"use client";

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

type PaintRollerProps = {
  text: string;
  className?: string;
  /** Paint colour. */
  paint?: string;
  /** Colour of the letters once painted. */
  ink?: string;
  /** Seconds for one pass. */
  duration?: number;
  /** Play only the first time it scrolls into view. */
  once?: boolean;
};

const PAD = "px-[0.45em] py-[0.18em]";
const DRIPS = [{ at: 16, size: 0.42 }, { at: 47, size: 0.26 }, { at: 78, size: 0.5 }];

// The roller leaves a dry, uneven edge along the top and bottom of the coat.
const dryEdge = (() => {
  const top: string[] = [];
  const bottom: string[] = [];
  for (let i = 0; i <= 40; i++) {
    const x = i * 2.5;
    top.push(`${x}% ${(i * 37) % 7}%`);
    bottom.push(`${100 - x}% ${100 - (i * 53) % 8}%`);
  }
  return `polygon(${[...top, ...bottom].join(",")})`;
})();

/* PaintRoller: letters pencilled on a wall until a real roller passes, laying a streaky wet coat and leaving drips. */
export function PaintRoller({
  text,
  className = "",
  paint = "#0f8b8d",
  ink = "#fff8ec",
  duration = 1.5,
  once = true,
}: PaintRollerProps) {
  const reduce = useReducedMotion();
  const box = useRef<HTMLSpanElement>(null);
  const inView = useInView(box, { once, amount: 0.6 });
  const done = useMotionValue(reduce ? 100 : 0);
  const left = useTransform(done, (d) => 100 - d);
  const coat = useMotionTemplate`inset(-10% ${left}% -10% 0)`;
  const rollerLeft = useMotionTemplate`${done}%`;
  const turn = useTransform(done, (d) => d * 3);
  const nap = useMotionTemplate`${turn}px 0, 0 0`;
  const drip0 = useTransform(done, [DRIPS[0].at + 8, DRIPS[0].at + 40], [0, 1]);
  const drip1 = useTransform(done, [DRIPS[1].at + 8, DRIPS[1].at + 40], [0, 1]);
  const drip2 = useTransform(done, [DRIPS[2].at + 8, 100], [0, 1]);
  const drips = [drip0, drip1, drip2];

  useEffect(() => {
    if (reduce) {
      done.set(100);
      return;
    }
    const pass = animate(done, inView ? 100 : 0, inView ? { duration, ease: "easeInOut" } : { duration: 0 });
    return () => pass.stop();
  }, [inView, reduce, duration, done]);

  return (
    <span ref={box} className={`relative inline-block ${className}`}>
      <span className="sr-only">{text}</span>
      <span aria-hidden className={`block ${PAD} opacity-40`} style={{ color: "transparent", WebkitTextStroke: `1px ${paint}` }}>
        {text}
      </span>
      {DRIPS.map((drip, i) => (
        <motion.span
          key={drip.at}
          aria-hidden
          className="absolute top-[97%] w-[0.07em] origin-top rounded-b-full"
          style={{ left: `${drip.at}%`, height: `${drip.size}em`, background: paint, scaleY: drips[i] }}
        />
      ))}
      <motion.span aria-hidden className="absolute inset-0" style={{ clipPath: coat }}>
        <span
          className="absolute inset-0"
          style={{
            clipPath: dryEdge,
            backgroundColor: paint,
            backgroundImage:
              "repeating-linear-gradient(0deg, rgba(255,255,255,0.09) 0 1px, transparent 1px 4px, rgba(0,0,0,0.08) 4px 5px, transparent 5px 9px)",
          }}
        />
        <span className={`relative block ${PAD}`} style={{ color: ink }}>
          {text}
        </span>
      </motion.span>
      <motion.span aria-hidden className="absolute -top-[0.14em] -bottom-[0.14em] w-[0.5em] -translate-x-1/2" style={{ left: rollerLeft }}>
        <motion.span
          className="absolute inset-0 rounded-[0.1em] shadow-[0_0.05em_0.15em_rgba(0,0,0,0.35)]"
          style={{
            backgroundColor: paint,
            backgroundImage:
              "repeating-linear-gradient(90deg, rgba(0,0,0,0.16) 0 2px, transparent 2px 6px), linear-gradient(90deg, rgba(0,0,0,0.4), rgba(255,255,255,0.3) 45%, rgba(0,0,0,0.45))",
            backgroundPosition: nap,
          }}
        />
        <svg viewBox="0 0 44 58" className="absolute top-full left-1/2 h-[1.2em] w-[0.92em] -translate-x-[0.04em]" fill="none">
          <path d="M3 0V9H30V24" stroke="#c6cbd3" strokeWidth="3" />
          <rect x="23" y="23" width="14" height="33" rx="6" fill="#2b2b33" />
        </svg>
      </motion.span>
    </span>
  );
}