/**
 * contrast-probe.mjs — 站点 chrome 的对比度探针（浏览器内测量，零依赖）。
 *
 * 判据：正文 ≥4.5:1（WCAG 1.4.3 AA），大字（≥24px 或 ≥18.66px 粗体）与图标字形 ≥3:1（1.4.11）。
 * 半透明背景沿父链合成后再算比值 —— 品牌浅底（`--kole-color-brand-bg`）就是半透明的，
 * 不合成会算错（实测差异可达 1 个数量级）。
 *
 * 用途：`tools/verify-dark.mjs`（暗色 7 条路由）与 `tools/verify-theme.mjs`（亮/暗双模式）
 * 共用同一套判据，避免两处各写一份、改一处漏一处。
 */
export const PROBE_SCOPE = '#sidebar *, #content *, .topbar *';

export async function probeContrast(page, { scope = PROBE_SCOPE, limit = 600 } = {}) {
  return page.evaluate(
    ({ scopeSel, maxNodes }) => {
      const bad = [];
      const toRGBA = (s) => {
        const m = (s || '').match(/rgba?\(([^)]+)\)/);
        if (!m) {
          if (/^#([0-9a-fA-F]{6})$/.test(s)) {
            const c = s.slice(1);
            return [parseInt(c.substr(0, 2), 16), parseInt(c.substr(2, 2), 16), parseInt(c.substr(4, 2), 16), 1];
          }
          return null;
        }
        const p = m[1].split(',').map((x) => parseFloat(x));
        return [p[0], p[1], p[2], p.length > 3 ? p[3] : 1];
      };
      const lumOf = (rgb) => {
        const f = (v) => { v /= 255; return v <= 0.03928 ? v / 12.92 : Math.pow((v + 0.055) / 1.055, 2.4); };
        return 0.2126 * f(rgb[0]) + 0.7152 * f(rgb[1]) + 0.0722 * f(rgb[2]);
      };
      const compBg = (el) => {
        let acc = null, p = el, d = 0;
        while (p && d < 10) {
          const rgba = toRGBA(getComputedStyle(p).backgroundColor);
          if (rgba) {
            if (!acc) acc = rgba.slice();
            else {
              const a = rgba[3] + acc[3] * (1 - rgba[3]);
              acc = [
                (rgba[0] * rgba[3] + acc[0] * acc[3] * (1 - rgba[3])) / (a || 1),
                (rgba[1] * rgba[3] + acc[1] * acc[3] * (1 - rgba[3])) / (a || 1),
                (rgba[2] * rgba[3] + acc[2] * acc[3] * (1 - rgba[3])) / (a || 1),
                a
              ];
            }
            if (acc[3] >= 0.999) break;
          }
          p = p.parentElement; d++;
        }
        return acc && acc[3] > 0 ? lumOf(acc) : null;
      };
      const isIcon = (t, cls) =>
        /^[\s\u2000-\u3300\u2190-\u21FF\u2600-\u27BF\u2B00-\u2BFF×✕✓⚠⌄⌃‹›«»]+$/.test(t) ||
        /\b(icon|arrow|caret|close|clear|toggle|sort|cross|star-|sep|bullet|chevron|indicator)\b/i.test(cls || '');
      let checked = 0;
      for (const el of document.querySelectorAll(scopeSel)) {
        if (checked > maxNodes) break;
        const cs = getComputedStyle(el);
        if (cs.display === 'none' || cs.visibility === 'hidden' || parseFloat(cs.opacity) === 0) continue;
        const txt = (el.textContent || '').trim();
        if (!txt) continue;
        let direct = false;
        for (const n of el.childNodes) if (n.nodeType === 3 && /\S/.test(n.nodeValue)) direct = true;
        if (!direct) continue;
        const rect = el.getBoundingClientRect();
        if (rect.width === 0 || rect.height === 0) continue;
        if (el.hasAttribute('disabled') || el.getAttribute('aria-disabled') === 'true') continue;
        const fg = toRGBA(cs.color);
        const bg = compBg(el);
        if (!fg || bg === null) continue;
        const r = (Math.max(lumOf(fg), bg) + 0.05) / (Math.min(lumOf(fg), bg) + 0.05);
        const fs = parseFloat(cs.fontSize) || 14;
        const fw = parseInt(cs.fontWeight, 10) || (cs.fontWeight === 'bold' ? 700 : 400);
        const large = fs >= 24 || (fs >= 18.66 && fw >= 700);
        const min = isIcon(txt, el.className) ? 3.0 : large ? 3.0 : 4.5;
        checked++;
        if (r < min) {
          bad.push(
            el.tagName.toLowerCase() + '.' + String(el.className || '').trim().split(/\s+/)[0] +
            ' "' + txt.slice(0, 10) + '" ' + r.toFixed(2) + ':1<' + min
          );
        }
        if (bad.length >= 5) break;
      }
      return { checked, bad };
    },
    { scopeSel: scope, maxNodes: limit }
  );
}