Add UI language switcher and ja/ko locales

Introduce a runtime UI language switcher and add Japanese/Korean locale support. Added _locales/ja and _locales/ko messages, updated en and zh_CN message files with new language-related keys and sendImage label. Implemented dynamic i18n handling: new i18n.js supports override messages, persistent uiLanguage in storage, and emits i18n:changed; background.js now loads override locales, updates context menu titles and listens for storage changes. Integrated dayjs locales (js/ja.js, js/ko.js) and made oper.js use a unified msg() helper and react to language changes. Added language selector UI in popup.html and styling in css/main.css.

js/i18n.js

@@ -1,50 +1,148 @@
-function getMessage(key) {
-	return chrome.i18n.getMessage(key) || ''
+const UI_LANGUAGE_STORAGE_KEY = 'uiLanguage'
+
+const SUPPORTED_UI_LANGUAGES = new Set(['auto', 'en', 'zh_CN', 'ja', 'ko'])
+
+function normalizeUiLanguage(value) {
+	const lang = String(value || 'auto')
+	return SUPPORTED_UI_LANGUAGES.has(lang) ? lang : 'auto'
+}
+
+function storageSyncGet(defaults) {
+	return new Promise((resolve) => {
+		chrome.storage.sync.get(defaults, (items) => resolve(items || {}))
+	})
+}
+
+function storageSyncSet(items) {
+	return new Promise((resolve) => {
+		chrome.storage.sync.set(items, () => resolve())
+	})
+}
+
+async function loadLocaleMessages(locale) {
+	if (!locale || locale === 'auto') return null
+	try {
+		const url = chrome.runtime.getURL(`_locales/${locale}/messages.json`)
+		const resp = await fetch(url)
+		if (!resp.ok) return null
+		return await resp.json()
+	} catch (_) {
+		return null
+	}
+}
+
+function formatSubstitutions(message, substitutions) {
+	if (!message) return ''
+	if (substitutions == null) return message
+	const subs = Array.isArray(substitutions) ? substitutions : [substitutions]
+	let out = message
+	for (let i = 0; i < subs.length; i++) {
+		const v = String(subs[i])
+		out = out.replaceAll(`$${i + 1}`, v)
+		out = out.replace('%s', v)
+	}
+	return out
+}
+
+let currentUiLanguage = 'auto'
+let overrideMessages = null
+
+function t(key, substitutions) {
+	const msg = overrideMessages && overrideMessages[key] && overrideMessages[key].message
+	if (typeof msg === 'string' && msg.length > 0) {
+		return formatSubstitutions(msg, substitutions)
+	}
+	const chromeMsg = chrome.i18n.getMessage(key, substitutions) || ''
+	return formatSubstitutions(chromeMsg, substitutions)
 }
 
 function setText(id, messageKey) {
 	const el = document.getElementById(id)
-	if (el) el.textContent = getMessage(messageKey)
+	if (el) el.textContent = t(messageKey)
 }
 
 function setPlaceholder(id, messageKey) {
 	const el = document.getElementById(id)
-	if (el) el.placeholder = getMessage(messageKey)
+	if (el) el.placeholder = t(messageKey)
 }
 
 function setTitle(id, messageKey) {
 	const el = document.getElementById(id)
-	if (el) el.title = getMessage(messageKey)
+	if (el) el.title = t(messageKey)
 }
 
-setText("saveKey", "saveBtn")
-setText("saveTag", "saveBtn")
+function applyStaticI18n() {
+	setText('saveKey', 'saveBtn')
+	setText('saveTag', 'saveBtn')
 
-setText("supportedMemosVersion", "supportedMemosVersion")
+	setText('supportedMemosVersion', 'supportedMemosVersion')
 
-setPlaceholder("apiUrl", "placeApiUrl")
-setPlaceholder("apiTokens", "placeApiTokens")
-setPlaceholder("content", "placeContent")
+	setPlaceholder('apiUrl', 'placeApiUrl')
+	setPlaceholder('apiTokens', 'placeApiTokens')
+	setPlaceholder('content', 'placeContent')
 
-setText("lockPrivate", "lockPrivate")
-setText("lockProtected", "lockProtected")
-setText("lockPublic", "lockPublic")
+	setText('lockPrivate', 'lockPrivate')
+	setText('lockProtected', 'lockProtected')
+	setText('lockPublic', 'lockPublic')
 
-setText("content_submit_text", "submitBtn")
+	setText('content_submit_text', 'submitBtn')
 
-setPlaceholder("hideInput", "placeHideInput")
-setPlaceholder("showInput", "placeShowInput")
+	setPlaceholder('hideInput', 'placeHideInput')
+	setPlaceholder('showInput', 'placeShowInput')
 
-setText("uploadlist-title", "uploadedListTitle")
+	setText('uploadlist-title', 'uploadedListTitle')
 
-// Native hover tooltips (title)
-setTitle("opensite", "tipOpenSite")
-setTitle("blog_info_edit", "tipSettings")
-setTitle("tags", "tipTags")
-setTitle("newtodo", "tipTodo")
-setTitle("upres", "tipUpload")
-setTitle("getlink", "tipLink")
-setTitle("random", "tipRandom")
-setTitle("search", "tipSearch")
-setTitle("lock", "tipVisibility")
-setTitle("content_submit_text", "tipSend")
+	// Language switcher
+	setText('langOptionAuto', 'langAuto')
+	setText('langOptionEn', 'langEnglish')
+	setText('langOptionZhCN', 'langChineseSimplified')
+	setText('langOptionJa', 'langJapanese')
+	setText('langOptionKo', 'langKorean')
+	setTitle('langSelect', 'tipLanguage')
+
+	// Native hover tooltips (title)
+	setTitle('opensite', 'tipOpenSite')
+	setTitle('blog_info_edit', 'tipSettings')
+	setTitle('tags', 'tipTags')
+	setTitle('newtodo', 'tipTodo')
+	setTitle('upres', 'tipUpload')
+	setTitle('getlink', 'tipLink')
+	setTitle('random', 'tipRandom')
+	setTitle('search', 'tipSearch')
+	setTitle('lock', 'tipVisibility')
+	setTitle('content_submit_text', 'tipSend')
+}
+
+async function setUiLanguage(nextLang, { persist = true } = {}) {
+	const lang = normalizeUiLanguage(nextLang)
+	currentUiLanguage = lang
+	overrideMessages = await loadLocaleMessages(lang)
+	applyStaticI18n()
+
+	const select = document.getElementById('langSelect')
+	if (select && select.value !== lang) select.value = lang
+
+	if (persist) await storageSyncSet({ [UI_LANGUAGE_STORAGE_KEY]: lang })
+	window.dispatchEvent(new CustomEvent('i18n:changed', { detail: { lang } }))
+}
+
+async function initLanguageSwitcher() {
+	const select = document.getElementById('langSelect')
+	if (select) {
+		select.addEventListener('change', async () => {
+			await setUiLanguage(select.value)
+		})
+	}
+
+	const items = await storageSyncGet({ [UI_LANGUAGE_STORAGE_KEY]: 'auto' })
+	const stored = normalizeUiLanguage(items[UI_LANGUAGE_STORAGE_KEY])
+	if (select) select.value = stored
+	await setUiLanguage(stored, { persist: false })
+}
+
+window.t = t
+window.setUiLanguage = setUiLanguage
+window.getUiLanguage = () => currentUiLanguage
+
+applyStaticI18n()
+window.i18nReady = initLanguageSwitcher()