Note: Allow tags to be read and serialized

This is just exposing the tags on the Note class. Not making it
available through any interface.

lib/core/note.dart

@@ -36,6 +36,7 @@ class Note with NotesNotifier {
   DateTime _modified;
   String _body = "";
   NoteType _type = NoteType.Unknown;
+  List<String> _tags = [];
 
   MdYamlDoc _data = MdYamlDoc();
   NoteSerializer noteSerializer = NoteSerializer();
@@ -124,6 +125,17 @@ class Note with NotesNotifier {
     _notifyModified();
   }
 
+  List<String> get tags {
+    return _tags;
+  }
+
+  set tags(List<String> tags) {
+    if (!canHaveMetadata) return;
+
+    _tags = tags;
+    _notifyModified();
+  }
+
   bool get canHaveMetadata {
     return Settings.instance.yamlHeaderEnabled;
   }

lib/core/note_serializer.dart

@@ -1,6 +1,8 @@
 import 'package:gitjournal/utils/datetime.dart';
 import 'package:gitjournal/settings.dart';
 import 'package:flutter_emoji/flutter_emoji.dart';
+import 'package:gitjournal/utils/logger.dart';
+import 'package:yaml/yaml.dart';
 
 import 'md_yaml_doc.dart';
 import 'note.dart';
@@ -17,6 +19,7 @@ class NoteSerializationSettings {
   String createdKey = "created";
   String titleKey = "title";
   String typeKey = "type";
+  String tagsKey = "tags";
 }
 
 class NoteSerializer implements NoteSerializerInterface {
@@ -54,6 +57,12 @@ class NoteSerializer implements NoteSerializerInterface {
       data.props.remove(settings.typeKey);
     }
 
+    if (note.tags.isEmpty) {
+      data.props.remove(settings.tagsKey);
+    } else {
+      data.props[settings.tagsKey] = note.tags;
+    }
+
     data.body = emojiParser.unemojify(note.body);
   }
 
@@ -95,5 +104,14 @@ class NoteSerializer implements NoteSerializerInterface {
         note.type = NoteType.Unknown;
         break;
     }
+
+    try {
+      var tags = data.props[settings.tagsKey] as YamlList;
+      if (tags != null) {
+        note.tags = tags.map((t) => t.toString()).toList();
+      }
+    } catch (e) {
+      Log.e("Note Decoding Failed: $e");
+    }
   }
 }

test/note_test.dart

@@ -71,6 +71,44 @@ title: Foo
 mod: 2019-12-02T04:00:00+00:00
 ---
 
+Hello""";
+
+      var actualContent = File(notePath).readAsStringSync();
+      expect(actualContent, equals(expectedContent));
+    });
+
+    test('Should read and write tags', () async {
+      var content = """---
+title: Foo
+modified: 2017-02-15T22:41:19+01:00
+tags: [A, B]
+---
+
+Hello""";
+
+      var notePath = p.join(tempDir.path, "note5.md");
+      File(notePath).writeAsString(content);
+
+      var parentFolder = NotesFolderFS(null, tempDir.path);
+      var note = Note(parentFolder, notePath);
+      await note.load();
+
+      expect(note.tags[0], 'A');
+      expect(note.tags[1], 'B');
+      expect(note.tags.length, 2);
+
+      note.tags = [...note.tags]..add('C');
+      note.tags.add('D');
+      note.tags.remove('B');
+
+      await note.save();
+
+      var expectedContent = """---
+title: Foo
+modified: 2017-02-15T22:41:19+01:00
+tags: [A, C, D]
+---
+
 Hello""";
 
       var actualContent = File(notePath).readAsStringSync();