/**
 * 图片提取 - 主图、SKU、详情图、视频
 * 从 docs/extension/plan.md §6.4 移植（核心逻辑）
 */
import { toAbsoluteUrl, toOriginalUrl, urlInBrackets, looksLikeImageUrl, dedupeKey } from './url';
import { queryAllDeep } from './dom';
import type { ImageGroupRule, SiteProfile, SrcProp } from '../profiles/types';

export interface ImageMaterial {
  key: string;           // 'main-001'
  groupKey: string;      // 'main'
  groupName: string;     // '主图'
  variantName?: string;  // SKU 规格名（仅 sku 组）
  url: string;           // 已还原为原图
  thumbUrl: string;      // 页面上的原始小图地址
  index: number;
  type: 'img' | 'video';
  width?: number;
  height?: number;
}

/**
 * 从元素上读出图片地址与名称，按 srcProps 顺序降级
 */
function readImageSource(
  el: Element,
  srcProps: SrcProp[],
  nameSelectors?: string[]
): { url: string; name: string; imgEl: HTMLImageElement | null } {
  let url = '';
  let name = '';
  // 真正承载图片的元素。选择器命中容器时它是子 <img>，
  // 尺寸过滤必须量它而不是容器，否则容器的 offsetWidth 会让小图蒙混过关
  let imgEl: HTMLImageElement | null = el instanceof HTMLImageElement ? el : null;

  for (const prop of srcProps) {
    if (url) break;

    if (prop === 'backgroundImage') {
      // SKU 组常用 CSS 背景图
      if (el.tagName === 'IMG') {
        const img = el as HTMLImageElement;
        url = img.currentSrc || img.src || '';
        name = img.alt || '';
      } else {
        // 尝试多种 SKU DOM 结构
        const bgCandidates = ['.prop-img', '.sku-item-image', '.single-sku-img-pop', '.item-image-icon'];
        for (const sel of bgCandidates) {
          const node = el.querySelector(sel);
          if (!node) continue;
          if (node instanceof HTMLImageElement && node.src) {
            url = node.src;
          } else {
            const bg = getComputedStyle(node).backgroundImage || '';
            url = (urlInBrackets(bg) || bg).replace(/['"]/g, '');
          }
          if (url) break;
        }
        // 兜底：元素自身背景图
        if (!url) {
          const bg = getComputedStyle(el).backgroundImage || '';
          const cand = (urlInBrackets(bg) || bg).replace(/['"]/g, '');
          if (looksLikeImageUrl(cand)) url = cand;
        }
      }
    } else {
      const raw = (el as any)[prop] || el.getAttribute(prop);
      if (raw) {
        // srcset 场景下 currentSrc 才是实际加载的那张
        url = prop === 'src' ? ((el as HTMLImageElement).currentSrc || (el as HTMLImageElement).src || '') : raw;
      }
    }
  }

  // 选择器命中的是容器、图在子节点上（淘宝 valueItem-- 就是这种）
  // 1688 的 SKU 是 CSS 背景图，走不到这里；淘宝的是真实 <img>，靠这段兜住
  if (!url && el.tagName !== 'IMG') {
    const inner = el.querySelector('img');
    if (inner) {
      url = inner.getAttribute('data-src') || inner.currentSrc || inner.src || '';
      imgEl = inner;
      if (!name) name = inner.alt || '';
    }
  }

  // 名称统一取（SKU 规格名）
  if (!name && nameSelectors?.length) {
    for (const sel of nameSelectors) {
      const t = el.querySelector(sel)?.textContent?.trim();
      if (t) { name = t; break; }
    }
  }

  return { url: url ? toAbsoluteUrl(url) : '', name, imgEl };
}

/**
 * 占位图识别。阿里系用 `-tps-1-1.png` / `-tps-2-2.png` 这类极小透明图
 * 占位，真实地址要等懒加载。采到它们等于污染数据。
 */
function isPlaceholder(url: string, imgEl: HTMLImageElement | null): boolean {
  if (/-tps-\d-\d\.(png|gif)/i.test(url)) return true;
  if (/^data:image\/gif/i.test(url)) return true;
  // 已加载完成但尺寸只有几像素 → 占位图
  if (imgEl?.complete && imgEl.naturalWidth > 0 && imgEl.naturalWidth <= 4) return true;
  return false;
}

export function collectImages(profile: SiteProfile): ImageMaterial[] {
  const result: ImageMaterial[] = [];

  for (const group of profile.imageGroups) {
    const srcProps = group.srcProps ?? profile.defaultSrcProps;

    // 去重按组独立：一张图同时是主图和 SKU 图是正常的，
    // 全局去重会让后处理的组丢图（连带丢掉 SKU 规格名）
    const seen = new Set<string>();

    // 排除"当前高亮"元素（画廊）
    const activeSet = new Set(group.activeSelectors ? queryAllDeep(group.activeSelectors) : []);

    for (const el of queryAllDeep(group.selectors)) {
      if (activeSet.has(el)) continue;

      // 跳过位于排除容器内的元素（如详情区里的用户评价图）
      if (group.excludeWithin?.some(sel => el.closest(sel))) continue;

      const { url: rawUrl, name, imgEl } = readImageSource(el, srcProps, group.nameSelectors);
      if (!rawUrl) continue;

      // 占位图不能进结果——它不是商品图
      if (group.type === 'img' && isPlaceholder(rawUrl, imgEl)) continue;

      // 视频校验
      if (group.type === 'video' && !/\.(mp4|avi|mov|wmv|m3u8)(\?|$)/i.test(rawUrl) && !/^https?:\/\//i.test(rawUrl)) {
        continue;
      }

      const url = group.type === 'img' ? toOriginalUrl(rawUrl) : rawUrl;

      // 尺寸过滤。量真正承载图片的 <img>，不是外层容器——
      // 否则容器的 offsetWidth 会让 2x2 占位图通过 minWidth 检查
      if (group.type === 'img' && (group.minWidth || group.minHeight)) {
        const measured = imgEl ?? (el as HTMLElement);
        const w = (measured as HTMLImageElement).naturalWidth || (measured as HTMLElement).offsetWidth || 0;
        const h = (measured as HTMLImageElement).naturalHeight || (measured as HTMLElement).offsetHeight || 0;
        // 尺寸为 0 说明还没加载完，放过它（别误杀懒加载图）
        if (w > 0 && h > 0 && (w < (group.minWidth ?? 0) || h < (group.minHeight ?? 0))) continue;
      }

      // 去重。SKU 组把规格名并入 key——不同规格共用同一张图时
      // 两条都要留下，否则规格与图的对应关系就断了
      const k = group.key === 'sku' ? `${dedupeKey(url)}::${name}` : dedupeKey(url);
      if (seen.has(k)) continue;
      seen.add(k);

      result.push({
        key: `${group.key}-${String(result.filter(r => r.groupKey === group.key).length + 1).padStart(3, '0')}`,
        groupKey: group.key,
        groupName: group.name,
        variantName: group.key === 'sku' ? name || undefined : undefined,
        url,
        thumbUrl: rawUrl,
        index: result.length,
        type: group.type
      });
    }
  }

  return result;
}