"use client";

import { useEffect, useId, useRef, useState, type ReactNode } from "react";
import { animate, motion, useMotionValue, useMotionValueEvent, useReducedMotion } from "motion/react";

type StitchButtonProps = {
  children: ReactNode;
  className?: string;
  onClick?: () => void;
  /** Colour of the thread. */
  thread?: string;
  /** Share of the edge already sewn at rest, 0 to 1. */
  rest?: number;
  /** Seconds to sew the whole edge. */
  duration?: number;
};

const INSET = 7;

/* StitchButton: a cloth patch, half sewn. Hover and a needle finishes the edge stitch by stitch. Leave and it unpicks. */
export function StitchButton({
  children,
  className = "rounded-[14px] px-10 py-5 text-[15px] font-semibold tracking-wide text-[#f3ead7]",
  onClick,
  thread = "#f2c14e",
  rest = 0.4,
  duration = 1.1,
}: StitchButtonProps) {
  const reduce = useReducedMotion();
  const box = useRef<HTMLButtonElement>(null);
  const line = useRef<SVGRectElement>(null);
  const needle = useRef<SVGGElement>(null);
  const [size, setSize] = useState({ w: 0, h: 0 });
  const progress = useMotionValue(rest);
  const maskId = useId();

  useEffect(() => {
    const el = box.current;
    if (!el) return;
    const ro = new ResizeObserver(() => setSize({ w: el.offsetWidth, h: el.offsetHeight }));
    ro.observe(el);
    return () => ro.disconnect();
  }, []);

  const placeNeedle = (p: number) => {
    const path = line.current;
    if (!path || !needle.current || !size.w) return;
    const total = path.getTotalLength();
    const a = path.getPointAtLength(total * p);
    const b = path.getPointAtLength((total * p + 2) % total);
    const turn = (Math.atan2(b.y - a.y, b.x - a.x) * 180) / Math.PI;
    needle.current.setAttribute("transform", `translate(${a.x} ${a.y}) rotate(${turn})`);
  };

  useMotionValueEvent(progress, "change", placeNeedle);
  useEffect(() => placeNeedle(progress.get()));

  const sew = (on: boolean) => {
    const target = on ? 1 : rest;
    if (reduce) progress.set(target);
    else animate(progress, target, { duration: duration * Math.abs(target - progress.get()), ease: "linear" });
  };

  const rectProps = {
    x: INSET,
    y: INSET,
    width: Math.max(0, size.w - INSET * 2),
    height: Math.max(0, size.h - INSET * 2),
    rx: 8,
    fill: "none",
  };

  return (
    <button
      ref={box}
      type="button"
      onClick={onClick}
      onPointerEnter={(e) => e.pointerType === "mouse" && sew(true)}
      onPointerLeave={() => sew(false)}
      onPointerDown={() => sew(true)}
      onFocus={() => sew(true)}
      onBlur={() => sew(false)}
      className={`relative isolate ${className}`}
      style={{
        backgroundColor: "#2b4a6f",
        backgroundImage:
          "repeating-linear-gradient(45deg, rgba(255,255,255,0.06) 0 2px, transparent 2px 4px), repeating-linear-gradient(-45deg, rgba(0,0,0,0.14) 0 2px, transparent 2px 4px)",
        boxShadow: "0 3px 0 #1a3049, 0 10px 18px rgba(0,0,0,0.4)",
      }}
    >
      <svg aria-hidden className="pointer-events-none absolute inset-0 size-full overflow-visible">
        <defs>
          <mask id={maskId} maskUnits="userSpaceOnUse" x={-20} y={-20} width={size.w + 40} height={size.h + 40}>
            <motion.rect {...rectProps} stroke="#fff" strokeWidth={8} style={{ pathLength: progress }} />
          </mask>
        </defs>
        {/* Needle holes where the thread has not reached yet. */}
        <rect {...rectProps} stroke="rgba(0,0,0,0.45)" strokeWidth={1.6} strokeDasharray="1.6 13.4" strokeLinecap="round" />
        <rect ref={line} {...rectProps} stroke={thread} strokeWidth={2.6} strokeDasharray="10 5" strokeLinecap="round" mask={`url(#${maskId})`} />
        <g ref={needle}>
          <path d="M-13 0 L9 -1.2 L13 0 L9 1.2 Z" fill="#dfe5ec" stroke="#6d7886" strokeWidth={0.6} />
          <circle cx={-9.5} r={0.9} fill="#2b4a6f" />
        </g>
      </svg>
      <span className="relative">{children}</span>
    </button>
  );
}