Auto formats and auto link implementation

packages/fleather/lib/fleather.dart

@@ -18,3 +18,4 @@ export 'src/widgets/field.dart';
 export 'src/widgets/link.dart' show LinkActionPickerDelegate, LinkMenuAction;
 export 'src/widgets/text_line.dart';
 export 'src/widgets/theme.dart';
+export 'src/widgets/autoformats.dart';

packages/fleather/lib/src/util.dart

@@ -0,0 +1,15 @@
+import 'package:quill_delta/quill_delta.dart';
+
+extension DeltaExtension on Delta {
+  int get textLength {
+    int length = 0;
+    toList().forEach((op) {
+      if (op.isDelete) {
+        length -= op.length;
+      } else {
+        length += op.length;
+      }
+    });
+    return length;
+  }
+}

packages/fleather/lib/src/widgets/autoformats.dart

@@ -0,0 +1,109 @@
+import 'package:fleather/fleather.dart';
+import 'package:quill_delta/quill_delta.dart';
+
+/// An [AutoFormat] is responsible for looking back for a pattern and apply a
+/// formatting suggestion.
+///
+/// For example, identify a link a automatically wrap it with a link attribute or
+/// apply formatting using Markdown shortcuts
+abstract class AutoFormat {
+  const AutoFormat();
+
+  /// Upon upon insertion of a space or new line run format detection
+  /// Returns a [Delta] with the resulting change to apply to th document
+  Delta? apply(Delta document, int position, String data);
+}
+
+/// Registry for [AutoFormats].
+class AutoFormats {
+  AutoFormats({required List<AutoFormat> autoFormats})
+      : _autoFormats = autoFormats;
+
+  /// Default set of autoformats.
+  factory AutoFormats.fallback() {
+    return AutoFormats(autoFormats: [const _AutoFormatLinks()]);
+  }
+
+  final List<AutoFormat> _autoFormats;
+
+  Delta? get activeSuggestion => _activeSuggestion;
+  Delta? _activeSuggestion;
+  Delta? _undoActiveSuggestion;
+
+  bool get hasActiveSuggestion => _activeSuggestion != null;
+
+  /// Perform detection of auto formats and apply changes to [document]
+  ///
+  /// Inserted data must be of type [String]
+  void run(ParchmentDocument document, int position, Object data) {
+    if (data is! String || data.isEmpty) return;
+
+    Delta documentDelta = document.toDelta();
+    for (final autoFormat in _autoFormats) {
+      _activeSuggestion = autoFormat.apply(documentDelta, position, data)
+        ?..trim();
+      if (_activeSuggestion != null) {
+        _undoActiveSuggestion = _activeSuggestion!.invert(documentDelta);
+        document.compose(_activeSuggestion!, ChangeSource.local);
+        return;
+      }
+    }
+  }
+
+  /// Remove auto format from [document] and de-activate current suggestion
+  void undoActive(ParchmentDocument document) {
+    if (_activeSuggestion == null) return;
+    document.compose(_undoActiveSuggestion!, ChangeSource.local);
+    _undoActiveSuggestion = null;
+    _activeSuggestion = null;
+  }
+
+  /// Cancel active auto format
+  void cancelActive() {
+    _undoActiveSuggestion = null;
+    _activeSuggestion = null;
+  }
+}
+
+class _AutoFormatLinks extends AutoFormat {
+  static final _urlRegex =
+      RegExp(r'^(.?)((?:https?:\/\/|www\.)[^\s/$.?#].[^\s]*)');
+  const _AutoFormatLinks();
+
+  @override
+  Delta? apply(Delta document, int index, String data) {
+    // This rule applies to a space or newline inserted after a link, so we can ignore
+    // everything else.
+    if (data != ' ' && data != '\n') return null;
+
+    final iter = DeltaIterator(document);
+    final previous = iter.skip(index);
+    // No previous operation means nothing to analyze.
+    if (previous == null || previous.data is! String) return null;
+    final previousText = previous.data as String;
+
+    // Split text of previous operation in lines and words and take the last
+    // word to test.
+    final candidate = previousText.split('\n').last.split(' ').last;
+    try {
+      final match = _urlRegex.firstMatch(candidate);
+      if (match == null) return null;
+
+      final attributes = previous.attributes ?? <String, dynamic>{};
+
+      // Do nothing if already formatted as link.
+      if (attributes.containsKey(ParchmentAttribute.link.key)) return null;
+
+      String url = candidate;
+      if (!url.startsWith('http')) url = 'https://$url';
+      attributes
+          .addAll(ParchmentAttribute.link.fromString(url.toString()).toJson());
+
+      return Delta()
+        ..retain(index - candidate.length)
+        ..retain(candidate.length, attributes);
+    } on FormatException {
+      return null; // Our candidate is not a link.
+    }
+  }
+}

packages/fleather/lib/src/widgets/controller.dart

@@ -2,12 +2,15 @@ import 'dart:async';
 import 'dart:math' as math;
 
 import 'package:collection/collection.dart';
-import 'package:fleather/src/widgets/history.dart';
 import 'package:fleather/util.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:parchment/parchment.dart';
 import 'package:quill_delta/quill_delta.dart';
 
+import '../util.dart';
+import 'history.dart';
+import 'autoformats.dart';
+
 /// List of style keys which can be toggled for insertion
 List<String> _insertionToggleableStyleKeys = [
   ParchmentAttribute.bold.key,
@@ -21,6 +24,7 @@ class FleatherController extends ChangeNotifier {
   FleatherController([ParchmentDocument? document])
       : document = document ?? ParchmentDocument(),
         _history = HistoryStack.doc(document),
+        _autoFormats = AutoFormats.fallback(),
         _selection = const TextSelection.collapsed(offset: 0) {
     _throttledPush = _throttle(
       duration: throttleDuration,
@@ -37,6 +41,9 @@ class FleatherController extends ChangeNotifier {
   late final _Throttled<Delta> _throttledPush;
   Timer? _throttleTimer;
 
+  // The autoformat handler
+  final AutoFormats _autoFormats;
+
   /// Currently selected text within the [document].
   TextSelection get selection => _selection;
   TextSelection _selection;
@@ -105,7 +112,7 @@ class FleatherController extends ChangeNotifier {
   }
 
   /// Replaces [length] characters in the document starting at [index] with
-  /// provided [text].
+  /// provided [data].
   ///
   /// Resulting change is registered as produced by user action, e.g.
   /// using [ChangeSource.local].
@@ -120,6 +127,9 @@ class FleatherController extends ChangeNotifier {
     Delta? delta;
 
     final isDataNotEmpty = data is String ? data.isNotEmpty : true;
+
+    captureAutoFormatCancelationOrUndo(document, index, length, data);
+
     if (length > 0 || isDataNotEmpty) {
       delta = document.replace(index, length, data);
       if (_shouldApplyToggledStyles(delta)) {
@@ -151,11 +161,32 @@ class FleatherController extends ChangeNotifier {
         // Only update history when text is being updated
         // We do not want to update it when selection is changed
         _updateHistory();
+        _autoFormats.run(document, index, data);
       }
     }
     notifyListeners();
   }
 
+  // Capture auto format cancelation
+  // Returns `true` is auto format undo is performed
+  bool captureAutoFormatCancelationOrUndo(
+      ParchmentDocument document, int position, int length, Object data) {
+    if (!_autoFormats.hasActiveSuggestion) return false;
+
+    final isDeletionOfOneChar = data is String && data.isEmpty && length == 1;
+    if (isDeletionOfOneChar) {
+      // Undo if deleting 1 character after retain of autoformat
+      if (position == _autoFormats.activeSuggestion!.textLength) {
+        _autoFormats.undoActive(document);
+        return true;
+      }
+    }
+
+    // Cancel active nevertheless
+    _autoFormats.cancelActive();
+    return false;
+  }
+
   void formatText(int index, int length, ParchmentAttribute attribute) {
     final change = document.format(index, length, attribute);
     // _lastChangeSource = ChangeSource.local;

packages/fleather/lib/src/widgets/history.dart

@@ -1,6 +1,7 @@
 import 'package:fleather/fleather.dart';
 import 'package:flutter/widgets.dart';
 import 'package:quill_delta/quill_delta.dart';
+import '../util.dart';
 
 /// Provides undo/redo capabilities for text editing.
 ///
@@ -200,17 +201,3 @@ class _Change {
   final Delta undoDelta;
   final Delta redoDelta;
 }
-
-extension on Delta {
-  int get textLength {
-    int length = 0;
-    toList().forEach((op) {
-      if (op.isDelete) {
-        length -= op.length;
-      } else {
-        length += op.length;
-      }
-    });
-    return length;
-  }
-}

packages/parchment/lib/src/heuristics.dart

@@ -31,13 +31,10 @@ class ParchmentHeuristics {
       // Blocks
       AutoExitBlockRule(), // must go first
       PreserveBlockStyleOnInsertRule(),
-      MarkdownBlockShortcutsInsertRule(),
       // Lines
       PreserveLineStyleOnSplitRule(),
       ResetLineFormatOnNewLineRule(),
-      AutoTextDirectionRule(),
       // Inlines
-      AutoFormatLinksRule(),
       PreserveInlineStylesRule(),
       // Catch-all
       CatchAllInsertRule(),

packages/parchment/lib/src/heuristics/insert_rules.dart

@@ -277,61 +277,6 @@ class PreserveInlineStylesRule extends InsertRule {
   }
 }
 
-/// Applies link format to text segment (which looks like a link) when user
-/// inserts space character after it.
-class AutoFormatLinksRule extends InsertRule {
-  const AutoFormatLinksRule();
-
-  static Delta? formatLink(Delta document, int index, Object data) {
-    if (data is! String) return null;
-
-    // This rule applies to a space or newline inserted after a link, so we can ignore
-    // everything else.
-    if (data != ' ' && data != '\n') return null;
-
-    final iter = DeltaIterator(document);
-    final previous = iter.skip(index);
-    // No previous operation means nothing to analyze.
-    if (previous == null || previous.data is! String) return null;
-    final previousText = previous.data as String;
-
-    // Split text of previous operation in lines and words and take the last
-    // word to test.
-    final candidate = previousText.split('\n').last.split(' ').last;
-    try {
-      final link = Uri.parse(candidate);
-      if (!['https', 'http'].contains(link.scheme)) {
-        // TODO: might need a more robust way of validating links here.
-        return null;
-      }
-      final attributes = previous.attributes ?? <String, dynamic>{};
-
-      // Do nothing if already formatted as link.
-      if (attributes.containsKey(ParchmentAttribute.link.key)) return null;
-
-      attributes
-          .addAll(ParchmentAttribute.link.fromString(link.toString()).toJson());
-      return Delta()
-        ..retain(index - candidate.length)
-        ..retain(candidate.length, attributes);
-    } on FormatException {
-      return null; // Our candidate is not a link.
-    }
-  }
-
-  @override
-  Delta? apply(Delta document, int index, Object data) {
-    final delta = formatLink(document, index, data);
-    if (delta == null) {
-      return null;
-    }
-
-    final iter = DeltaIterator(document);
-    final previous = iter.skip(index);
-    return delta..insert(data, previous?.attributes);
-  }
-}
-
 /// Forces text inserted on the same line with a block embed (before or after it)
 /// to be moved to a new line adjacent to the original line.
 ///
@@ -426,9 +371,7 @@ class PreserveBlockStyleOnInsertRule extends InsertRule {
     // Go over each inserted line and ensure block style is applied.
     final lines = data.split('\n');
 
-    // Try to format link after hitting newline
-    final linkDelta = AutoFormatLinksRule.formatLink(document, index, data);
-    final result = linkDelta ?? (Delta()..retain(index));
+    final result = Delta()..retain(index);
 
     for (var i = 0; i < lines.length; i++) {
       final line = lines[i];