Initial commit

packages/sw/src/scripts/lang.ts

@@ -0,0 +1,45 @@
+/*
+ * Language manager for SW
+ */
+import { get, set } from "idb-keyval";
+import { I18n, type Locale } from "@/scripts/i18n";
+
+class SwLang {
+	public cacheName = `mk-cache-${_VERSION_}`;
+
+	public lang: Promise<string> = get("lang").then(async (prelang) => {
+		if (!prelang) return "en-US";
+		return prelang;
+	});
+
+	public setLang(newLang: string): Promise<I18n<Locale>> {
+		this.lang = Promise.resolve(newLang);
+		set("lang", newLang);
+		return this.fetchLocale();
+	}
+
+	public i18n: Promise<I18n> | null = null;
+
+	public fetchLocale(): Promise<I18n<Locale>> {
+		return (this.i18n = this._fetch());
+	}
+
+	private async _fetch(): Promise<I18n<Locale>> {
+		// Service Workerは何度も起動しそのたびにlocaleを読み込むので、CacheStorageを使う
+		const localeUrl = `/assets/locales/${await this.lang}.${_VERSION_}.json`;
+		let localeRes = await caches.match(localeUrl);
+
+		// _DEV_がtrueの場合は常に最新化
+		if (!localeRes || _DEV_) {
+			localeRes = await fetch(localeUrl);
+			const clone = localeRes.clone();
+			if (!clone.clone().ok) throw new Error("locale fetching error");
+
+			caches.open(this.cacheName).then((cache) => cache.put(localeUrl, clone));
+		}
+
+		return new I18n<Locale>(await localeRes.json());
+	}
+}
+
+export const swLang = new SwLang();