"use client";

import Link from "next/link";
import { usePathname } from "next/navigation";
import { useEffect, useState } from "react";
import Logo from "./logo";
import { localeNames, localeShort, locales, localize, splitLocale, type Locale } from "@/i18n/config";
import type { NavItem } from "@/i18n/nav";

export type HeaderLabels = {
  primary: string;
  bookCall: string;
  openMenu: string;
  closeMenu: string;
  language: string;
  logoHome: string;
};

function LanguageSwitch({ locale, path, label }: { locale: Locale; path: string; label: string }) {
  return (
    <nav className="lang-switch" aria-label={label}>
      {locales.map((l) =>
        // A plain link: switching language swaps the document's lang and direction.
        l === locale ? (
          <span key={l} aria-current="true" lang={l} title={localeNames[l]}>
            {localeShort[l]}
          </span>
        ) : (
          <a key={l} href={localize(path, l)} hrefLang={l} lang={l} title={localeNames[l]}>
            {localeShort[l]}
          </a>
        ),
      )}
    </nav>
  );
}

export default function SiteHeader({ locale, nav, t }: { locale: Locale; nav: NavItem[]; t: HeaderLabels }) {
  const pathname = usePathname();
  const { path } = splitLocale(pathname);
  const current = localize(path, locale);
  const [scrolled, setScrolled] = useState(false);
  const [hidden, setHidden] = useState(false);
  const [open, setOpen] = useState(false);
  const [menuPath, setMenuPath] = useState(pathname);

  // Close the mobile menu whenever the route changes.
  if (menuPath !== pathname) {
    setMenuPath(pathname);
    setOpen(false);
  }

  // Drop focus left on a nav link after navigating so its dropdown doesn't stay pinned open.
  useEffect(() => {
    const el = document.activeElement;
    if (el instanceof HTMLElement && el.closest(".site-header")) el.blur();
  }, [pathname]);

  useEffect(() => {
    let lastY = window.scrollY;
    const onScroll = () => {
      const y = window.scrollY;
      setScrolled(y > 24);
      setHidden(y > 480 && y > lastY + 4);
      if (y < lastY - 4 || y < 480) setHidden(false);
      lastY = y;
    };
    onScroll();
    window.addEventListener("scroll", onScroll, { passive: true });
    return () => window.removeEventListener("scroll", onScroll);
  }, []);

  useEffect(() => {
    document.body.style.overflow = open ? "hidden" : "";
    const onKey = (e: KeyboardEvent) => e.key === "Escape" && setOpen(false);
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, [open]);

  const isActive = (href: string) => current === href || current.startsWith(href + "/");
  const contactHref = localize("/contact", locale);
  const classes = ["site-header", scrolled || open ? "is-scrolled" : "", hidden && !open ? "is-hidden" : ""]
    .filter(Boolean)
    .join(" ");

  return (
    <>
      <header className={classes}>
        <div className="wrap bar">
          <Logo href={localize("/", locale)} label={t.logoHome} />
          <nav className="nav" aria-label={t.primary}>
            {nav.map((l) =>
              l.children ? (
                <div key={l.href} className="nav-group">
                  <Link href={l.href} className={isActive(l.href) ? "is-active" : undefined}>
                    {l.label}
                  </Link>
                  <div className="nav-panel">
                    <div className="nav-panel-inner">
                      <Link href={l.href} className="nav-panel-all">
                        {l.allLabel} <span className="arrow" aria-hidden="true">→</span>
                      </Link>
                      <ul>
                        {l.children.map((c) => (
                          <li key={c.href}>
                            <Link href={c.href} className={current === c.href ? "is-active" : undefined}>
                              {c.label}
                            </Link>
                          </li>
                        ))}
                      </ul>
                    </div>
                  </div>
                </div>
              ) : (
                <Link key={l.href} href={l.href} className={isActive(l.href) ? "is-active" : undefined}>
                  {l.label}
                </Link>
              ),
            )}
          </nav>
          <LanguageSwitch locale={locale} path={path} label={t.language} />
          <Link href={contactHref} className="btn btn-solid header-cta">
            {t.bookCall} <span className="arrow">→</span>
          </Link>
          <button
            type="button"
            className="menu-toggle"
            aria-expanded={open}
            aria-controls="mobile-menu"
            aria-label={open ? t.closeMenu : t.openMenu}
            onClick={() => setOpen((v) => !v)}
          >
            <span />
            <span />
          </button>
        </div>
      </header>
      <div id="mobile-menu" className={`mobile-menu${open ? " is-open" : ""}`} aria-hidden={!open} inert={!open}>
        <ul>
          {nav.map((l) => (
            <li key={l.href}>
              <Link href={l.href}>
                {l.label} <span className="arrow" aria-hidden="true">→</span>
              </Link>
              {l.children && (
                <div className="mobile-sub">
                  {l.children.map((c) => (
                    <Link key={c.href} href={c.href}>
                      {c.label}
                    </Link>
                  ))}
                </div>
              )}
            </li>
          ))}
        </ul>
        <LanguageSwitch locale={locale} path={path} label={t.language} />
        <Link href={contactHref} className="btn btn-solid">
          {t.bookCall} <span className="arrow">→</span>
        </Link>
      </div>
    </>
  );
}