"use client";

import Script from "next/script";
import { useCallback, useEffect, useRef, useState } from "react";
import {
  type AnalyticsConsent,
  CONSENT_STORAGE_KEY,
  COOKIE_BAR_ID,
  GA_DISABLE_KEY,
  GA_MEASUREMENT_ID,
  GOOGLE_ADS_ID,
  type Gtag,
  OPEN_COOKIE_PREFERENCES_EVENT,
  readConsent,
} from "@/lib/analytics";
import "./conversion.css";

const GA_SCRIPT_SRC = `https://www.googletagmanager.com/gtag/js?id=${GA_MEASUREMENT_ID}`;
const SITE_DOMAIN = "evandro.dev.br";

const deniedConsent = {
  analytics_storage: "denied",
  ad_storage: "denied",
  ad_user_data: "denied",
  ad_personalization: "denied",
} as const;

function persistConsent(value: AnalyticsConsent): boolean {
  try {
    localStorage.setItem(CONSENT_STORAGE_KEY, value);
    return true;
  } catch {
    return false;
  }
}

function getGtag(): Gtag {
  window.dataLayer ??= [];
  const dataLayer = window.dataLayer;
  if (!window.gtag) {
    window.gtag = function gtag() {
      // biome-ignore lint/complexity/noArguments: The official gtag bootstrap requires an IArguments entry, not an Array.
      dataLayer.push(arguments);
    };
  }
  return window.gtag;
}

function removeAnalyticsLoader() {
  document.getElementById("google-analytics-script")?.remove();
}

function writeCookie(value: string) {
  // biome-ignore lint/suspicious/noDocumentCookie: Cookie Store is not universal and domain-scoped GA cookies must also be expired.
  document.cookie = value;
}
function expireAnalyticsCookies() {
  const cookieNames = new Set(
    document.cookie
      .split(";")
      .map((cookie) => cookie.split("=")[0]?.trim())
      .filter(
        (name): name is string =>
          name === "_ga" || Boolean(name?.startsWith("_ga_")),
      ),
  );
  const { hostname } = window.location;
  const domains =
    hostname === SITE_DOMAIN || hostname.endsWith(`.${SITE_DOMAIN}`)
      ? new Set([hostname, SITE_DOMAIN])
      : new Set<string>();

  for (const name of cookieNames) {
    const expiration = `${name}=; Max-Age=0; Expires=Thu, 01 Jan 1970 00:00:00 GMT; Path=/; SameSite=Lax`;
    writeCookie(expiration);
    for (const domain of domains) {
      writeCookie(`${expiration}; Domain=${domain}`);
    }
  }
}

const barButtonClassName =
  "cv-btn inline-flex min-h-10 min-w-11 items-center justify-center border px-[10px] py-sp-1 transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-white focus-visible:ring-offset-2 focus-visible:ring-offset-[var(--ink)] motion-reduce:transition-none";

function GoogleAnalyticsConsent() {
  const [consent, setConsent] = useState<AnalyticsConsent | null>();
  const [preferencesOpen, setPreferencesOpen] = useState(false);
  const [consentError, setConsentError] = useState<string | null>(null);
  const configuredRef = useRef(false);
  const barRef = useRef<HTMLElement>(null);
  const acceptRef = useRef<HTMLButtonElement>(null);
  const openerRef = useRef<HTMLElement | null>(null);

  const enableAnalytics = useCallback(() => {
    const gtag = getGtag();
    window[GA_DISABLE_KEY] = false;
    if (!configuredRef.current) {
      gtag("consent", "default", deniedConsent);
      gtag("set", "ads_data_redaction", true);
      gtag("js", new Date());
      configuredRef.current = true;
    }
    gtag("consent", "update", {
      ...deniedConsent,
      analytics_storage: "granted",
    });
    gtag("config", GA_MEASUREMENT_ID, {
      allow_ad_personalization_signals: false,
      anonymize_ip: true,
    });
    // One loader serves both destinations; GT IDs are aliases, not extra installs.
    gtag("config", GOOGLE_ADS_ID, {
      allow_ad_personalization_signals: false,
    });
  }, []);

  useEffect(() => {
    const storedConsent = readConsent();
    if (storedConsent === "granted") enableAnalytics();
    setConsent(storedConsent);
  }, [enableAnalytics]);

  useEffect(() => {
    if (consent !== "granted" && consent !== undefined) {
      removeAnalyticsLoader();
    }
  }, [consent]);

  // O link "Preferências de cookies" do rodapé reabre a barra; quem pediu recebe o foco de volta ao fechar.
  useEffect(() => {
    const reopen = () => {
      openerRef.current =
        document.activeElement instanceof HTMLElement
          ? document.activeElement
          : null;
      setPreferencesOpen(true);
    };
    window.addEventListener(OPEN_COOKIE_PREFERENCES_EVENT, reopen);
    return () =>
      window.removeEventListener(OPEN_COOKIE_PREFERENCES_EVENT, reopen);
  }, []);

  const barOpen = consent === null || preferencesOpen;

  // Enquanto a barra está na tela, publica a altura dela para o botão flutuante do WhatsApp subir.
  useEffect(() => {
    const bar = barRef.current;
    if (!barOpen || !bar) return;
    const root = document.documentElement;
    const publish = () =>
      root.style.setProperty("--cookie-bar-height", `${bar.offsetHeight}px`);
    publish();
    root.setAttribute("data-cookie-bar", "open");
    const observer = new ResizeObserver(publish);
    observer.observe(bar);
    return () => {
      observer.disconnect();
      root.style.removeProperty("--cookie-bar-height");
      root.removeAttribute("data-cookie-bar");
    };
  }, [barOpen]);

  // Reaberta pelo rodapé, a barra está no começo do documento: leva o foco para ela.
  useEffect(() => {
    if (preferencesOpen) acceptRef.current?.focus();
  }, [preferencesOpen]);

  function closePreferences() {
    setPreferencesOpen(false);
    openerRef.current?.focus();
    openerRef.current = null;
  }

  function acceptAnalytics() {
    if (consent === "granted") {
      closePreferences();
      return;
    }
    if (!persistConsent("granted")) {
      setConsentError(
        "Não foi possível salvar sua aceitação. Tente novamente para concluir.",
      );
      return;
    }
    setConsentError(null);
    enableAnalytics();
    setConsent("granted");
    closePreferences();
  }

  function denyAnalytics() {
    const revoking = consent === "granted";
    if (!persistConsent("denied")) {
      setConsentError(
        revoking
          ? "Não foi possível salvar a revogação. Tente novamente para concluir."
          : "Não foi possível salvar sua recusa. Tente novamente para concluir.",
      );
      return;
    }
    setConsentError(null);
    if (revoking) {
      window[GA_DISABLE_KEY] = true;
      window.gtag?.("consent", "update", deniedConsent);
      expireAnalyticsCookies();
    }
    setConsent("denied");
    closePreferences();
  }

  if (consent === undefined) return null;

  return (
    <>
      {consent === "granted" && process.env.NODE_ENV === "production" && (
        <Script
          id="google-analytics-script"
          data-testid="google-analytics-script"
          src={GA_SCRIPT_SRC}
          strategy="afterInteractive"
        />
      )}
      {barOpen && (
        <section
          ref={barRef}
          id={COOKIE_BAR_ID}
          role="dialog"
          aria-modal="false"
          aria-label="Cookies e privacidade"
          aria-describedby="analytics-consent-description"
          onKeyDown={(event) => {
            if (event.key === "Escape" && preferencesOpen) closePreferences();
          }}
          className="ds-enter fixed inset-x-0 bottom-0 z-[9980] border-t border-white/20 bg-[var(--ink)] px-sp-4 pt-sp-2 pb-[max(var(--sp-2),env(safe-area-inset-bottom))] text-white shadow-[0_-8px_24px_rgba(0,0,0,0.35)] [--enter-y:16px] sm:px-sp-6"
        >
          <div className="mx-auto flex max-w-[1100px] items-center gap-sp-3 sm:gap-sp-6">
            {/* Até 72 px de altura em 390 px: três linhas de 13 px ao lado dos botões (15 px de 640 px em diante). */}
            <p
              id="analytics-consent-description"
              className="min-w-0 flex-1 font-display text-[13px] leading-[1.3] text-white/85 sm:text-[15px]"
            >
              Métricas de navegação do Google, só se você permitir.{" "}
              {/* o preenchimento vertical dá ao link 24 px de alvo de toque sem engordar a linha */}
              <a
                className="whitespace-nowrap py-1 underline underline-offset-2 hover:text-white hover:decoration-2 focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-white"
                href="/privacidade"
              >
                Política de privacidade
              </a>
              {preferencesOpen && consent && (
                <span className="sr-only">
                  {" "}
                  Escolha atual:{" "}
                  {consent === "granted" ? "permitido" : "recusado"}.
                </span>
              )}
            </p>
            <div className="flex shrink-0 gap-sp-2">
              <button
                type="button"
                ref={acceptRef}
                className={`${barButtonClassName} cv-fill border-[#f4f2ed] bg-[#f4f2ed] text-[var(--ink)] [--block:var(--slash)]`}
                onClick={acceptAnalytics}
              >
                Aceitar
              </button>
              <button
                type="button"
                className={`${barButtonClassName} cv-outline-dark border-white/45 bg-transparent text-white`}
                onClick={denyAnalytics}
              >
                Recusar
              </button>
            </div>
          </div>
          {consentError && (
            <p
              role="alert"
              aria-label="Falha ao salvar o consentimento"
              className="mx-auto mt-sp-1 max-w-[1100px] font-display text-[15px] leading-5 text-[#ff9d94]"
            >
              {consentError}
            </p>
          )}
        </section>
      )}
    </>
  );
}

/**
 * A barra de cookies e o consentimento aparecem em qualquer ambiente: no desenvolvimento a página fica igual à da
 * produção (ordem do Tab, altura da barra, rodapé). Só o carregamento do gtag (o <Script> acima) fica preso à produção.
 */
export default function GoogleAnalytics() {
  return <GoogleAnalyticsConsent />;
}