import { Inject, Injectable } from '@nestjs/common';

import type {
  DependencyHealthDto,
  HealthResponseDto,
} from '../../../libs/http-contracts/src/health.dto';

/** 依赖注入令牌避免健康服务耦合 ioredis 或 mysql2 客户端。 */
export const REDIS_HEALTH_PORT = Symbol('REDIS_HEALTH_PORT');
export const MYSQL_HEALTH_PORT = Symbol('MYSQL_HEALTH_PORT');

/** 健康端口只要求只读检查，便于禁用态和测试实现遵循同一契约。 */
export interface DependencyHealthPort {
  check(): Promise<DependencyHealthDto>;
}

@Injectable()
/** 聚合依赖状态并统一清洗底层错误，禁止连接信息进入 HTTP 响应。 */
export class HealthService {
  constructor(
    @Inject(REDIS_HEALTH_PORT) private readonly redis: DependencyHealthPort,
    @Inject(MYSQL_HEALTH_PORT) private readonly mysql: DependencyHealthPort,
  ) {}

  async check(): Promise<HealthResponseDto> {
    const [redis, mysql] = await Promise.all([
      this.checkSafely(this.redis),
      this.checkSafely(this.mysql),
    ]);
    const status =
      redis.status === 'healthy' && mysql.status !== 'unavailable' ? 'healthy' : 'unavailable';

    return {
      status,
      process: 'api',
      checkedAt: new Date().toISOString(),
      dependencies: {
        redis,
        mysql,
        rocketMq: { status: 'disabled', detail: 'GOV-009 尚未启用 RocketMQ 客户端' },
      },
    };
  }

  private async checkSafely(port: DependencyHealthPort): Promise<DependencyHealthDto> {
    try {
      const result = await port.check();
      if (result.status === 'healthy' || result.status === 'disabled') return result;
    } catch {
      // 外部错误可能包含 DSN、用户名或密码；HTTP 健康响应只暴露固定安全文案。
    }
    return { status: 'unavailable', detail: '依赖检查失败' };
  }
}