"use client";

import { useEffect, useRef } from "react";

const LETTERS = ["D", "K", "0"] as const;

// Ruhezustand und Spannweite der variablen Achsen von Bricolage Grotesque
const REST = { wght: 800, wdth: 100 };
const NEAR = { wght: 220, wdth: 75 };
const REACH_PX = 520;

/**
 * Das große „DK0“ im Plakat. Die Buchstaben werden dünner und schmaler, je näher
 * der Zeiger kommt, geglättet über eine kritisch gedämpfte Feder.
 * Ohne Maus oder bei reduzierter Bewegung bleibt es statisch. Das Markup ist
 * vollständig server-gerendert, JS fügt nur die Reaktion hinzu.
 */
export default function KineticWordmark() {
  const rootRef = useRef<HTMLDivElement>(null);
  const letterRefs = useRef<(HTMLSpanElement | null)[]>([]);

  useEffect(() => {
    const root = rootRef.current;
    const area = root?.closest("section");
    if (!root || !area) return;

    const fine = window.matchMedia?.("(hover: hover) and (pointer: fine)")?.matches ?? false;
    const reduce = window.matchMedia?.("(prefers-reduced-motion: reduce)")?.matches ?? false;
    if (!fine || reduce) return;

    const state = LETTERS.map(() => ({ w: REST.wght, d: REST.wdth, vw: 0, vd: 0, tw: REST.wght, td: REST.wdth }));
    let raf = 0;

    const loop = () => {
      let moving = false;
      state.forEach((s, i) => {
        s.vw = (s.vw + (s.tw - s.w) * 0.08) * 0.78;
        s.w += s.vw;
        s.vd = (s.vd + (s.td - s.d) * 0.08) * 0.78;
        s.d += s.vd;
        if (Math.abs(s.vw) + Math.abs(s.vd) > 0.05) moving = true;
        const el = letterRefs.current[i];
        if (el) el.style.fontVariationSettings = `"wght" ${s.w.toFixed(1)}, "wdth" ${s.d.toFixed(1)}`;
      });
      raf = moving ? requestAnimationFrame(loop) : 0;
    };
    const kick = () => {
      if (!raf) raf = requestAnimationFrame(loop);
    };

    const onMove = (e: PointerEvent) => {
      letterRefs.current.forEach((el, i) => {
        if (!el) return;
        const r = el.getBoundingClientRect();
        const dist = Math.hypot(e.clientX - (r.left + r.width / 2), e.clientY - (r.top + r.height / 2));
        const f = Math.min(1, dist / REACH_PX);
        state[i].tw = NEAR.wght + f * (REST.wght - NEAR.wght);
        state[i].td = NEAR.wdth + f * (REST.wdth - NEAR.wdth);
      });
      kick();
    };
    const onLeave = () => {
      state.forEach((s) => {
        s.tw = REST.wght;
        s.td = REST.wdth;
      });
      kick();
    };

    area.addEventListener("pointermove", onMove);
    area.addEventListener("pointerleave", onLeave);
    return () => {
      cancelAnimationFrame(raf);
      area.removeEventListener("pointermove", onMove);
      area.removeEventListener("pointerleave", onLeave);
    };
  }, []);

  return (
    <div
      ref={rootRef}
      aria-hidden="true"
      className="flex select-none items-end justify-between font-display text-[clamp(8.5rem,33vw,31rem)] leading-[0.78] tracking-[-0.05em]"
    >
      {LETTERS.map((letter, i) => (
        <span
          key={letter}
          ref={(el) => {
            letterRefs.current[i] = el;
          }}
          className={`inline-block animate-wordmark-up ${letter === "0" ? "text-paper" : ""}`}
          style={{ fontVariationSettings: `"wght" ${REST.wght}, "wdth" ${REST.wdth}`, animationDelay: `${i * 80}ms` }}
        >
          {letter}
        </span>
      ))}
    </div>
  );
}