"use client";

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

type NeonTubeProps = {
  text: string;
  className?: string;
  /** Gas colour. */
  color?: string;
  /** Power. Set false to switch the sign off. */
  on?: boolean;
  /** Index of the worn letter that keeps stuttering, -1 for none. */
  stutter?: number;
};

const SCRIPT = "font-['Segoe_Script','Snell_Roundhand','Brush_Script_MT',cursive]";

type LetterProps = { ch: string; delay: number; lit: boolean; worn: boolean; color: string; reduce: boolean };

function Letter({ ch, delay, lit, worn, color, reduce }: LetterProps) {
  const glow = useMotionValue(0);

  useEffect(() => {
    if (reduce) {
      glow.set(lit ? 1 : 0);
      return;
    }
    if (!lit) {
      const off = animate(glow, 0, { duration: 0.18 });
      return () => off.stop();
    }
    let loop: ReturnType<typeof animate> | undefined;
    const strike = animate(glow, [0, 1, 0.1, 0, 0.85, 0.15, 1], { duration: 0.8, delay, times: [0, 0.14, 0.26, 0.5, 0.64, 0.78, 1] });
    if (worn) {
      strike.then(() => {
        loop = animate(glow, [1, 0.2, 1, 0.45, 1], { duration: 0.45, repeat: Infinity, repeatDelay: 4.5 });
      });
    }
    return () => {
      strike.stop();
      loop?.stop();
    };
  }, [lit, delay, worn, reduce, glow]);

  return (
    <>
      <span style={{ color: "rgba(255,255,255,0.2)", textShadow: "0 1px 0 rgba(255,255,255,0.28), 0 -1px 0 rgba(0,0,0,0.65)" }}>{ch}</span>
      <motion.span
        className="absolute inset-0"
        style={{
          opacity: glow,
          color: "#fffdf8",
          textShadow: `0 0 0.03em #fff, 0 0 0.1em ${color}, 0 0 0.26em ${color}, 0 0 0.6em ${color}, 0 0 1.1em ${color}`,
        }}
      >
        {ch}
      </motion.span>
    </>
  );
}

/* NeonTube: bent glass tube on clips, grey and dead at rest. Power up and each letter strikes on its own, one worn letter keeps stuttering. */
export function NeonTube({ text, className = SCRIPT, color = "#ff3d81", on = true, stutter = 3 }: NeonTubeProps) {
  const reduce = useReducedMotion() ?? false;
  const box = useRef<HTMLSpanElement>(null);
  const inView = useInView(box, { amount: 0.6 });
  const lit = on && inView;
  const words = text.split(" ");

  return (
    <span ref={box} className={`relative inline-block ${className}`}>
      <span className="sr-only">{text}</span>
      <motion.span
        aria-hidden
        className="pointer-events-none absolute -inset-[0.7em] rounded-full"
        style={{ background: `radial-gradient(closest-side, ${color}44, transparent)` }}
        initial={{ opacity: 0 }}
        animate={{ opacity: lit ? 1 : 0 }}
        transition={{ duration: 0.5, delay: lit ? 0.5 : 0 }}
      />
      <span aria-hidden className="relative">
        {words.map((word, w) => {
          const start = words.slice(0, w).join(" ").length + (w ? 1 : 0);
          return (
            <span key={w}>
              {w > 0 && " "}
              <span className="inline-block whitespace-nowrap">
                {[...word].map((ch, c) => {
                  const i = start + c;
                  return (
                    <span key={i} className="relative inline-block">
                      <Letter ch={ch} lit={lit} color={color} reduce={reduce} worn={i === stutter} delay={((i * 7) % 11) * 0.09} />
                      {i % 3 === 1 && (
                        <span className="absolute bottom-[0.27em] left-1/2 h-[0.07em] w-[0.34em] -translate-x-1/2 rounded-full bg-[#8d9099] shadow-[0_1px_1px_rgba(0,0,0,0.7)]" />
                      )}
                    </span>
                  );
                })}
              </span>
            </span>
          );
        })}
      </span>
    </span>
  );
}