61 lines
2.1 KiB
JavaScript
61 lines
2.1 KiB
JavaScript
import languages, { languageKeys } from '../lib/languages.js'
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import parser from 'accept-language-parser'
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const chineseRegions = ['CN', 'HK']
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// This value is replicated in two places! See <LanguagePicker/> component.
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// Note, the only reason this is exported is to benefit the tests.
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export const PREFERRED_LOCALE_COOKIE_NAME = 'preferredlang'
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function translationExists(language) {
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if (language.code === 'zh') {
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return chineseRegions.includes(language.region)
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}
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return languageKeys.includes(language.code)
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}
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function getLanguageCode(language) {
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return language.code === 'zh' && chineseRegions.includes(language.region) ? 'cn' : language.code
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}
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function getUserLanguage(browserLanguages) {
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try {
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let numTopPreferences = 1
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for (let lang = 0; lang < browserLanguages.length; lang++) {
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// If language has multiple regions, Chrome adds the non-region language to list
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if (lang > 0 && browserLanguages[lang].code !== browserLanguages[lang - 1].code)
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numTopPreferences++
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if (translationExists(browserLanguages[lang]) && numTopPreferences < 3) {
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return getLanguageCode(browserLanguages[lang])
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}
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}
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} catch {
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return undefined
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}
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}
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function getUserLanguageFromCookie(req) {
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const value = req.cookies[PREFERRED_LOCALE_COOKIE_NAME]
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// But if it's a WIP language, reject it.
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if (value && languages[value] && !languages[value].wip) {
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return value
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}
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}
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// determine language code from a path. Default to en if no valid match
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export function getLanguageCodeFromPath(path) {
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const maybeLanguage = (path.split('/')[path.startsWith('/_next/data/') ? 4 : 1] || '').slice(0, 2)
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return languageKeys.includes(maybeLanguage) ? maybeLanguage : 'en'
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}
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export default function detectLanguage(req, res, next) {
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req.language = getLanguageCodeFromPath(req.path)
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// Detecting browser language by user preference
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req.userLanguage = getUserLanguageFromCookie(req)
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if (!req.userLanguage) {
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const browserLanguages = parser.parse(req.headers['accept-language'])
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req.userLanguage = getUserLanguage(browserLanguages)
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}
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return next()
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}
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