From f20678cb95e9f32328380e2bc1a6ddba607279f6 Mon Sep 17 00:00:00 2001
From: Karlo Verde <42245236+mrverdant13@users.noreply.github.com>
Date: Thu, 6 Jan 2022 11:15:31 -0500
Subject: [PATCH] feat: support multiple links insertion on the go (#579)

---
 lib/src/models/rules/insert.dart | 105 +++++++++++++++++++++++++++++++
 lib/src/models/rules/rule.dart   |   1 +
 2 files changed, 106 insertions(+)

diff --git a/lib/src/models/rules/insert.dart b/lib/src/models/rules/insert.dart
index 57b7117f..ab46e031 100644
--- a/lib/src/models/rules/insert.dart
+++ b/lib/src/models/rules/insert.dart
@@ -1,5 +1,6 @@
 import 'package:tuple/tuple.dart';
 
+import '../../../models/documents/document.dart';
 import '../documents/attribute.dart';
 import '../documents/style.dart';
 import '../quill_delta.dart';
@@ -286,6 +287,110 @@ class InsertEmbedsRule extends InsertRule {
   }
 }
 
+/// Applies link format to text segments within the inserted text that matches
+/// the URL pattern.
+///
+/// The link attribute is applied as the user types.
+class AutoFormatMultipleLinksRule extends InsertRule {
+  const AutoFormatMultipleLinksRule();
+
+  /// Link pattern.
+  ///
+  /// This pattern is used to match a links within a text segment.
+  static const _linkPattern =
+      r'(https?:\/\/|www\.)[\w-\.]+\.[\w-\.]+(\/([\S]+)?)?';
+  static final _linkRegExp = RegExp(_linkPattern);
+
+  @override
+  Delta? applyRule(
+    Delta document,
+    int index, {
+    int? len,
+    Object? data,
+    Attribute? attribute,
+  }) {
+    // Only format when inserting text.
+    if (data is! String) return null;
+
+    // Get current text.
+    final entireText = Document.fromDelta(document).toPlainText();
+
+    // Get word before insertion.
+    final leftWordPart = entireText
+        // Keep all text before insertion.
+        .substring(0, index)
+        // Keep last paragraph.
+        .split('\n')
+        .last
+        // Keep last word.
+        .split(' ')
+        .last
+        .trimLeft();
+
+    // Get word after insertion.
+    final rightWordPart = entireText
+        // Keep all text after insertion.
+        .substring(index)
+        // Keep first paragraph.
+        .split('\n')
+        .first
+        // Keep first word.
+        .split(' ')
+        .first
+        .trimRight();
+
+    // Build the segment of affected words.
+    final affectedWords = '$leftWordPart$data$rightWordPart';
+
+    // Check for URL pattern.
+    final matches = _linkRegExp.allMatches(affectedWords);
+
+    // If there are no matches, do not apply any format.
+    if (matches.isEmpty) return null;
+
+    // Build base delta.
+    // The base delta is a simple insertion delta.
+    final baseDelta = Delta()
+      ..retain(index)
+      ..insert(data);
+
+    // Get unchanged text length.
+    final unmodifiedLength = index - leftWordPart.length;
+
+    // Create formatter delta.
+    // The formatter delta will only include links formatting when needed.
+    final formatterDelta = Delta()..retain(unmodifiedLength);
+
+    var previousLinkEndRelativeIndex = 0;
+    for (final match in matches) {
+      // Get the size of the leading segment of text that is not part of the
+      // link.
+      final separationLength = match.start - previousLinkEndRelativeIndex;
+
+      // Get the identified link.
+      final link = affectedWords.substring(match.start, match.end);
+
+      // Keep the leading segment of text and add link with its proper
+      // attribute.
+      formatterDelta
+        ..retain(separationLength, LinkAttribute(null).toJson())
+        ..retain(link.length, LinkAttribute(link).toJson());
+
+      // Update reference index.
+      previousLinkEndRelativeIndex = match.end;
+    }
+
+    // Get remaining text length.
+    final remainingLength = affectedWords.length - previousLinkEndRelativeIndex;
+
+    // Remove links from remaining non-link text.
+    formatterDelta.retain(remainingLength, LinkAttribute(null).toJson());
+
+    // Build and return resulting change delta.
+    return baseDelta.compose(formatterDelta);
+  }
+}
+
 /// Applies link format to text segment (which looks like a link) when user
 /// inserts space character after it.
 class AutoFormatLinksRule extends InsertRule {
diff --git a/lib/src/models/rules/rule.dart b/lib/src/models/rules/rule.dart
index f01eb438..d29bc9a1 100644
--- a/lib/src/models/rules/rule.dart
+++ b/lib/src/models/rules/rule.dart
@@ -43,6 +43,7 @@ class Rules {
     const PreserveLineStyleOnSplitRule(),
     const ResetLineFormatOnNewLineRule(),
     const AutoFormatLinksRule(),
+    const AutoFormatMultipleLinksRule(),
     const PreserveInlineStylesRule(),
     const CatchAllInsertRule(),
     const EnsureEmbedLineRule(),