import { Injectable, Logger } from '@nestjs/common';
import { KafkaService } from './kafka.service';
import { DomainEvent } from '../../domain';

export const KAFKA_TOPICS = {
  REFERRAL_EVENTS: 'referral.events',
  TEAM_STATISTICS_EVENTS: 'referral.team-statistics.events',
} as const;

@Injectable()
export class EventPublisherService {
  private readonly logger = new Logger(EventPublisherService.name);

  constructor(private readonly kafkaService: KafkaService) {}

  async publishDomainEvents(events: DomainEvent[]): Promise<void> {
    if (events.length === 0) return;

    const messages = events.map((event) => ({
      topic: this.getTopicForEvent(event),
      key: event.eventId,
      value: event.toPayload(),
    }));

    await this.kafkaService.publishBatch(messages);
    this.logger.log(`Published ${events.length} domain events`);
  }

  async publishEvent(event: DomainEvent): Promise<void> {
    await this.kafkaService.publish({
      topic: this.getTopicForEvent(event),
      key: event.eventId,
      value: event.toPayload(),
    });
    this.logger.debug(`Published event: ${event.eventName}`);
  }

  private getTopicForEvent(event: DomainEvent): string {
    if (event.eventName.includes('team_statistics')) {
      return KAFKA_TOPICS.TEAM_STATISTICS_EVENTS;
    }
    return KAFKA_TOPICS.REFERRAL_EVENTS;
  }
}