import { Injectable, Logger } from '@nestjs/common';
import { DataSource } from 'typeorm';
import { ConfigService } from '@nestjs/config';
import Redis from 'ioredis';
import type { HealthCheckResponseDto } from '@nick-tracker/shared-types';

@Injectable()
export class HealthService {
  private readonly logger = new Logger(HealthService.name);
  private redis: Redis | null = null;

  constructor(
    private readonly dataSource: DataSource,
    private readonly configService: ConfigService,
  ) {
    this.initRedis();
  }

  private initRedis() {
    const redisUrl = this.configService.get<string>('REDIS_URL');
    if (redisUrl) {
      try {
        this.redis = new Redis(redisUrl);
      } catch (error) {
        this.logger.warn('Failed to connect to Redis:', error);
      }
    }
  }

  async check(): Promise<HealthCheckResponseDto> {
    const dbStatus = await this.checkDatabase();
    const redisStatus = await this.checkRedis();

    return {
      status: dbStatus === 'connected' && redisStatus === 'connected' ? 'ok' : 'error',
      database: dbStatus,
      redis: redisStatus,
    };
  }

  private async checkDatabase(): Promise<'connected' | 'disconnected'> {
    try {
      if (this.dataSource.isInitialized) {
        await this.dataSource.query('SELECT 1');
        return 'connected';
      }
      return 'disconnected';
    } catch (error) {
      this.logger.warn('Database health check failed:', error);
      return 'disconnected';
    }
  }

  private async checkRedis(): Promise<'connected' | 'disconnected'> {
    if (!this.redis) {
      return 'disconnected';
    }

    try {
      const result = await this.redis.ping();
      return result === 'PONG' ? 'connected' : 'disconnected';
    } catch (error) {
      this.logger.warn('Redis health check failed:', error);
      return 'disconnected';
    }
  }
}