import { useLayoutEffect, useRef, useState } from "react";
import { FESTIVAL_GREETINGS, getNewYearDisplayYear, type FestivalId } from "@/lib/festival";
import "./festival.css";
import "./newyear.css";

/**
 * VU 区的静态插画横幅：两端角色保持比例，中央背景平铺，文字独立缩放。
 * 按容器宽度切换横排/双行，保留顶部设备信息；不参与布局、不拦截点击。
 */
export default function FestivalGreeting({
  festival,
}: {
  festival: FestivalId;
}) {
  const boxRef = useRef<HTMLDivElement>(null);
  const textBoxRef = useRef<HTMLDivElement>(null);
  const innerRef = useRef<HTMLDivElement>(null);
  const [scale, setScale] = useState(1);
  const [newYear] = useState(() => getNewYearDisplayYear());
  const isNewYear = festival === "newyear";
  const artworkRoot = `${import.meta.env.BASE_URL}images/festival/${festival}/`;

  useLayoutEffect(() => {
    const box = boxRef.current;
    const textBox = textBoxRef.current;
    const inner = innerRef.current;
    if (!box || !textBox || !inner) return;
    const status = box.parentElement?.querySelector<HTMLElement>(
      ".festival-vu-status"
    );
    let disposed = false;
    const fit = () => {
      if (disposed) return;
      // 先应用排版再测量；使用容器宽度，兼容横屏、分屏及 legacy。
      box.dataset.layout = box.clientWidth >= 420 ? "wide" : "compact";
      // 极窄屏的格式和音量分成两行，标题跟随实际状态栏高度下移。
      textBox.style.top = `${Math.max(17, status?.offsetHeight ?? 0) + 2}px`;
      const bw = textBox.clientWidth - 8;
      const bh = textBox.clientHeight - 4;
      const tw = inner.offsetWidth;
      const th = inner.offsetHeight;
      if (bw <= 0 || bh <= 0 || tw <= 0 || th <= 0) return;
      setScale(Math.min(bw / tw, bh / th));
    };
    fit();
    const ro =
      typeof ResizeObserver === "undefined" ? null : new ResizeObserver(fit);
    ro?.observe(box);
    ro?.observe(inner);
    if (status) ro?.observe(status);
    window.addEventListener("resize", fit);
    // 字体就绪后重新测量，避免初次回退字体导致文字越界。
    void document.fonts?.ready.then(fit);
    return () => {
      disposed = true;
      ro?.disconnect();
      window.removeEventListener("resize", fit);
    };
  }, [festival]);

  return (
    <div
      ref={boxRef}
      className={`festival-greeting festival-greeting--${festival}`}
      role="img"
      aria-label={isNewYear ? `${FESTIVAL_GREETINGS[festival]} ${newYear}` : FESTIVAL_GREETINGS[festival]}
    >
      <div
        className="festival-greeting-backdrop"
        style={{ backgroundImage: `url("${artworkRoot}banner-center.jpg")` }}
        aria-hidden="true"
      />
      {(["left", "right"] as const).map(side => (
        <img
          key={side}
          src={`${artworkRoot}banner-${side}.jpg`}
          className={`festival-greeting-art festival-greeting-art--${side}`}
          alt=""
          aria-hidden="true"
          draggable={false}
        />
      ))}
      <div className="festival-greeting-shade" aria-hidden="true" />
      {isNewYear && (
        <img
          src={`${artworkRoot}calendar.svg`}
          className="newyear-greeting-calendar"
          alt=""
          aria-hidden="true"
          draggable={false}
        />
      )}
      <div
        ref={textBoxRef}
        className="festival-greeting-title"
        aria-hidden="true"
      >
        <div
          ref={innerRef}
          className={`${festival}-greeting-text festival-greeting-inner`}
          style={{ transform: `scale(${scale})` }}
        >
          {isNewYear ? (
            <>
              <div className="newyear-greeting-heading">
                <div className="newyear-greeting-words">
                  <span>Happy</span>
                  <span>New Year</span>
                </div>
                <strong className="newyear-greeting-year">{newYear}</strong>
              </div>
              <span className="newyear-greeting-tagline">
                NEW YEAR · NEW CHAPTER · MORE POSSIBILITIES
              </span>
            </>
          ) : FESTIVAL_GREETINGS[festival].split(" ").map(word => (
            <span key={word} className="festival-greeting-line">
              {word}
            </span>
          ))}
        </div>
      </div>
    </div>
  );
}