import { useCallback, useEffect, useLayoutEffect, useMemo, useRef, useState } from 'react';
import { imageURL, shareURL } from './assets.js';
import { detailOf, GENERIC_HEADING } from './detail.js';

/**
 * Full-screen viewer shared by the interior field and the product catalogue.
 *
 * A `photo` is either an interior record ({ id, url, ar, blur, source }) or
 * a product photo ({ sku, src, images, name, price, specs }). Interior records
 * carry no `images` field, but keying the gallery off product identity anyway
 * keeps the two paths unambiguous rather than merely incidental.
 */
function resolveSrc(photo, width) {
  if (photo.src) return photo.src;
  if (typeof photo.url === 'string' && /^https?:\/\//i.test(photo.url)) return photo.url;
  return imageURL(photo, width);
}

export default function PhotoViewer({ photo, timeList, onClose }) {
  const dialog = useRef(null);
  const frame = useRef(null);
  const closing = useRef(false);
  const animations = useRef([]);
  const zoomOrigin = useRef(null);
  const [loaded, setLoaded] = useState(false);
  const [zoomed, setZoomed] = useState(false);
  // Measured from the decoded image, so a product photo is not letterboxed
  // against an assumed ratio on first paint.
  const [measured, setMeasured] = useState(0);
  const [position, setPosition] = useState(0);     // product gallery index
  const [timePosition, setTimePosition] = useState(0); // time-ordered navigation index

  /**
   * A catalogue product, or a photograph?
   *
   * Not `Boolean(photo.sku)`: a photograph published on vai-avatar carries a
   * namespaced `sku` too (`avatarimg:<image_id>`), which is what lets it share
   * this viewer and the field with a product. Keying on it announced every such
   * photograph as "Sản phẩm (avatarimg:...)" and rendered the product price and
   * spec caption underneath it. `avatarImageId` is present only on records read
   * from the vai-avatar interior index -- and detail.js derives the flag from the
   * same field, so the two cannot disagree.
   */
  const isProduct = Boolean(photo.sku) && !photo.avatarImageId;

  // Only a product has a gallery worth paging through.
  const gallery = useMemo(
    () => (isProduct && Array.isArray(photo.images) ? photo.images.filter(Boolean) : null),
    [isProduct, photo.images],
  );

  /**
   * Time-ordered list of interiors (newest → oldest) handed down from the
   * field. When active, the arrows step through photographs by `addedAt`, and
   * the counter shows both the slot and the date of the current photo.
   *
   * If absent, the viewer falls back to the existing behaviour: a single
   * photograph or a product's own gallery.
   */
  const steppableList = useMemo(() => {
    if (timeList && Array.isArray(timeList) && timeList.length > 1) {
      return timeList;
    }
    return gallery;
  }, [timeList, gallery]);

  /**
   * The frame actually on screen.
   *
   * This has to read `position`, not just `photo`: resolving the URL straight
   * from the record pins the viewer to the first image, so the arrows would move
   * the counter while the photograph stayed frozen.
   */
  const src = useMemo(
    () => {
      const list = steppableList;
      const idx = timeList && timeList.length > 1 ? timePosition : position;
      return (list && list[idx]) ? resolveSrc(list[idx], 2400) : resolveSrc(photo, 2400);
    },
    [steppableList, timePosition, position, photo],
  );
  const preview = steppableList
    ? resolveSrc(steppableList[timeList && timeList.length > 1 ? timePosition : position], 640)
    : (photo.previewURL || resolveSrc(photo, 640));
  const ar = photo.ar || measured || 4 / 3;

  const sourceTransform = useCallback(() => {
    const rect = frame.current.getBoundingClientRect();
    const origin = photo.origin;
    if (!origin || !rect.width || !rect.height) return 'scale(.96)';
    return `translate(${origin.x + origin.width / 2 - rect.x - rect.width / 2}px, ${origin.y + origin.height / 2 - rect.y - rect.height / 2}px) scale(${origin.width / rect.width}, ${origin.height / rect.height})`;
  }, [photo.origin]);

  // A new frame re-arms the loading fade, the measured ratio and the zoom. This
  // deliberately does NOT touch `position`: `src` moves while paging, so
  // resetting the index here would snap every arrow press back to photo 1.
  useEffect(() => { setLoaded(false); setMeasured(0); setZoomed(false); }, [src]);

  // Opening a different photo starts that product's gallery from the beginning.
  useEffect(() => { setPosition(0); setTimePosition(0); }, [photo]);

  useEffect(() => {
    const previous = document.activeElement;
    dialog.current.showModal();
    if (!matchMedia('(prefers-reduced-motion: reduce)').matches) {
      animations.current = [frame.current.animate([
        { transform: sourceTransform(), opacity: 0.7 },
        { transform: 'none', opacity: 1 },
      ], { duration: 560, easing: 'cubic-bezier(.22,1,.36,1)' })];
    }
    return () => {
      animations.current.forEach(animation => animation.cancel());
      if (previous?.isConnected) previous.focus({ preventScroll: true });
    };
  }, [sourceTransform]);

  useLayoutEffect(() => {
    const before = zoomOrigin.current;
    zoomOrigin.current = null;
    if (!before || matchMedia('(prefers-reduced-motion: reduce)').matches) return;
    const after = frame.current.getBoundingClientRect();
    animations.current = [frame.current.animate([
      { transform: `translate(${before.x + before.width / 2 - after.x - after.width / 2}px, ${before.y + before.height / 2 - after.y - after.height / 2}px) scale(${before.width / after.width}, ${before.height / after.height})` },
      { transform: 'none' },
    ], { duration: 460, easing: 'cubic-bezier(.22,1,.36,1)' })];
  }, [zoomed]);

  const close = useCallback(async () => {
    if (closing.current) return;
    closing.current = true;
    if (!matchMedia('(prefers-reduced-motion: reduce)').matches) {
      const from = getComputedStyle(frame.current).transform;
      animations.current.forEach(animation => animation.cancel());
      const animation = frame.current.animate([
        { transform: from === 'none' ? 'none' : from, opacity: 1 },
        { transform: sourceTransform(), opacity: 0 },
      ], { duration: 320, easing: 'cubic-bezier(.4,0,.2,1)', fill: 'forwards' });
      animations.current = [animation];
      dialog.current.classList.add('is-closing');
      await animation.finished.catch(() => {});
    }
    onClose();
  }, [onClose, sourceTransform]);

  /**
   * Step through the steppable list (product gallery OR time-ordered interiors),
   * clamped at the ends.
   *
   * The clamp lives inside the updater so rapid arrow presses cannot drift the
   * index past the end and land on an empty frame.
   */
  const step = useCallback(delta => {
    const total = steppableList?.length ?? 0;
    if (total < 2) return;
    const setTime = timeList && timeList.length > 1 ? setTimePosition : setPosition;
    setTime(current => {
      const next = current + delta;
      return next < 0 || next >= total ? current : next;
    });
  }, [steppableList, timeList]);

  useEffect(() => {
    if (!steppableList || steppableList.length < 2) return;
    const onKey = event => {
      if (event.key === 'ArrowRight') { event.preventDefault(); step(1); }
      else if (event.key === 'ArrowLeft') { event.preventDefault(); step(-1); }
    };
    window.addEventListener('keydown', onKey);
    return () => window.removeEventListener('keydown', onKey);
  }, [steppableList, step]);

  // Escape stays with the dialog's own cancel event; only arrows are added here.
  const alt = isProduct
    ? `${photo.name || 'Sản phẩm'}${photo.sku ? ` (${photo.sku})` : ''}`
    : 'Ảnh nội thất đã phóng to';

  /**
   * A plain label, never a link.
   *
   * This used to render "View source ↗" pointed at photo.source. Nothing in the
   * viewer names or links to the scraped origin any more -- not the button, not
   * a "Nguồn" row in the fact table. The share link in the toolbar is the single
   * way out of the app, and the photograph's address is the only URL it needs.
   */
  const caption = <span className="photo-origin">
    {isProduct ? (photo.name || photo.sku) : ((photo.categories || [])[0] || photo.title || 'Interior design')}
  </span>;

  // Paging controls appear only when there is somewhere to go.
  const stepping = Boolean(steppableList && steppableList.length > 1);
  const usingTimeList = Boolean(timeList && timeList.length > 1);

  /**
   * What the share sheet shows above the URL.
   *
   * The record's own name, falling back to the heading the panel uses so the
   * sheet is never blank. Nothing scraped: a share card titled after daibau.vn
   * or noithatphuphat.com would carry somebody else's site name into the
   * reader's own messages, which is the same reason the panel stopped naming
   * them.
   */
  const shareTitle = (isProduct
    ? [photo.name, photo.n, photo.sku].find(value => typeof value === 'string' && value.trim())
    : [photo.title, detail.heading].find(value => typeof value === 'string' && value.trim())
  ) || 'Ảnh nội thất V.AI STUDIO';

  const share = shareURL(photo);
  const specs = isProduct && Array.isArray(photo.specs) ? photo.specs : null;

  const [shareLabel, setShareLabel] = useState('');
  const onShare = useCallback(async ({ url, title, label }) => {
    const announce = text => {
      label(text);
      window.clearTimeout(announce.timer);
      announce.timer = window.setTimeout(() => label(''), 1800);
    };
    if (navigator.share) {
      try {
        await navigator.share({ title, url });
        announce('Đã chia sẻ');
      } catch {
        // AbortError here means the sheet was swiped away. Nothing to report.
      }
      return;
    }
    if (navigator.clipboard?.writeText) {
      try {
        await navigator.clipboard.writeText(url);
        announce('Đã sao chép liên kết');
        return;
      } catch { /* fall through to the legacy path */ }
    }
    // Last resort, for a non-secure context or a blocked clipboard: a temporary
    // input selected and copied synchronously, which still works where the async
    // API above does not.
    const field = document.createElement('input');
    field.value = url;
    field.setAttribute('aria-hidden', 'true');
    document.body.append(field);
    field.select();
    const copied = document.execCommand?.('copy');
    field.remove();
    announce(copied ? 'Đã sao chép liên kết' : 'Không chia sẻ được');
  }, []);

  const detail = useMemo(() => detailOf(photo), [photo]);
  const generic = detail.description.startsWith('Ảnh trong bộ sưu tập');
  const hasDetail = Boolean(
    detail.room
    || detail.tags.length > 1
    || (detail.heading && detail.heading !== GENERIC_HEADING)
    || (detail.description && !generic),
  );

  const nowIdx = timeList && timeList.length > 1 ? timePosition : position;
  const currentItem = steppableList ? steppableList[nowIdx] : null;
  const dateLabel = (currentItem?.addedAt || photo.createdAt || '').slice(0, 10);

  return <dialog ref={dialog} className="photo-viewer" aria-label="Ảnh toàn màn hình"
    onCancel={event => { event.preventDefault(); close(); }}
    onClick={event => { if (event.target === dialog.current) close(); }}>
    <div className="photo-toolbar">
      {share ? <>
        {/*
          Two different jobs, two different controls.

          This button hands the photograph to whatever the reader already uses --
          Messages, Zalo, Telegram, the system sheet on iOS and Android. That is
          the gesture the icon already implied, and the old <a target="_blank">
          could not offer it: it opened a browser tab, not the reader's own apps.
          navigator.share is where the platform's share sheet lives; where it is
          absent or the user dismisses it, the clipboard takes over so there is
          always something to paste.

          A dismissal is not an error -- navigator.share rejects with AbortError
          every time the sheet is swiped away -- so a refusal is swallowed
          silently and nothing is announced.
        */}
        <button type="button" className="photo-share" onClick={() => onShare({ url: share, title: shareTitle, label: setShareLabel })}>
          <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.5" aria-hidden="true"><path d="M14 4h6v6M20 4l-9 9M18 14v5a1 1 0 0 1-1 1H5a1 1 0 0 1-1-1V7a1 1 0 0 1 1-1h5" /></svg>
          <span>{shareLabel || (isProduct ? 'Chia sẻ sản phẩm' : 'Chia sẻ ảnh')}</span>
        </button>
        <a className="photo-open" href={share} target="_blank" rel="noopener noreferrer"
          title={isProduct ? 'Xem sản phẩm trên V.AI STUDIO' : 'Xem ảnh nội thất trên V.AI STUDIO'}>
          <span>Xem trang</span>
        </a>
      </> : null}
      {caption}
      <button type="button" aria-label="Đóng ảnh" autoFocus onClick={close}>
        <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.5" aria-hidden="true"><path d="m6 6 12 12M6 18 18 6" /></svg>
      </button>
    </div>
    <div className={`photo-viewport ${zoomed ? 'is-zoomed' : ''}`} onClick={event => { if (event.target === event.currentTarget) close(); }}>
      {stepping && nowIdx > 0 && <button type="button" className="photo-step is-prev" aria-label="Ảnh trước"
        onClick={event => { event.stopPropagation(); step(-1); }}>
        <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.5" aria-hidden="true"><path d="m14 6-6 6 6 6" /></svg>
      </button>}
      <button ref={frame} type="button" className="photo-frame" aria-label={zoomed ? 'Thu nhỏ' : 'Phóng to ảnh'} aria-pressed={zoomed}
        style={{ '--photo-ar': ar, backgroundImage: `url("${preview}")` }}
        onClick={() => {
          zoomOrigin.current = frame.current.getBoundingClientRect();
          animations.current.forEach(animation => animation.cancel());
          setZoomed(value => !value);
        }}>
        <img src={src} alt={alt} className={loaded ? 'loaded' : ''}
          onLoad={event => {
            setLoaded(true);
            const image = event.currentTarget;
            if (image.naturalWidth && image.naturalHeight) {
              setMeasured(image.naturalWidth / image.naturalHeight);
            }
          }} />
      </button>
      {stepping && nowIdx < steppableList.length - 1 && <button type="button" className="photo-step is-next" aria-label="Ảnh tiếp theo"
        onClick={event => { event.stopPropagation(); step(1); }}>
        <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.5" aria-hidden="true"><path d="m10 6 6 6-6 6" /></svg>
      </button>}
    </div>
    {isProduct && (photo.price || (specs && specs.length)) ? <div className="photo-caption">
      {photo.price && <p className="photo-caption-price">{photo.price}</p>}
      {specs && specs.length > 0 ? <dl className="photo-caption-specs">
        {specs.slice(0, 6).map(([key, value], index) => (
          <div key={index}><dt>{key}</dt><dd>{value}</dd></div>
        ))}
      </dl> : null}
    </div> : null}
    {/*
      Detail panel, for BOTH kinds of record.

      Collapsible rather than always-open because the viewer is a photo first:
      on a phone there is no room for both. Closed by default keeps the first
      impression the photograph, while the summary line still shows the title
      and the price.

      <details>/<summary> rather than a button plus state: keyboard- and
      screen-reader-correct for free, and it survives a re-render mid-read.
    */}
    {hasDetail ? (
      <details className="photo-detail">
        <summary className="photo-detail-summary">
          <span className="photo-detail-title">{detail.heading}</span>
          {photo.price ? <span className="photo-detail-price">{photo.price}</span> : null}
          <span className="photo-detail-toggle" aria-hidden="true">Chi tiết</span>
        </summary>
        <div className="photo-detail-body">
          {detail.description ? <p className="photo-detail-desc">{detail.description}</p> : null}
          {detail.tags.length > 0 ? <ul className="photo-detail-tags">
            {detail.tags.map(tag => <li key={tag}>{tag}</li>)}
          </ul> : null}
          {detail.facts.length > 0 ? <dl className="photo-detail-facts">
            {detail.facts.map(([key, value], index) => (
              <div key={index}><dt>{key}</dt><dd>{value}</dd></div>
            ))}
          </dl> : null}
          {/*
            No "Xem bài gốc" link here, and no "Nguồn" row either. The panel
            answers "what am I looking at", and the share link in the toolbar
            above already carries the photograph's public address. Naming the
            scraped origin -- daibau.vn, noithatphuphat.com -- in the table put
            somebody else's domain in the middle of our own interface, on 1,113
            of the 1,222 photographs, for no gain to a reader.
          */}
        </div>
      </details>
    ) : null}
    {stepping ? (
      <p className="photo-counter" role="status" aria-live="polite"
        title={usingTimeList ? `Duyệt theo thời gian: ${dateLabel}` : ''}>
        {usingTimeList && dateLabel
          ? <span className="photo-date" title={currentItem.addedAt}>{dateLabel}</span>
          : `${nowIdx + 1} / ${steppableList.length}`}
      </p>
    ) : null}
  </dialog>;
}