import webpush from 'web-push';
import { storage } from '../storage';

const VAPID_KEY_CONFIG_KEY = 'vapid_public_key';

interface WebPushSubscription {
  endpoint: string;
  keys: {
    p256dh: string;
    auth: string;
  };
}

class WebPushService {
  private initialized = false;
  private vapidPublicKey: string = '';
  private vapidPrivateKey: string = '';

  constructor() {
    this.initialize();
  }

  private initialize() {
    const publicKey = process.env.VAPID_PUBLIC_KEY;
    const privateKey = process.env.VAPID_PRIVATE_KEY;

    if (!publicKey || !privateKey) {
      console.warn('[WebPush] WARNING: VAPID_PUBLIC_KEY and/or VAPID_PRIVATE_KEY are not set.');
      console.warn('[WebPush] Generating temporary VAPID keys for this session only.');
      console.warn('[WebPush] All existing push subscriptions will be invalidated on every server restart!');
      console.warn('[WebPush] To fix this, generate permanent keys and set them as environment variables:');
      console.warn('[WebPush]   npx web-push generate-vapid-keys');
      console.warn('[WebPush]   Then set VAPID_PUBLIC_KEY and VAPID_PRIVATE_KEY in your environment secrets.');
      const keys = webpush.generateVAPIDKeys();
      this.vapidPublicKey = keys.publicKey;
      this.vapidPrivateKey = keys.privateKey;
    } else {
      this.vapidPublicKey = publicKey;
      this.vapidPrivateKey = privateKey;
    }

    webpush.setVapidDetails(
      'mailto:admin@iistwin.ru',
      this.vapidPublicKey,
      this.vapidPrivateKey
    );

    this.initialized = true;
    console.log('[WebPush] Service initialized');
  }

  async checkVapidKeyRotation(): Promise<void> {
    try {
      const storedKey = await storage.getSystemConfig(VAPID_KEY_CONFIG_KEY);

      if (storedKey === null) {
        await storage.setSystemConfig(VAPID_KEY_CONFIG_KEY, this.vapidPublicKey);
        console.log('[WebPush] VAPID public key stored in system config for future rotation checks.');
        return;
      }

      if (storedKey !== this.vapidPublicKey) {
        console.warn('[WebPush] VAPID public key has changed! Previous key does not match current key.');
        console.warn('[WebPush] Clearing all existing web push subscriptions — they are no longer valid.');
        const count = await storage.clearAllWebPushSubscriptions();
        console.warn(`[WebPush] Removed ${count} stale push subscription(s).`);
        await storage.setSystemConfig(VAPID_KEY_CONFIG_KEY, this.vapidPublicKey);
        console.log('[WebPush] System config updated with new VAPID public key.');
      }
    } catch (err) {
      console.error('[WebPush] Error during VAPID key rotation check:', err);
    }
  }

  getVapidPublicKey(): string {
    return this.vapidPublicKey;
  }

  async registerSubscription(
    userId: number,
    organizationId: number,
    subscription: WebPushSubscription
  ): Promise<void> {
    await storage.registerWebPushSubscription(userId, organizationId, subscription.endpoint, JSON.stringify(subscription));
    console.log(`[WebPush] Subscription registered for user ${userId}`);
  }

  async unregisterSubscription(endpoint: string): Promise<void> {
    await storage.unregisterWebPushSubscription(endpoint);
    console.log(`[WebPush] Subscription unregistered: ${endpoint.substring(0, 50)}...`);
  }

  async sendNotification(
    subscription: WebPushSubscription,
    payload: {
      title?: string;
      body?: string;
      icon?: string;
      url?: string;
      tag?: string;
      data?: Record<string, any>;
      type?: string;
      [key: string]: any;
    }
  ): Promise<boolean> {
    if (!this.initialized) {
      console.log('[WebPush] Service not initialized');
      return false;
    }

    try {
      const result = await webpush.sendNotification(
        subscription,
        JSON.stringify(payload)
      );
      console.log(`[WebPush] FCM response status=${result.statusCode}, body=${result.body?.substring?.(0, 200) ?? result.body}`);
      return true;
    } catch (error: any) {
      if (error.statusCode === 410 || error.statusCode === 404) {
        console.log('[WebPush] Subscription expired, removing...');
        await this.unregisterSubscription(subscription.endpoint);
      } else {
        console.error('[WebPush] Send error:', error.message);
      }
      return false;
    }
  }

  async sendToUser(
    userId: number,
    organizationId: number,
    payload: {
      title?: string;
      body?: string;
      icon?: string;
      url?: string;
      tag?: string;
      data?: Record<string, any>;
      type?: string;
      [key: string]: any;
    }
  ): Promise<number> {
    const subscriptions = await storage.getWebPushSubscriptions(userId, organizationId);
    let sent = 0;

    for (const sub of subscriptions) {
      try {
        const subscription = JSON.parse(sub.subscription);
        const success = await this.sendNotification(subscription, payload);
        if (success) sent++;
      } catch (error) {
        console.error('[WebPush] Parse error for subscription:', error);
      }
    }

    return sent;
  }
}

export const webPushService = new WebPushService();