"use client";

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

type BlurEntranceProps = {
  src: string;
  alt: string;
  /** Blur at the start, in pixels. */
  blur?: number;
  /** Seconds the picture takes to come into focus. */
  duration?: number;
  /** Seconds to wait first. Use it to stagger a row. */
  delay?: number;
  /** Play once, or again each time it comes back on screen. */
  once?: boolean;
  /** Set the size here. */
  className?: string;
};

/* BlurEntrance: the picture waits blurred and slightly enlarged, then settles into sharp focus once it is loaded and on screen. */
export function BlurEntrance({ src, alt, blur = 24, duration = 1.2, delay = 0, once = true, className = "aspect-video" }: BlurEntranceProps) {
  const reduce = useReducedMotion();
  const box = useRef<HTMLDivElement>(null);
  const picture = useRef<HTMLImageElement>(null);
  const seen = useInView(box, { once, amount: 0.3 });
  const [ready, setReady] = useState(false);

  useEffect(() => {
    let live = true;
    const done = () => {
      if (live) setReady(true);
    };
    picture.current?.decode().then(done, done);
    return () => {
      live = false;
    };
  }, [src]);

  const hidden = { filter: `blur(${blur}px)`, scale: 1.12, opacity: 0.4 };
  const sharp = reduce || (seen && ready);

  return (
    <div ref={box} className={`relative overflow-hidden ${className}`}>
      <motion.img
        ref={picture}
        src={src}
        alt={alt}
        className="absolute inset-0 size-full object-cover"
        initial={hidden}
        animate={sharp ? { filter: "blur(0px)", scale: 1, opacity: 1 } : hidden}
        transition={reduce ? { duration: 0 } : sharp ? { duration, delay, ease: [0.16, 1, 0.3, 1] } : { duration: 0.3 }}
      />
    </div>
  );
}