fix(viewport): suppress ios facebook keyboard resize

src/providers/viewport-css-vars-provider.tsx

@@ -2,6 +2,8 @@
 
 import { useEffect, type ReactNode } from "react";
 
+import { BrowserDetector, Logger, PlatformDetector } from "@/utils";
+
 const CSS_VAR_VIEWPORT_HEIGHT = "--app-viewport-height";
 const CSS_VAR_VISIBLE_HEIGHT = "--app-visible-height";
 const CSS_VAR_VISIBLE_OFFSET_TOP = "--app-visible-offset-top";
@@ -9,6 +11,9 @@ const CSS_VAR_SAFE_TOP = "--app-safe-top";
 const CSS_VAR_SAFE_RIGHT = "--app-safe-right";
 const CSS_VAR_SAFE_BOTTOM = "--app-safe-bottom";
 const CSS_VAR_SAFE_LEFT = "--app-safe-left";
+const IOS_KEYBOARD_VIEWPORT_DELTA_PX = 120;
+
+const log = new Logger("ProvidersViewportCssVarsProvider");
 
 export interface ViewportCssVarsProviderProps {
   children: ReactNode;
@@ -28,6 +33,12 @@ export function ViewportCssVarsProvider({
     if (typeof window === "undefined") return;
 
     let frameId: number | null = null;
+    let stableLayoutHeight = window.innerHeight;
+    let stableVisibleHeight = window.visualViewport?.height ?? window.innerHeight;
+    let stableVisibleOffsetTop = window.visualViewport?.offsetTop ?? 0;
+    let iosFacebookKeyboardSuppressed = false;
+    const isIOSFacebookInAppBrowser =
+      PlatformDetector.isIOS() && BrowserDetector.isFacebookInAppBrowser();
 
     const applyVars = () => {
       frameId = null;
@@ -38,12 +49,42 @@ export function ViewportCssVarsProvider({
       const visibleHeight = viewport?.height ?? layoutHeight;
       const visibleWidth = viewport?.width ?? layoutWidth;
       const visibleOffsetTop = viewport?.offsetTop ?? 0;
+      const shouldSuppressIOSFacebookKeyboardViewport =
+        isIOSFacebookInAppBrowser &&
+        isEditableElementFocused() &&
+        stableLayoutHeight - visibleHeight > IOS_KEYBOARD_VIEWPORT_DELTA_PX;
+      const nextLayoutHeight = shouldSuppressIOSFacebookKeyboardViewport
+        ? stableLayoutHeight
+        : layoutHeight;
+      const nextVisibleHeight = shouldSuppressIOSFacebookKeyboardViewport
+        ? stableVisibleHeight
+        : visibleHeight;
+      const nextVisibleOffsetTop = shouldSuppressIOSFacebookKeyboardViewport
+        ? stableVisibleOffsetTop
+        : visibleOffsetTop;
 
-      root.style.setProperty(CSS_VAR_VIEWPORT_HEIGHT, `${layoutHeight}px`);
+      if (!shouldSuppressIOSFacebookKeyboardViewport) {
-      root.style.setProperty(CSS_VAR_VISIBLE_HEIGHT, `${visibleHeight}px`);
+        stableLayoutHeight = layoutHeight;
+        stableVisibleHeight = visibleHeight;
+        stableVisibleOffsetTop = visibleOffsetTop;
+        iosFacebookKeyboardSuppressed = false;
+      } else if (!iosFacebookKeyboardSuppressed) {
+        iosFacebookKeyboardSuppressed = true;
+        log.debug("[viewport] suppress ios facebook keyboard viewport", {
+          layoutHeight: Math.round(layoutHeight),
+          visibleHeight: Math.round(visibleHeight),
+          visibleOffsetTop: Math.round(visibleOffsetTop),
+          stableLayoutHeight: Math.round(stableLayoutHeight),
+          stableVisibleHeight: Math.round(stableVisibleHeight),
+          stableVisibleOffsetTop: Math.round(stableVisibleOffsetTop),
+        });
+      }
+
+      root.style.setProperty(CSS_VAR_VIEWPORT_HEIGHT, `${nextLayoutHeight}px`);
+      root.style.setProperty(CSS_VAR_VISIBLE_HEIGHT, `${nextVisibleHeight}px`);
       root.style.setProperty(
         CSS_VAR_VISIBLE_OFFSET_TOP,
-        `${visibleOffsetTop}px`,
+        `${nextVisibleOffsetTop}px`,
       );
       root.style.setProperty(CSS_VAR_SAFE_TOP, "env(safe-area-inset-top, 0px)");
       root.style.setProperty(
@@ -59,7 +100,7 @@ export function ViewportCssVarsProvider({
         "env(safe-area-inset-left, 0px)",
       );
       root.dataset.viewportWidth = String(Math.round(visibleWidth));
-      root.dataset.viewportHeight = String(Math.round(visibleHeight));
+      root.dataset.viewportHeight = String(Math.round(nextVisibleHeight));
     };
 
     const scheduleApply = () => {
@@ -85,3 +126,15 @@ export function ViewportCssVarsProvider({
 
   return children;
 }
+
+function isEditableElementFocused(): boolean {
+  const activeElement = document.activeElement;
+  if (!(activeElement instanceof HTMLElement)) return false;
+
+  const tagName = activeElement.tagName.toLowerCase();
+  return (
+    tagName === "input" ||
+    tagName === "textarea" ||
+    activeElement.isContentEditable
+  );
+}