rwadurian/backend/services/contribution-service/src/application/event-handlers/transfer-ownership.handler.ts

/**
 * 转让所有权事件处理器（纯新增）
 * 消费 planting.ownership.removed + planting.ownership.added 事件
 * 调用 TransferAdjustmentService 执行 88% 算力调整
 *
 * 消费模式：kafkajs 原生消费者（与 CDCConsumerService 同架构）
 * 幂等性：ProcessedEvent 表（sourceService + eventId）
 *
 * 回滚方式：删除此文件并从 application.module.ts 中移除引用
 */

import { Injectable, Logger, OnModuleInit, OnModuleDestroy } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { Kafka, Consumer, EachMessagePayload } from 'kafkajs';
import { PrismaService } from '../../infrastructure/persistence/prisma/prisma.service';
import {
  TransferAdjustmentService,
  OwnershipRemovedEvent,
  OwnershipAddedEvent,
} from '../services/transfer-adjustment.service';

@Injectable()
export class TransferOwnershipHandler implements OnModuleInit, OnModuleDestroy {
  private readonly logger = new Logger(TransferOwnershipHandler.name);
  private kafka: Kafka;
  private removedConsumer: Consumer;
  private addedConsumer: Consumer;

  constructor(
    private readonly configService: ConfigService,
    private readonly prisma: PrismaService,
    private readonly transferAdjustmentService: TransferAdjustmentService,
  ) {
    const brokers = this.configService
      .get<string>('KAFKA_BROKERS', 'localhost:9092')
      .split(',');

    this.kafka = new Kafka({
      clientId: 'contribution-service-transfer',
      brokers,
    });

    this.removedConsumer = this.kafka.consumer({
      groupId: 'contribution-service-transfer-removed',
    });

    this.addedConsumer = this.kafka.consumer({
      groupId: 'contribution-service-transfer-added',
    });
  }

  async onModuleInit(): Promise<void> {
    try {
      // 订阅卖方减持事件
      await this.removedConsumer.connect();
      await this.removedConsumer.subscribe({
        topic: 'planting.ownership.removed',
        fromBeginning: false,
      });
      await this.removedConsumer.run({
        eachMessage: async (payload) => {
          await this.handleOwnershipRemoved(payload);
        },
      });

      // 订阅买方增持事件
      await this.addedConsumer.connect();
      await this.addedConsumer.subscribe({
        topic: 'planting.ownership.added',
        fromBeginning: false,
      });
      await this.addedConsumer.run({
        eachMessage: async (payload) => {
          await this.handleOwnershipAdded(payload);
        },
      });

      this.logger.log(
        'Subscribed to planting.ownership.removed + planting.ownership.added',
      );
    } catch (error) {
      this.logger.error('Failed to initialize transfer ownership consumers', error);
    }
  }

  async onModuleDestroy(): Promise<void> {
    try {
      await this.removedConsumer.disconnect();
      await this.addedConsumer.disconnect();
    } catch (error) {
      this.logger.error('Failed to disconnect transfer consumers', error);
    }
  }

  /**
   * 处理卖方减持事件
   */
  private async handleOwnershipRemoved(payload: EachMessagePayload): Promise<void> {
    const { message } = payload;
    if (!message.value) return;

    let event: OwnershipRemovedEvent;
    try {
      const raw = JSON.parse(message.value.toString());
      // 支持两种消息格式：直接 payload 或嵌套在 value 字段中
      event = raw.value ? raw.value : raw;
    } catch (error) {
      this.logger.error('[TRANSFER-REMOVED] Failed to parse message', error);
      return;
    }

    const processedEventId = `removed:${event.transferOrderNo}`;

    this.logger.log(
      `[TRANSFER-REMOVED] Processing: ${event.transferOrderNo}, ` +
        `seller=${event.sellerAccountSequence}, trees=${event.treeCount}`,
    );

    try {
      // 幂等性检查
      const existing = await this.prisma.processedEvent.findFirst({
        where: {
          sourceService: 'planting-service',
          eventId: processedEventId,
        },
      });

      if (existing) {
        this.logger.log(`[TRANSFER-REMOVED] Already processed: ${processedEventId}`);
        return;
      }

      // 执行卖方算力扣减
      await this.transferAdjustmentService.processOwnershipRemoved(event);

      // 记录已处理
      await this.prisma.processedEvent.create({
        data: {
          sourceService: 'planting-service',
          eventId: processedEventId,
          eventType: 'PlantingOwnershipRemoved',
        },
      });

      this.logger.log(
        `[TRANSFER-REMOVED] ✓ Processed: ${event.transferOrderNo}, seller=${event.sellerAccountSequence}`,
      );
    } catch (error) {
      this.logger.error(
        `[TRANSFER-REMOVED] ✗ Failed for ${event.transferOrderNo}:`,
        error,
      );
      throw error; // 让 kafkajs 重试
    }
  }

  /**
   * 处理买方增持事件
   */
  private async handleOwnershipAdded(payload: EachMessagePayload): Promise<void> {
    const { message } = payload;
    if (!message.value) return;

    let event: OwnershipAddedEvent;
    try {
      const raw = JSON.parse(message.value.toString());
      event = raw.value ? raw.value : raw;
    } catch (error) {
      this.logger.error('[TRANSFER-ADDED] Failed to parse message', error);
      return;
    }

    const processedEventId = `added:${event.transferOrderNo}`;

    this.logger.log(
      `[TRANSFER-ADDED] Processing: ${event.transferOrderNo}, ` +
        `buyer=${event.buyerAccountSequence}, trees=${event.treeCount}`,
    );

    try {
      // 幂等性检查
      const existing = await this.prisma.processedEvent.findFirst({
        where: {
          sourceService: 'planting-service',
          eventId: processedEventId,
        },
      });

      if (existing) {
        this.logger.log(`[TRANSFER-ADDED] Already processed: ${processedEventId}`);
        return;
      }

      // 执行买方算力新增
      await this.transferAdjustmentService.processOwnershipAdded(event);

      // 记录已处理
      await this.prisma.processedEvent.create({
        data: {
          sourceService: 'planting-service',
          eventId: processedEventId,
          eventType: 'PlantingOwnershipAdded',
        },
      });

      this.logger.log(
        `[TRANSFER-ADDED] ✓ Processed: ${event.transferOrderNo}, buyer=${event.buyerAccountSequence}`,
      );
    } catch (error) {
      this.logger.error(
        `[TRANSFER-ADDED] ✗ Failed for ${event.transferOrderNo}:`,
        error,
      );
      throw error; // 让 kafkajs 重试
    }
  }
}