datahub/site/components/Layout.tsx

import { siteConfig } from '@/config/siteConfig';
import { NextSeo } from 'next-seo';
import { useTheme } from 'next-themes';
import Link from 'next/link';
import { useCallback, useEffect, useState } from 'react';

import Nav from './Nav';
import { Hero } from './Hero';
import { Navigation } from './Navigation';

function useTableOfContents(tableOfContents) {
  const [currentSection, setCurrentSection] = useState(tableOfContents[0]?.id);

  const getHeadings = useCallback((toc) => {
    return toc
      .flatMap((node) => [node.id, ...node.children.map((child) => child.id)])
      .map((id) => {
        const el = document.getElementById(id);
        if (!el) return null;

        const style = window.getComputedStyle(el);
        const scrollMt = parseFloat(style.scrollMarginTop);

        const top = window.scrollY + el.getBoundingClientRect().top - scrollMt;
        return { id, top };
      })
      .filter((el) => !!el);
  }, []);

  useEffect(() => {
    if (tableOfContents.length === 0) return;
    const headings = getHeadings(tableOfContents);
    function onScroll() {
      const top = window.scrollY + 4.5;
      let current = headings[0].id;
      headings.forEach((heading) => {
        if (top >= heading.top) {
          current = heading.id;
        }
        return current;
      });
      setCurrentSection(current);
    }
    window.addEventListener('scroll', onScroll, { passive: true });
    onScroll();
    return () => {
      window.removeEventListener('scroll', onScroll);
    };
  }, [getHeadings, tableOfContents]);

  return currentSection;
}

export default function Layout({
  children,
  title,
  tableOfContents = [],
  isHomePage = false,
  sidebarTree = [],
}: {
  children;
  title?: string;
  tableOfContents?;
  urlPath?: string;
  sidebarTree?: [];
  isHomePage?: boolean;
}) {
  // const { toc } = children.props;
  const { theme, setTheme } = useTheme();

  const currentSection = useTableOfContents(tableOfContents);

  function isActive(section) {
    if (section.id === currentSection) {
      return true;
    }
    if (!section.children) {
      return false;
    }
    return section.children.findIndex(isActive) > -1;
  }

  return (
    <>
      {title && <NextSeo title={title} />}
      <Nav />
      <div className="mx-auto p-6 bg-background dark:bg-background-dark">
        {isHomePage && <Hero />}

        <div className="relative mx-auto flex max-w-8xl justify-center sm:px-2 lg:px-8 xl:px-12">
          {!!sidebarTree.length && (
            <div className="hidden lg:relative lg:block lg:flex-none">
              <div className="absolute inset-y-0 right-0 w-[50vw] bg-slate-50 dark:hidden" />
              <div className="absolute bottom-0 right-0 top-16 hidden h-12 w-px bg-gradient-to-t from-slate-800 dark:block" />
              <div className="absolute bottom-0 right-0 top-28 hidden w-px bg-slate-800 dark:block" />
              <div className="sticky top-[4.5rem] -ml-0.5 h-[calc(100vh-4.5rem)] overflow-y-auto overflow-x-hidden py-16 pl-0.5">
                <Navigation
                  navigation={sidebarTree}
                  className="w-64 pr-8 xl:w-72 xl:pr-16"
                />
              </div>
            </div>
          )}
          <div className="min-w-0 max-w-2xl flex-auto px-4 py-16 lg:max-w-none lg:pl-8 lg:pr-0 ">
            {children}
          </div>
          {/** TABLE OF CONTENTS */}
          <div className="hidden xl:sticky xl:right-0 xl:top-[4.5rem] xl:block xl:h-[calc(100vh-4.5rem)] xl:flex-none xl:overflow-y-auto xl:py-16 xl:mb-16">
            {tableOfContents.length > 0 && siteConfig.tableOfContents && (
              <nav aria-labelledby="on-this-page-title" className="w-56">
                <h2 className="font-display text-sm font-medium text-primary dark:text-primary-dark">
                  On this page
                </h2>
                <ol className="mt-4 space-y-4 text-sm">
                  {tableOfContents.map((section) => (
                    <li key={section.id}>
                      <h3>
                        <Link
                          href={`#${section.id}`}
                          className={
                            isActive(section)
                              ? 'text-secondary font-semibold'
                              : 'font-normal text-slate-500 hover:text-slate-700 dark:text-slate-400 dark:hover:text-slate-300'
                          }
                        >
                          {section.title}
                        </Link>
                      </h3>
                      {section.children && section.children.length > 0 && (
                        <ol className="mt-4 space-y-4 pl-5 text-slate-500 dark:text-slate-400">
                          {section.children.map((subSection) => (
                            <li key={subSection.id}>
                              <Link
                                href={`#${subSection.id}`}
                                className={
                                  isActive(subSection)
                                    ? 'text-secondary font-semibold'
                                    : 'hover:text-slate-600 dark:hover:text-slate-300'
                                }
                              >
                                {subSection.title}
                              </Link>
                            </li>
                          ))}
                        </ol>
                      )}
                    </li>
                  ))}
                </ol>
              </nav>
            )}
          </div>
        </div>
      </div>
      <footer className="flex items-center justify-center w-full h-24 border-t dark:border-slate-900 bg-background dark:bg-background-dark">
        <a
          className="flex items-center justify-center"
          href="https://datopian.com/"
          target="_blank"
          rel="noopener noreferrer"
        >
          Built by{' '}
          <img
            src={
              theme === 'dark'
                ? '/images/datopian-light-logotype.svg'
                : '/images/datopian-dark-logotype.svg'
            }
            alt="Datopian Logo"
            className="h-6 ml-2"
          />
        </a>
      </footer>
    </>
  );
}