Fix iframe reloaded on each theme change (#3491)

* Fix iframe reloaded on each theme change

* CR

src/apps/components/AppFrame/AppFrame.tsx

@@ -1,15 +1,14 @@
 import { useAppDashboardUpdates } from "@dashboard/apps/components/AppFrame/useAppDashboardUpdates";
 import {
   AppDetailsUrlQueryParams,
-  AppUrls,
   prepareFeatureFlagsList,
 } from "@dashboard/apps/urls";
 import { useAllFlags } from "@dashboard/hooks/useFlags";
 import { CircularProgress } from "@material-ui/core";
-import { useTheme } from "@saleor/macaw-ui";
 import clsx from "clsx";
-import React from "react";
+import React, { useCallback, useMemo } from "react";
 
+import { AppIFrame } from "./AppIFrame";
 import { useStyles } from "./styles";
 import { useAppActions } from "./useAppActions";
 import useTokenRefresh from "./useTokenRefresh";
@@ -21,7 +20,6 @@ interface Props {
   className?: string;
   params?: AppDetailsUrlQueryParams;
   refetch?: () => void;
-  onLoad?(): void;
   onError?(): void;
 }
 
@@ -32,13 +30,11 @@ export const AppFrame: React.FC<Props> = ({
   appToken,
   appId,
   className,
-  params = {},
-  onLoad,
+  params,
   onError,
   refetch,
 }) => {
   const frameRef = React.useRef<HTMLIFrameElement | null>(null);
-  const { themeType } = useTheme();
   const classes = useStyles();
   const appOrigin = getOrigin(src);
   const flags = useAllFlags();
@@ -60,7 +56,7 @@ export const AppFrame: React.FC<Props> = ({
 
   useTokenRefresh(appToken, refetch);
 
-  const handleLoad = () => {
+  const handleLoad = useCallback(() => {
     /**
      * @deprecated
      *
@@ -76,11 +72,9 @@ export const AppFrame: React.FC<Props> = ({
     });
 
     setHandshakeDone(true);
+  }, [appToken, postToExtension, setHandshakeDone]);
 
-    if (onLoad) {
-      onLoad();
-    }
-  };
+  const featureFlags = useMemo(() => prepareFeatureFlagsList(flags), [flags]);
 
   return (
     <>
@@ -89,19 +83,17 @@ export const AppFrame: React.FC<Props> = ({
           <CircularProgress color="primary" />
         </div>
       )}
-      <iframe
+      <AppIFrame
         ref={frameRef}
-        src={AppUrls.resolveAppIframeUrl(appId, src, {
-          ...params,
-          featureFlags: prepareFeatureFlagsList(flags),
-          theme: themeType,
-        })}
-        onError={onError}
+        src={src}
+        appId={appId}
+        featureFlags={featureFlags}
+        params={params}
         onLoad={handleLoad}
+        onError={onError}
         className={clsx(classes.iframe, className, {
           [classes.iframeHidden]: !handshakeDone,
         })}
-        sandbox="allow-same-origin allow-forms allow-scripts"
       />
     </>
   );

src/apps/components/AppFrame/AppIFrame.tsx

@@ -0,0 +1,50 @@
+import { AppDetailsUrlQueryParams, AppUrls } from "@dashboard/apps/urls";
+import { ThemeType } from "@saleor/app-sdk/app-bridge";
+import { useTheme } from "@saleor/macaw-ui";
+import isEqualWith from "lodash/isEqualWith";
+import React, { forwardRef, memo, useEffect, useRef } from "react";
+
+interface AppIFrameProps {
+  appId: string;
+  src: string;
+  featureFlags: Record<string, string>;
+  params: AppDetailsUrlQueryParams;
+  onLoad: () => void;
+  onError: () => void;
+  className: string;
+}
+
+const _AppIFrame = forwardRef<HTMLIFrameElement, AppIFrameProps>(
+  ({ appId, src, featureFlags, params, onLoad, onError, className }, ref) => {
+    const themeRef = useRef<ThemeType>();
+    const { themeType } = useTheme();
+
+    // Ignore updates to themeType - iframe will be notified via events
+    // Otherwise this will cause reload of entire iframe
+    useEffect(() => {
+      themeRef.current = themeType;
+      // eslint-disable-next-line react-hooks/exhaustive-deps
+    }, []);
+
+    const iframeSrc = AppUrls.resolveAppIframeUrl(appId, src, {
+      ...params,
+      featureFlags,
+      theme: themeRef.current,
+    });
+
+    return (
+      <iframe
+        ref={ref}
+        src={iframeSrc}
+        onLoad={onLoad}
+        onError={onError}
+        className={className}
+        sandbox="allow-same-origin allow-forms allow-scripts"
+      />
+    );
+  },
+);
+
+export const AppIFrame = memo(_AppIFrame, (prev, next) =>
+  isEqualWith(prev, next),
+);