import { Injectable, Logger } from '@nestjs/common';
import { CDCEvent } from '../../infrastructure/kafka/cdc-consumer.service';
import { SyncedDataRepository } from '../../infrastructure/persistence/repositories/synced-data.repository';
import { ContributionAccountRepository } from '../../infrastructure/persistence/repositories/contribution-account.repository';
import { ContributionAccountAggregate } from '../../domain/aggregates/contribution-account.aggregate';
import { UnitOfWork } from '../../infrastructure/persistence/unit-of-work/unit-of-work';

/**
 * 用户 CDC 事件处理器
 * 处理从身份服务同步过来的用户数据
 */
@Injectable()
export class UserSyncedHandler {
  private readonly logger = new Logger(UserSyncedHandler.name);

  constructor(
    private readonly syncedDataRepository: SyncedDataRepository,
    private readonly contributionAccountRepository: ContributionAccountRepository,
    private readonly unitOfWork: UnitOfWork,
  ) {}

  async handle(event: CDCEvent): Promise<void> {
    const { op, before, after } = event.payload;

    this.logger.log(`[CDC] User event received: op=${op}, seq=${event.sequenceNum}`);
    this.logger.debug(`[CDC] User event payload: ${JSON.stringify(after || before)}`);

    try {
      switch (op) {
        case 'c': // create
        case 'r': // read (snapshot)
          await this.handleCreate(after, event.sequenceNum);
          break;
        case 'u': // update
          await this.handleUpdate(after, event.sequenceNum);
          break;
        case 'd': // delete
          await this.handleDelete(before);
          break;
        default:
          this.logger.warn(`[CDC] Unknown CDC operation: ${op}`);
      }
    } catch (error) {
      this.logger.error(`[CDC] Failed to handle user CDC event, op=${op}, seq=${event.sequenceNum}`, error);
      throw error;
    }
  }

  private async handleCreate(data: any, sequenceNum: bigint): Promise<void> {
    if (!data) {
      this.logger.warn(`[CDC] User create: empty data received`);
      return;
    }

    // 兼容不同的字段命名（CDC 使用 snake_case）
    const userId = data.user_id ?? data.id;
    const accountSequence = data.account_sequence ?? data.accountSequence;
    const phone = data.phone_number ?? data.phone ?? null;
    const status = data.status ?? 'ACTIVE';

    this.logger.log(`[CDC] User create: userId=${userId}, accountSequence=${accountSequence}, phone=${phone}, status=${status}`);

    if (!userId || !accountSequence) {
      this.logger.warn(`[CDC] Invalid user data: missing user_id or account_sequence`, { data });
      return;
    }

    await this.unitOfWork.executeInTransaction(async () => {
      // 保存同步的用户数据
      this.logger.log(`[CDC] Upserting synced user: ${accountSequence}`);
      await this.syncedDataRepository.upsertSyncedUser({
        originalUserId: BigInt(userId),
        accountSequence,
        phone,
        status,
        sourceSequenceNum: sequenceNum,
      });

      // 为用户创建算力账户（如果不存在）
      const existingAccount = await this.contributionAccountRepository.findByAccountSequence(accountSequence);

      if (!existingAccount) {
        const newAccount = ContributionAccountAggregate.create(accountSequence);
        await this.contributionAccountRepository.save(newAccount);
        this.logger.log(`[CDC] Created contribution account for user: ${accountSequence}`);
      } else {
        this.logger.debug(`[CDC] Contribution account already exists for user: ${accountSequence}`);
      }
    });

    this.logger.log(`[CDC] User synced successfully: ${accountSequence}`);
  }

  private async handleUpdate(data: any, sequenceNum: bigint): Promise<void> {
    if (!data) {
      this.logger.warn(`[CDC] User update: empty data received`);
      return;
    }

    // 兼容不同的字段命名（CDC 使用 snake_case）
    const userId = data.user_id ?? data.id;
    const accountSequence = data.account_sequence ?? data.accountSequence;
    const phone = data.phone_number ?? data.phone ?? null;
    const status = data.status ?? 'ACTIVE';

    this.logger.log(`[CDC] User update: userId=${userId}, accountSequence=${accountSequence}, status=${status}`);

    if (!userId || !accountSequence) {
      this.logger.warn(`[CDC] Invalid user update data: missing user_id or account_sequence`, { data });
      return;
    }

    await this.syncedDataRepository.upsertSyncedUser({
      originalUserId: BigInt(userId),
      accountSequence,
      phone,
      status,
      sourceSequenceNum: sequenceNum,
    });

    this.logger.log(`[CDC] User updated successfully: ${accountSequence}`);
  }

  private async handleDelete(data: any): Promise<void> {
    if (!data) {
      this.logger.warn(`[CDC] User delete: empty data received`);
      return;
    }
    const accountSequence = data.account_sequence ?? data.accountSequence;
    // 用户删除一般不处理，保留历史数据
    this.logger.log(`[CDC] User delete event received: ${accountSequence} (not processed, keeping history)`);
  }
}