initial commit

app/hooks/useI18n.ts

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+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
+import de from "@/locales/de.json";
+import en from "@/locales/en.json";
+import es from "@/locales/es.json";
+import fr from "@/locales/fr.json";
+import it from "@/locales/it.json";
+import sv from "@/locales/sv.json";
+
+const bundles = { en, es, fr, de, it, sv } as const;
+
+export type Locale = keyof typeof bundles;
+export type MessageKey = string;
+
+export type LocaleOption = {
+  code: Locale;
+  name: string;
+  emoji: string;
+};
+
+const localeOptions: LocaleOption[] = [
+  { code: "en", name: "English", emoji: "🇺🇸" },
+  { code: "es", name: "Español", emoji: "🇪🇸" },
+  { code: "fr", name: "Français", emoji: "🇫🇷" },
+  { code: "de", name: "Deutsch", emoji: "🇩🇪" },
+  { code: "it", name: "Italiano", emoji: "🇮🇹" },
+  { code: "sv", name: "Svenska", emoji: "🇸🇪" },
+];
+
+export function useI18n(defaultLocale: Locale = "en") {
+  const [locale, setLocale] = useState<Locale>(defaultLocale);
+  const hasDetectedLocale = useRef(false);
+
+  useEffect(() => {
+    if (hasDetectedLocale.current) return;
+    hasDetectedLocale.current = true;
+    const navLangs =
+      typeof navigator !== "undefined" ? navigator.languages || [navigator.language] : [];
+    const mapToLocale = (lang: string | undefined | null): Locale | null => {
+      if (!lang) return null;
+      const lower = lang.toLowerCase();
+      if (lower.startsWith("es")) return "es";
+      if (lower.startsWith("fr")) return "fr";
+      if (lower.startsWith("de")) return "de";
+      if (lower.startsWith("it")) return "it";
+      if (lower.startsWith("sv")) return "sv";
+      if (lower.startsWith("en")) return "en";
+      return null;
+    };
+    const detected = navLangs.map((l) => mapToLocale(l)).find(Boolean);
+    if (detected && detected !== locale) {
+      setLocale(detected);
+    }
+  }, [locale]);
+
+  const t = useCallback(
+    (key: MessageKey, vars?: Record<string, string>): string => {
+      const parts = key.split(".");
+      const dict = bundles[locale] ?? bundles.en;
+      const fallbackDict = bundles.en;
+      const resolveKey = (source: unknown) =>
+        parts.reduce<unknown>(
+          (acc, part) =>
+            acc && typeof acc === "object" ? (acc as Record<string, unknown>)[part] : undefined,
+          source
+        );
+      const value = resolveKey(dict) ?? resolveKey(fallbackDict);
+      const text = typeof value === "string" ? value : key;
+      if (!vars) return text;
+      return text.replace(/\{(\w+)\}/g, (_: string, k: string) => (vars[k] ? vars[k] : `{${k}}`));
+    },
+    [locale]
+  );
+
+  const options = useMemo(() => localeOptions, []);
+
+  return { locale, setLocale, t, localeOptions: options };
+}