From d8a258d0921546a2a8ea665b0da1912f7509c54d Mon Sep 17 00:00:00 2001
From: Alexander Zinchuk <alx.zinchuk@gmail.com>
Date: Fri, 16 Jun 2023 12:44:46 +0200
Subject: [PATCH] Teact: Properly clean up function refs

---
 src/components/test/TestUpdateRef.tsx | 34 +++++++++++++++++-------
 src/lib/teact/teact-dom.ts            | 38 +++++++++++++++------------
 2 files changed, 46 insertions(+), 26 deletions(-)

diff --git a/src/components/test/TestUpdateRef.tsx b/src/components/test/TestUpdateRef.tsx
index 727e4622c..4b5172b87 100644
--- a/src/components/test/TestUpdateRef.tsx
+++ b/src/components/test/TestUpdateRef.tsx
@@ -3,22 +3,38 @@ import React, { useEffect, useRef, useState } from '../../lib/teact/teact';
 function TestUpdateRef() {
   const [isShown, setIsShown] = useState(true);
   // eslint-disable-next-line no-null/no-null
-  const shownRef = useRef<HTMLInputElement>(null);
+  const inputRef = useRef<HTMLInputElement>(null);
+  // eslint-disable-next-line no-null/no-null
+  const headingRef = useRef<HTMLDivElement>(null);
 
   useEffect(() => {
     // Input content should preserve, but ref should clean up
     // eslint-disable-next-line no-console
-    console.log('!!!', shownRef.current);
+    console.log('!!!', inputRef.current);
+
+    // Ref should update
+    // eslint-disable-next-line no-console
+    console.log('!!!', headingRef.current);
   }, [isShown]);
 
   return (
-    <div onClick={() => setIsShown(!isShown)}>
-      {isShown ? (
-        <input ref={shownRef} />
-      ) : (
-        <input />
-      )}
-    </div>
+    <>
+      <div onClick={() => setIsShown(!isShown)}>
+        {isShown ? (
+          <input ref={inputRef} />
+        ) : (
+          <input />
+        )}
+      </div>
+
+      <div onClick={() => setIsShown(!isShown)}>
+        {isShown ? (
+          <h1 ref={headingRef}>Shown</h1>
+        ) : (
+          <h2 ref={headingRef}>Hidden</h2>
+        )}
+      </div>
+    </>
   );
 }
 
diff --git a/src/lib/teact/teact-dom.ts b/src/lib/teact/teact-dom.ts
index c90b29e4d..70594144c 100644
--- a/src/lib/teact/teact-dom.ts
+++ b/src/lib/teact/teact-dom.ts
@@ -129,6 +129,10 @@ function renderWithVirtual<T extends VirtualElement | undefined>(
       const node = createNode($newAsReal);
       $newAsReal.target = node;
       insertBefore(fragment || parentEl, node, nextSibling);
+
+      if (isTagElement($newAsReal)) {
+        setElementRef($newAsReal, node as HTMLElement);
+      }
     }
   } else if ($current && !$new) {
     remount(parentEl, $current, undefined);
@@ -149,6 +153,10 @@ function renderWithVirtual<T extends VirtualElement | undefined>(
         const node = createNode($newAsReal);
         $newAsReal.target = node;
         remount(parentEl, $current, node, nextSibling);
+
+        if (isTagElement($newAsReal)) {
+          setElementRef($newAsReal, node as HTMLElement);
+        }
       }
     } else {
       const isComponent = isCurrentComponent && isNewComponent;
@@ -173,13 +181,8 @@ function renderWithVirtual<T extends VirtualElement | undefined>(
         if (isTag) {
           const $newAsTag = $new as VirtualElementTag;
 
-          if ($current.props.ref?.current === currentTarget) {
-            $current.props.ref.current = undefined;
-          }
-
-          if ($newAsTag.props.ref) {
-            $newAsTag.props.ref.current = currentTarget;
-          }
+          setElementRef($current, undefined);
+          setElementRef($newAsTag, currentTarget as HTMLElement);
 
           if (nextSibling || options.forceMoveToEnd) {
             insertBefore(parentEl, currentTarget, nextSibling);
@@ -280,12 +283,6 @@ function createNode($element: VirtualElementReal): Node {
   const { tag, props, children = [] } = $element;
   const element = document.createElement(tag);
 
-  if (typeof props.ref === 'object') {
-    props.ref.current = element;
-  } else if (typeof props.ref === 'function') {
-    props.ref(element);
-  }
-
   processControlled(tag, props);
 
   Object.entries(props).forEach(([key, value]) => {
@@ -343,10 +340,7 @@ function unmountRealTree($element: VirtualElement) {
       if (target) {
         extraClasses.delete(target);
         removeAllDelegatedListeners(target);
-
-        if ($element.props.ref?.current === target) {
-          $element.props.ref.current = undefined;
-        }
+        setElementRef($element, undefined);
       }
     }
 
@@ -559,6 +553,16 @@ function renderFragment(
   return newChildren;
 }
 
+function setElementRef($element: VirtualElementTag, htmlElement: HTMLElement | undefined) {
+  const { ref } = $element.props;
+
+  if (typeof ref === 'object') {
+    ref.current = htmlElement;
+  } else if (typeof ref === 'function') {
+    ref(htmlElement);
+  }
+}
+
 function processControlled(tag: string, props: AnyLiteral) {
   // TODO Remove after tests
   if (!props.teactExperimentControlled) {