import { useEffect, useRef, useState } from "react";
import { useLocation, useNavigate } from "react-router-dom";
import menuSvg from "@/assets/menu.min.svg";

const NAV_ITEMS = [
  { label: "Browse", path: "/browse" },
  { label: "Compose", path: "/" },
] as const;

/**
 * Smooth scroll-following: tracks the scroll container and lerps
 * the menu's vertical offset so it glides into place with eased acceleration.
 */
function useSmoothScroll(scrollSelector: string, ease = 0.08) {
  const [offset, setOffset] = useState(0);
  const targetRef = useRef(0);
  const currentRef = useRef(0);
  const rafRef = useRef(0);

  useEffect(() => {
    const container = document.querySelector(scrollSelector);
    if (!container) return;

    const onScroll = () => {
      targetRef.current = container.scrollTop;
    };
    container.addEventListener("scroll", onScroll, { passive: true });

    const tick = () => {
      const diff = targetRef.current - currentRef.current;
      if (Math.abs(diff) < 0.5) {
        currentRef.current = targetRef.current;
      } else {
        currentRef.current += diff * ease;
      }
      setOffset(currentRef.current);
      rafRef.current = requestAnimationFrame(tick);
    };
    rafRef.current = requestAnimationFrame(tick);

    return () => {
      container.removeEventListener("scroll", onScroll);
      cancelAnimationFrame(rafRef.current);
    };
  }, [scrollSelector, ease]);

  return offset;
}

export default function NavMenu() {
  const navigate = useNavigate();
  const location = useLocation();
  const scrollY = useSmoothScroll("[data-scroll-root]", 0.07);

  return (
    <div
      className="nav-menu-root"
      style={{ transform: `translateY(${scrollY}px)` }}
    >
      {/* Frame — menu.min.svg as mask, colored by theme */}
      <div
        className="nav-menu-frame"
        style={{
          WebkitMaskImage: `url(${menuSvg})`,
          maskImage: `url(${menuSvg})`,
        }}
      />

      {/* Navigation links */}
      <nav className="nav-menu-links">
        {NAV_ITEMS.map(({ label, path }) => {
          const active = location.pathname === path;
          return (
            <button
              key={path}
              onClick={() => navigate(path)}
              className="nav-menu-item"
              data-active={active || undefined}
            >
              {label}
            </button>
          );
        })}
      </nav>
    </div>
  );
}
