feat: add built-in markdown editor with search jump and typing helpers

test/markdown_editing_test.dart

@@ -0,0 +1,145 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:muzzle_velocity/markdown_editing.dart';
+
+final _formatter = MarkdownInputFormatter();
+
+TextEditingValue _value(String text, int start, [int? end]) => TextEditingValue(
+      text: text,
+      selection: TextSelection(baseOffset: start, extentOffset: end ?? start),
+    );
+
+/// Simulates typing [typed] over the current selection of [old].
+TextEditingValue _type(TextEditingValue old, String typed) {
+  final s = old.selection.start;
+  final raw = _value(old.text.replaceRange(s, old.selection.end, typed),
+      s + typed.length);
+  return _formatter.formatEditUpdate(old, raw);
+}
+
+/// Text with `|` marking the caret.
+TextEditingValue _caret(String marked) =>
+    _value(marked.replaceFirst('|', ''), marked.indexOf('|'));
+
+String _marked(TextEditingValue v) =>
+    v.text.replaceRange(v.selection.start, v.selection.start, '|');
+
+Map<String, String> _classes(String text) => {
+      for (final s in highlightMarkdown(text))
+        text.substring(s.start, s.end): s.className,
+    };
+
+void main() {
+  group('wrap selection', () {
+    test('asterisk wraps and keeps the word selected', () {
+      final once = _type(_value('a word here', 2, 6), '*');
+      expect(once.text, 'a *word* here');
+      expect(once.selection, const TextSelection(baseOffset: 3, extentOffset: 7));
+      expect(_type(once, '*').text, 'a **word** here');
+    });
+
+    test('bracket uses its closing pair', () {
+      expect(_type(_value('see link', 4, 8), '[').text, 'see [link]');
+    });
+
+    test('a letter still replaces the selection', () {
+      final result = _type(_value('a word', 2, 6), 'x');
+      expect(result.text, 'a x');
+    });
+  });
+
+  group('new line', () {
+    test('keeps indentation', () {
+      expect(_marked(_type(_caret('    code|'), '\n')), '    code\n    |');
+    });
+
+    test('continues bullets, numbers, tasks and quotes', () {
+      expect(_marked(_type(_caret('- one|'), '\n')), '- one\n- |');
+      expect(_marked(_type(_caret('  * one|'), '\n')), '  * one\n  * |');
+      expect(_marked(_type(_caret('9. nine|'), '\n')), '9. nine\n10. |');
+      expect(_marked(_type(_caret('1) a|'), '\n')), '1) a\n2) |');
+      expect(_marked(_type(_caret('- [x] done|'), '\n')), '- [x] done\n- [ ] |');
+      expect(_marked(_type(_caret('> quote|'), '\n')), '> quote\n> |');
+    });
+
+    test('splits an item when the caret is mid-line', () {
+      expect(_marked(_type(_caret('- one|two'), '\n')), '- one\n- |two');
+    });
+
+    test('an empty item ends the list', () {
+      expect(_marked(_type(_caret('- one\n- |'), '\n')), '- one\n|');
+      expect(_marked(_type(_caret('1. a\n2. |'), '\n')), '1. a\n|');
+    });
+
+    test('inside a code fence only indentation carries over', () {
+      expect(_marked(_type(_caret('```\n  - x|'), '\n')), '```\n  - x\n  |');
+    });
+
+    test('emphasis at line start is not a bullet', () {
+      expect(_marked(_type(_caret('*bold* text|'), '\n')), '*bold* text\n|');
+    });
+  });
+
+  group('indentLines', () {
+    test('indents and outdents all selected lines', () {
+      final value = _value('a\nb\nc', 0, 3);
+      final indented = indentLines(value);
+      expect(indented.text, '  a\n  b\nc');
+      expect(indentLines(indented, outdent: true).text, 'a\nb\nc');
+    });
+  });
+
+  group('highlightMarkdown', () {
+    test('line and inline syntax', () {
+      final classes = _classes(
+          '## Title\n- [ ] task **bold** and *it* `code` ~~gone~~\n[text](url) #tag +proj @ctx');
+      expect(classes['## Title'], 'header-h2');
+      expect(classes['- [ ] '], 'task-list');
+      expect(classes['**bold**'], 'bold');
+      expect(classes['*it*'], 'italic');
+      expect(classes['`code`'], 'code');
+      expect(classes['~~gone~~'], 'strikethrough');
+      expect(classes['[text]'], 'link-text');
+      expect(classes['(url)'], 'link-url');
+      expect(classes['#tag'], 'tag-hash');
+      expect(classes['+proj'], 'tag-plus');
+      expect(classes['@ctx'], 'tag-at');
+    });
+
+    test('fenced code spans lines without inline highlighting', () {
+      final classes = _classes('```\n**not bold**\n```\n**bold**');
+      expect(classes['**not bold**'], 'code');
+      expect(classes['**bold**'], 'bold');
+    });
+
+    test('segments are sorted and do not overlap', () {
+      final segments = highlightMarkdown('- a **b** #c\n> q\n---');
+      for (var i = 1; i < segments.length; i++) {
+        expect(segments[i].start, greaterThanOrEqualTo(segments[i - 1].end));
+      }
+    });
+  });
+
+  group('MarkdownController search', () {
+    test('finds terms case-insensitively and follows edits', () {
+      final controller =
+          MarkdownController(text: 'Foo bar foo #tag', theme: const {});
+      controller.search(['foo', '#tag']);
+      expect(controller.matches.map((m) => m.start), [0, 8, 12]);
+
+      controller.text = 'bar foo';
+      expect(controller.matches.map((m) => m.start), [4]);
+    });
+
+    test('builds spans covering the whole text', () {
+      final controller =
+          MarkdownController(text: '# Hi **there**', theme: const {});
+      controller.search(['there']);
+      final span = controller.buildTextSpan(
+          context: _FakeContext(), withComposing: false);
+      expect(span.toPlainText(), '# Hi **there**');
+    });
+  });
+}
+
+class _FakeContext extends Fake implements BuildContext {}