[Beta] Anchor for individual challenges & deepdive (#5318)

* [Beta] open deepdive content once access

* [Beta] anchor individual challenges

* [Beta] fix challenges anchor scroll when multiple

* [Beta] refactor chanllenges anchor effects

Co-authored-by: Jiawei.Jing <jiawei.jing@ambergroup.co.jp>

beta/src/components/MDX/Challenges/Challenge.tsx

@@ -9,6 +9,7 @@ import {ChallengeContents} from './Challenges';
 import {IconHint} from '../../Icon/IconHint';
 import {IconSolution} from '../../Icon/IconSolution';
 import {IconArrowSmall} from '../../Icon/IconArrowSmall';
+import {H4} from '../Heading';
 
 interface ChallengeProps {
   isRecipes?: boolean;
@@ -45,14 +46,16 @@ export function Challenge({
   return (
     <div className="p-5 sm:py-8 sm:px-8">
       <div>
-        <h3 className="text-xl text-primary dark:text-primary-dark mb-2">
+        <H4
+          className="text-xl text-primary dark:text-primary-dark mb-2 mt-0 font-medium"
+          id={currentChallenge.id}>
           <div className="font-bold block md:inline">
             {isRecipes ? 'Example' : 'Challenge'} {currentChallenge.order} of{' '}
             {totalChallenges}
             <span className="text-primary dark:text-primary-dark">: </span>
           </div>
           {currentChallenge.name}
-        </h3>
+        </H4>
         {currentChallenge.content}
       </div>
       <div className="flex justify-between items-center mt-4">

beta/src/components/MDX/Challenges/Challenges.tsx

@@ -9,6 +9,7 @@ import {H2} from 'components/MDX/Heading';
 import {H4} from 'components/MDX/Heading';
 import {Challenge} from './Challenge';
 import {Navigation} from './Navigation';
+import {useRouter} from 'next/router';
 
 interface ChallengesProps {
   children: React.ReactElement[];
@@ -67,6 +68,11 @@ const parseChallengeContents = (
   return contents;
 };
 
+enum QueuedScroll {
+  INIT = 'init',
+  NEXT = 'next',
+}
+
 export function Challenges({
   children,
   isRecipes,
@@ -76,19 +82,32 @@ export function Challenges({
   const challenges = parseChallengeContents(children);
   const totalChallenges = challenges.length;
   const scrollAnchorRef = useRef<HTMLDivElement>(null);
-  const queuedScrollRef = useRef<boolean>(false);
+  const queuedScrollRef = useRef<undefined | QueuedScroll>(QueuedScroll.INIT);
   const [activeIndex, setActiveIndex] = useState(0);
   const currentChallenge = challenges[activeIndex];
+  const {asPath} = useRouter();
 
   useEffect(() => {
-    if (queuedScrollRef.current === true) {
+    if (queuedScrollRef.current === QueuedScroll.INIT) {
-      queuedScrollRef.current = false;
+      const initIndex = challenges.findIndex(
+        (challenge) => challenge.id === asPath.split('#')[1]
+      );
+      if (initIndex === -1) {
+        queuedScrollRef.current = undefined;
+      } else if (initIndex !== activeIndex) {
+        setActiveIndex(initIndex);
+      }
+    }
+    if (queuedScrollRef.current) {
       scrollAnchorRef.current!.scrollIntoView({
         block: 'start',
-        behavior: 'smooth',
+        ...(queuedScrollRef.current === QueuedScroll.NEXT && {
+          behavior: 'smooth',
+        }),
       });
+      queuedScrollRef.current = undefined;
     }
-  });
+  }, [activeIndex, asPath, challenges]);
 
   const handleChallengeChange = (index: number) => {
     setActiveIndex(index);
@@ -129,7 +148,7 @@ export function Challenges({
           hasNextChallenge={activeIndex < totalChallenges - 1}
           handleClickNextChallenge={() => {
             setActiveIndex((i) => i + 1);
-            queuedScrollRef.current = true;
+            queuedScrollRef.current = QueuedScroll.NEXT;
           }}
         />
       </div>

beta/src/components/MDX/ExpandableExample.tsx

@@ -9,6 +9,8 @@ import {IconDeepDive} from '../Icon/IconDeepDive';
 import {IconCodeBlock} from '../Icon/IconCodeBlock';
 import {Button} from '../Button';
 import {H4} from './Heading';
+import {useRouter} from 'next/router';
+import {useEffect, useRef, useState} from 'react';
 
 interface ExpandableExampleProps {
   children: React.ReactNode;
@@ -17,15 +19,29 @@ interface ExpandableExampleProps {
 }
 
 function ExpandableExample({children, excerpt, type}: ExpandableExampleProps) {
-  const [isExpanded, setIsExpanded] = React.useState(false);
-  const isDeepDive = type === 'DeepDive';
-  const isExample = type === 'Example';
-
   if (!Array.isArray(children) || children[0].type.mdxName !== 'h4') {
     throw Error(
       `Expandable content ${type} is missing a corresponding title at the beginning`
     );
   }
+  const isDeepDive = type === 'DeepDive';
+  const isExample = type === 'Example';
+  const id = children[0].props.id;
+
+  const queuedExpandRef = useRef<boolean>(true);
+  const {asPath} = useRouter();
+  // init as expanded to prevent flash
+  const [isExpanded, setIsExpanded] = useState(true);
+
+  // asPath would mismatch between server and client, reset here instead of put it into init state
+  useEffect(() => {
+    if (queuedExpandRef.current) {
+      queuedExpandRef.current = false;
+      if (id !== asPath.split('#')[1]) {
+        setIsExpanded(false);
+      }
+    }
+  }, [asPath, id]);
 
   return (
     <details
@@ -67,7 +83,7 @@ function ExpandableExample({children, excerpt, type}: ExpandableExampleProps) {
         </h5>
         <div className="mb-4">
           <H4
-            id={children[0].props.id}
+            id={id}
             className="text-xl font-bold text-primary dark:text-primary-dark">
             {children[0].props.children}
           </H4>