"use client";

import { useEffect, useState } from "react";
import { useReducedMotion } from "motion/react";

const GLYPHS = "!<>-_\\/[]{}=+*^?#ABCDEFX01";

type TextScrambleProps = {
  /** Words to cycle through. */
  words: string[];
  className?: string;
  /** Milliseconds each word stays. */
  interval?: number;
  /** Characters shown while a letter is scrambling. */
  glyphs?: string;
};

/* TextScramble: letters shuffle through glyphs before settling, then the next word. */
export function TextScramble({ words, className = "", interval = 2600, glyphs = GLYPHS }: TextScrambleProps) {
  const reduce = useReducedMotion();
  const [index, setIndex] = useState(0);
  const target = words[index % words.length] ?? "";
  const [text, setText] = useState(target);

  useEffect(() => {
    if (words.length < 2) return;
    const id = window.setInterval(() => {
      if (!document.hidden) setIndex((i) => (i + 1) % words.length);
    }, interval);
    return () => window.clearInterval(id);
  }, [interval, words.length]);

  useEffect(() => {
    if (reduce) return;
    let tick = 0;
    let frame = 0;
    const step = () => {
      tick++;
      const out = target
        .split("")
        .map((ch, i) => (ch === " " || tick > i * 3 + 6 ? ch : glyphs[Math.floor(Math.random() * glyphs.length)]))
        .join("");
      setText(out);
      if (out !== target) frame = requestAnimationFrame(step);
    };
    frame = requestAnimationFrame(step);
    return () => cancelAnimationFrame(frame);
  }, [target, reduce, glyphs]);

  return (
    <span className={className}>
      <span className="sr-only">{target}</span>
      <span aria-hidden>{reduce ? target : text}</span>
    </span>
  );
}