import { useEffect, useState } from 'react';

interface BeforeInstallPromptEvent extends Event {
  prompt: () => Promise<void>;
  userChoice: Promise<{ outcome: 'accepted' | 'dismissed' }>;
}

declare global {
  interface Navigator { standalone?: boolean }
  interface WindowEventMap {
    beforeinstallprompt: BeforeInstallPromptEvent;
  }
}

const LAST_SHOWN_KEY = 'pwaInstallPrompt_lastShown';
const ANDROID_DISMISSED_KEY = 'pwaInstallPrompt_androidDismissed';

function isIOS(): boolean {
  if (typeof navigator === 'undefined') return false;
  const ua = navigator.userAgent || '';
  const iOS = /iPhone|iPad|iPod/i.test(ua);
  const iPadOS13Plus = /Macintosh/.test(ua) && 'ontouchend' in document;
  return iOS || iPadOS13Plus;
}

function isSafari(): boolean {
  const ua = navigator.userAgent || '';
  const isSafari = /Safari/i.test(ua) && !/CriOS|FxiOS|EdgiOS/i.test(ua);
  return isSafari;
}

function isStandalone(): boolean {
  const navStandalone = (navigator as any)?.standalone === true;
  const mm = typeof window !== 'undefined' && window.matchMedia
    ? window.matchMedia('(display-mode: standalone)').matches
    : false;
  return Boolean(navStandalone || mm);
}

export function PWAInstallPrompt({ hidden = false }: { hidden?: boolean }) {
  if (hidden) return null;
  const [show, setShow] = useState(false);
  const [promptType, setPromptType] = useState<'ios' | 'android' | null>(null);
  const [deferredPrompt, setDeferredPrompt] = useState<BeforeInstallPromptEvent | null>(null);
  const [initialized, setInitialized] = useState(false);

  useEffect(() => {
    // Only run on client
    if (typeof window === 'undefined') return;

    // Check if already in standalone mode
    if (isStandalone()) {
      setInitialized(true);
      return;
    }

    // Handle iOS
    const isIOSDevice = isIOS() && isSafari();
    if (isIOSDevice) {
      let lastShown = 0;
      try {
        lastShown = Number(localStorage.getItem(LAST_SHOWN_KEY) || 0);
      } catch {}
      const oneWeek = 7 * 24 * 60 * 60 * 1000;
      const shouldShow = !lastShown || Date.now() - lastShown > oneWeek;

      if (shouldShow) {
        setPromptType('ios');
        setShow(true);
      }
      setInitialized(true);
      return;
    }

    // Handle Android (beforeinstallprompt)
    const handleBeforeInstall = (e: BeforeInstallPromptEvent) => {
      e.preventDefault();
      
      // Check if user has dismissed Android prompt before
      let dismissed = false;
      try {
        dismissed = localStorage.getItem(ANDROID_DISMISSED_KEY) === 'true';
      } catch {}
      
      if (!dismissed) {
        setDeferredPrompt(e);
        setPromptType('android');
        setShow(true);
      }
    };

    window.addEventListener('beforeinstallprompt', handleBeforeInstall);
    setInitialized(true);

    return () => {
      window.removeEventListener('beforeinstallprompt', handleBeforeInstall);
    };
  }, []);

  const dismiss = () => {
    if (promptType === 'ios') {
      try { localStorage.setItem(LAST_SHOWN_KEY, String(Date.now())); } catch {}
    } else if (promptType === 'android') {
      try { localStorage.setItem(ANDROID_DISMISSED_KEY, 'true'); } catch {}
    }
    setShow(false);
  };

  const handleAndroidInstall = async () => {
    if (!deferredPrompt) return;

    try {
      await deferredPrompt.prompt();
      const choiceResult = await deferredPrompt.userChoice;
      
      if (choiceResult.outcome === 'accepted') {
        console.log('PWA installation accepted');
      }
      
      setDeferredPrompt(null);
      setShow(false);
    } catch (error) {
      console.error('Error during PWA installation:', error);
    }
  };

  if (!initialized || !show || !promptType) return null;

  return (
    <div
      role="dialog"
      aria-label={promptType === 'android' ? 'PWA Installation' : 'PWA Installation Anleitung'}
      className="fixed bottom-0 left-0 right-0 z-50 px-4 pb-4"
      style={{ paddingBottom: `max(env(safe-area-inset-bottom), 1rem)` }}
    >
      <div className="relative max-w-3xl mx-auto rounded-xl shadow-lg bg-gradient-to-r from-pink-500 to-purple-600 text-white p-4 sm:p-6">
        <button aria-label="Hinweis schließen" onClick={dismiss} className="absolute top-2 right-2 text-white/90 hover:text-white text-2xl leading-none">×</button>
        
        {promptType === 'android' ? (
          // Android: Direct install button
          <div className="flex items-center gap-4">
            <div className="text-3xl">📱</div>
            <div className="flex-1">
              <h3 className="text-lg sm:text-xl font-bold mb-2">App installieren</h3>
              <p className="text-white/90 mb-3">
                Installiere Stargirlnails als App für schnellen Zugriff direkt vom Startbildschirm!
              </p>
              <div className="flex gap-2">
                <button
                  onClick={handleAndroidInstall}
                  className="bg-white text-pink-600 px-4 py-2 rounded-lg font-semibold hover:bg-pink-50 transition-colors"
                >
                  Jetzt installieren
                </button>
                <button
                  onClick={dismiss}
                  className="bg-white/20 text-white px-4 py-2 rounded-lg font-semibold hover:bg-white/30 transition-colors"
                >
                  Später
                </button>
              </div>
            </div>
          </div>
        ) : (
          // iOS: Manual instructions
          <div className="flex items-start gap-3">
            <div className="text-2xl">📱</div>
            <div className="flex-1">
              <h3 className="text-lg sm:text-xl font-bold mb-2">App installieren</h3>
              <p className="text-white/90 mb-2">So installierst du Stargirlnails als App auf deinem iPhone/iPad:</p>
              <ol className="list-decimal pl-5 space-y-1 text-white/95">
                <li>Öffne diese Seite in Safari (nicht Chrome oder andere Browser).</li>
                <li>Tippe auf das Teilen-Symbol (□↑) unten in der Mitte.</li>
                <li>Scrolle nach unten und wähle „Zum Home-Bildschirm".</li>
                <li>Tippe auf „Hinzufügen".</li>
              </ol>
              <p className="mt-3 text-sm text-white/90">✨ Schneller Zugriff, keine App-Store-Installation nötig, automatische Updates.</p>
            </div>
          </div>
        )}
      </div>
    </div>
  );
}

export default PWAInstallPrompt;