feat: double hyphen to em dash (#395)

* feat: double hyphen to em dash

* chore: fix tests

---------

Co-authored-by: Lucas.Xu <lucas.xu@appflowy.io>

lib/src/editor/block_component/divider_block_component/divider_character_shortcut.dart

@@ -1,6 +1,7 @@
 import 'package:appflowy_editor/appflowy_editor.dart';
 
-/// insert divider into a document by typing three minuses(-).
+/// insert divider into a document by typing three dashes (-)
+/// or one em dash (—) and one dash (-)
 ///
 /// - support
 ///   - desktop

lib/src/editor/editor_component/service/shortcuts/character_shortcut_events/character_shortcut_events.dart

@@ -10,3 +10,4 @@ export 'format_single_character/format_strikethrough.dart';
 export 'format_double_characters/format_double_characters.dart';
 export 'format_double_characters/format_bold.dart';
 export 'format_double_characters/format_strikethrough.dart';
+export 'format_double_characters/format_double_hyphen.dart';

lib/src/editor/editor_component/service/shortcuts/character_shortcut_events/format_double_characters/format_double_hyphen.dart

@@ -0,0 +1,72 @@
+import 'package:appflowy_editor/appflowy_editor.dart';
+
+const _hyphen = '-';
+const _emDash = '—'; // This is an em dash — not a single dash - !!
+
+/// format two hyphens into an em dash
+///
+/// - support
+///   - desktop
+///   - mobile
+///   - web
+///
+final CharacterShortcutEvent formatDoubleHyphenEmDash = CharacterShortcutEvent(
+  key: 'format double hyphen into an em dash',
+  character: _hyphen,
+  handler: (editorState) async => handleDoubleCharacterReplacement(
+    editorState: editorState,
+    character: _hyphen,
+    replacement: _emDash,
+  ),
+);
+
+Future<bool> handleDoubleCharacterReplacement({
+  required EditorState editorState,
+  required String character,
+  required String replacement,
+}) async {
+  assert(character.length == 1);
+
+  Selection? selection = editorState.selection;
+  if (selection == null) {
+    return false;
+  }
+
+  if (!selection.isCollapsed) {
+    await editorState.deleteSelection(selection);
+  }
+
+  selection = editorState.selection;
+  if (selection == null) {
+    return false;
+  }
+
+  final node = editorState.getNodeAtPath(selection.end.path);
+  final delta = node?.delta;
+  if (node == null || delta == null || delta.isEmpty) {
+    return false;
+  }
+
+  if (selection.end.offset > 0) {
+    final plain = delta.toPlainText();
+
+    final previousCharacter = plain[selection.end.offset - 1];
+    if (previousCharacter != _hyphen) {
+      return false;
+    }
+
+    final replace = editorState.transaction
+      ..replaceText(
+        node,
+        selection.end.offset - 1,
+        1,
+        _emDash,
+      );
+
+    await editorState.apply(replace);
+
+    return true;
+  }
+
+  return false;
+}

lib/src/editor/editor_component/service/shortcuts/character_shortcut_events/format_single_character/format_single_character.dart

@@ -37,7 +37,7 @@ bool handleFormatByWrappingWithSingleCharacter({
   // Determine if a 'Character' already exists in the node and only once.
   // 1. This is no 'Character' in the plainText: indexOf returns -1.
   // 2. More than one 'Character' in the plainText: the headCharIndex and endCharIndex are supposed to be the same, if not, which means plainText has more than one character. For example: when plainText is '_abc', it will trigger formatting(remind:the last char is used to trigger the formatting,so it won't be counted in the plainText.). But adding '_' after 'a__ab' won't trigger formatting.
-  // 3. there're two characters connecting together, like adding '_' after 'abc_' won't trigger formatting.
+  // 3. there are two characters connecting together, like adding '_' after 'abc_' won't trigger formatting.
   if (headCharIndex == -1 ||
       headCharIndex != endCharIndex ||
       headCharIndex == selection.end.offset - 1) {

lib/src/editor/editor_component/service/shortcuts/character_shortcut_events/markdown_syntax_character_shortcut_events.dart

@@ -29,4 +29,7 @@ final List<CharacterShortcutEvent> markdownSyntaxShortcutEvents = [
   // format bold, **bold** or __bold__
   formatDoubleAsterisksToBold,
   formatDoubleUnderscoresToBold,
+
+  // format -- into em dash
+  formatDoubleHyphenEmDash,
 ];

test/new/editor_component/service/shortcuts/character_shortcuts/format_double_hyphen_test.dart

@@ -0,0 +1,67 @@
+import 'package:appflowy_editor/appflowy_editor.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import '../../../../infra/testable_editor.dart';
+
+const _hyphen = '-';
+const _emDash = '—'; // This is an em dash
+
+void main() async {
+  group('format_double_hyphen.dart', () {
+    testWidgets('two dashes to em dash', (tester) async {
+      final editor = tester.editor..addEmptyParagraph();
+      await editor.startTesting();
+
+      await editor.updateSelection(Selection.collapsed(Position(path: [0])));
+
+      await editor.ime.typeText(_hyphen);
+      await editor.ime.typeText(_hyphen);
+
+      final delta = editor.nodeAtPath([0])!.delta!;
+      expect(delta.length, 1);
+      expect(delta.toPlainText(), _emDash);
+
+      await editor.dispose();
+    });
+
+    testWidgets('two dashes to em dash with selection', (tester) async {
+      const welcome = 'Welcome';
+      const initialText = '$_hyphen$welcome';
+
+      final editor = tester.editor..addParagraph(initialText: initialText);
+      await editor.startTesting();
+
+      await editor.updateSelection(
+        Selection.single(
+          path: [0],
+          startOffset: 1,
+          endOffset: initialText.length,
+        ),
+      );
+
+      await editor.ime.typeText(_hyphen);
+
+      final delta = editor.nodeAtPath([0])!.delta!;
+      expect(delta.length, 1);
+      expect(delta.toPlainText(), _emDash);
+
+      await editor.dispose();
+    });
+
+    testWidgets('em dash + dash to divider', (tester) async {
+      final editor = tester.editor..addParagraph(initialText: _emDash);
+      await editor.startTesting();
+
+      await editor.updateSelection(
+        Selection.collapsed(Position(path: [0], offset: 1)),
+      );
+
+      await editor.ime.typeText(_hyphen);
+
+      final node = editor.nodeAtPath([0]);
+      expect(node!.type, DividerBlockKeys.type);
+
+      await editor.dispose();
+    });
+  });
+}

test/new/infra/testable_editor.dart

@@ -315,14 +315,24 @@ class MockIMEInput {
   }
 
   Future<void> replaceText(String text) async {
-    final selection = editorState.selection?.normalized;
+    var selection = editorState.selection?.normalized;
-    if (selection == null || selection.isCollapsed) {
+    if (selection == null) {
       return;
     }
-    final texts = editorState.getTextInSelection(selection).join('\n');
+    if (!selection.isSingle || !selection.isCollapsed) {
+      await editorState.deleteSelection(selection);
+    }
+    selection = editorState.selection?.normalized;
+    if (selection == null) {
+      return;
+    }
+
+    final oldText =
+        editorState.getNodeAtPath(selection.start.path)!.delta!.toPlainText();
+
     await imeInput.apply([
       TextEditingDeltaReplacement(
-        oldText: ' $texts',
+        oldText: ' $oldText',
         replacementText: text,
         replacedRange: TextSelection(
           baseOffset: selection.startIndex + 1,