"use client";

import Link from "next/link";
import { usePathname } from "next/navigation";
import { useEffect, useState } from "react";
import { AnimatePresence, motion } from "framer-motion";
import { Logo } from "../ui/Logo";
import { ScrollProgress } from "../ui/ScrollProgress";
import { NAV_LINKS, STUDIO } from "@/lib/site";
import { EASE_OUT_EXPO } from "@/lib/motion";

export function Navbar() {
  const pathname = usePathname();
  const [scrolled, setScrolled] = useState(false);

  // The drawer stores the route it was opened on, so any navigation closes it
  // by derivation — no effect syncing state to the router.
  const [openedOn, setOpenedOn] = useState<string | null>(null);
  const open = openedOn === pathname;
  const close = () => setOpenedOn(null);

  useEffect(() => {
    const onScroll = () => setScrolled(window.scrollY > 20);
    onScroll();
    window.addEventListener("scroll", onScroll, { passive: true });
    return () => window.removeEventListener("scroll", onScroll);
  }, []);

  // Lock the page and allow Escape to dismiss while the drawer is open.
  useEffect(() => {
    if (!open) return;
    const onKeyDown = (event: KeyboardEvent) => {
      if (event.key === "Escape") setOpenedOn(null);
    };
    document.addEventListener("keydown", onKeyDown);
    const previousOverflow = document.body.style.overflow;
    document.body.style.overflow = "hidden";
    return () => {
      document.removeEventListener("keydown", onKeyDown);
      document.body.style.overflow = previousOverflow;
    };
  }, [open]);

  const isActive = (href: string) =>
    pathname === href || pathname.startsWith(`${href}/`);

  return (
    <header
      className={`fixed inset-x-0 top-0 z-50 transition-colors duration-300 ${
        scrolled || open
          ? "border-b border-border bg-background/85 backdrop-blur-md"
          : "border-b border-transparent bg-transparent"
      }`}
    >
      <nav className="mx-auto flex h-16 max-w-7xl items-center justify-between px-6 lg:h-20 lg:px-10">
        <Link
          href="/"
          aria-label={`${STUDIO.name} home`}
          className="group flex items-center gap-3"
        >
          <Logo
            width={44}
            priority
            className="transition-transform duration-300 ease-out group-hover:-translate-y-0.5 group-hover:scale-105"
          />
          <span className="hidden font-display text-xl tracking-wider transition-colors group-hover:text-accent sm:block">
            {STUDIO.shortName}
          </span>
        </Link>

        <ul className="hidden items-center gap-1 md:flex">
          {NAV_LINKS.map((link) => {
            const active = isActive(link.href);

            return (
              <li key={link.href}>
                <Link
                  href={link.href}
                  aria-current={active ? "page" : undefined}
                  className={`group/nav relative px-3 py-2 text-sm tracking-wide transition-colors ${
                    active
                      ? "text-accent"
                      : "text-foreground-muted hover:text-foreground"
                  }`}
                >
                  {link.label}

                  {/* Hover hairline for the pages you are not on. Sits under
                      the active marker, so the two never stack visibly. */}
                  {!active && (
                    <span
                      aria-hidden
                      className="absolute inset-x-3 -bottom-0.5 h-px origin-left scale-x-0 bg-foreground-muted/60 transition-transform duration-300 ease-out group-hover/nav:scale-x-100"
                    />
                  )}

                  {/* One shared element for every link: Framer moves it from
                      the old tab to the new one instead of cross-fading two
                      separate underlines. */}
                  {active && (
                    <motion.span
                      layoutId="nav-active"
                      aria-hidden
                      transition={{ type: "spring", stiffness: 420, damping: 34 }}
                      className="absolute inset-x-3 -bottom-0.5 h-px bg-accent"
                    />
                  )}
                </Link>
              </li>
            );
          })}
        </ul>

        <button
          type="button"
          aria-label={open ? "Close menu" : "Open menu"}
          aria-expanded={open}
          aria-controls="mobile-menu"
          onClick={() => setOpenedOn(open ? null : pathname)}
          className="relative flex h-10 w-10 items-center justify-center text-foreground transition-transform duration-200 hover:text-accent active:scale-90 md:hidden"
        >
          <span className="relative flex h-4 w-6 flex-col justify-between">
            <motion.span
              animate={open ? { rotate: 45, y: 7 } : { rotate: 0, y: 0 }}
              transition={{ duration: 0.25 }}
              className="block h-px origin-center bg-current"
            />
            <motion.span
              animate={{ opacity: open ? 0 : 1 }}
              transition={{ duration: 0.15 }}
              className="block h-px bg-current"
            />
            <motion.span
              animate={open ? { rotate: -45, y: -7 } : { rotate: 0, y: 0 }}
              transition={{ duration: 0.25 }}
              className="block h-px origin-center bg-current"
            />
          </span>
        </button>
      </nav>

      <AnimatePresence>
        {open && (
          <motion.div
            id="mobile-menu"
            initial={{ opacity: 0, y: -8 }}
            animate={{ opacity: 1, y: 0 }}
            exit={{ opacity: 0, y: -8 }}
            transition={{ duration: 0.25, ease: EASE_OUT_EXPO }}
            className="border-t border-border bg-background/95 backdrop-blur-md md:hidden"
          >
            {/* The rows deal out one by one. The drawer is the only place on
                the site where a whole navigation appears at once, and a block
                of four identical lines arriving together reads as a flash. */}
            <motion.ul
              initial="hidden"
              animate="visible"
              variants={{
                visible: { transition: { staggerChildren: 0.06, delayChildren: 0.05 } },
              }}
              className="flex flex-col px-6 py-4"
            >
              {NAV_LINKS.map((link) => (
                <motion.li
                  key={link.href}
                  variants={{
                    hidden: { opacity: 0, x: -12 },
                    visible: {
                      opacity: 1,
                      x: 0,
                      transition: { duration: 0.3, ease: EASE_OUT_EXPO },
                    },
                  }}
                >
                  <Link
                    href={link.href}
                    onClick={close}
                    aria-current={isActive(link.href) ? "page" : undefined}
                    className={`group flex items-center justify-between border-b border-border py-4 font-display text-2xl tracking-wider transition-colors last:border-b-0 ${
                      isActive(link.href)
                        ? "text-accent"
                        : "text-foreground hover:text-accent"
                    }`}
                  >
                    {link.label.toUpperCase()}
                    <span
                      aria-hidden
                      className="text-base opacity-0 transition-all duration-300 ease-out group-hover:translate-x-1 group-hover:opacity-100"
                    >
                      →
                    </span>
                  </Link>
                </motion.li>
              ))}
            </motion.ul>
          </motion.div>
        )}
      </AnimatePresence>

      <ScrollProgress />
    </header>
  );
}