feat: polish

src/lib/i18n/index.ts

@@ -0,0 +1,87 @@
+import { derived, writable, type Readable } from 'svelte/store';
+import { browser } from '$app/environment';
+
+/**
+ * Minimal i18n layer — no external deps.
+ *
+ * Lookup is key-based (`t('panel.title')`) against flat or nested JSON
+ * dictionaries. Interpolation uses `{name}` placeholders. Missing keys fall
+ * back to the key itself so screens remain functional during translation.
+ *
+ * Adding a locale
+ * ---------------
+ * 1. Drop a JSON file into `src/lib/i18n/locales/<code>.json`.
+ * 2. Register it in `loaders` below.
+ * 3. Expose it in the `Locale` type.
+ */
+
+export type Locale = 'ru' | 'en';
+
+export const DEFAULT_LOCALE: Locale = 'ru';
+export const SUPPORTED_LOCALES: Locale[] = ['ru', 'en'];
+const STORAGE_KEY = 'locale';
+
+type Messages = Record<string, unknown>;
+
+const loaders: Record<Locale, () => Promise<{ default: Messages }>> = {
+	ru: () => import('./locales/ru.json'),
+	en: () => import('./locales/en.json'),
+};
+
+const messages = writable<Record<Locale, Messages>>({} as Record<Locale, Messages>);
+const locale = writable<Locale>(DEFAULT_LOCALE);
+
+async function loadLocale(code: Locale): Promise<void> {
+	const mod = await loaders[code]();
+	messages.update((m) => ({ ...m, [code]: mod.default }));
+}
+
+export async function setLocale(code: Locale): Promise<void> {
+	if (!SUPPORTED_LOCALES.includes(code)) return;
+	await loadLocale(code);
+	locale.set(code);
+	if (browser) localStorage.setItem(STORAGE_KEY, code);
+}
+
+export async function initI18n(): Promise<void> {
+	const stored = browser ? (localStorage.getItem(STORAGE_KEY) as Locale | null) : null;
+	const next = stored && SUPPORTED_LOCALES.includes(stored) ? stored : DEFAULT_LOCALE;
+	await setLocale(next);
+}
+
+function lookup(dict: Messages, key: string): string | undefined {
+	const parts = key.split('.');
+	let node: unknown = dict;
+	for (const p of parts) {
+		if (node && typeof node === 'object' && p in (node as Messages)) {
+			node = (node as Messages)[p];
+		} else {
+			return undefined;
+		}
+	}
+	return typeof node === 'string' ? node : undefined;
+}
+
+function interpolate(template: string, values: Record<string, string | number>): string {
+	return template.replace(/\{(\w+)\}/g, (_, name) =>
+		name in values ? String(values[name]) : `{${name}}`,
+	);
+}
+
+export interface Translator {
+	(key: string, values?: Record<string, string | number>): string;
+}
+
+export const t: Readable<Translator> = derived(
+	[locale, messages],
+	([$locale, $messages]) => {
+		const dict = $messages[$locale];
+		return (key: string, values?: Record<string, string | number>) => {
+			const str = dict ? lookup(dict, key) : undefined;
+			if (str === undefined) return key;
+			return values ? interpolate(str, values) : str;
+		};
+	},
+);
+
+export const currentLocale: Readable<Locale> = { subscribe: locale.subscribe };