'use client';

import { useState, useEffect } from 'react';

export function usePushNotifications() {
  const [permission, setPermission] = useState<NotificationPermission>('default');
  const [isSubscribed, setIsSubscribed] = useState(false);
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if ('Notification' in window) {
      setPermission(Notification.permission);
      checkSubscription();
    }
  }, []);

  const checkSubscription = async () => {
    if (!('serviceWorker' in navigator) || !('PushManager' in window)) {
      return;
    }

    try {
      const registration = await navigator.serviceWorker.ready;
      const subscription = await registration.pushManager.getSubscription();
      setIsSubscribed(!!subscription);
    } catch (err) {
      console.error('Failed to check subscription:', err);
    }
  };

  const requestPermission = async () => {
    if (!('Notification' in window)) {
      setError('Notifications not supported');
      return false;
    }

    try {
      const result = await Notification.requestPermission();
      setPermission(result);
      return result === 'granted';
    } catch (err) {
      console.error('Failed to request permission:', err);
      setError('Failed to request permission');
      return false;
    }
  };

  const subscribe = async () => {
    if (!('serviceWorker' in navigator) || !('PushManager' in window)) {
      setError('Push notifications not supported');
      return false;
    }

    setIsLoading(true);
    setError(null);

    try {
      // Request permission if not granted
      if (permission !== 'granted') {
        const granted = await requestPermission();
        if (!granted) {
          setError('Permission denied');
          setIsLoading(false);
          return false;
        }
      }

      // Get service worker registration
      const registration = await navigator.serviceWorker.ready;

      // Get VAPID public key from server
      const response = await fetch('/api/push/vapid-key');
      const { publicKey } = await response.json();

      if (!publicKey) {
        throw new Error('VAPID public key not available');
      }

      // Subscribe to push notifications
      const subscription = await registration.pushManager.subscribe({
        userVisibleOnly: true,
        applicationServerKey: urlBase64ToUint8Array(publicKey),
      });

      // Send subscription to server
      const saveResponse = await fetch('/api/push/subscribe', {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify(subscription.toJSON()),
      });

      if (!saveResponse.ok) {
        throw new Error('Failed to save subscription');
      }

      setIsSubscribed(true);
      setIsLoading(false);
      return true;
    } catch (err) {
      console.error('Failed to subscribe:', err);
      setError(err instanceof Error ? err.message : 'Failed to subscribe');
      setIsLoading(false);
      return false;
    }
  };

  const unsubscribe = async () => {
    if (!('serviceWorker' in navigator) || !('PushManager' in window)) {
      return false;
    }

    setIsLoading(true);
    setError(null);

    try {
      const registration = await navigator.serviceWorker.ready;
      const subscription = await registration.pushManager.getSubscription();

      if (subscription) {
        // Unsubscribe from push manager
        await subscription.unsubscribe();

        // Remove subscription from server
        await fetch('/api/push/unsubscribe', {
          method: 'POST',
          headers: {
            'Content-Type': 'application/json',
          },
          body: JSON.stringify({ endpoint: subscription.endpoint }),
        });
      }

      setIsSubscribed(false);
      setIsLoading(false);
      return true;
    } catch (err) {
      console.error('Failed to unsubscribe:', err);
      setError(err instanceof Error ? err.message : 'Failed to unsubscribe');
      setIsLoading(false);
      return false;
    }
  };

  return {
    permission,
    isSubscribed,
    isLoading,
    error,
    subscribe,
    unsubscribe,
    requestPermission,
  };
}

// Helper function to convert VAPID key
function urlBase64ToUint8Array(base64String: string): Uint8Array {
  const padding = '='.repeat((4 - (base64String.length % 4)) % 4);
  const base64 = (base64String + padding).replace(/-/g, '+').replace(/_/g, '/');

  const rawData = window.atob(base64);
  const outputArray = new Uint8Array(rawData.length);

  for (let i = 0; i < rawData.length; ++i) {
    outputArray[i] = rawData.charCodeAt(i);
  }
  return outputArray;
}