loader.ts

import type { LoaderOptions, MdxPath, PageOpts } from './types'

import path from 'node:path'
import grayMatter from 'gray-matter'
import slash from 'slash'
import { LoaderContext } from 'webpack'
import { findPagesDir } from 'next/dist/lib/find-pages-dir.js'

import { addPage } from './content-dump'
import { parseFileName } from './utils'
import { compileMdx } from './compile'
import { getPageMap } from './page-map'
import { collectFiles, collectMdx } from './plugin'
import {
  IS_PRODUCTION,
  DEFAULT_LOCALE,
  OFFICIAL_THEMES,
  MARKDOWN_EXTENSION_REGEX,
  CWD
} from './constants'

const PAGES_DIR = findPagesDir(CWD).pages

// TODO: create this as a webpack plugin.
const indexContentEmitted = new Set<string>()

const IS_WEB_CONTAINER = !!process.versions.webcontainer

const initGitRepo = (async () => {
  if (!IS_WEB_CONTAINER) {
    const { Repository } = await import('@napi-rs/simple-git')
    try {
      const repository = Repository.discover(CWD)
      if (repository.isShallow()) {
        if (process.env.VERCEL) {
          console.warn(
            '[nextra] The repository is shallow cloned, so the latest modified time will not be presented. Set the VERCEL_DEEP_CLONE=true environment variable to enable deep cloning.'
          )
        } else if (process.env.GITHUB_ACTION) {
          console.warn(
            '[nextra] The repository is shallow cloned, so the latest modified time will not be presented. See https://github.com/actions/checkout#fetch-all-history-for-all-tags-and-branches to fetch all the history.'
          )
        } else {
          console.warn(
            '[nextra] The repository is shallow cloned, so the latest modified time will not be presented.'
          )
        }
      }
      // repository.path() returns the `/path/to/repo/.git`, we need the parent directory of it
      const gitRoot = path.join(repository.path(), '..')
      return { repository, gitRoot }
    } catch (e) {
      console.warn('[nextra] Init git repository failed', e)
    }
  }
  return {}
})()

async function loader(
  context: LoaderContext<LoaderOptions>,
  source: string
): Promise<string> {
  const {
    pageImport,
    theme,
    themeConfig,
    defaultLocale,
    unstable_defaultShowCopyCode,
    unstable_flexsearch,
    unstable_staticImage,
    unstable_readingTime,
    mdxOptions,
    pageMapCache,
    newNextLinkBehavior,
    allowFutureImage
  } = context.getOptions()

  context.cacheable(true)

  // Check if there's a theme provided
  if (!theme) {
    throw new Error('No Nextra theme found!')
  }

  const mdxPath = context.resourcePath as MdxPath

  if (mdxPath.includes('/pages/api/')) {
    console.warn(
      `[nextra] Ignoring ${mdxPath} because it is located in the "pages/api" folder.`
    )
    return ''
  }

  const { items, fileMap } = IS_PRODUCTION
    ? pageMapCache.get()!
    : await collectFiles(PAGES_DIR)

  // mdx is imported but is outside the `pages` directory
  if (!fileMap[mdxPath]) {
    fileMap[mdxPath] = await collectMdx(mdxPath)
    context.addMissingDependency(mdxPath)
  }

  const { locale } = parseFileName(mdxPath)

  for (const [filePath, file] of Object.entries(fileMap)) {
    if (file.kind === 'Meta' && (!locale || file.locale === locale)) {
      context.addDependency(filePath)
    }
  }
  // Add the entire directory `pages` as the dependency,
  // so we can generate the correct page map.
  context.addContextDependency(PAGES_DIR)

  // Extract frontMatter information if it exists
  const { data: frontMatter, content } = grayMatter(source)

  const { result, headings, structurizedData, hasJsxInH1, readingTime } =
    await compileMdx(
      content,
      {
        mdxOptions,
        unstable_readingTime,
        unstable_defaultShowCopyCode,
        unstable_staticImage,
        unstable_flexsearch,
        allowFutureImage
      },
      mdxPath
    )
  // @ts-expect-error
  const cssImport = OFFICIAL_THEMES.includes(theme)
    ? `import '${theme}/style.css'`
    : ''

  // Imported as a normal component, no need to add the layout.
  if (!pageImport) {
    return `
${cssImport}
${result}
export default MDXContent`.trimStart()
  }

  const { route, title, pageMap } = getPageMap({
    filePath: mdxPath,
    fileMap,
    defaultLocale,
    pageMap: items
  })

  const skipFlexsearchIndexing =
    IS_PRODUCTION && indexContentEmitted.has(mdxPath)
  if (unstable_flexsearch && !skipFlexsearchIndexing) {
    if (frontMatter.searchable !== false) {
      addPage({
        locale: locale || DEFAULT_LOCALE,
        route,
        title,
        structurizedData
      })
    }
    indexContentEmitted.add(mdxPath)
  }

  let timestamp: PageOpts['timestamp']
  const { repository, gitRoot } = await initGitRepo
  if (repository && gitRoot) {
    try {
      timestamp = await repository.getFileLatestModifiedDateAsync(
        path.relative(gitRoot, mdxPath)
      )
    } catch {
      // Failed to get timestamp for this file. Silently ignore it.
    }
  }

  // Relative path instead of a package name
  const layout =
    theme.startsWith('.') || theme.startsWith('/') ? path.resolve(theme) : theme

  const themeConfigImport = themeConfig
    ? `import __nextra_themeConfig__ from '${slash(path.resolve(themeConfig))}'`
    : ''

  const pageOpts: Omit<PageOpts, 'title'> = {
    filePath: slash(path.relative(CWD, mdxPath)),
    route,
    frontMatter,
    pageMap,
    headings,
    hasJsxInH1,
    timestamp,
    unstable_flexsearch,
    newNextLinkBehavior,
    readingTime
  }

  const pageNextRoute =
    '/' +
    slash(path.relative(PAGES_DIR, mdxPath))
      // Remove the `mdx?` extension
      .replace(MARKDOWN_EXTENSION_REGEX, '')
      // Remove the `*/index` suffix
      .replace(/\/index$/, '')
      // Remove the only `index` route
      .replace(/^index$/, '')

  return `
import { SSGContext as __nextra_SSGContext__ } from 'nextra/ssg'
${themeConfigImport}
${cssImport}

const __nextra_pageOpts__ = ${JSON.stringify(pageOpts)}

globalThis.__nextra_internal__ = {
  pageMap: __nextra_pageOpts__.pageMap,
  route: __nextra_pageOpts__.route
}

${result}

__nextra_pageOpts__.title =
  ${JSON.stringify(frontMatter.title)} ||
  (typeof __nextra_title__ === 'string' && __nextra_title__) ||
  ${JSON.stringify(title /* Fallback as sidebar link name */)}

const Content = props => (
  <__nextra_SSGContext__.Provider value={props}>
    <MDXContent />
  </__nextra_SSGContext__.Provider>
)

globalThis.__nextra_pageContext__ ||= Object.create(null)

// Make sure the same component is always returned so Next.js will render the
// stable layout. We then put the actual content into a global store and use
// the route to identify it.
globalThis.__nextra_pageContext__[${JSON.stringify(pageNextRoute)}] = {
  Content,
  pageOpts: __nextra_pageOpts__,
  themeConfig: ${themeConfigImport ? '__nextra_themeConfig__' : 'null'}
}

export { default } from '${layout}'`.trimStart()
}

export default function syncLoader(
  this: LoaderContext<LoaderOptions>,
  source: string,
  callback: (err?: null | Error, content?: string | Buffer) => void
): void {
  loader(this, source)
    .then(result => callback(null, result))
    .catch(err => callback(err))
}