// Google Ads (gtag) — lazily injected so it stays out of the initial bundle and
// off entirely when VITE_GOOGLE_ADS_ID is unset (dev/preview). All exported
// functions are fire-and-forget; tracking loss on failure is acceptable.
//
// Reports conversions client-side to Google Ads. The Google tag auto-captures
// gclid into its own _gcl_* cookies for click attribution; we additionally stash
// the raw gclid in a first-party cookie so a future server-side conversion import
// (Google Ads API, gated on Basic access) can attribute the same click.

type GtagArgs = unknown[];

declare global {
  interface Window {
    gtag?: (...args: GtagArgs) => void;
    dataLayer?: GtagArgs[];
  }
}

let _initialized = false;
let _adsId: string | undefined;

function captureGclid(): void {
  try {
    const p = new URLSearchParams(window.location.search);
    const gclid = p.get("gclid") || p.get("gbraid") || p.get("wbraid");
    if (gclid) {
      // 90-day first-party cookie for later server-side conversion import.
      document.cookie = `sase_gclid=${encodeURIComponent(gclid)}; path=/; max-age=${90 * 24 * 60 * 60}; SameSite=Lax`;
    }
  } catch {
    // URL/cookie access can throw in locked-down embeds — ignore.
  }
}

export function initGoogleAds(): void {
  const id = import.meta.env.VITE_GOOGLE_ADS_ID; // e.g. "AW-1234567890"
  if (!id || _initialized || typeof window === "undefined") return;
  _initialized = true;
  _adsId = id;

  window.dataLayer = window.dataLayer || [];
  // gtag.js executes only queue entries that are the `arguments` object; pushing a
  // plain array (rest params → `args`) is stored as inert dataLayer data and the
  // command (config/event) NEVER runs. That silently disabled ALL conversion
  // tracking — no _gcl_aw linker cookie, no conversion pings, 0 conversions in the
  // panel. Use Google's canonical snippet form that pushes `arguments`.
  function gtag() {
    // biome-ignore lint/style/noArguments: gtag.js only processes the raw arguments object
    window.dataLayer?.push(arguments as unknown as GtagArgs);
  }
  if (!window.gtag) window.gtag = gtag;

  const script = document.createElement("script");
  script.async = true;
  script.src = `https://www.googletagmanager.com/gtag/js?id=${encodeURIComponent(id)}`;
  const first = document.getElementsByTagName("script")[0];
  first?.parentNode?.insertBefore(script, first);

  window.gtag("js", new Date());
  // allow_enhanced_conversions lets hashed first-party data (email set below)
  // improve match rate without exposing PII to the page.
  window.gtag("config", id, { allow_enhanced_conversions: true });

  captureGclid();
}

// Enhanced Conversions: provide first-party data; the tag hashes it in-browser.
export function setGoogleAdsUserData(email?: string): void {
  if (!_initialized || !email) return;
  window.gtag?.("set", "user_data", { email });
}

// Fire a conversion. `label` is the conversion action's label (from Google Ads
// → Conversions); the event is sent to "<AW-id>/<label>". When unset (no label
// configured) this is a no-op, so the call sites stay safe before setup.
export function trackGoogleAdsConversion(
  label: string | undefined,
  opts?: { value?: number; currency?: string; transactionId?: string; email?: string },
): void {
  if (!_initialized || !_adsId || !label) return;
  if (opts?.email) setGoogleAdsUserData(opts.email);
  const params: Record<string, unknown> = { send_to: `${_adsId}/${label}` };
  if (opts?.value != null) params.value = opts.value;
  if (opts?.currency) params.currency = opts.currency;
  if (opts?.transactionId) params.transaction_id = opts.transactionId;
  window.gtag?.("event", "conversion", params);
}