newOne) {
+    for (final s in _snippets) {
+      if (s.tags?.contains(old) ?? false) {
+        s.tags?.remove(old);
+        s.tags?.add(newOne);
+      }
+    }
+    for (final s in _snippets) {
+      _store.put(s);
+    }
+    notifyListeners();
+    _updateTags();
   }
 
   String get export => json.encode(snippets);