/**
 * The script that runs inside the search results page.
 *
 * It is a string rather than a function because it is shipped to Chrome via
 * `Runtime.evaluate` — nothing in here is typechecked, so it is kept small,
 * defensive, and free of anything that could throw on an unexpected DOM.
 *
 * ## Why it does not select on class names
 *
 * Google's result classes (`MjjYud`, `kb0PBd`, `yuRUbf`, …) are generated and
 * change without notice; the `data-` hooks (`data-snhf` for the title/source
 * header, `data-sncf` for the description) are more stable but not promised
 * either. So the extractor uses them when present and otherwise falls back to a
 * structural walk that only assumes "an <h3> inside a link, with the
 * description somewhere in a shared ancestor":
 *
 *   - anchor  = nearest enclosing <a href>
 *   - header  = nearest [data-snhf], else the anchor itself
 *   - container = climb from the header until the text grows past the header's,
 *                 abandoning the climb if a second <h3> comes into scope
 *                 (that would mean we had swallowed the next result)
 *   - snippet = [data-sncf] if present, else the container's lines minus the
 *               header's lines, minus URL/breadcrumb noise
 *
 * Verified against both the classic SERP and the `udm=14` "Web" layout.
 */

/** One search hit, as the page script reports it. */
export type SearchResult = {
  title: string;
  url: string;
  snippet: string;
};

/** What the page script returns in a single round trip. */
export type PageProbe = {
  /** Where the page actually ended up — redirects and consent walls move it. */
  url: string;
  title: string;
  readyState: string;
  /** Non-null when a human check is in the way. */
  challenge: { kind: string; detail: string } | null;
  /**
   * Which results container the page rendered. "none" means Google served a
   * shell with no results area at all — a different failure from an empty one,
   * and worth telling apart when diagnosing a zero-hit search.
   */
  container: "rso" | "search" | "none";
  results: SearchResult[];
};

/**
 * Detection order matters: a `/sorry/` interstitial also contains a recaptcha
 * iframe, and reporting the specific page beats reporting the widget on it.
 */
export const PROBE_SCRIPT = String.raw`(() => {
  const norm = (s) => (s || "").replace(/\s+/g, " ").trim();
  const linesOf = (el) =>
    el && el.innerText ? el.innerText.split("\n").map((l) => l.trim()).filter(Boolean) : [];

  const bodyText = document.body ? norm(document.body.innerText).slice(0, 4000) : "";

  const detectChallenge = () => {
    const href = location.href;
    if (/\/sorry\//.test(href)) {
      return { kind: "google-block-page", detail: bodyText.slice(0, 300) };
    }
    if (location.hostname.indexOf("consent.") === 0 || /\/consent\b/.test(location.pathname)) {
      return { kind: "consent-wall", detail: bodyText.slice(0, 300) };
    }
    if (document.querySelector("#captcha-form, form#captcha-form")) {
      return { kind: "captcha-form", detail: bodyText.slice(0, 300) };
    }
    if (document.querySelector('iframe[src*="recaptcha"], iframe[src*="hcaptcha"], iframe[title*="challenge"]')) {
      return { kind: "captcha-widget", detail: bodyText.slice(0, 300) };
    }
    if (document.querySelector("#challenge-form, #cf-chl-widget, #cf-challenge-running")) {
      return { kind: "cloudflare-challenge", detail: bodyText.slice(0, 300) };
    }
    if (/unusual traffic|are you a robot|verify (that )?you('| a)?re human|not a robot|automated queries/i.test(bodyText)) {
      return { kind: "bot-check", detail: bodyText.slice(0, 300) };
    }
    return null;
  };

  const extract = () => {
    const root = document.querySelector("#rso") || document.querySelector("#search");
    if (!root) return [];
    const out = [];
    const seen = new Set();

    const headings = root.querySelectorAll("h3");
    for (let i = 0; i < headings.length; i++) {
      const h3 = headings[i];
      const anchor = h3.closest("a[href]") || (h3.parentElement && h3.parentElement.querySelector("a[href]"));
      if (!anchor) continue;

      const url = anchor.href;
      if (!/^https?:/.test(url)) continue;
      // Drop Google's own links (image search, cached copies, "more results").
      if (/^https?:\/\/(www\.)?google\.[a-z.]+\//.test(url)) continue;
      if (seen.has(url)) continue;

      const title = norm(h3.innerText);
      if (!title) continue;

      const header = h3.closest("[data-snhf]") || anchor;
      const headerLines = new Set(linesOf(header).map(norm));
      const baseline = norm(header.innerText || "").length;

      let container = header.parentElement;
      for (let depth = 0; depth < 6 && container && container !== root; depth++) {
        if (container.querySelectorAll("h3").length > 1) {
          container = null;
          break;
        }
        if (norm(container.innerText || "").length > baseline + 40) break;
        container = container.parentElement;
      }

      let snippet = "";
      if (container && container !== root) {
        const explicit = container.querySelector("[data-sncf]");
        const body = explicit ? linesOf(explicit) : linesOf(container).filter((l) => !headerLines.has(norm(l)));
        snippet = norm(
          body
            .filter((l) => !/^https?:\/\//.test(l) && l.indexOf("›") === -1 && l !== "Web results")
            .join(" "),
        )
          .replace(/Read more$/, "")
          .trim();
      }

      seen.add(url);
      out.push({ title: title, url: url, snippet: snippet.slice(0, 600) });
    }
    return out;
  };

  let challenge = null;
  let results = [];
  let container = "none";
  try {
    challenge = detectChallenge();
  } catch (e) {
    challenge = null;
  }
  try {
    container = document.querySelector("#rso") ? "rso" : document.querySelector("#search") ? "search" : "none";
    results = challenge ? [] : extract();
  } catch (e) {
    results = [];
  }

  return {
    url: location.href,
    title: document.title || "",
    readyState: document.readyState,
    challenge: challenge,
    container: container,
    results: results,
  };
})()`;