From 7bb75dd25625a08654bbaf837333c003e6acb1b7 Mon Sep 17 00:00:00 2001
From: Ihor Romaniuk <ihor.romaniuk@raccoongang.com>
Date: Thu, 6 Jun 2024 14:09:09 +0200
Subject: [PATCH] fix: optimize scroll position observer after video fullscreen
 exit (#1405)

---
 .../course/sequence/Unit/hooks/useIFrameBehavior.js  | 12 ++++++------
 .../sequence/Unit/hooks/useIFrameBehavior.test.js    |  5 ++++-
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/courseware/course/sequence/Unit/hooks/useIFrameBehavior.js b/src/courseware/course/sequence/Unit/hooks/useIFrameBehavior.js
index b41cec0b5f..034978566d 100644
--- a/src/courseware/course/sequence/Unit/hooks/useIFrameBehavior.js
+++ b/src/courseware/course/sequence/Unit/hooks/useIFrameBehavior.js
@@ -50,12 +50,6 @@ const useIFrameBehavior = ({
     if (type === messageTypes.resize) {
       setIframeHeight(payload.height);
 
-      // We observe exit from the video xblock fullscreen mode
-      // and scroll to the previously saved scroll position
-      if (windowTopOffset !== null) {
-        window.scrollTo(0, Number(windowTopOffset));
-      }
-
       if (!hasLoaded && iframeHeight === 0 && payload.height > 0) {
         setHasLoaded(true);
         if (onLoaded) {
@@ -63,6 +57,12 @@ const useIFrameBehavior = ({
         }
       }
     } else if (type === messageTypes.videoFullScreen) {
+      // We observe exit from the video xblock fullscreen mode
+      // and scroll to the previously saved scroll position
+      if (!payload.open && windowTopOffset !== null) {
+        window.scrollTo(0, Number(windowTopOffset));
+      }
+
       // We listen for this message from LMS to know when we need to
       // save or reset scroll position on toggle video xblock fullscreen mode
       setWindowTopOffset(payload.open ? window.scrollY : null);
diff --git a/src/courseware/course/sequence/Unit/hooks/useIFrameBehavior.test.js b/src/courseware/course/sequence/Unit/hooks/useIFrameBehavior.test.js
index 9daec9c522..4a4142d29f 100644
--- a/src/courseware/course/sequence/Unit/hooks/useIFrameBehavior.test.js
+++ b/src/courseware/course/sequence/Unit/hooks/useIFrameBehavior.test.js
@@ -154,6 +154,9 @@ describe('useIFrameBehavior hook', () => {
         const resizeMessage = (height = 23) => ({
           data: { type: messageTypes.resize, payload: { height } },
         });
+        const videoFullScreenMessage = (open = false) => ({
+          data: { type: messageTypes.videoFullScreen, payload: { open } },
+        });
         const testSetIFrameHeight = (height = 23) => {
           const { cb } = useEventListener.mock.calls[0][1];
           cb(resizeMessage(height));
@@ -209,7 +212,7 @@ describe('useIFrameBehavior hook', () => {
           state.mockVals({ ...defaultStateVals, windowTopOffset });
           hook = useIFrameBehavior(props);
           const { cb } = useEventListener.mock.calls[0][1];
-          cb(resizeMessage());
+          cb(videoFullScreenMessage());
           expect(window.scrollTo).toHaveBeenCalledWith(0, windowTopOffset);
         });
         it('does not scroll if towverticalp offset is not set', () => {