"use client";

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

import { cn } from "@/lib/utils";

const CHARSET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789/_-";

type ScrambleTextProps = {
  text: string;
  className?: string;
  durationMs?: number;
};

export function ScrambleText({ text, className, durationMs = 1200 }: ScrambleTextProps) {
  const reduceMotion = useReducedMotion();
  const [display, setDisplay] = useState(text);

  useEffect(() => {
    if (reduceMotion) {
      setDisplay(text);
      return;
    }

    let frame = 0;
    const totalFrames = Math.ceil(durationMs / 32);
    const locked = new Set<number>();

    const id = window.setInterval(() => {
      frame += 1;
      const progress = frame / totalFrames;

      for (let i = 0; i < text.length; i++) {
        if (text[i] === " ") continue;
        if (Math.random() < progress * 0.15 + 0.05) locked.add(i);
      }

      const next = text
        .split("")
        .map((char, i) => {
          if (char === " ") return " ";
          if (locked.has(i) || progress > 0.92) return char;
          return CHARSET[Math.floor(Math.random() * CHARSET.length)] ?? char;
        })
        .join("");

      setDisplay(next);

      if (frame >= totalFrames) {
        window.clearInterval(id);
        setDisplay(text);
      }
    }, 32);

    return () => window.clearInterval(id);
  }, [text, durationMs, reduceMotion]);

  return (
    <motion.span className={cn("inline-block", className)} initial={{ opacity: 0 }} animate={{ opacity: 1 }}>
      {display}
    </motion.span>
  );
}