refactor: migrate project to TypeScript and translate comments to English

app/context/LanguageContext.tsx

@@ -0,0 +1,51 @@
+'use client';
+
+import type {Dispatch, SetStateAction, ReactNode} from 'react';
+import type {Locale, SiteContent, Direction} from '@/types/domain';
+import {createContext, useContext, useEffect, useState} from 'react';
+import {content} from '@/data/content';
+
+interface LanguageContextValue {
+    locale: Locale;
+    setLocale: Dispatch<SetStateAction<Locale>>;
+    toggleLocale: () => void;
+    t: SiteContent;
+    dir: Direction;
+    mounted: boolean;
+}
+
+const LanguageContext = createContext<LanguageContextValue | null>(null);
+
+export function LanguageProvider({children}: {children: ReactNode}) {
+    const [locale, setLocale] = useState<Locale>('fa');
+    const [mounted, setMounted] = useState(false);
+
+    useEffect(() => {
+        const saved = window.localStorage.getItem('rm-locale');
+        if (saved === 'fa' || saved === 'en') setLocale(saved);
+        setMounted(true);
+    }, []);
+
+    useEffect(() => {
+        const root = document.documentElement;
+        root.lang = locale;
+        root.dir = content[locale].dir;
+        window.localStorage.setItem('rm-locale', locale);
+    }, [locale]);
+
+    const toggleLocale = () => setLocale((l) => (l === 'fa' ? 'en' : 'fa'));
+
+    return (
+        <LanguageContext.Provider
+            value={{locale, setLocale, toggleLocale, t: content[locale], dir: content[locale].dir, mounted}}
+        >
+            {children}
+        </LanguageContext.Provider>
+    );
+}
+
+export function useLanguage() {
+    const ctx = useContext(LanguageContext);
+    if (!ctx) throw new Error('useLanguage must be used within LanguageProvider');
+    return ctx;
+}