config.service.ts

import * as dotenv from 'dotenv'
import * as fs from 'fs'

export class ConfigService {
  private readonly envConfig: { [key: string]: string }

  constructor(mode: 'development' | 'production') {
    this.envConfig = dotenv.parse(fs.readFileSync(`${mode}.env`))
  }

  get(key: string): string {
    return this.envConfig[key]
  }
}