import { Injectable, OnModuleInit } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { connect, Connection, Channel } from 'amqplib';

@Injectable()
export class RabbitMQService implements OnModuleInit {
  private connection!: Connection;
  private channel!: Channel;

  constructor(private configService: ConfigService) {}

  async onModuleInit() {
    await this.connectWithRetry();
  }

  async connect(): Promise<void> {
    const user = this.configService.get<string>('rabbitmq.user');
    const pass = this.configService.get<string>('rabbitmq.pass');
    const host = this.configService.get<string>('rabbitmq.host');
    const port = this.configService.get<string>('rabbitmq.port');
    
    this.connection = await connect(`amqp://${user}:${pass}@${host}:${port}`);
    this.channel = await this.connection.createChannel();
    console.log('Connected to RabbitMQ');
  }

  async connectWithRetry(retries = 5, delayMs = 3000): Promise<void> {
    for (let i = 0; i < retries; i++) {
      try {
        await this.connect();
        return;
      } catch (err) {
        console.error(
          `RabbitMQ connection failed, retrying in ${delayMs}ms... (${i + 1}/${retries})`,
        );
        await new Promise((res) => setTimeout(res, delayMs));
      }
    }
    throw new Error('Could not connect to RabbitMQ after multiple attempts');
  }

  async sendToQueue(queue: string, message: any) {
    if (!this.channel) throw new Error('RabbitMQ channel not initialized');
    await this.channel.assertQueue(queue, { durable: true });
    this.channel.sendToQueue(queue, Buffer.from(JSON.stringify(message)));
    console.log(`Sent message to queue "${queue}"`);
  }
}