utils.ts

import type { NextConfigComplete, ServerRuntime } from '../server/config-shared'

import '../server/node-polyfill-fetch'
import chalk from 'next/dist/compiled/chalk'
import getGzipSize from 'next/dist/compiled/gzip-size'
import textTable from 'next/dist/compiled/text-table'
import path from 'path'
import { promises as fs } from 'fs'
import { isValidElementType } from 'next/dist/compiled/react-is'
import stripAnsi from 'next/dist/compiled/strip-ansi'
import {
  Redirect,
  Rewrite,
  Header,
  CustomRoutes,
} from '../lib/load-custom-routes'
import {
  SSG_GET_INITIAL_PROPS_CONFLICT,
  SERVER_PROPS_GET_INIT_PROPS_CONFLICT,
  SERVER_PROPS_SSG_CONFLICT,
  MIDDLEWARE_FILENAME,
  SERVER_RUNTIME,
} from '../lib/constants'
import prettyBytes from '../lib/pretty-bytes'
import { getRouteRegex } from '../shared/lib/router/utils/route-regex'
import { getRouteMatcher } from '../shared/lib/router/utils/route-matcher'
import { isDynamicRoute } from '../shared/lib/router/utils/is-dynamic'
import escapePathDelimiters from '../shared/lib/router/utils/escape-path-delimiters'
import { findPageFile } from '../server/lib/find-page-file'
import { GetStaticPaths, PageConfig } from 'next/types'
import { BuildManifest } from '../server/get-page-files'
import { removeTrailingSlash } from '../shared/lib/router/utils/remove-trailing-slash'
import { UnwrapPromise } from '../lib/coalesced-function'
import { normalizeLocalePath } from '../shared/lib/i18n/normalize-locale-path'
import * as Log from './output/log'
import { loadComponents } from '../server/load-components'
import { trace } from '../trace'
import { setHttpAgentOptions } from '../server/config'
import { recursiveDelete } from '../lib/recursive-delete'
import { Sema } from 'next/dist/compiled/async-sema'
import { MiddlewareManifest } from './webpack/plugins/middleware-plugin'
import { denormalizePagePath } from '../shared/lib/page-path/denormalize-page-path'
import { normalizePagePath } from '../shared/lib/page-path/normalize-page-path'
import { AppBuildManifest } from './webpack/plugins/app-build-manifest-plugin'

export type ROUTER_TYPE = 'pages' | 'app'

const RESERVED_PAGE = /^\/(_app|_error|_document|api(\/|$))/
const fileGzipStats: { [k: string]: Promise<number> | undefined } = {}
const fsStatGzip = (file: string) => {
  const cached = fileGzipStats[file]
  if (cached) return cached
  return (fileGzipStats[file] = getGzipSize.file(file))
}

const fileSize = async (file: string) => (await fs.stat(file)).size

const fileStats: { [k: string]: Promise<number> | undefined } = {}
const fsStat = (file: string) => {
  const cached = fileStats[file]
  if (cached) return cached
  return (fileStats[file] = fileSize(file))
}

export interface PageInfo {
  isHybridAmp?: boolean
  size: number
  totalSize: number
  static: boolean
  isSsg: boolean
  ssgPageRoutes: string[] | null
  initialRevalidateSeconds: number | false
  pageDuration: number | undefined
  ssgPageDurations: number[] | undefined
  runtime: ServerRuntime
}

export async function printTreeView(
  lists: {
    pages: ReadonlyArray<string>
    app?: ReadonlyArray<string>
  },
  pageInfos: Map<string, PageInfo>,
  serverless: boolean,
  {
    distPath,
    buildId,
    pagesDir,
    pageExtensions,
    buildManifest,
    appBuildManifest,
    middlewareManifest,
    useStatic404,
    gzipSize = true,
  }: {
    distPath: string
    buildId: string
    pagesDir: string
    pageExtensions: string[]
    buildManifest: BuildManifest
    appBuildManifest?: AppBuildManifest
    middlewareManifest: MiddlewareManifest
    useStatic404: boolean
    gzipSize?: boolean
  }
) {
  const getPrettySize = (_size: number): string => {
    const size = prettyBytes(_size)
    // green for 0-130kb
    if (_size < 130 * 1000) return chalk.green(size)
    // yellow for 130-170kb
    if (_size < 170 * 1000) return chalk.yellow(size)
    // red for >= 170kb
    return chalk.red.bold(size)
  }

  const MIN_DURATION = 300
  const getPrettyDuration = (_duration: number): string => {
    const duration = `${_duration} ms`
    // green for 300-1000ms
    if (_duration < 1000) return chalk.green(duration)
    // yellow for 1000-2000ms
    if (_duration < 2000) return chalk.yellow(duration)
    // red for >= 2000ms
    return chalk.red.bold(duration)
  }

  const getCleanName = (fileName: string) =>
    fileName
      // Trim off `static/`
      .replace(/^static\//, '')
      // Re-add `static/` for root files
      .replace(/^<buildId>/, 'static')
      // Remove file hash
      .replace(/(?:^|[.-])([0-9a-z]{6})[0-9a-z]{14}(?=\.)/, '.$1')

  // Check if we have a custom app.
  const hasCustomApp = await findPageFile(pagesDir, '/_app', pageExtensions)

  const filterAndSortList = (list: ReadonlyArray<string>) =>
    list
      .slice()
      .filter(
        (e) =>
          !(
            e === '/_document' ||
            e === '/_error' ||
            (!hasCustomApp && e === '/_app')
          )
      )
      .sort((a, b) => a.localeCompare(b))

  // Collect all the symbols we use so we can print the icons out.
  const usedSymbols = new Set()

  const messages: [string, string, string][] = []

  const stats = await computeFromManifest(
    { build: buildManifest, app: appBuildManifest },
    distPath,
    gzipSize,
    pageInfos
  )

  const printFileTree = async ({
    list,
    routerType,
  }: {
    list: ReadonlyArray<string>
    routerType: ROUTER_TYPE
  }) => {
    messages.push(
      [routerType === 'app' ? 'Route' : 'Page', 'Size', 'First Load JS'].map(
        (entry) => chalk.underline(entry)
      ) as [string, string, string]
    )

    filterAndSortList(list).forEach((item, i, arr) => {
      const border =
        i === 0
          ? arr.length === 1
            ? '─'
            : '┌'
          : i === arr.length - 1
          ? '└'
          : '├'

      const pageInfo = pageInfos.get(item)
      const ampFirst = buildManifest.ampFirstPages.includes(item)
      const totalDuration =
        (pageInfo?.pageDuration || 0) +
        (pageInfo?.ssgPageDurations?.reduce((a, b) => a + (b || 0), 0) || 0)

      const symbol =
        routerType === 'app' || item === '/_app' || item === '/_app.server'
          ? ' '
          : pageInfo?.static
          ? '○'
          : pageInfo?.isSsg
          ? '●'
          : pageInfo?.runtime === SERVER_RUNTIME.edge
          ? 'ℇ'
          : 'λ'

      usedSymbols.add(symbol)

      if (pageInfo?.initialRevalidateSeconds) usedSymbols.add('ISR')

      messages.push([
        `${border} ${routerType === 'pages' ? `${symbol} ` : ''}${
          pageInfo?.initialRevalidateSeconds
            ? `${item} (ISR: ${pageInfo?.initialRevalidateSeconds} Seconds)`
            : item
        }${
          totalDuration > MIN_DURATION
            ? ` (${getPrettyDuration(totalDuration)})`
            : ''
        }`,
        pageInfo
          ? ampFirst
            ? chalk.cyan('AMP')
            : pageInfo.size >= 0
            ? prettyBytes(pageInfo.size)
            : ''
          : '',
        pageInfo
          ? ampFirst
            ? chalk.cyan('AMP')
            : pageInfo.size >= 0
            ? getPrettySize(pageInfo.totalSize)
            : ''
          : '',
      ])

      const uniqueCssFiles =
        buildManifest.pages[item]?.filter(
          (file) =>
            file.endsWith('.css') &&
            stats.router[routerType]?.unique.files.includes(file)
        ) || []

      if (uniqueCssFiles.length > 0) {
        const contSymbol = i === arr.length - 1 ? ' ' : '├'

        uniqueCssFiles.forEach((file, index, { length }) => {
          const innerSymbol = index === length - 1 ? '└' : '├'
          const size = stats.sizes.get(file)
          messages.push([
            `${contSymbol}   ${innerSymbol} ${getCleanName(file)}`,
            typeof size === 'number' ? prettyBytes(size) : '',
            '',
          ])
        })
      }

      if (pageInfo?.ssgPageRoutes?.length) {
        const totalRoutes = pageInfo.ssgPageRoutes.length
        const contSymbol = i === arr.length - 1 ? ' ' : '├'

        let routes: { route: string; duration: number; avgDuration?: number }[]
        if (
          pageInfo.ssgPageDurations &&
          pageInfo.ssgPageDurations.some((d) => d > MIN_DURATION)
        ) {
          const previewPages = totalRoutes === 8 ? 8 : Math.min(totalRoutes, 7)
          const routesWithDuration = pageInfo.ssgPageRoutes
            .map((route, idx) => ({
              route,
              duration: pageInfo.ssgPageDurations![idx] || 0,
            }))
            .sort(({ duration: a }, { duration: b }) =>
              // Sort by duration
              // keep too small durations in original order at the end
              a <= MIN_DURATION && b <= MIN_DURATION ? 0 : b - a
            )
          routes = routesWithDuration.slice(0, previewPages)
          const remainingRoutes = routesWithDuration.slice(previewPages)
          if (remainingRoutes.length) {
            const remaining = remainingRoutes.length
            const avgDuration = Math.round(
              remainingRoutes.reduce(
                (total, { duration }) => total + duration,
                0
              ) / remainingRoutes.length
            )
            routes.push({
              route: `[+${remaining} more paths]`,
              duration: 0,
              avgDuration,
            })
          }
        } else {
          const previewPages = totalRoutes === 4 ? 4 : Math.min(totalRoutes, 3)
          routes = pageInfo.ssgPageRoutes
            .slice(0, previewPages)
            .map((route) => ({ route, duration: 0 }))
          if (totalRoutes > previewPages) {
            const remaining = totalRoutes - previewPages
            routes.push({ route: `[+${remaining} more paths]`, duration: 0 })
          }
        }

        routes.forEach(
          ({ route, duration, avgDuration }, index, { length }) => {
            const innerSymbol = index === length - 1 ? '└' : '├'
            messages.push([
              `${contSymbol}   ${innerSymbol} ${route}${
                duration > MIN_DURATION
                  ? ` (${getPrettyDuration(duration)})`
                  : ''
              }${
                avgDuration && avgDuration > MIN_DURATION
                  ? ` (avg ${getPrettyDuration(avgDuration)})`
                  : ''
              }`,
              '',
              '',
            ])
          }
        )
      }
    })

    const sharedFilesSize = stats.router[routerType]?.common.size.total
    const sharedFiles = stats.router[routerType]?.common.files ?? []

    messages.push([
      '+ First Load JS',
      typeof sharedFilesSize === 'number' ? getPrettySize(sharedFilesSize) : '',
      '',
    ])
    const sharedCssFiles: string[] = []
    ;[
      ...sharedFiles
        .filter((file) => {
          if (file.endsWith('.css')) {
            sharedCssFiles.push(file)
            return false
          }
          return true
        })
        .map((e) => e.replace(buildId, '<buildId>'))
        .sort(),
      ...sharedCssFiles.map((e) => e.replace(buildId, '<buildId>')).sort(),
    ].forEach((fileName, index, { length }) => {
      const innerSymbol = index === length - 1 ? '└' : '├'

      const originalName = fileName.replace('<buildId>', buildId)
      const cleanName = getCleanName(fileName)
      const size = stats.sizes.get(originalName)

      messages.push([
        `  ${innerSymbol} ${cleanName}`,
        typeof size === 'number' ? prettyBytes(size) : '',
        '',
      ])
    })
  }

  // If enabled, then print the tree for the app directory.
  if (lists.app && stats.router.app) {
    messages.push(['App', '', ''])
    await printFileTree({
      routerType: 'app',
      list: lists.app,
    })

    messages.push(['', '', ''])
  }

  pageInfos.set('/404', {
    ...(pageInfos.get('/404') || pageInfos.get('/_error')),
    static: useStatic404,
  } as any)

  if (!lists.pages.includes('/404')) {
    if (lists.app && stats.router.app) {
      messages.push(['Pages', '', ''])
    }

    lists.pages = [...lists.pages, '/404']
  }

  // Print the tree view for the pages directory.
  await printFileTree({
    routerType: 'pages',
    list: lists.pages,
  })

  const middlewareInfo = middlewareManifest.middleware?.['/']
  if (middlewareInfo?.files.length > 0) {
    const middlewareSizes = await Promise.all(
      middlewareInfo.files
        .map((dep) => `${distPath}/${dep}`)
        .map(gzipSize ? fsStatGzip : fsStat)
    )

    messages.push(['', '', ''])
    messages.push(['ƒ Middleware', getPrettySize(sum(middlewareSizes)), ''])
  }

  console.log(
    textTable(messages, {
      align: ['l', 'l', 'r'],
      stringLength: (str) => stripAnsi(str).length,
    })
  )

  console.log()
  console.log(
    textTable(
      [
        usedSymbols.has('ℇ') && [
          'ℇ',
          '(Streaming)',
          `server-side renders with streaming (uses React 18 SSR streaming or Server Components)`,
        ],
        usedSymbols.has('λ') && [
          'λ',
          serverless ? '(Lambda)' : '(Server)',
          `server-side renders at runtime (uses ${chalk.cyan(
            'getInitialProps'
          )} or ${chalk.cyan('getServerSideProps')})`,
        ],
        usedSymbols.has('○') && [
          '○',
          '(Static)',
          'automatically rendered as static HTML (uses no initial props)',
        ],
        usedSymbols.has('●') && [
          '●',
          '(SSG)',
          `automatically generated as static HTML + JSON (uses ${chalk.cyan(
            'getStaticProps'
          )})`,
        ],
        usedSymbols.has('ISR') && [
          '',
          '(ISR)',
          `incremental static regeneration (uses revalidate in ${chalk.cyan(
            'getStaticProps'
          )})`,
        ],
      ].filter((x) => x) as [string, string, string][],
      {
        align: ['l', 'l', 'l'],
        stringLength: (str) => stripAnsi(str).length,
      }
    )
  )

  console.log()
}

export function printCustomRoutes({
  redirects,
  rewrites,
  headers,
}: CustomRoutes) {
  const printRoutes = (
    routes: Redirect[] | Rewrite[] | Header[],
    type: 'Redirects' | 'Rewrites' | 'Headers'
  ) => {
    const isRedirects = type === 'Redirects'
    const isHeaders = type === 'Headers'
    console.log(chalk.underline(type))
    console.log()

    /*
        ┌ source
        ├ permanent/statusCode
        └ destination
     */
    const routesStr = (routes as any[])
      .map((route: { source: string }) => {
        let routeStr = `┌ source: ${route.source}\n`

        if (!isHeaders) {
          const r = route as Rewrite
          routeStr += `${isRedirects ? '├' : '└'} destination: ${
            r.destination
          }\n`
        }
        if (isRedirects) {
          const r = route as Redirect
          routeStr += `└ ${
            r.statusCode
              ? `status: ${r.statusCode}`
              : `permanent: ${r.permanent}`
          }\n`
        }

        if (isHeaders) {
          const r = route as Header
          routeStr += `└ headers:\n`

          for (let i = 0; i < r.headers.length; i++) {
            const header = r.headers[i]
            const last = i === headers.length - 1

            routeStr += `  ${last ? '└' : '├'} ${header.key}: ${header.value}\n`
          }
        }

        return routeStr
      })
      .join('\n')

    console.log(routesStr, '\n')
  }

  if (redirects.length) {
    printRoutes(redirects, 'Redirects')
  }
  if (headers.length) {
    printRoutes(headers, 'Headers')
  }

  const combinedRewrites = [
    ...rewrites.beforeFiles,
    ...rewrites.afterFiles,
    ...rewrites.fallback,
  ]
  if (combinedRewrites.length) {
    printRoutes(combinedRewrites, 'Rewrites')
  }
}

type ComputeFilesGroup = {
  files: ReadonlyArray<string>
  size: {
    total: number
  }
}

type ComputeFilesManifest = {
  unique: ComputeFilesGroup
  common: ComputeFilesGroup
}

type ComputeFilesManifestResult = {
  router: {
    pages: ComputeFilesManifest
    app?: ComputeFilesManifest
  }
  sizes: Map<string, number>
}

let cachedBuildManifest: BuildManifest | undefined
let cachedAppBuildManifest: AppBuildManifest | undefined

let lastCompute: ComputeFilesManifestResult | undefined
let lastComputePageInfo: boolean | undefined

export async function computeFromManifest(
  manifests: {
    build: BuildManifest
    app?: AppBuildManifest
  },
  distPath: string,
  gzipSize: boolean = true,
  pageInfos?: Map<string, PageInfo>
): Promise<ComputeFilesManifestResult> {
  if (
    Object.is(cachedBuildManifest, manifests.build) &&
    lastComputePageInfo === !!pageInfos &&
    Object.is(cachedAppBuildManifest, manifests.app)
  ) {
    return lastCompute!
  }

  // Determine the files that are in pages and app and count them, this will
  // tell us if they are unique or common.

  const countBuildFiles = (
    map: Map<string, number>,
    key: string,
    manifest: Record<string, ReadonlyArray<string>>
  ) => {
    for (const file of manifest[key]) {
      if (key === '/_app') {
        map.set(file, Infinity)
      } else if (map.has(file)) {
        map.set(file, map.get(file)! + 1)
      } else {
        map.set(file, 1)
      }
    }
  }

  const files: {
    pages: {
      each: Map<string, number>
      expected: number
    }
    app?: {
      each: Map<string, number>
      expected: number
    }
  } = {
    pages: { each: new Map(), expected: 0 },
  }

  for (const key in manifests.build.pages) {
    if (pageInfos) {
      const pageInfo = pageInfos.get(key)
      // don't include AMP pages since they don't rely on shared bundles
      // AMP First pages are not under the pageInfos key
      if (pageInfo?.isHybridAmp) {
        continue
      }
    }

    files.pages.expected++
    countBuildFiles(files.pages.each, key, manifests.build.pages)
  }

  // Collect the build files form the app manifest.
  if (manifests.app?.pages) {
    files.app = { each: new Map<string, number>(), expected: 0 }

    for (const key in manifests.app.pages) {
      files.app.expected++
      countBuildFiles(files.app.each, key, manifests.app.pages)
    }
  }

  const getSize = gzipSize ? fsStatGzip : fsStat
  const stats = new Map<string, number>()

  // For all of the files in the pages and app manifests, compute the file size
  // at once.

  await Promise.all(
    [
      ...new Set<string>([
        ...files.pages.each.keys(),
        ...(files.app?.each.keys() ?? []),
      ]),
    ].map(async (f) => {
      try {
        // Add the file size to the stats.
        stats.set(f, await getSize(path.join(distPath, f)))
      } catch {}
    })
  )

  const groupFiles = async (listing: {
    each: Map<string, number>
    expected: number
  }): Promise<ComputeFilesManifest> => {
    const entries = [...listing.each.entries()]

    const shapeGroup = (group: [string, number][]): ComputeFilesGroup =>
      group.reduce(
        (acc, [f]) => {
          acc.files.push(f)

          const size = stats.get(f)
          if (typeof size === 'number') {
            acc.size.total += size
          }

          return acc
        },
        {
          files: [] as string[],
          size: {
            total: 0,
          },
        }
      )

    return {
      unique: shapeGroup(entries.filter(([, len]) => len === 1)),
      common: shapeGroup(
        entries.filter(
          ([, len]) => len === listing.expected || len === Infinity
        )
      ),
    }
  }

  lastCompute = {
    router: {
      pages: await groupFiles(files.pages),
      app: files.app ? await groupFiles(files.app) : undefined,
    },
    sizes: stats,
  }

  cachedBuildManifest = manifests.build
  cachedAppBuildManifest = manifests.app
  lastComputePageInfo = !!pageInfos
  return lastCompute!
}

export function unique<T>(main: ReadonlyArray<T>, sub: ReadonlyArray<T>): T[] {
  return [...new Set([...main, ...sub])]
}

export function difference<T>(
  main: ReadonlyArray<T> | ReadonlySet<T>,
  sub: ReadonlyArray<T> | ReadonlySet<T>
): T[] {
  const a = new Set(main)
  const b = new Set(sub)
  return [...a].filter((x) => !b.has(x))
}

/**
 * Return an array of the items shared by both arrays.
 */
function intersect<T>(main: ReadonlyArray<T>, sub: ReadonlyArray<T>): T[] {
  const a = new Set(main)
  const b = new Set(sub)
  return [...new Set([...a].filter((x) => b.has(x)))]
}

function sum(a: ReadonlyArray<number>): number {
  return a.reduce((size, stat) => size + stat, 0)
}

function denormalizeAppPagePath(page: string): string {
  return page + '/page'
}

export async function getJsPageSizeInKb(
  routerType: ROUTER_TYPE,
  page: string,
  distPath: string,
  buildManifest: BuildManifest,
  appBuildManifest?: AppBuildManifest,
  gzipSize: boolean = true,
  cachedStats?: ComputeFilesManifestResult
): Promise<[number, number]> {
  const pageManifest = routerType === 'pages' ? buildManifest : appBuildManifest
  if (!pageManifest) {
    throw new Error('expected appBuildManifest with an "app" pageType')
  }

  // If stats was not provided, then compute it again.
  const stats =
    cachedStats ??
    (await computeFromManifest(
      { build: buildManifest, app: appBuildManifest },
      distPath,
      gzipSize
    ))

  const pageData = stats.router[routerType]
  if (!pageData) {
    // This error shouldn't happen and represents an error in Next.js.
    throw new Error('expected "app" manifest data with an "app" pageType')
  }

  const pagePath =
    routerType === 'pages'
      ? denormalizePagePath(page)
      : denormalizeAppPagePath(page)

  const fnFilterJs = (entry: string) => entry.endsWith('.js')

  const pageFiles = (pageManifest.pages[pagePath] ?? []).filter(fnFilterJs)
  const appFiles = (pageManifest.pages['/_app'] ?? []).filter(fnFilterJs)

  const fnMapRealPath = (dep: string) => `${distPath}/${dep}`

  const allFilesReal = unique(pageFiles, appFiles).map(fnMapRealPath)
  const selfFilesReal = difference(
    // Find the files shared by the pages files and the unique files...
    intersect(pageFiles, pageData.unique.files),
    // but without the common files.
    pageData.common.files
  ).map(fnMapRealPath)

  const getSize = gzipSize ? fsStatGzip : fsStat

  // Try to get the file size from the page data if available, otherwise do a
  // raw compute.
  const getCachedSize = async (file: string) => {
    const key = file.slice(distPath.length + 1)
    const size: number | undefined = stats.sizes.get(key)

    // If the size wasn't in the stats bundle, then get it from the file
    // directly.
    if (typeof size !== 'number') {
      return getSize(file)
    }

    return size
  }

  try {
    // Doesn't use `Promise.all`, as we'd double compute duplicate files. This
    // function is memoized, so the second one will instantly resolve.
    const allFilesSize = sum(await Promise.all(allFilesReal.map(getCachedSize)))
    const selfFilesSize = sum(
      await Promise.all(selfFilesReal.map(getCachedSize))
    )

    return [selfFilesSize, allFilesSize]
  } catch {}
  return [-1, -1]
}

export async function buildStaticPaths(
  page: string,
  getStaticPaths: GetStaticPaths,
  configFileName: string,
  locales?: string[],
  defaultLocale?: string
): Promise<
  Omit<UnwrapPromise<ReturnType<GetStaticPaths>>, 'paths'> & {
    paths: string[]
    encodedPaths: string[]
  }
> {
  const prerenderPaths = new Set<string>()
  const encodedPrerenderPaths = new Set<string>()
  const _routeRegex = getRouteRegex(page)
  const _routeMatcher = getRouteMatcher(_routeRegex)

  // Get the default list of allowed params.
  const _validParamKeys = Object.keys(_routeMatcher(page))

  const staticPathsResult = await getStaticPaths({ locales, defaultLocale })

  const expectedReturnVal =
    `Expected: { paths: [], fallback: boolean }\n` +
    `See here for more info: https://nextjs.org/docs/messages/invalid-getstaticpaths-value`

  if (
    !staticPathsResult ||
    typeof staticPathsResult !== 'object' ||
    Array.isArray(staticPathsResult)
  ) {
    throw new Error(
      `Invalid value returned from getStaticPaths in ${page}. Received ${typeof staticPathsResult} ${expectedReturnVal}`
    )
  }

  const invalidStaticPathKeys = Object.keys(staticPathsResult).filter(
    (key) => !(key === 'paths' || key === 'fallback')
  )

  if (invalidStaticPathKeys.length > 0) {
    throw new Error(
      `Extra keys returned from getStaticPaths in ${page} (${invalidStaticPathKeys.join(
        ', '
      )}) ${expectedReturnVal}`
    )
  }

  if (
    !(
      typeof staticPathsResult.fallback === 'boolean' ||
      staticPathsResult.fallback === 'blocking'
    )
  ) {
    throw new Error(
      `The \`fallback\` key must be returned from getStaticPaths in ${page}.\n` +
        expectedReturnVal
    )
  }

  const toPrerender = staticPathsResult.paths

  if (!Array.isArray(toPrerender)) {
    throw new Error(
      `Invalid \`paths\` value returned from getStaticPaths in ${page}.\n` +
        `\`paths\` must be an array of strings or objects of shape { params: [key: string]: string }`
    )
  }

  toPrerender.forEach((entry) => {
    // For a string-provided path, we must make sure it matches the dynamic
    // route.
    if (typeof entry === 'string') {
      entry = removeTrailingSlash(entry)

      const localePathResult = normalizeLocalePath(entry, locales)
      let cleanedEntry = entry

      if (localePathResult.detectedLocale) {
        cleanedEntry = entry.slice(localePathResult.detectedLocale.length + 1)
      } else if (defaultLocale) {
        entry = `/${defaultLocale}${entry}`
      }

      const result = _routeMatcher(cleanedEntry)
      if (!result) {
        throw new Error(
          `The provided path \`${cleanedEntry}\` does not match the page: \`${page}\`.`
        )
      }

      // If leveraging the string paths variant the entry should already be
      // encoded so we decode the segments ensuring we only escape path
      // delimiters
      prerenderPaths.add(
        entry
          .split('/')
          .map((segment) =>
            escapePathDelimiters(decodeURIComponent(segment), true)
          )
          .join('/')
      )
      encodedPrerenderPaths.add(entry)
    }
    // For the object-provided path, we must make sure it specifies all
    // required keys.
    else {
      const invalidKeys = Object.keys(entry).filter(
        (key) => key !== 'params' && key !== 'locale'
      )

      if (invalidKeys.length) {
        throw new Error(
          `Additional keys were returned from \`getStaticPaths\` in page "${page}". ` +
            `URL Parameters intended for this dynamic route must be nested under the \`params\` key, i.e.:` +
            `\n\n\treturn { params: { ${_validParamKeys
              .map((k) => `${k}: ...`)
              .join(', ')} } }` +
            `\n\nKeys that need to be moved: ${invalidKeys.join(', ')}.\n`
        )
      }

      const { params = {} } = entry
      let builtPage = page
      let encodedBuiltPage = page

      _validParamKeys.forEach((validParamKey) => {
        const { repeat, optional } = _routeRegex.groups[validParamKey]
        let paramValue = params[validParamKey]
        if (
          optional &&
          params.hasOwnProperty(validParamKey) &&
          (paramValue === null ||
            paramValue === undefined ||
            (paramValue as any) === false)
        ) {
          paramValue = []
        }
        if (
          (repeat && !Array.isArray(paramValue)) ||
          (!repeat && typeof paramValue !== 'string')
        ) {
          throw new Error(
            `A required parameter (${validParamKey}) was not provided as ${
              repeat ? 'an array' : 'a string'
            } in getStaticPaths for ${page}`
          )
        }
        let replaced = `[${repeat ? '...' : ''}${validParamKey}]`
        if (optional) {
          replaced = `[${replaced}]`
        }
        builtPage = builtPage
          .replace(
            replaced,
            repeat
              ? (paramValue as string[])
                  .map((segment) => escapePathDelimiters(segment, true))
                  .join('/')
              : escapePathDelimiters(paramValue as string, true)
          )
          .replace(/(?!^)\/$/, '')

        encodedBuiltPage = encodedBuiltPage
          .replace(
            replaced,
            repeat
              ? (paramValue as string[]).map(encodeURIComponent).join('/')
              : encodeURIComponent(paramValue as string)
          )
          .replace(/(?!^)\/$/, '')
      })

      if (entry.locale && !locales?.includes(entry.locale)) {
        throw new Error(
          `Invalid locale returned from getStaticPaths for ${page}, the locale ${entry.locale} is not specified in ${configFileName}`
        )
      }
      const curLocale = entry.locale || defaultLocale || ''

      prerenderPaths.add(
        `${curLocale ? `/${curLocale}` : ''}${
          curLocale && builtPage === '/' ? '' : builtPage
        }`
      )
      encodedPrerenderPaths.add(
        `${curLocale ? `/${curLocale}` : ''}${
          curLocale && encodedBuiltPage === '/' ? '' : encodedBuiltPage
        }`
      )
    }
  })

  return {
    paths: [...prerenderPaths],
    fallback: staticPathsResult.fallback,
    encodedPaths: [...encodedPrerenderPaths],
  }
}

export async function isPageStatic(
  page: string,
  distDir: string,
  serverless: boolean,
  configFileName: string,
  runtimeEnvConfig: any,
  httpAgentOptions: NextConfigComplete['httpAgentOptions'],
  locales?: string[],
  defaultLocale?: string,
  parentId?: any
): Promise<{
  isStatic?: boolean
  isAmpOnly?: boolean
  isHybridAmp?: boolean
  hasServerProps?: boolean
  hasStaticProps?: boolean
  prerenderRoutes?: string[]
  encodedPrerenderRoutes?: string[]
  prerenderFallback?: boolean | 'blocking'
  isNextImageImported?: boolean
  traceIncludes?: string[]
  traceExcludes?: string[]
}> {
  const isPageStaticSpan = trace('is-page-static-utils', parentId)
  return isPageStaticSpan
    .traceAsyncFn(async () => {
      require('../shared/lib/runtime-config').setConfig(runtimeEnvConfig)
      setHttpAgentOptions(httpAgentOptions)

      const mod = await loadComponents(distDir, page, serverless)
      const Comp = mod.Component

      if (!Comp || !isValidElementType(Comp) || typeof Comp === 'string') {
        throw new Error('INVALID_DEFAULT_EXPORT')
      }

      const hasGetInitialProps = !!(Comp as any).getInitialProps
      const hasStaticProps = !!mod.getStaticProps
      const hasStaticPaths = !!mod.getStaticPaths
      const hasServerProps = !!mod.getServerSideProps
      const hasLegacyServerProps = !!(await mod.ComponentMod
        .unstable_getServerProps)
      const hasLegacyStaticProps = !!(await mod.ComponentMod
        .unstable_getStaticProps)
      const hasLegacyStaticPaths = !!(await mod.ComponentMod
        .unstable_getStaticPaths)
      const hasLegacyStaticParams = !!(await mod.ComponentMod
        .unstable_getStaticParams)

      if (hasLegacyStaticParams) {
        throw new Error(
          `unstable_getStaticParams was replaced with getStaticPaths. Please update your code.`
        )
      }

      if (hasLegacyStaticPaths) {
        throw new Error(
          `unstable_getStaticPaths was replaced with getStaticPaths. Please update your code.`
        )
      }

      if (hasLegacyStaticProps) {
        throw new Error(
          `unstable_getStaticProps was replaced with getStaticProps. Please update your code.`
        )
      }

      if (hasLegacyServerProps) {
        throw new Error(
          `unstable_getServerProps was replaced with getServerSideProps. Please update your code.`
        )
      }

      // A page cannot be prerendered _and_ define a data requirement. That's
      // contradictory!
      if (hasGetInitialProps && hasStaticProps) {
        throw new Error(SSG_GET_INITIAL_PROPS_CONFLICT)
      }

      if (hasGetInitialProps && hasServerProps) {
        throw new Error(SERVER_PROPS_GET_INIT_PROPS_CONFLICT)
      }

      if (hasStaticProps && hasServerProps) {
        throw new Error(SERVER_PROPS_SSG_CONFLICT)
      }

      const pageIsDynamic = isDynamicRoute(page)
      // A page cannot have static parameters if it is not a dynamic page.
      if (hasStaticProps && hasStaticPaths && !pageIsDynamic) {
        throw new Error(
          `getStaticPaths can only be used with dynamic pages, not '${page}'.` +
            `\nLearn more: https://nextjs.org/docs/routing/dynamic-routes`
        )
      }

      if (hasStaticProps && pageIsDynamic && !hasStaticPaths) {
        throw new Error(
          `getStaticPaths is required for dynamic SSG pages and is missing for '${page}'.` +
            `\nRead more: https://nextjs.org/docs/messages/invalid-getstaticpaths-value`
        )
      }

      let prerenderRoutes: Array<string> | undefined
      let encodedPrerenderRoutes: Array<string> | undefined
      let prerenderFallback: boolean | 'blocking' | undefined
      if (hasStaticProps && hasStaticPaths) {
        ;({
          paths: prerenderRoutes,
          fallback: prerenderFallback,
          encodedPaths: encodedPrerenderRoutes,
        } = await buildStaticPaths(
          page,
          mod.getStaticPaths!,
          configFileName,
          locales,
          defaultLocale
        ))
      }

      const isNextImageImported = (global as any).__NEXT_IMAGE_IMPORTED
      const config: PageConfig = mod.pageConfig
      return {
        isStatic: !hasStaticProps && !hasGetInitialProps && !hasServerProps,
        isHybridAmp: config.amp === 'hybrid',
        isAmpOnly: config.amp === true,
        prerenderRoutes,
        prerenderFallback,
        encodedPrerenderRoutes,
        hasStaticProps,
        hasServerProps,
        isNextImageImported,
        traceIncludes: config.unstable_includeFiles || [],
        traceExcludes: config.unstable_excludeFiles || [],
      }
    })
    .catch((err) => {
      if (err.message === 'INVALID_DEFAULT_EXPORT') {
        throw err
      }
      console.error(err)
      throw new Error(`Failed to collect page data for ${page}`)
    })
}

export async function hasCustomGetInitialProps(
  page: string,
  distDir: string,
  isLikeServerless: boolean,
  runtimeEnvConfig: any,
  checkingApp: boolean
): Promise<boolean> {
  require('../shared/lib/runtime-config').setConfig(runtimeEnvConfig)

  const components = await loadComponents(distDir, page, isLikeServerless)
  let mod = components.ComponentMod

  if (checkingApp) {
    mod = (await mod._app) || mod.default || mod
  } else {
    mod = mod.default || mod
  }
  mod = await mod
  return mod.getInitialProps !== mod.origGetInitialProps
}

export async function getNamedExports(
  page: string,
  distDir: string,
  isLikeServerless: boolean,
  runtimeEnvConfig: any
): Promise<Array<string>> {
  require('../shared/lib/runtime-config').setConfig(runtimeEnvConfig)
  const components = await loadComponents(distDir, page, isLikeServerless)
  let mod = components.ComponentMod

  return Object.keys(mod)
}

export function detectConflictingPaths(
  combinedPages: string[],
  ssgPages: Set<string>,
  additionalSsgPaths: Map<string, string[]>
) {
  const conflictingPaths = new Map<
    string,
    Array<{
      path: string
      page: string
    }>
  >()

  const dynamicSsgPages = [...ssgPages].filter((page) => isDynamicRoute(page))

  additionalSsgPaths.forEach((paths, pathsPage) => {
    paths.forEach((curPath) => {
      const lowerPath = curPath.toLowerCase()
      let conflictingPage = combinedPages.find(
        (page) => page.toLowerCase() === lowerPath
      )

      if (conflictingPage) {
        conflictingPaths.set(lowerPath, [
          { path: curPath, page: pathsPage },
          { path: conflictingPage, page: conflictingPage },
        ])
      } else {
        let conflictingPath: string | undefined

        conflictingPage = dynamicSsgPages.find((page) => {
          if (page === pathsPage) return false

          conflictingPath = additionalSsgPaths
            .get(page)
            ?.find((compPath) => compPath.toLowerCase() === lowerPath)
          return conflictingPath
        })

        if (conflictingPage && conflictingPath) {
          conflictingPaths.set(lowerPath, [
            { path: curPath, page: pathsPage },
            { path: conflictingPath, page: conflictingPage },
          ])
        }
      }
    })
  })

  if (conflictingPaths.size > 0) {
    let conflictingPathsOutput = ''

    conflictingPaths.forEach((pathItems) => {
      pathItems.forEach((pathItem, idx) => {
        const isDynamic = pathItem.page !== pathItem.path

        if (idx > 0) {
          conflictingPathsOutput += 'conflicts with '
        }

        conflictingPathsOutput += `path: "${pathItem.path}"${
          isDynamic ? ` from page: "${pathItem.page}" ` : ' '
        }`
      })
      conflictingPathsOutput += '\n'
    })

    Log.error(
      'Conflicting paths returned from getStaticPaths, paths must be unique per page.\n' +
        'See more info here: https://nextjs.org/docs/messages/conflicting-ssg-paths\n\n' +
        conflictingPathsOutput
    )
    process.exit(1)
  }
}

/**
 * With RSC we automatically add .server and .client to page extensions. This
 * function allows to remove them for cases where we just need to strip out
 * the actual extension keeping the .server and .client.
 */
export function withoutRSCExtensions(pageExtensions: string[]): string[] {
  return pageExtensions.filter(
    (ext) => !ext.startsWith('client.') && !ext.startsWith('server.')
  )
}

export function isServerComponentPage(
  nextConfig: NextConfigComplete,
  filePath: string
): boolean {
  if (!nextConfig.experimental.serverComponents) {
    return false
  }

  const rawPageExtensions = withoutRSCExtensions(
    nextConfig.pageExtensions || []
  )
  return rawPageExtensions.some((ext) => {
    return filePath.endsWith(`.server.${ext}`)
  })
}

export async function copyTracedFiles(
  dir: string,
  distDir: string,
  pageKeys: ReadonlyArray<string>,
  tracingRoot: string,
  serverConfig: { [key: string]: any },
  middlewareManifest: MiddlewareManifest
) {
  const outputPath = path.join(distDir, 'standalone')
  const copiedFiles = new Set()
  await recursiveDelete(outputPath)

  async function handleTraceFiles(traceFilePath: string) {
    const traceData = JSON.parse(await fs.readFile(traceFilePath, 'utf8')) as {
      files: string[]
    }
    const copySema = new Sema(10, { capacity: traceData.files.length })
    const traceFileDir = path.dirname(traceFilePath)

    await Promise.all(
      traceData.files.map(async (relativeFile) => {
        await copySema.acquire()

        const tracedFilePath = path.join(traceFileDir, relativeFile)
        const fileOutputPath = path.join(
          outputPath,
          path.relative(tracingRoot, tracedFilePath)
        )

        if (!copiedFiles.has(fileOutputPath)) {
          copiedFiles.add(fileOutputPath)

          await fs.mkdir(path.dirname(fileOutputPath), { recursive: true })
          const symlink = await fs.readlink(tracedFilePath).catch(() => null)

          if (symlink) {
            await fs.symlink(symlink, fileOutputPath)
          } else {
            await fs.copyFile(tracedFilePath, fileOutputPath)
          }
        }

        await copySema.release()
      })
    )
  }

  for (const middleware of Object.values(middlewareManifest.middleware) || []) {
    if (isMiddlewareFilename(middleware.name)) {
      for (const file of middleware.files) {
        const originalPath = path.join(distDir, file)
        const fileOutputPath = path.join(
          outputPath,
          path.relative(tracingRoot, distDir),
          file
        )
        await fs.mkdir(path.dirname(fileOutputPath), { recursive: true })
        await fs.copyFile(originalPath, fileOutputPath)
      }
    }
  }

  for (const page of pageKeys) {
    const pageFile = path.join(
      distDir,
      'server',
      'pages',
      `${normalizePagePath(page)}.js`
    )
    const pageTraceFile = `${pageFile}.nft.json`
    await handleTraceFiles(pageTraceFile)
  }
  await handleTraceFiles(path.join(distDir, 'next-server.js.nft.json'))
  const serverOutputPath = path.join(
    outputPath,
    path.relative(tracingRoot, dir),
    'server.js'
  )
  await fs.writeFile(
    serverOutputPath,
    `
process.env.NODE_ENV = 'production'
process.chdir(__dirname)
const NextServer = require('next/dist/server/next-server').default
const http = require('http')
const path = require('path')

// Make sure commands gracefully respect termination signals (e.g. from Docker)
// Allow the graceful termination to be manually configurable
if (!process.env.NEXT_MANUAL_SIG_HANDLE) {
  process.on('SIGTERM', () => process.exit(0))
  process.on('SIGINT', () => process.exit(0))
}

let handler

const server = http.createServer(async (req, res) => {
  try {
    await handler(req, res)
  } catch (err) {
    console.error(err);
    res.statusCode = 500
    res.end('internal server error')
  }
})
const currentPort = parseInt(process.env.PORT, 10) || 3000

server.listen(currentPort, (err) => {
  if (err) {
    console.error("Failed to start server", err)
    process.exit(1)
  }
  const nextServer = new NextServer({
    hostname: 'localhost',
    port: currentPort,
    dir: path.join(__dirname),
    dev: false,
    customServer: false,
    conf: ${JSON.stringify({
      ...serverConfig,
      distDir: `./${path.relative(dir, distDir)}`,
    })},
  })
  handler = nextServer.getRequestHandler()

  console.log("Listening on port", currentPort)
})
    `
  )
}
export function isReservedPage(page: string) {
  return RESERVED_PAGE.test(page)
}

export function isCustomErrorPage(page: string) {
  return page === '/404' || page === '/500'
}

export function isMiddlewareFile(file: string) {
  return (
    file === `/${MIDDLEWARE_FILENAME}` || file === `/src/${MIDDLEWARE_FILENAME}`
  )
}

export function isMiddlewareFilename(file?: string) {
  return file === MIDDLEWARE_FILENAME || file === `src/${MIDDLEWARE_FILENAME}`
}

export function getPossibleMiddlewareFilenames(
  folder: string,
  extensions: string[]
) {
  return extensions.map((extension) =>
    path.join(folder, `${MIDDLEWARE_FILENAME}.${extension}`)
  )
}

export class MiddlewareInServerlessTargetError extends Error {
  constructor() {
    super(
      'Next.js Middleware is not supported in the deprecated serverless target.\n' +
        'Please remove `target: "serverless" from your next.config.js to use Middleware.'
    )
    this.name = 'MiddlewareInServerlessTargetError'
  }
}

export class NestedMiddlewareError extends Error {
  constructor(nestedFileNames: string[], mainDir: string, pagesDir: string) {
    super(
      `Nested Middleware is not allowed, found:\n` +
        `${nestedFileNames.map((file) => `pages${file}`).join('\n')}\n` +
        `Please move your code to a single file at ${path.join(
          path.posix.sep,
          path.relative(mainDir, path.resolve(pagesDir, '..')),
          'middleware'
        )} instead.\n` +
        `Read More - https://nextjs.org/docs/messages/nested-middleware`
    )
  }
}