import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { InjectDataSource } from '@nestjs/typeorm';
import { DataSource } from 'typeorm';
import { InjectRedis } from '@nestjs-modules/ioredis';
import Redis from 'ioredis';

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

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

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

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

  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 };
    }
  }

  private async checkRedis() {
    const redisUrl = this.configService.get('REDIS_URL') || '';
    let host = this.configService.get('REDIS_HOST') || 'unknown';
    let port = parseInt(this.configService.get('REDIS_PORT')) || 6379;

    if (redisUrl) {
      try {
        const url = new URL(redisUrl);
        host = url.hostname;
        port = parseInt(url.port) || 6379;
      } catch {}
    }

    try {
      const pong = await this.redis.ping();
      return {
        host,
        port,
        status: pong === 'PONG' ? 'connected' as const : 'disconnected' as const,
      };
    } catch (error) {
      return { host, port, status: 'disconnected' as const, error: error.message };
    }
  }
}