"use client";

import { useEffect, useRef, type ReactNode } from "react";
import { animate, motion, useMotionTemplate, useMotionValue, useReducedMotion, useTransform } from "motion/react";

type PeelStickerProps = {
  children: ReactNode;
  className?: string;
  onClick?: () => void;
  /** Label printed on the paper under the sticker. */
  under?: ReactNode;
  /** Seconds before a peeled sticker lands back. */
  resetAfter?: number;
};

const REST = 12;
const HOVER = 17;

/* PeelSticker: a die-cut sticker with one corner lifted. Hover lifts it more, a click peels it right off the paper, then it lands back. */
export function PeelSticker({
  children,
  className = "bg-[#ff5d73] px-10 py-5 text-[16px] font-bold text-white",
  onClick,
  under = "Stuck on you",
  resetAfter = 1.6,
}: PeelStickerProps) {
  const reduce = useReducedMotion();
  const box = useRef<HTMLButtonElement>(null);
  const timer = useRef<ReturnType<typeof setTimeout>>(undefined);
  const peeled = useRef(false);
  const size = useMotionValue(0);
  const peel = useMotionValue(REST);
  const keep = useTransform(peel, (p) => 100 - p);

  // A line at 135deg is x + y = constant, so the fold stays true on any button size.
  const stickerMask = useMotionTemplate`linear-gradient(135deg, #000 ${keep}%, transparent ${keep}%)`;
  const flapMask = useMotionTemplate`linear-gradient(135deg, transparent ${keep}%, #000 ${keep}%)`;
  // Mirror across that same line: the lifted part folds over the sticker.
  const flapTransform = useTransform([peel, size], ([p, s]: number[]) => {
    const c = s * (1 - p / 100);
    return `matrix(0, -1, -1, 0, ${c}, ${c})`;
  });
  const flapOpacity = useTransform(peel, [96, 100], [1, 0]);

  useEffect(() => {
    const el = box.current;
    if (!el) return;
    const ro = new ResizeObserver(() => size.set(el.offsetWidth + el.offsetHeight));
    ro.observe(el);
    return () => {
      ro.disconnect();
      clearTimeout(timer.current);
    };
  }, [size]);

  const go = (to: number, seconds = 0.3) => {
    if (reduce) peel.set(to);
    else animate(peel, to, { duration: seconds, ease: "easeOut" });
  };

  return (
    <button
      ref={box}
      type="button"
      onClick={() => {
        onClick?.();
        peeled.current = true;
        go(100, 0.55);
        clearTimeout(timer.current);
        timer.current = setTimeout(() => {
          peeled.current = false;
          go(REST, 0.4);
        }, resetAfter * 1000);
      }}
      onPointerEnter={() => !peeled.current && go(HOVER)}
      onPointerLeave={() => !peeled.current && go(REST)}
      onFocus={() => !peeled.current && go(HOVER)}
      onBlur={() => !peeled.current && go(REST)}
      className="relative isolate inline-block rounded-2xl"
    >
      <span
        aria-hidden
        className="absolute inset-0 -z-10 grid place-items-center rounded-2xl border-2 border-dashed border-white/25 bg-[#17161f] text-[13px] text-white/70"
      >
        {under}
      </span>
      <span className="block [filter:drop-shadow(0_3px_4px_rgba(0,0,0,0.45))]">
        <motion.span
          className={`block rounded-2xl border-4 border-white ${className}`}
          style={{ maskImage: stickerMask, WebkitMaskImage: stickerMask }}
        >
          {children}
        </motion.span>
      </span>
      <span aria-hidden className="pointer-events-none absolute inset-0 [filter:drop-shadow(-3px_-3px_4px_rgba(0,0,0,0.4))]">
        <motion.span
          className="absolute inset-0 origin-top-left rounded-2xl bg-[linear-gradient(135deg,#ffffff,#e6e3dc_55%,#c9c5bb)]"
          style={{ transform: flapTransform, opacity: flapOpacity, maskImage: flapMask, WebkitMaskImage: flapMask }}
        />
      </span>
    </button>
  );
}