アイヌ語追加 (#428) (#433)

Reviewed-on: #433
Co-authored-by: miteruzo <miteruzo@naver.com>

frontend/src/lib/i18n.ts

@@ -0,0 +1,141 @@
+import { createInstance } from 'i18next'
+import { initReactI18next } from 'react-i18next'
+
+import type { i18n as I18n, TOptions } from 'i18next'
+
+import type { LocaleCode } from '@/lib/locales'
+
+// Keep Japanese placeholders editable without reporting them as completed translations.
+const translatedResource = (resource: Record<string, unknown>): Record<string, unknown> => {
+  const untranslated = new Set (
+      Array.isArray (resource._untranslated) ? resource._untranslated : [])
+  if (untranslated.has ('*'))
+    return { }
+  const select = (entries: Record<string, unknown>, prefix = ''): Record<string, unknown> =>
+      Object.fromEntries (Object.entries (entries).flatMap (([key, value]) => {
+	const path = prefix ? `${ prefix }.${ key }` : key
+	if (key === '_untranslated' || untranslated.has (path))
+	  return []
+	const translated =
+	    (value != null && typeof value === 'object' && !(Array.isArray (value)))
+	    ? select (value as Record<string, unknown>, path)
+	    : value
+	return [[key, translated]]
+      }))
+  return select (resource)
+}
+
+
+const dictionaries = import.meta.glob<Record<string, unknown>> ('../locales/*/*.json', {
+    eager: true, import: 'default' })
+const resources: Record<string, Record<string, Record<string, unknown>>> = { }
+for (const [path, dictionary] of Object.entries (dictionaries))
+{
+  const [, , locale, filename] = path.split ('/')
+  resources[locale] ??= { }
+  resources[locale][filename.slice (0, -5)] =
+      locale === 'ain-Kana' ? translatedResource (dictionary) : dictionary
+}
+const namespaces = Object.keys (resources.ja ?? { })
+
+
+export const createUII18n = (locale: string): I18n => {
+  const instance = createInstance ()
+  void instance.init ({
+      lng: locale,
+      fallbackLng: 'ja',
+      supportedLngs: ['ja', 'ain-Kana'],
+      load: 'currentOnly',
+      initAsync: false,
+      defaultNS: 'navigation',
+      ns: namespaces,
+      resources,
+      interpolation: { escapeValue: false },
+      returnNull: false,
+      returnEmptyString: false,
+      saveMissing: import.meta.env.DEV,
+      missingKeyHandler: (languages, namespace, key) => {
+	console.warn ('[i18n] missing key', { languages, namespace, key })
+      },
+      react: { useSuspense: false } })
+  return instance
+}
+
+// This instance is used only by legacy helpers with an explicit lng option.
+export const i18n = createUII18n ('ja')
+initReactI18next.init (i18n)
+
+
+export const translateUIMessage = (
+    key: string,
+    namespace: string,
+    locale: string,
+    values: Record<string, string | number> = { },
+    instance: I18n = i18n,
+): { text: string; language: string } => {
+  const languages = new Set<string> ()
+  const visiting = new Set<string> ()
+  const collectLanguages = (reference: string, options: TOptions): string => {
+    const details = instance.t (reference, { ...options,
+	returnDetails: true, returnObjects: false, nest: false, skipInterpolation: true })
+    const identity = `${details.usedLng}:${details.usedNS}:${details.exactUsedKey}`
+    if (visiting.has (identity) || typeof details.res !== 'string')
+      return details.usedLng
+    visiting.add (identity)
+    const nestingOptions = { ...instance.options.interpolation, ...options,
+	ns: details.usedNS, lng: details.usedLng }
+    const remainder = instance.services.interpolator.nest (details.res,
+	(nestedKey: string, nestedOptions: TOptions) => {
+	  collectLanguages (nestedKey, nestedOptions)
+	  return ' '
+	}, nestingOptions)
+    // References, punctuation and supplied values do not define the wrapper's language.
+    if (/\p{L}/u.test (remainder.replace (/\{\{[^}]*\}\}/g, '')))
+      languages.add (details.usedLng)
+    visiting.delete (identity)
+    return details.usedLng
+  }
+  const options = { ...values, ns: namespace, lng: locale }
+  const resolvedLanguage = collectLanguages (key, options)
+  // A single lang attribute cannot describe mixed fallback text: use the full Japanese message.
+  const mixed = languages.size > 1
+  const language = mixed ? 'ja' : languages.values ().next ().value ?? resolvedLanguage
+  const text = instance.t (key, { ...options, lng: mixed ? 'ja' : resolvedLanguage,
+      returnDetails: false, returnObjects: false })
+  if (typeof text !== 'string')
+  {
+    console.warn ('[i18n] UI message must be a string', { key, namespace, locale })
+    return { text: key, language }
+  }
+  return { text, language }
+}
+
+
+export const untranslatedKeys = (
+    locale: LocaleCode,
+    namespace = 'navigation',
+): string[] => {
+  const collect = (resource: Record<string, unknown>, prefix = ''): string[] =>
+      Object.entries (resource).flatMap (([key, value]) => {
+	const path = prefix ? `${ prefix }.${ key }` : key
+	return (value != null && typeof value === 'object')
+	    ? collect (value as Record<string, unknown>, path)
+	    : [path]
+      })
+  const baseline = i18n.getResourceBundle ('ja', namespace) ?? { }
+  return collect (baseline).filter (key => {
+    const value = i18n.getResource (locale, namespace, key)
+    return typeof value !== 'string' || value.length === 0
+  })
+}
+
+
+if (import.meta.env.DEV)
+{
+  for (const namespace of namespaces)
+  {
+    const missing = untranslatedKeys ('ain-Kana', namespace)
+    if (missing.length > 0)
+      console.warn (`[i18n] ain-Kana: untranslated ${ namespace } keys`, missing)
+  }
+}