"use client";

import { useEffect, useState, useRef, useCallback } from "react";
import { createBrowserClient } from "@supabase/ssr";
import { useRouter } from "next/navigation";
import { signOut } from "@/lib/actions/auth";
import { resolveSupabaseUrl } from "@/lib/utils";
import {
  Dialog,
  DialogContent,
  DialogHeader,
  DialogTitle,
  DialogDescription,
  DialogFooter,
} from "@/components/ui/dialog";
import { Button } from "@/components/ui/button";
import { Clock } from "lucide-react";

// Inaktivitäts-Schwellenwert (10 Minuten = 600.000 ms)
const INACTIVITY_TIMEOUT_MS = 10 * 60 * 1000;
// Countdown-Dauer vor automatischem Logout (10 Sekunden)
const COUNTDOWN_SECONDS = 10;

export function InactivityTracker() {
  const router = useRouter();

  const [isLoggedIn, setIsLoggedIn] = useState(false);
  const [showModal, setShowModal] = useState(false);
  const [countdown, setCountdown] = useState(COUNTDOWN_SECONDS);

  const lastActivityRef = useRef<number>(Date.now());
  const countdownIntervalRef = useRef<NodeJS.Timeout | null>(null);

  // Supabase URL & Anon Key auslesen (für Browser-Client)
  const supabaseUrl = process.env.SUPABASE_URL || process.env.NEXT_PUBLIC_SUPABASE_URL;
  const supabaseAnonKey = process.env.SUPABASE_ANON_KEY || process.env.NEXT_PUBLIC_SUPABASE_PUBLISHABLE_KEY || process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY;

  const supabase = createBrowserClient(
    resolveSupabaseUrl(supabaseUrl)!,
    supabaseAnonKey!,
    {
      cookieOptions: {
        name: "webshop-auth-token",
      },
    }
  );

  // Cookie-Hilfsfunktionen für Aktivitätssynchronisation mit dem Server
  const updateLastActivityCookie = useCallback(() => {
    const now = Date.now();
    lastActivityRef.current = now;
    document.cookie = `webshop-last-activity=${now}; path=/; SameSite=Lax`;
  }, []);

  const getLastActivityFromCookie = useCallback((): number => {
    const match = document.cookie.match(/(?:^|; )webshop-last-activity=([^;]*)/);
    if (match && match[1]) {
      const val = parseInt(match[1], 10);
      if (!isNaN(val)) return val;
    }
    return lastActivityRef.current;
  }, []);

  const handleLogout = useCallback(async (reason = "inactivity") => {
    if (countdownIntervalRef.current) {
      clearInterval(countdownIntervalRef.current);
    }
    setShowModal(false);
    document.cookie = "webshop-last-activity=; path=/; max-age=0";
    try {
      await signOut();
    } catch (e) {
      console.error("Fehler beim Server-Signout:", e);
    }
    await supabase.auth.signOut();
    router.push(`/auth/login?message=${reason}`);
    router.refresh();
  }, [supabase, router]);

  // Session-Prüfung & Inaktivitäts-Überwachung
  useEffect(() => {
    // 1. Session prüfen
    const checkSession = async () => {
      const { data: { session } } = await supabase.auth.getSession();
      setIsLoggedIn(!!session);
    };
    checkSession();

    // 2. Regelmäßige Intervall-Prüfung (alle 5s)
    const interval = setInterval(async () => {
      const { data: { session } } = await supabase.auth.getSession();
      if (!session) {
        setIsLoggedIn(false);
        return;
      }
      setIsLoggedIn(true);

      // Prüfen, ob Session auf Server noch gültig ist
      const { data: { user }, error } = await supabase.auth.getUser();
      if (error) {
        const isAuthError = error.status === 400 || error.status === 401 || error.status === 403;
        if (isAuthError) {
          handleLogout("concurrent");
          return;
        }
      } else if (!user) {
        handleLogout("concurrent");
        return;
      }

      // Inaktivitätszeitraum (Client + Cookie-Synchronisation) prüfen
      const lastActive = getLastActivityFromCookie();
      const now = Date.now();
      if (!showModal && now - lastActive >= INACTIVITY_TIMEOUT_MS) {
        setShowModal(true);
        setCountdown(COUNTDOWN_SECONDS);
      }
    }, 5000);

    return () => {
      clearInterval(interval);
    };
  }, [supabase, handleLogout, showModal, getLastActivityFromCookie]);

  // Aktivitätsevents registrieren
  useEffect(() => {
    if (!isLoggedIn) return;

    let lastEventTime = 0;
    const handleUserActivity = () => {
      const now = Date.now();
      // Throttling: max. 1x pro Sekunde aktualisieren
      if (now - lastEventTime > 1000) {
        lastEventTime = now;
        // Wenn Modal bereits offen ist, Aktivität nicht im Hintergrund zurücksetzen
        if (!showModal) {
          updateLastActivityCookie();
        }
      }
    };

    const events = ["mousemove", "keydown", "click", "scroll", "touchstart"];
    events.forEach((event) => {
      window.addEventListener(event, handleUserActivity, { passive: true });
    });

    return () => {
      events.forEach((event) => {
        window.removeEventListener(event, handleUserActivity);
      });
    };
  }, [isLoggedIn, showModal, updateLastActivityCookie]);

  // Countdown-Timer verwalten, wenn Modal geöffnet wird
  useEffect(() => {
    if (!showModal) {
      if (countdownIntervalRef.current) {
        clearInterval(countdownIntervalRef.current);
      }
      return;
    }

    countdownIntervalRef.current = setInterval(() => {
      setCountdown((prev) => {
        if (prev <= 1) {
          clearInterval(countdownIntervalRef.current!);
          handleLogout("inactivity");
          return 0;
        }
        return prev - 1;
      });
    }, 1000);

    return () => {
      if (countdownIntervalRef.current) {
        clearInterval(countdownIntervalRef.current);
      }
    };
  }, [showModal, handleLogout]);

  // Inaktivität zurücksetzen / Modal schließen
  const handleStayLoggedIn = () => {
    updateLastActivityCookie();
    setShowModal(false);
    if (countdownIntervalRef.current) {
      clearInterval(countdownIntervalRef.current);
    }
  };

  if (!isLoggedIn) return null;

  // Werte für den radialen SVG-Timer (Kreisumfang)
  const radius = 40;
  const circumference = 2 * Math.PI * radius;
  const strokeDashoffset = circumference - (countdown / COUNTDOWN_SECONDS) * circumference;

  return (
    <Dialog open={showModal} onOpenChange={(open) => { if (!open) handleStayLoggedIn(); }}>
      <DialogContent showCloseButton={false} className="sm:max-w-md text-center flex flex-col items-center gap-6 p-8">
        <DialogHeader className="items-center text-center">
          <div className="w-12 h-12 rounded-full bg-amber-500/10 text-amber-500 flex items-center justify-center mb-2">
            <Clock className="w-6 h-6 animate-pulse" />
          </div>
          <DialogTitle className="text-xl font-bold text-foreground">
            Noch da?
          </DialogTitle>
          <DialogDescription className="text-muted-foreground text-sm max-w-xs mt-1">
            Sie sind seit längerem inaktiv. Aus Sicherheitsgründen werden Sie gleich abgemeldet.
          </DialogDescription>
        </DialogHeader>

        {/* Radialer SVG-Timer */}
        <div className="relative flex items-center justify-center my-2">
          <svg className="w-32 h-32 transform -rotate-90" viewBox="0 0 100 100">
            {/* Hintergrundkreis */}
            <circle
              cx="50"
              cy="50"
              r={radius}
              className="stroke-muted/20"
              strokeWidth="8"
              fill="transparent"
            />
            {/* Countdown-Fortschrittskreis */}
            <circle
              cx="50"
              cy="50"
              r={radius}
              className="stroke-amber-500 transition-all duration-1000 ease-linear"
              strokeWidth="8"
              strokeDasharray={circumference}
              strokeDashoffset={strokeDashoffset}
              strokeLinecap="round"
              fill="transparent"
            />
          </svg>
          {/* Numerische Restzeit in Sekunden */}
          <div className="absolute inset-0 flex flex-col items-center justify-center">
            <span className="text-3xl font-extrabold text-foreground tracking-tight">
              {countdown}s
            </span>
            <span className="text-[10px] text-muted-foreground uppercase tracking-widest font-semibold mt-0.5">
              Verbleibend
            </span>
          </div>
        </div>

        <DialogFooter className="w-full sm:justify-center">
          <Button
            onClick={handleStayLoggedIn}
            className="w-full sm:w-auto px-8 bg-amber-500 hover:bg-amber-600 text-black font-semibold shadow-lg shadow-amber-500/20"
          >
            Ich bin noch da
          </Button>
        </DialogFooter>
      </DialogContent>
    </Dialog>
  );
}