"use client";

import { useState, useEffect } from 'react';
import { Bell, BellOff, Send } from 'lucide-react';
import { urlBase64ToUint8Array } from '../utils/webPush';

export default function PushSubscription() {
  const [isSubscribed, setIsSubscribed] = useState(false);
  const [subscription, setSubscription] = useState<PushSubscription | null>(null);
  const [registration, setRegistration] = useState<ServiceWorkerRegistration | null>(null);
  const [isMenuOpen, setIsMenuOpen] = useState(false);

  useEffect(() => {
    if (typeof window !== 'undefined' && 'serviceWorker' in navigator && 'PushManager' in window) {
      // Register SW if not already (though it might be done in layout or separate file)
      navigator.serviceWorker.ready.then(reg => {
        setRegistration(reg);
        reg.pushManager.getSubscription().then(sub => {
          if (sub) {
            setSubscription(sub);
            setIsSubscribed(true);
          }
        });
      });
    }
  }, []);

  const subscribeUser = async () => {
    if (!registration) return;

    try {
      const response = await fetch('/api/push/vapid-public-key');
      const { publicKey } = await response.json();
      const convertedVapidKey = urlBase64ToUint8Array(publicKey);

      const sub = await registration.pushManager.subscribe({
        userVisibleOnly: true,
        applicationServerKey: convertedVapidKey
      });

      await fetch('/api/push/subscribe', {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify(sub),
      });

      setSubscription(sub);
      setIsSubscribed(true);
      alert('订阅成功！');
    } catch (error) {
      console.error('Failed to subscribe the user: ', error);
      alert('订阅失败，请检查控制台日志。');
    }
  };

  const unsubscribeUser = async () => {
    if (!subscription) return;
    try {
      await subscription.unsubscribe();
      // Optionally notify backend to remove subscription
      setSubscription(null);
      setIsSubscribed(false);
      alert('已取消订阅。');
    } catch (error) {
      console.error('Error unsubscribing', error);
    }
  };

  const sendTestPush = async () => {
    try {
      const res = await fetch('/api/push/test', { method: 'POST' });
      if (!res.ok) throw new Error('Failed to send test push');
      alert('测试推送已发送，请检查通知！');
    } catch (error) {
      console.error('Failed to send test push', error);
      alert('发送测试推送失败');
    }
  };

  if (!registration) {
    return null; // Service Worker not ready or not supported
  }

  if (!isSubscribed) {
    return (
      <button
        onClick={subscribeUser}
        className="inline-flex items-center justify-center px-3 py-2 border border-transparent text-sm font-medium rounded-md text-gray-700 bg-gray-100 hover:bg-gray-200 dark:text-gray-200 dark:bg-gray-700 dark:hover:bg-gray-600 transition-colors focus:outline-none focus:ring-2 focus:ring-offset-2 focus:ring-blue-500"
        title="开启推送通知"
      >
        <BellOff className="h-4 w-4 sm:mr-2" />
        <span className="hidden sm:inline">订阅通知</span>
      </button>
    );
  }

  return (
    <div className="relative">
      <button
        onClick={() => setIsMenuOpen(!isMenuOpen)}
        className="inline-flex items-center justify-center px-3 py-2 border border-transparent text-sm font-medium rounded-md transition-colors focus:outline-none focus:ring-2 focus:ring-offset-2 focus:ring-blue-500 text-blue-600 bg-blue-50 hover:bg-blue-100 dark:bg-blue-900/20 dark:text-blue-400 dark:hover:bg-blue-900/40"
      >
        <Bell className="h-4 w-4 sm:mr-2" />
        <span className="hidden sm:inline">已订阅</span>
      </button>
      
      {isMenuOpen && (
        <>
          <div 
            className="fixed inset-0 z-40"
            onClick={() => setIsMenuOpen(false)}
          />
          <div className="absolute right-0 top-full w-40 pt-1 z-50">
            <div className="bg-white dark:bg-gray-800 rounded-md shadow-lg border border-gray-200 dark:border-gray-700 py-1">
              <button
                onClick={() => {
                  sendTestPush();
                  setIsMenuOpen(false);
                }}
                className="w-full text-left px-4 py-2 text-sm text-gray-700 dark:text-gray-200 hover:bg-gray-100 dark:hover:bg-gray-700 flex items-center"
              >
                <Send className="h-3 w-3 mr-2" />
                发送测试
              </button>
              <button
                onClick={() => {
                  unsubscribeUser();
                  setIsMenuOpen(false);
                }}
                className="w-full text-left px-4 py-2 text-sm text-red-600 dark:text-red-400 hover:bg-red-50 dark:hover:bg-red-900/20 flex items-center"
              >
                <BellOff className="h-3 w-3 mr-2" />
                取消订阅
              </button>
            </div>
          </div>
        </>
      )}
    </div>
  );
}