Note: Add an API to get the images from a note

This will be used in the future to display the images in the grid/card
view.

lib/core/note.dart

@@ -7,6 +7,7 @@ import 'package:gitjournal/core/links_loader.dart';
 import 'package:gitjournal/core/md_yaml_doc_loader.dart';
 import 'package:gitjournal/core/note_notifier.dart';
 import 'package:gitjournal/core/notes_folder_fs.dart';
+import 'package:gitjournal/core/processors/image_extractor.dart';
 import 'package:gitjournal/core/processors/inline_tags.dart';
 import 'package:gitjournal/error_reporting.dart';
 import 'package:gitjournal/settings.dart';
@@ -64,6 +65,7 @@ class Note with NotesNotifier {
   String _summary;
   List<Link> _links;
   Set<String> _inlineTags;
+  Set<NoteImage> _images;
 
   static final _mdYamlDocLoader = MdYamlDocLoader();
   static final _linksLoader = LinksLoader();
@@ -153,6 +155,7 @@ class Note with NotesNotifier {
     _summary = null;
     _links = null;
     _inlineTags = null;
+    _images = null;
 
     _notifyModified();
   }
@@ -200,6 +203,15 @@ class Note with NotesNotifier {
     return _inlineTags;
   }
 
+  Set<NoteImage> get images {
+    if (_loadState != NoteLoadState.Loaded) return {};
+
+    var p = ImageExtractor();
+    _images ??= p.extract(body);
+
+    return _images;
+  }
+
   Map<String, dynamic> get extraProps {
     return _extraProps;
   }

lib/core/processors/image_extractor.dart

@@ -0,0 +1,32 @@
+import 'package:equatable/equatable.dart';
+import 'package:meta/meta.dart';
+
+class NoteImage extends Equatable {
+  final String url;
+  final String alt;
+
+  NoteImage({@required this.url, @required this.alt});
+
+  @override
+  List<Object> get props => [url, alt];
+
+  @override
+  bool get stringify => true;
+}
+
+class ImageExtractor {
+  static final _regexp = RegExp(r"!\[(.*)\]\((.*)\)");
+
+  Set<NoteImage> extract(String body) {
+    var images = <NoteImage>{};
+    var matches = _regexp.allMatches(body);
+    for (var match in matches) {
+      var alt = match.group(1);
+      var url = match.group(2);
+
+      images.add(NoteImage(alt: alt, url: url));
+    }
+
+    return images;
+  }
+}

test/processors/image_extractor_test.dart

@@ -0,0 +1,20 @@
+import 'package:test/test.dart';
+
+import 'package:gitjournal/core/processors/image_extractor.dart';
+
+void main() {
+  test('Should parse simple tags', () {
+    var body = """#hello Hi
+![alt](../final.img)
+![alt2](../final2.img)
+""";
+
+    var p = ImageExtractor();
+    var images = p.extract(body);
+
+    expect(images, {
+      NoteImage(alt: 'alt', url: '../final.img'),
+      NoteImage(alt: 'alt2', url: '../final2.img'),
+    });
+  });
+}