From 7d47f1f25930e63f593beaff9cba7d0b4de62f8f Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Fri, 13 Sep 2024 10:52:49 -0400
Subject: [PATCH] Fix detecting mentions while typing

---
 .../Sources/ComposeUI/Views/NewMainTextView.swift  | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/Packages/ComposeUI/Sources/ComposeUI/Views/NewMainTextView.swift b/Packages/ComposeUI/Sources/ComposeUI/Views/NewMainTextView.swift
index 49c998c8..d352026e 100644
--- a/Packages/ComposeUI/Sources/ComposeUI/Views/NewMainTextView.swift
+++ b/Packages/ComposeUI/Sources/ComposeUI/Views/NewMainTextView.swift
@@ -101,6 +101,9 @@ private struct NewMainTextViewRepresentable: UIViewRepresentable {
     }
 }
 
+// laxer than the CharacterCounter regex, because we want to find mentions that are being typed but aren't yet complete (e.g., "@a@b")
+private let mentionRegex = try! NSRegularExpression(pattern: "(@[a-z0-9_]+)(?:@[a-z0-9\\-\\.]+)?", options: .caseInsensitive)
+
 private final class WrappedTextViewCoordinator: NSObject {
     private static let attachment: NSTextAttachment = {
         let font = UIFont.systemFont(ofSize: 20)
@@ -149,6 +152,7 @@ private final class WrappedTextViewCoordinator: NSObject {
     private func updateAttributes(in textView: UITextView) {
         let str = NSMutableAttributedString(attributedString: textView.attributedText!)
         var changed = false
+        var cursorOffset = 0
         
         // remove existing mentions that aren't valid
         str.enumerateAttribute(.mention, in: NSRange(location: 0, length: str.length), options: .reverse) { value, range, stop in
@@ -157,18 +161,19 @@ private final class WrappedTextViewCoordinator: NSObject {
             if hasTextAttachment {
                 substr = String(substr.dropFirst())
             }
-            if CharacterCounter.mention.numberOfMatches(in: substr, range: NSRange(location: 0, length: substr.utf16.count)) == 0 {
+            if mentionRegex.numberOfMatches(in: substr, range: NSRange(location: 0, length: substr.utf16.count)) == 0 {
                 changed = true
                 str.removeAttribute(.mention, range: range)
                 str.removeAttribute(.foregroundColor, range: range)
                 if hasTextAttachment {
                     str.deleteCharacters(in: NSRange(location: range.location, length: 1))
+                    cursorOffset -= 1
                 }
             }
         }
         
         // add mentions for those missing
-        let mentionMatches = CharacterCounter.mention.matches(in: str.string, range: NSRange(location: 0, length: str.length))
+        let mentionMatches = mentionRegex.matches(in: str.string, range: NSRange(location: 0, length: str.length))
         for match in mentionMatches.reversed() {
             var attributeRange = NSRange()
             let attribute = str.attribute(.mention, at: match.range.location, effectiveRange: &attributeRange)
@@ -179,6 +184,7 @@ private final class WrappedTextViewCoordinator: NSObject {
                 if attribute == nil {
                     str.insert(NSAttributedString(attachment: Self.attachment), at: match.range.location)
                     newAttributeRange = NSRange(location: match.range.location, length: match.range.length + 1)
+                    cursorOffset += 1
                 } else {
                     newAttributeRange = match.range
                 }
@@ -190,7 +196,11 @@ private final class WrappedTextViewCoordinator: NSObject {
         }
         
         if changed {
+            let selection = textView.selectedRange
+            
             textView.attributedText = str
+            
+            textView.selectedRange = NSRange(location: selection.location + cursorOffset, length: selection.length)
         }
     }
 }