export const GA_MEASUREMENT_ID = "G-QTT9QT0T3S";
export const GOOGLE_ADS_ID = "AW-18432694647";
export const CONSENT_STORAGE_KEY = "evandro.analytics-consent.v1";
export const GA_DISABLE_KEY = "ga-disable-G-QTT9QT0T3S";

export type AnalyticsConsent = "granted" | "denied";
export type Gtag = (...args: unknown[]) => void;

declare global {
  interface Window {
    dataLayer?: IArguments[];
    "ga-disable-G-QTT9QT0T3S"?: boolean;
    gtag?: Gtag;
  }
}

export function readConsent(): AnalyticsConsent | null {
  try {
    const value = localStorage.getItem(CONSENT_STORAGE_KEY);
    return value === "granted" || value === "denied" ? value : null;
  } catch {
    return null;
  }
}

function analyticsPagePath(): string {
  const path = window.location.pathname.replace(/\/$/, "") || "/";
  switch (path) {
    case "/":
    case "/servicos":
    case "/cases":
    case "/curriculo":
    case "/privacidade":
    case "/ia":
      return path;
    default:
      // Route templates keep arbitrary slugs and personal data out of metrics.
      if (path.startsWith("/servicos/")) return "/servicos/[slug]";
      if (path.startsWith("/cases/")) return "/cases/[slug]";
      return "/other";
  }
}

type EventParams = Record<string, string>;

/**
 * Sends one GA4 event only while the visitor has granted consent; every other state is silent.
 * Callers must supply static labels, never form values or destination URLs.
 * Returns true when the event was handed to gtag, so the Ads conversion is only sent for a counted click.
 */
function sendEvent(name: string, params: EventParams): boolean {
  if (
    process.env.NODE_ENV !== "production" ||
    typeof window === "undefined" ||
    readConsent() !== "granted" ||
    window[GA_DISABLE_KEY] === true ||
    typeof window.gtag !== "function"
  ) {
    return false;
  }

  try {
    const pagePath = analyticsPagePath();
    window.gtag("event", name, {
      send_to: GA_MEASUREMENT_ID,
      ...params,
      page_path: pagePath,
      // Override gtag's URL defaults so query/hash/referrer data cannot leak.
      page_location: `https://evandro.dev.br${pagePath}`,
      page_referrer: "",
    });
    return true;
  } catch {
    // Analytics must never interrupt navigation. Dropped events are not replayed.
    return false;
  }
}

/**
 * Google Ads conversion for the same click, only when a conversion label is configured.
 * Without NEXT_PUBLIC_GOOGLE_ADS_CONVERSION_LABEL nothing is sent to Ads.
 */
function sendAdsConversion(): void {
  const label = process.env.NEXT_PUBLIC_GOOGLE_ADS_CONVERSION_LABEL;
  if (!label) return;
  try {
    window.gtag?.("event", "conversion", {
      send_to: `${GOOGLE_ADS_ID}/${label}`,
    });
  } catch {
    // Same rule as above: a blocked tag never interrupts navigation.
  }
}

/** Measures an attempted handoff, not an opened app, delivered message or lead. */
export function trackWhatsAppOpen({
  service,
  placement,
}: {
  service: string;
  placement: string;
}): void {
  if (sendEvent("whatsapp_open", { service, placement })) sendAdsConversion();
}

/** Measures a click on a mailto: link, not a sent e-mail. */
export function trackEmailClick({ placement }: { placement: string }): void {
  if (sendEvent("email_click", { placement })) sendAdsConversion();
}

/** Measures a click on a social profile; `network` is a static name such as "linkedin". */
export function trackSocialClick({ network }: { network: string }): void {
  sendEvent("social_click", { network });
}

/** Measures a click on the résumé PDF download. */
export function trackCvDownload({ placement }: { placement: string }): void {
  sendEvent("cv_download", { placement });
}

/** O rodapé pede a reabertura da barra de cookies; quem a monta (GoogleAnalytics) escuta este evento. */
export const OPEN_COOKIE_PREFERENCES_EVENT = "evandro:open-cookie-preferences";

/** Id da barra de cookies: o menu do celular a inclui na armadilha de foco enquanto ela está aberta (Header). */
export const COOKIE_BAR_ID = "cookie-bar";

export function openCookiePreferences(): void {
  if (typeof window === "undefined") return;
  window.dispatchEvent(new Event(OPEN_COOKIE_PREFERENCES_EVENT));
}