import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { InjectDataSource } from '@nestjs/typeorm';
import { DataSource } from 'typeorm';

export interface SystemHealthResponse {
  status: 'ok' | 'error';
  timestamp: string;
  environment: string;
  database: {
    host: string;
    port: number;
    database: string;
    user: string;
    status: 'connected' | 'disconnected';
    error?: string;
  };
}

@Injectable()
export class SystemService {
  constructor(
    private configService: ConfigService,
    @InjectDataSource() private dataSource: DataSource,
  ) {}

  async getHealth(): Promise<SystemHealthResponse> {
    const dbHealth = await this.checkDatabase();

    return {
      status: dbHealth.status === 'connected' ? 'ok' : 'error',
      timestamp: new Date().toISOString(),
      environment: this.configService.get('NODE_ENV') || 'development',
      database: dbHealth,
    };
  }

  private async checkDatabase() {
    const config = {
      host: this.configService.get('POSTGRES_HOST') || 'unknown',
      port: parseInt(this.configService.get('POSTGRES_PORT')) || 5432,
      database: this.configService.get('POSTGRES_DB') || 'unknown',
      user: this.configService.get('POSTGRES_USER') || 'unknown',
    };

    try {
      await this.dataSource.query('SELECT 1');
      return { ...config, status: 'connected' as const };
    } catch (error) {
      return { ...config, status: 'disconnected' as const, error: error.message };
    }
  }
}