Add initial changes for i18n support

packages/next/build/entries.ts

@@ -97,6 +97,9 @@ export function createEntrypoints(
     loadedEnvFiles: Buffer.from(JSON.stringify(loadedEnvFiles)).toString(
       'base64'
     ),
+    i18n: config.experimental.i18n
+      ? JSON.stringify(config.experimental.i18n)
+      : '',
   }
 
   Object.keys(pages).forEach((page) => {

packages/next/build/index.ts

@@ -563,7 +563,9 @@ export default async function build(
           let workerResult = await staticCheckWorkers.isPageStatic(
             page,
             serverBundle,
-            runtimeEnvConfig
+            runtimeEnvConfig,
+            config.experimental.i18n?.locales,
+            config.experimental.i18n?.defaultLocale
           )
 
           if (workerResult.isHybridAmp) {

packages/next/build/utils.ts

@@ -27,6 +27,7 @@ import { denormalizePagePath } from '../next-server/server/normalize-page-path'
 import { BuildManifest } from '../next-server/server/get-page-files'
 import { removePathTrailingSlash } from '../client/normalize-trailing-slash'
 import type { UnwrapPromise } from '../lib/coalesced-function'
+import { normalizeLocalePath } from '../next-server/lib/i18n/normalize-locale-path'
 
 const fileGzipStats: { [k: string]: Promise<number> } = {}
 const fsStatGzip = (file: string) => {
@@ -530,7 +531,9 @@ export async function getJsPageSizeInKb(
 
 export async function buildStaticPaths(
   page: string,
-  getStaticPaths: GetStaticPaths
+  getStaticPaths: GetStaticPaths,
+  locales?: string[],
+  defaultLocale?: string
 ): Promise<
   Omit<UnwrapPromise<ReturnType<GetStaticPaths>>, 'paths'> & { paths: string[] }
 > {
@@ -595,7 +598,17 @@ export async function buildStaticPaths(
     // route.
     if (typeof entry === 'string') {
       entry = removePathTrailingSlash(entry)
-      const result = _routeMatcher(entry)
+
+      const localePathResult = normalizeLocalePath(entry, locales)
+      let cleanedEntry = entry
+
+      if (localePathResult.detectedLocale) {
+        cleanedEntry = entry.substr(localePathResult.detectedLocale.length + 1)
+      } else if (defaultLocale) {
+        entry = `/${defaultLocale}${entry}`
+      }
+
+      const result = _routeMatcher(cleanedEntry)
       if (!result) {
         throw new Error(
           `The provided path \`${entry}\` does not match the page: \`${page}\`.`
@@ -607,7 +620,10 @@ export async function buildStaticPaths(
     // For the object-provided path, we must make sure it specifies all
     // required keys.
     else {
-      const invalidKeys = Object.keys(entry).filter((key) => key !== 'params')
+      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 "${page}". ` +
@@ -657,7 +673,14 @@ export async function buildStaticPaths(
           .replace(/(?!^)\/$/, '')
       })
 
-      prerenderPaths?.add(builtPage)
+      if (entry.locale && !locales?.includes(entry.locale)) {
+        throw new Error(
+          `Invalid locale returned from getStaticPaths for ${page}, the locale ${entry.locale} is not specified in next.config.js`
+        )
+      }
+      const curLocale = entry.locale || defaultLocale || ''
+
+      prerenderPaths?.add(`${curLocale ? `/${curLocale}` : ''}${builtPage}`)
     }
   })
 
@@ -667,7 +690,9 @@ export async function buildStaticPaths(
 export async function isPageStatic(
   page: string,
   serverBundle: string,
-  runtimeEnvConfig: any
+  runtimeEnvConfig: any,
+  locales?: string[],
+  defaultLocale?: string
 ): Promise<{
   isStatic?: boolean
   isAmpOnly?: boolean
@@ -755,7 +780,12 @@ export async function isPageStatic(
       ;({
         paths: prerenderRoutes,
         fallback: prerenderFallback,
-      } = await buildStaticPaths(page, mod.getStaticPaths))
+      } = await buildStaticPaths(
+        page,
+        mod.getStaticPaths,
+        locales,
+        defaultLocale
+      ))
     }
 
     const config = mod.config || {}

packages/next/build/webpack-config.ts

@@ -986,6 +986,9 @@ export default async function getBaseWebpackConfig(
         ),
         'process.env.__NEXT_ROUTER_BASEPATH': JSON.stringify(config.basePath),
         'process.env.__NEXT_HAS_REWRITES': JSON.stringify(hasRewrites),
+        'process.env.__NEXT_i18n_SUPPORT': JSON.stringify(
+          !!config.experimental.i18n
+        ),
         ...(isServer
           ? {
               // Fix bad-actors in the npm ecosystem (e.g. `node-formidable`)

packages/next/build/webpack/loaders/next-serverless-loader.ts

@@ -28,6 +28,7 @@ export type ServerlessLoaderQuery = {
   runtimeConfig: string
   previewProps: string
   loadedEnvFiles: string
+  i18n: string
 }
 
 const vercelHeader = 'x-vercel-id'
@@ -49,6 +50,7 @@ const nextServerlessLoader: loader.Loader = function () {
     runtimeConfig,
     previewProps,
     loadedEnvFiles,
+    i18n,
   }: ServerlessLoaderQuery =
     typeof this.query === 'string' ? parse(this.query.substr(1)) : this.query
 
@@ -66,6 +68,8 @@ const nextServerlessLoader: loader.Loader = function () {
     JSON.parse(previewProps) as __ApiPreviewProps
   )
 
+  const i18nEnabled = !!i18n
+
   const defaultRouteRegex = pageIsDynamicRoute
     ? `
       const defaultRouteRegex = getRouteRegex("${page}")
@@ -212,6 +216,58 @@ const nextServerlessLoader: loader.Loader = function () {
   `
     : ''
 
+  const handleLocale = i18nEnabled
+    ? `
+      // get pathname from URL with basePath stripped for locale detection
+      const i18n = ${i18n}
+      const accept = require('@hapi/accept')
+      const { detectLocaleCookie } = require('next/dist/next-server/lib/i18n/detect-locale-cookie')
+      const { normalizeLocalePath } = require('next/dist/next-server/lib/i18n/normalize-locale-path')
+      let detectedLocale = detectLocaleCookie(req, i18n.locales)
+
+      if (!detectedLocale) {
+        detectedLocale = accept.language(
+          req.headers['accept-language'],
+          i18n.locales
+        ) || i18n.defaultLocale
+      }
+
+      if (
+        !nextStartMode &&
+        i18n.localeDetection !== false &&
+        denormalizePagePath(parsedUrl.pathname || '/') === '/'
+      ) {
+        res.setHeader(
+          'Location',
+          formatUrl({
+            // make sure to include any query values when redirecting
+            ...parsedUrl,
+            pathname: \`/\${detectedLocale}\`,
+          })
+        )
+        res.statusCode = 307
+        res.end()
+      }
+
+      // TODO: domain based locales (domain to locale mapping needs to be provided in next.config.js)
+      const localePathResult = normalizeLocalePath(parsedUrl.pathname, i18n.locales)
+
+      if (localePathResult.detectedLocale) {
+        detectedLocale = localePathResult.detectedLocale
+        req.url = formatUrl({
+          ...parsedUrl,
+          pathname: localePathResult.pathname,
+        })
+        parsedUrl.pathname = localePathResult.pathname
+      }
+
+      detectedLocale = detectedLocale || i18n.defaultLocale
+    `
+    : `
+      const i18n = {}
+      const detectedLocale = undefined
+    `
+
   if (page.match(API_ROUTE)) {
     return `
       import initServer from 'next-plugin-loader?middleware=on-init-server!'
@@ -305,6 +361,7 @@ const nextServerlessLoader: loader.Loader = function () {
     const { renderToHTML } = require('next/dist/next-server/server/render');
     const { tryGetPreviewData } = require('next/dist/next-server/server/api-utils');
     const { denormalizePagePath } = require('next/dist/next-server/server/denormalize-page-path')
+    const { setLazyProp, getCookieParser } = require('next/dist/next-server/server/api-utils')
     const {sendPayload} = require('next/dist/next-server/server/send-payload');
     const buildManifest = require('${buildManifest}');
     const reactLoadableManifest = require('${reactLoadableManifest}');
@@ -338,6 +395,9 @@ const nextServerlessLoader: loader.Loader = function () {
     export const _app = App
     export async function renderReqToHTML(req, res, renderMode, _renderOpts, _params) {
       const fromExport = renderMode === 'export' || renderMode === true;
+      const nextStartMode = renderMode === 'passthrough'
+
+      setLazyProp({ req }, 'cookies', getCookieParser(req))
 
       const options = {
         App,
@@ -388,12 +448,16 @@ const nextServerlessLoader: loader.Loader = function () {
           routeNoAssetPath = parsedUrl.pathname
         }
 
+        ${handleLocale}
+
         const renderOpts = Object.assign(
           {
             Component,
             pageConfig: config,
             nextExport: fromExport,
             isDataReq: _nextData,
+            locale: detectedLocale,
+            locales: i18n.locales,
           },
           options,
         )

packages/next/client/index.tsx

@@ -11,7 +11,11 @@ import type {
   AppProps,
   PrivateRouteInfo,
 } from '../next-server/lib/router/router'
-import { delBasePath, hasBasePath } from '../next-server/lib/router/router'
+import {
+  delBasePath,
+  hasBasePath,
+  delLocale,
+} from '../next-server/lib/router/router'
 import { isDynamicRoute } from '../next-server/lib/router/utils/is-dynamic'
 import * as querystring from '../next-server/lib/router/utils/querystring'
 import * as envConfig from '../next-server/lib/runtime-config'
@@ -60,8 +64,11 @@ const {
   dynamicIds,
   isFallback,
   head: initialHeadData,
+  locales,
 } = data
 
+let { locale } = data
+
 const prefix = assetPrefix || ''
 
 // With dynamic assetPrefix it's no longer possible to set assetPrefix at the build time
@@ -80,6 +87,23 @@ if (hasBasePath(asPath)) {
   asPath = delBasePath(asPath)
 }
 
+asPath = delLocale(asPath, locale)
+
+if (process.env.__NEXT_i18n_SUPPORT) {
+  const {
+    normalizeLocalePath,
+  } = require('../next-server/lib/i18n/normalize-locale-path')
+
+  if (isFallback && locales) {
+    const localePathResult = normalizeLocalePath(asPath, locales)
+
+    if (localePathResult.detectedLocale) {
+      asPath = asPath.substr(localePathResult.detectedLocale.length + 1)
+      locale = localePathResult.detectedLocale
+    }
+  }
+}
+
 type RegisterFn = (input: [string, () => void]) => void
 
 const pageLoader = new PageLoader(buildId, prefix, page)
@@ -291,6 +315,8 @@ export default async (opts: { webpackHMR?: any } = {}) => {
     isFallback: Boolean(isFallback),
     subscription: ({ Component, styleSheets, props, err }, App) =>
       render({ App, Component, styleSheets, props, err }),
+    locale,
+    locales,
   })
 
   // call init-client middleware

packages/next/client/link.tsx

@@ -2,6 +2,7 @@ import React, { Children } from 'react'
 import { UrlObject } from 'url'
 import {
   addBasePath,
+  addLocale,
   isLocalURL,
   NextRouter,
   PrefetchOptions,
@@ -331,7 +332,7 @@ function Link(props: React.PropsWithChildren<LinkProps>) {
   // If child is an <a> tag and doesn't have a href attribute, or if the 'passHref' property is
   // defined, we specify the current 'href', so that repetition is not needed by the user
   if (props.passHref || (child.type === 'a' && !('href' in child.props))) {
-    childProps.href = addBasePath(as)
+    childProps.href = addBasePath(addLocale(as, router && router.locale))
   }
 
   return React.cloneElement(child, childProps)

packages/next/client/page-loader.ts

@@ -7,6 +7,7 @@ import {
   addBasePath,
   markLoadingError,
   interpolateAs,
+  addLocale,
 } from '../next-server/lib/router/router'
 
 import getAssetPathFromRoute from '../next-server/lib/router/utils/get-asset-path-from-route'
@@ -202,13 +203,13 @@ export default class PageLoader {
    * @param {string} href the route href (file-system path)
    * @param {string} asPath the URL as shown in browser (virtual path); used for dynamic routes
    */
-  getDataHref(href: string, asPath: string, ssg: boolean) {
+  getDataHref(href: string, asPath: string, ssg: boolean, locale?: string) {
     const { pathname: hrefPathname, query, search } = parseRelativeUrl(href)
     const { pathname: asPathname } = parseRelativeUrl(asPath)
     const route = normalizeRoute(hrefPathname)
 
     const getHrefForSlug = (path: string) => {
-      const dataRoute = getAssetPathFromRoute(path, '.json')
+      const dataRoute = addLocale(getAssetPathFromRoute(path, '.json'), locale)
       return addBasePath(
         `/_next/data/${this.buildId}${dataRoute}${ssg ? '' : search}`
       )

packages/next/client/router.ts

@@ -37,6 +37,8 @@ const urlPropertyFields = [
   'components',
   'isFallback',
   'basePath',
+  'locale',
+  'locales',
 ]
 const routerEvents = [
   'routeChangeStart',
@@ -144,7 +146,10 @@ export function makePublicRouterInstance(router: Router): NextRouter {
 
   for (const property of urlPropertyFields) {
     if (typeof _router[property] === 'object') {
-      instance[property] = Object.assign({}, _router[property]) // makes sure query is not stateful
+      instance[property] = Object.assign(
+        Array.isArray(_router[property]) ? [] : {},
+        _router[property]
+      ) // makes sure query is not stateful
       continue
     }
 

packages/next/export/index.ts

@@ -298,6 +298,8 @@ export default async function exportApp(
     ampValidatorPath: nextConfig.experimental.amp?.validator || undefined,
     ampSkipValidation: nextConfig.experimental.amp?.skipValidation || false,
     ampOptimizerConfig: nextConfig.experimental.amp?.optimizer || undefined,
+    locales: nextConfig.experimental.i18n?.locales,
+    locale: nextConfig.experimental.i18n?.defaultLocale,
   }
 
   const { serverRuntimeConfig, publicRuntimeConfig } = nextConfig