Refactor/header component

src/app/[lang]/Header.tsx

@@ -8,7 +8,7 @@ import Link from '@/components/Link';
 import useScroll, { ScrollHandler } from '@/hooks/useScroll';
 import useRafState from '@/hooks/useRafState';
 import cn from '@/utils/cn';
-import { clamp, pipe, toFixedNumber } from '@/utils/math';
+import { toFixedNumber } from '@/utils/math';
 
 type HeaderProps = {
   avatar: React.ReactNode;
@@ -17,91 +17,100 @@ type HeaderProps = {
 
 function Header({ avatar, children, scrollThreshold = 100 }: HeaderProps) {
   const [avatarScale, setAvatarScale] = useRafState(0);
-  const [willChange, setWillChange] = useState(true);
-  const [avatarTranslateY, setAvatarTranslateY] = useState(0);
-  const [headerTranslateY, setHeaderTranslateY] = useState(0);
   const [headerFixed, setHeaderFixed] = useState(true);
-  const headerRef = useRef<HTMLDivElement>(null);
+  const [headerTranslateY, setHeaderTranslateY] = useState(0);
+  const [willChange, setWillChange] = useState(true);
   const previousScrollY = useRef(0);
 
+  const handleScrollDown = useCallback(
+    (scrollY: number) => {
+      if (scrollY < scrollThreshold) {
+        setHeaderFixed(true);
+      } else if (headerFixed) {
+        setHeaderTranslateY(scrollY - scrollThreshold);
+        setHeaderFixed(false);
+      }
+    },
+    [scrollThreshold, headerFixed]
+  );
+
+  const handleScrollUp = useCallback(
+    (scrollY: number) => {
+      const newHeaderTranslateY = scrollY - scrollThreshold * 2;
+
+      if (newHeaderTranslateY > headerTranslateY) {
+        setHeaderTranslateY(newHeaderTranslateY);
+      } else if (scrollY - scrollThreshold < headerTranslateY) {
+        setHeaderFixed(true);
+      }
+    },
+    [scrollThreshold, headerTranslateY]
+  );
+
+  const handleAvatarScale = useCallback(
+    (scrollY: number) => {
+      setWillChange(scrollY < scrollThreshold + 100);
+      if (scrollY > scrollThreshold) {
+        setAvatarScale(1);
+      } else {
+        setAvatarScale(
+          toFixedNumber(2)(1.5 - scrollY / (scrollThreshold * 2))
+        );
+      }
+    },
+    [scrollThreshold, setAvatarScale]
+  );
+
   const scrollHandler = useCallback<ScrollHandler>(
     ({ y }) => {
       const currentScrollY = Math.floor(y);
-      const headerHeight = headerRef.current?.clientHeight || 0;
       const deltaScrollY = currentScrollY - previousScrollY.current;
       const isScrollingDown = deltaScrollY > 0;
 
       previousScrollY.current = currentScrollY;
 
       if (isScrollingDown) {
-        if (currentScrollY < scrollThreshold) {
-          setHeaderFixed(true);
-        } else if (headerFixed) {
-          setHeaderTranslateY(currentScrollY);
-          setAvatarTranslateY(currentScrollY - headerHeight);
-          setHeaderFixed(false);
-        }
+        handleScrollDown(currentScrollY);
       } else {
-        const newHeaderTranslateY = currentScrollY - headerHeight;
-
-        if (newHeaderTranslateY > headerTranslateY) {
-          setHeaderTranslateY(newHeaderTranslateY);
-          setAvatarTranslateY(newHeaderTranslateY - headerHeight);
-        } else if (currentScrollY < headerTranslateY) {
-          setHeaderFixed(true);
-        }
+        handleScrollUp(currentScrollY);
       }
 
-      setWillChange(currentScrollY < scrollThreshold + 100);
-      setAvatarScale(
-        pipe(
-          currentScrollY,
-          clamp(0, scrollThreshold),
-          (y) => y / (scrollThreshold * 2),
-          (y) => 1.5 - y,
-          toFixedNumber(2)
-        )
-      );
+      handleAvatarScale(currentScrollY);
     },
-    [scrollThreshold, headerFixed, headerTranslateY, setAvatarScale]
+    [handleScrollDown, handleScrollUp, handleAvatarScale]
   );
 
   useScroll({ handler: scrollHandler, initial: true });
 
   const headerStyles = {
+    '--scroll-threshold': `-${scrollThreshold}px`,
     '--header-translate-y': `${headerTranslateY}px`,
-  } as CSSProperties;
-
-  const avatarStyles = {
-    '--avatar-translate-y': `${avatarTranslateY}px`,
     '--avatar-scale': avatarScale,
   } as CSSProperties;
 
   return (
-    <>
-      <Container
-        as="header"
-        ref={headerRef}
-        className={cn(
-          'sticky top-0 z-10 flex items-center justify-between py-7 before:w-11 before:content-[""]',
-          !headerFixed && 'top-auto translate-y-[var(--header-translate-y)]',
-          willChange && 'will-change-[top]'
-        )}
-        style={headerStyles}
-      >
+    <Container
+      as="header"
+      className={cn(
+        'sticky top-auto z-10 translate-y-[var(--header-translate-y)]',
+        headerFixed && 'top-[var(--scroll-threshold)] translate-y-0'
+      )}
+      style={headerStyles}
+    >
+      <div className="sticky top-0 z-10 flex items-center justify-between py-7 before:w-11 before:content-['']">
         {children}
-      </Container>
-      <Container
-        className={cn(
-          'pointer-events-none sticky top-0 z-10 pt-7',
-          !headerFixed && 'top-auto translate-y-[var(--avatar-translate-y)]',
-          willChange && 'will-change-transform'
-        )}
-        style={avatarStyles}
-      >
-        {avatar}
-      </Container>
-    </>
+      </div>
+      <div className="py-7">
+        <div
+          className={cn(
+            'relative z-10 inline-block origin-bottom-left scale-[var(--avatar-scale)] rounded-full',
+            willChange && 'will-change-transform'
+          )}
+        >
+          {avatar}
+        </div>
+      </div>
+    </Container>
   );
 }
 
@@ -112,14 +121,11 @@ type AvatarProps = {
 
 export const Avatar = ({ src, alt }: AvatarProps) => {
   return (
-    <Link
-      href="/"
-      className="pointer-events-auto inline-block origin-bottom-left scale-[var(--avatar-scale)]"
-    >
+    <Link href="/" className="inline-block rounded-full">
       <Image
-        className="rounded-full shadow-black drop-shadow-xl"
-        width={42}
-        height={42}
+        className="inline-block rounded-full border-2 border-transparent"
+        width={44}
+        height={44}
         src={src}
         alt={alt}
         priority

src/app/[lang]/__tests__/header.test.tsx

@@ -16,11 +16,6 @@ describe('Header component', () => {
   });
 
   it('should hide header on scroll down and show on scroll up', async () => {
-    Object.defineProperty(HTMLElement.prototype, 'clientHeight', {
-      configurable: true,
-      value: 50,
-    });
-
     render(<Header avatar={avatar} scrollThreshold={100} />);
 
     const header = screen.getByRole('banner');
@@ -57,51 +52,40 @@ describe('Header component', () => {
     });
 
     await waitFor(() => {
-      expect(header).toHaveStyle({ '--header-translate-y': '150px' });
+      expect(header).toHaveStyle({ '--header-translate-y': '50px' });
     });
 
     act(() => {
-      window.scrollY = 251;
+      window.scrollY = 299;
       window.dispatchEvent(new Event('scroll'));
-      window.scrollY = 250;
+      window.scrollY = 300;
       window.dispatchEvent(new Event('scroll'));
     });
 
     await waitFor(() => {
-      expect(header).toHaveStyle({ '--header-translate-y': '200px' });
+      expect(header).toHaveStyle({ '--header-translate-y': '50px' });
     });
 
     act(() => {
-      window.scrollY = 1;
+      window.scrollY = 501;
       window.dispatchEvent(new Event('scroll'));
-      window.scrollY = 0;
+      window.scrollY = 500;
       window.dispatchEvent(new Event('scroll'));
     });
 
     await waitFor(() => {
-      expect(header).toHaveStyle({ '--header-translate-y': '200px' });
+      expect(header).toHaveStyle({ '--header-translate-y': '300px' });
     });
-  });
-
-  it('should calculate the correct styles even when `clientHeight` is `undefined`', async () => {
-    Object.defineProperty(HTMLElement.prototype, 'clientHeight', {
-      configurable: true,
-      value: undefined,
-    });
-
-    render(<Header avatar={avatar} scrollThreshold={100} />);
-
-    const header = screen.getByRole('banner');
-
-    expect(header.tagName).toBe('HEADER');
 
     act(() => {
-      window.scrollY = 200;
+      window.scrollY = 1;
+      window.dispatchEvent(new Event('scroll'));
+      window.scrollY = 0;
       window.dispatchEvent(new Event('scroll'));
     });
 
     await waitFor(() => {
-      expect(header).toHaveStyle({ '--header-translate-y': '200px' });
+      expect(header).toHaveStyle({ '--header-translate-y': '300px' });
     });
   });
 });

src/app/[lang]/page.tsx

@@ -24,7 +24,7 @@ async function RootPage({ params: { lang } }: RootParams) {
 
   return (
     <>
-      <Container className="py-8">
+      <Container className="pb-8">
         <H1 className="mb-4 text-3xl font-bold dark:text-white">
           {metadata.title}
         </H1>

src/app/[lang]/posts/[postId]/page.tsx

@@ -39,7 +39,7 @@ async function PostPage({ params: { postId } }: PostParams) {
 
   return (
     <>
-      <Container className="py-8">
+      <Container className="pb-8">
         <H1 className="mb-4 text-3xl font-bold dark:text-white">
           {frontmatter.title}
         </H1>

src/app/[lang]/posts/page.tsx

@@ -24,7 +24,7 @@ async function RootPage({ params: { lang } }: RootParams) {
 
   return (
     <>
-      <Container className="py-8">
+      <Container className="pb-8">
         <H1 className="mb-4 text-3xl font-bold dark:text-white">
           {metadata.title}
         </H1>

src/components/Container/Container.tsx

@@ -1,27 +1,24 @@
-import { HTMLAttributes, forwardRef } from 'react';
+import type { HTMLAttributes } from 'react';
 import cn from '@/utils/cn';
 
 type ContainerProps = {
   as?: 'main' | 'header' | 'footer' | 'div';
 } & HTMLAttributes<HTMLElement>;
 
-const Container = forwardRef<HTMLDivElement, ContainerProps>(
-  function InternalContainer({ as = 'div', className, ...props }, ref) {
-    const Component = as;
+function Container({ as = 'div', className, ...props }: ContainerProps) {
+  const Component = as;
 
-    return (
-      <Component
-        className={cn(
-          'px-7 md:mx-8 lg:mx-16 lg:px-14',
-          as === 'main' &&
-            'mt-4 rounded-lg border-2 border-zinc-500 bg-zinc-100/70 dark:bg-zinc-900/70',
-          className
-        )}
-        ref={ref}
-        {...props}
-      />
-    );
-  }
-);
+  return (
+    <Component
+      className={cn(
+        'px-7 mx-2 md:mx-8 lg:mx-16 lg:px-14',
+        as === 'main' &&
+          'rounded-lg border-2 border-zinc-500 bg-zinc-100/70 dark:bg-zinc-900/70',
+        className
+      )}
+      {...props}
+    />
+  );
+}
 
 export default Container;