From 89323ffa1fb73e00c7c2fefdbc92eab809107288 Mon Sep 17 00:00:00 2001
From: Mm2PL <miau@mail.kotmisia.pl>
Date: Mon, 31 Jul 2023 23:34:53 +0200
Subject: [PATCH] Fixed tab completion rarely completing the wrong word.
 (#4735)

* Fixed tab completion rarely completing the wrong word.

Fixes: #3101

* Use QSignalBlocker instead of janky bool, add comment about hidden logic

* copypasteo
---
 CHANGELOG.md                            |  1 +
 src/widgets/helper/ResizingTextEdit.cpp | 29 ++++++++++++++++++++++---
 src/widgets/helper/ResizingTextEdit.hpp |  2 +-
 3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 713f1f63f..0f8c817dc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,7 @@
 - Bugfix: Fixed crash that could occurr when closing the usercard too quickly after blocking or unblocking a user. (#4711)
 - Bugfix: Fixed highlights sometimes not working after changing sound device, or switching users in your operating system. (#4729)
 - Bugfix: Fixed key bindings not showing in context menus on Mac. (#4722)
+- Bugfix: Fixed tab completion rarely completing the wrong word. (#4735)
 - Dev: Added command to set Qt's logging filter/rules at runtime (`/c2-set-logging-rules`). (#4637)
 - Dev: Added the ability to see & load custom themes from the Themes directory. No stable promises are made of this feature, changes might be made that breaks custom themes without notice. (#4570)
 - Dev: Added test cases for emote and tab completion. (#4644)
diff --git a/src/widgets/helper/ResizingTextEdit.cpp b/src/widgets/helper/ResizingTextEdit.cpp
index 9494a6cf1..aa93299fb 100644
--- a/src/widgets/helper/ResizingTextEdit.cpp
+++ b/src/widgets/helper/ResizingTextEdit.cpp
@@ -2,10 +2,12 @@
 
 #include "common/Common.hpp"
 #include "common/CompletionModel.hpp"
+#include "common/QLogging.hpp"
 #include "singletons/Settings.hpp"
 
 #include <QMimeData>
 #include <QMimeDatabase>
+#include <QObject>
 
 namespace chatterino {
 
@@ -20,6 +22,19 @@ ResizingTextEdit::ResizingTextEdit()
     QObject::connect(this, &QTextEdit::textChanged, this,
                      &QWidget::updateGeometry);
 
+    QObject::connect(this, &QTextEdit::cursorPositionChanged, [this]() {
+        // If tab was pressed and we're completing/replacing the current word,
+        // this code will not even be called, see ResizingTextEdit::keyPressEvent
+
+        if (!this->completionInProgress_)
+        {
+            return;
+        }
+        qCDebug(chatterinoCommon)
+            << "Finishing completion because cursor moved";
+        this->completionInProgress_ = false;
+    });
+
     // Whenever the setting for emote completion changes, force a
     // refresh on the completion model the next time "Tab" is pressed
     getSettings()->prefixOnlyEmoteCompletion.connect([this] {
@@ -156,8 +171,12 @@ void ResizingTextEdit::keyPressEvent(QKeyEvent *event)
             completionModel->refresh(currentCompletionPrefix,
                                      this->isFirstWord());
             this->completionInProgress_ = true;
-            this->completer_->setCompletionPrefix(currentCompletionPrefix);
-            this->completer_->complete();
+            {
+                // this blocks cursor movement events from resetting tab completion
+                QSignalBlocker dontTriggerCursorMovement(this);
+                this->completer_->setCompletionPrefix(currentCompletionPrefix);
+                this->completer_->complete();
+            }
             return;
         }
 
@@ -182,7 +201,11 @@ void ResizingTextEdit::keyPressEvent(QKeyEvent *event)
             }
         }
 
-        this->completer_->complete();
+        {
+            // this blocks cursor movement events from updating tab completion
+            QSignalBlocker dontTriggerCursorMovement(this);
+            this->completer_->complete();
+        }
         return;
     }
 
diff --git a/src/widgets/helper/ResizingTextEdit.hpp b/src/widgets/helper/ResizingTextEdit.hpp
index 71d4d152b..01a174cda 100644
--- a/src/widgets/helper/ResizingTextEdit.hpp
+++ b/src/widgets/helper/ResizingTextEdit.hpp
@@ -61,7 +61,7 @@ private:
      * `Tab` pressed again:
      *   - complete ["pog"] to "PogChamp"
      *
-     * [other key] pressed - updating the input text:
+     * [other key] pressed or cursor moved - updating the input text:
      *   - set `completionInProgress_ = false`
      */
     bool completionInProgress_ = false;