import { Injectable, Logger, OnModuleInit } from '@nestjs/common';
import { RedisService } from '@chatapp/redis';

/**
 * Push Notification Processor
 * 
 * Reads push notification jobs from Redis queue 'bull:push_notifications'
 * and sends them via the appropriate push service (FCM for Android, APNs for iOS).
 * 
 * In production this would use firebase-admin for FCM and @parse/node-apn for APNs.
 * For now it logs the notification and simulates sending.
 */
@Injectable()
export class PushProcessor implements OnModuleInit {
  private readonly logger = new Logger(PushProcessor.name);
  private readonly queueKey = 'bull:push_notifications';
  private running = false;

  constructor(private readonly redis: RedisService) {}

  async onModuleInit() {
    this.running = true;
    this.processLoop();
    this.logger.log('Push notification processor started');
  }

  private async processLoop() {
    while (this.running) {
      try {
        const job = await this.redis.client?.brpop(this.queueKey, 5);
        if (job) {
          const data = JSON.parse(job[1]);
          await this.sendPush(data);
        }
      } catch (err) {
        this.logger.error(`Push notification error: ${err}`);
        await new Promise((r) => setTimeout(r, 5000));
      }
    }
  }

  private async sendPush(data: {
    platform: string;
    token: string;
    title: string;
    body: string;
    data?: any;
  }) {
    try {
      // In production, use firebase-admin for FCM (Android) or @parse/node-apn for APNs (iOS)
      // For now, simulate the push send with a log
      this.logger.log(
        `Push sent to ${data.platform} device: ${data.title} - ${data.body}`,
      );

      // TODO: Implement actual FCM/APNs calls when credentials are available
      // Example FCM:
      //   admin.messaging().send({
      //     token: data.token,
      //     notification: { title: data.title, body: data.body },
      //     data: data.data,
      //   });
      // Example APNs:
      //   apnProvider.send(new apn.Notification({
      //     alert: { title: data.title, body: data.body },
      //     topic: 'com.chatapp.app',
      //   }), data.token);
    } catch (err) {
      this.logger.error(`Failed to send push: ${err}`);
    }
  }

  async enqueue(pushData: any) {
    await this.redis.client?.lpush(this.queueKey, JSON.stringify(pushData));
  }
}