'use client';

import { useCallback, useMemo } from 'react';
import {
  useRouter as useNextRouter,
  usePathname as useNextPathname,
} from 'next/navigation';
import { locales, type Locale } from './config';
import { useLocale } from './I18nProvider';

const localePrefixes = locales.map((l) => `/${l}`);

/** Prefix an internal href with the given locale. Leaves external/hash/already-prefixed hrefs untouched. */
export function localizeHref(href: string, locale: Locale): string {
  if (!href.startsWith('/')) return href; // external, hash, or relative
  // already locale-prefixed?
  if (localePrefixes.some((p) => href === p || href.startsWith(p + '/'))) return href;
  return href === '/' ? `/${locale}` : `/${locale}${href}`;
}

/** Strip a leading locale segment from a pathname, returning the locale-agnostic path. */
export function stripLocale(pathname: string): string {
  for (const p of localePrefixes) {
    if (pathname === p) return '/';
    if (pathname.startsWith(p + '/')) return pathname.slice(p.length);
  }
  return pathname;
}

/** Replace (or add) the locale segment of a pathname. Used by the language switcher. */
export function swapLocale(pathname: string, locale: Locale): string {
  return localizeHref(stripLocale(pathname), locale);
}

/** A next/navigation router whose push/replace/prefetch auto-prefix the active locale. */
export function useLocalizedRouter() {
  const router = useNextRouter();
  const locale = useLocale();
  return useMemo(
    () => ({
      ...router,
      push: (href: string, opts?: Parameters<typeof router.push>[1]) =>
        router.push(localizeHref(href, locale), opts),
      replace: (href: string, opts?: Parameters<typeof router.replace>[1]) =>
        router.replace(localizeHref(href, locale), opts),
      prefetch: (href: string, opts?: Parameters<typeof router.prefetch>[1]) =>
        router.prefetch(localizeHref(href, locale), opts),
    }),
    [router, locale],
  );
}

/** The current pathname with the locale segment stripped (e.g. /dashboard/apps). */
export function usePathname(): string {
  const pathname = useNextPathname();
  return useMemo(() => stripLocale(pathname ?? '/'), [pathname]);
}

/** Returns a memoized localizer bound to the active locale. */
export function useLocalize() {
  const locale = useLocale();
  return useCallback((href: string) => localizeHref(href, locale), [locale]);
}