import React from "react";
import CookieBanner from "./CookieBanner";

export const CONSENT_COOKIE_NAME = "omniasr_transcription_consent";

// Declare gtag global function
declare global {
  interface Window {
    gtag: (...args: any[]) => void;
    dataLayer: any[];
  }
}

const Analytics = () => {
  const [analyticsEnabled, setAnalyticsEnabled] = React.useState(false);
  const [consentState, setConsentState] = React.useState<boolean | null>(null); // In-memory fallback
  const [showBanner, setShowBanner] = React.useState(false); // Control banner visibility

  // Check if we're in iframe (like HuggingFace Spaces)
  const isInIframe = () => {
    try {
      return window.self !== window.top;
    } catch (e) {
      return true;
    }
  };

  // Get consent with fallback chain: memory -> localStorage -> sessionStorage -> cookies
  const getConsent = (): boolean => {
    // First check in-memory state (for HF spaces that block all storage)
    if (consentState !== null) {
      return consentState;
    }

    // Try localStorage
    try {
      const localValue = window.localStorage.getItem(CONSENT_COOKIE_NAME);
      if (localValue !== null) {
        return localValue === "true";
      }
    } catch (e) {}

    // Try sessionStorage
    try {
      const sessionValue = window.sessionStorage.getItem(CONSENT_COOKIE_NAME);
      if (sessionValue !== null) {
        return sessionValue === "true";
      }
    } catch (e) {}

    // Try cookies
    try {
      return document.cookie.includes(`${CONSENT_COOKIE_NAME}=true`);
    } catch (e) {}

    return false;
  };

  // Set consent with fallback chain
  const setConsent = (accepted: boolean) => {
    // Always set in-memory state first (works in all environments)
    setConsentState(accepted);

    // Try localStorage
    try {
      window.localStorage.setItem(CONSENT_COOKIE_NAME, accepted.toString());
    } catch (e) {}

    // Try sessionStorage as fallback
    try {
      window.sessionStorage.setItem(CONSENT_COOKIE_NAME, accepted.toString());
    } catch (e) {}

    // Try cookies (mainly for non-iframe environments)
    if (!isInIframe()) {
      try {
        const expires = new Date();
        expires.setFullYear(expires.getFullYear() + 1);
        document.cookie = `${CONSENT_COOKIE_NAME}=${accepted}; expires=${expires.toUTCString()}; path=/; SameSite=Lax`;
      } catch (e) {}
    }
  };

  // Load gtag script dynamically
  const loadGtagScript = (gaId: string) => {
    return new Promise<void>((resolve, reject) => {
      // Check if gtag is already loaded
      if (window.gtag) {
        resolve();
        return;
      }

      // Create script element
      const script = document.createElement('script');
      script.async = true;
      script.src = `https://www.googletagmanager.com/gtag/js?id=${gaId}`;

      script.onload = () => {
        // Initialize gtag
        window.dataLayer = window.dataLayer || [];
        window.gtag = function gtag() {
          window.dataLayer.push(arguments);
        };
        window.gtag('js', new Date());
        window.gtag('config', gaId, {
          // Settings for iframe environments
          send_page_view: false, // We'll send manually
          cookie_flags: 'max-age=7200;secure;samesite=none', // For iframe support
        });

        console.log('GA: gtag script loaded');
        resolve();
      };

      script.onerror = () => {
        console.error('❌ Failed to load gtag script');
        reject(new Error('Failed to load gtag script'));
      };

      document.head.appendChild(script);
    });
  };

  // Enable analytics if consent given
  const handleAcceptCookie = React.useCallback(() => {
    console.log('User accepted analytics cookies');
    setConsent(true);
    setShowBanner(false); // Hide banner after acceptance

    const gaId = import.meta.env.VITE_REACT_APP_GOOGLE_ANALYTICS_ID;
    const analyticsEnabled = import.meta.env.VITE_ENABLE_ANALYTICS === 'true';

    if (gaId && analyticsEnabled) {
      loadGtagScript(gaId)
        .then(() => {
          setAnalyticsEnabled(true);
          console.log('GA initialized successfully');

          // Send initial pageview
          const pathname = window.location.pathname;
          window.gtag('event', 'page_view', {
            page_title: document.title,
            page_location: window.location.href,
            page_path: pathname,
          });
        })
        .catch((e) => {
          console.error('GA initialization failed:', e);
        });
    }
  }, []);

  const handleDeclineCookie = React.useCallback(() => {
    console.log('User declined analytics cookies');
    setConsent(false);
    setShowBanner(false); // Hide banner after decline
  }, []);

  // Check for existing consent on mount
  React.useEffect(() => {
    const existingConsent = getConsent();
    if (existingConsent) {
      console.log('GA: Found existing consent, initializing...');
      handleAcceptCookie();
      setShowBanner(false); // Don't show banner if consent already exists
    } else {
      setShowBanner(true); // Show banner if no consent
    }
  }, [handleAcceptCookie]);

  // Note: pageview is now sent directly in handleAcceptCookie when gtag is loaded

  return showBanner ? (
    <CookieBanner
      onAccept={handleAcceptCookie}
      onDecline={handleDeclineCookie}
    />
  ) : null;
};

export default Analytics;