Fix language preference fallback display

Author: oldj

src/renderer/components/Pref/General.tsx

@@ -11,6 +11,7 @@ import { agent } from '@renderer/core/agent'
 import useI18n from '@renderer/models/useI18n'
 import { normalizeTheme } from '@renderer/utils/theme'
 import type { CSSProperties } from 'react'
+import { languageOptions, resolveLanguageSelectValue } from './languageOptions'
 
 interface IProps {
   data: ConfigsType
@@ -26,7 +27,7 @@ const segmentedControlLabelStyle: CSSProperties = {
 
 const General = (props: IProps) => {
   const { data, onChange } = props
-  const { lang } = useI18n()
+  const { lang, locale } = useI18n()
   const { platform } = agent
 
   return (
@@ -42,18 +43,9 @@ const General = (props: IProps) => {
       >
         <Box>{lang.language}</Box>
         <Select
-          value={data.locale}
+          value={resolveLanguageSelectValue(data.locale, locale)}
           onChange={(v) => v && onChange({ locale: v as LocaleName })}
-          data={[
-            { value: 'zh', label: '简体中文' },
-            { value: 'zh_hant', label: '繁體中文' },
-            { value: 'en', label: 'English' },
-            { value: 'fr', label: 'Français' },
-            { value: 'de', label: 'Deutsch' },
-            { value: 'ja', label: '日本語' },
-            { value: 'tr', label: 'Türkçe' },
-            { value: 'ko', label: '한국어' },
-          ]}
+          data={languageOptions}
           w={200}
           allowDeselect={false}
         />

src/renderer/components/Pref/languageOptions.test.ts

@@ -0,0 +1,37 @@
+import { describe, expect, it } from 'vitest'
+
+import {
+  languageOptions,
+  normalizeLanguageOptionValue,
+  resolveLanguageSelectValue,
+} from './languageOptions'
+
+describe('language preference options', () => {
+  it('shows the active system language when no locale is saved', () => {
+    expect(resolveLanguageSelectValue(undefined, 'zh-CN')).toBe('zh')
+  })
+
+  it('normalizes locale aliases to selectable option values', () => {
+    expect(normalizeLanguageOptionValue('cn')).toBe('zh')
+    expect(normalizeLanguageOptionValue('zh-CN')).toBe('zh')
+    expect(normalizeLanguageOptionValue('zh-TW')).toBe('zh_hant')
+  })
+
+  it('prefers a saved language over the active system language', () => {
+    expect(resolveLanguageSelectValue('de', 'zh-CN')).toBe('de')
+  })
+
+  it('lists every canonical bundled language', () => {
+    expect(languageOptions.map(({ value }) => value)).toEqual([
+      'zh',
+      'zh_hant',
+      'en',
+      'fr',
+      'de',
+      'ja',
+      'tr',
+      'ko',
+      'pl',
+    ])
+  })
+})

src/renderer/components/Pref/languageOptions.ts

@@ -0,0 +1,47 @@
+import type { LocaleName } from '@common/i18n'
+
+export const languageOptions = [
+  { value: 'zh', label: '简体中文' },
+  { value: 'zh_hant', label: '繁體中文' },
+  { value: 'en', label: 'English' },
+  { value: 'fr', label: 'Français' },
+  { value: 'de', label: 'Deutsch' },
+  { value: 'ja', label: '日本語' },
+  { value: 'tr', label: 'Türkçe' },
+  { value: 'ko', label: '한국어' },
+  { value: 'pl', label: 'Polski' },
+] as const satisfies ReadonlyArray<{ value: LocaleName; label: string }>
+
+type LanguageOptionValue = (typeof languageOptions)[number]['value']
+
+const languageOptionValues = new Set<LocaleName>(
+  languageOptions.map(({ value }) => value),
+)
+
+const localeAliases: Partial<Record<LocaleName, LanguageOptionValue>> = {
+  cn: 'zh',
+  'zh-CN': 'zh',
+  'zh-TW': 'zh_hant',
+}
+
+export function normalizeLanguageOptionValue(
+  locale?: LocaleName,
+): LanguageOptionValue | undefined {
+  if (!locale) return undefined
+
+  const alias = localeAliases[locale]
+  if (alias) return alias
+
+  return languageOptionValues.has(locale) ? (locale as LanguageOptionValue) : undefined
+}
+
+export function resolveLanguageSelectValue(
+  configLocale: LocaleName | undefined,
+  activeLocale: LocaleName,
+): LanguageOptionValue {
+  return (
+    normalizeLanguageOptionValue(configLocale) ??
+    normalizeLanguageOptionValue(activeLocale) ??
+    'en'
+  )
+}