components/DefaultLayout.tsx

import Head from 'next/head'
import { useRouter } from 'next/router'

import { SidebarNav } from 'components/sidebar/SidebarNav'
import { Header } from 'components/page-header/Header'
import { LegalFooter } from 'components/page-footer/LegalFooter'
import { ScrollButton } from 'components/ui/ScrollButton'
import { SupportSection } from 'components/page-footer/SupportSection'
import { DeprecationBanner } from 'src/versions/components/DeprecationBanner'
import { RestBanner } from 'src/rest/components/RestBanner'
import { useMainContext } from 'components/context/MainContext'
import { useTranslation } from 'src/languages/components/useTranslation'
import { Breadcrumbs } from 'components/page-header/Breadcrumbs'
import { useLanguages } from 'src/languages/components/LanguagesContext'

const MINIMAL_RENDER = Boolean(JSON.parse(process.env.MINIMAL_RENDER || 'false'))

type Props = { children?: React.ReactNode }
export const DefaultLayout = (props: Props) => {
  const {
    page,
    error,
    isHomepageVersion,
    currentPathWithoutLanguage,
    currentVersion,
    currentProduct,
    relativePath,
    fullUrl,
    status,
  } = useMainContext()
  const { t } = useTranslation(['meta', 'scroll_button'])
  const router = useRouter()
  const metaDescription = page.introPlainText ? page.introPlainText : t('default_description')
  const { languages } = useLanguages()

  // This is only true when we do search indexing which renders every page
  // just to be able to `cheerio` load the main body (and the meta
  // keywords tag).
  if (MINIMAL_RENDER) {
    return (
      <div>
        <Head>
          <title>{page.fullTitle}</title>
        </Head>

        {/* For local site search indexing */}
        <div className="d-none d-xl-block" data-search="breadcrumbs">
          <Breadcrumbs />
        </div>

        <main id="main-content" style={{ scrollMarginTop: '5rem' }}>
          {props.children}
        </main>
      </div>
    )
  }

  return (
    <>
      <Head>
        {error === '404' ? (
          <title>{t('oops')}</title>
        ) : (!isHomepageVersion && page.fullTitle) ||
          (currentPathWithoutLanguage.includes('enterprise-server') && page.fullTitle) ? (
          <title>{page.fullTitle}</title>
        ) : null}

        {/* For Google and Bots */}
        <meta name="description" content={metaDescription} />
        {page.hidden && <meta name="robots" content="noindex" />}
        {Object.values(languages)
          .filter((lang) => lang.code !== router.locale)
          .map((variant) => {
            return (
              <link
                key={variant.code}
                rel="alternate"
                hrefLang={variant.hreflang || variant.code}
                href={`https://docs.github.com/${variant.code}${
                  router.asPath === '/' ? '' : router.asPath
                }`}
              />
            )
          })}

        {/* For local site search indexing */}
        {page.topics.length > 0 && <meta name="keywords" content={page.topics.join(',')} />}

        {/* For analytics events */}
        {router.locale && <meta name="path-language" content={router.locale} />}
        {currentVersion && <meta name="path-version" content={currentVersion} />}
        {currentProduct && <meta name="path-product" content={currentProduct.id} />}
        {relativePath && (
          <meta
            name="path-article"
            content={relativePath.replace('/index.md', '').replace('.md', '')}
          />
        )}
        {page.type && <meta name="page-type" content={page.type} />}
        {page.documentType && <meta name="page-document-type" content={page.documentType} />}
        {status && <meta name="status" content={status.toString()} />}

        {/* OpenGraph data */}
        {page.fullTitle && (
          <>
            <meta property="og:site_name" content="GitHub Docs" />
            <meta property="og:title" content={page.fullTitle} />
            <meta property="og:type" content="article" />
            <meta property="og:url" content={fullUrl} />
            <meta
              property="og:image"
              content="https://github.githubassets.com/images/modules/open_graph/github-logo.png"
            />
          </>
        )}
      </Head>
      <a
        href="#main-content"
        className="visually-hidden skip-button color-bg-accent-emphasis color-fg-on-emphasis"
      >
        Skip to main content
      </a>
      <Header />
      <div className="d-lg-flex">
        {isHomepageVersion ? null : <SidebarNav />}
        {/* Need to set an explicit height for sticky elements since we also
          set overflow to auto */}
        <div className="flex-column flex-1 min-width-0">
          <main id="main-content" style={{ scrollMarginTop: '5rem' }}>
            <DeprecationBanner />
            <RestBanner />

            {props.children}
          </main>
          <footer data-container="footer">
            <SupportSection />
            <LegalFooter />
            <ScrollButton
              className="position-fixed bottom-0 mb-4 right-0 mr-4 z-1"
              ariaLabel={t('scroll_to_top')}
            />
          </footer>
        </div>
      </div>
    </>
  )
}