Pierre-Darcas-The-github-repo/src/modules/core/config/config.service.ts

import { Inject, Injectable } from '@nestjs/common';
import * as Joi from 'joi';
import { config as parseConfig } from 'dotenv';

interface EnvConfig {
  [key: string]: any;
}

@Injectable()
export class ConfigService {
  private readonly envConfig: EnvConfig;

  constructor() {
    try {
      parseConfig();
    } catch (e) {}

    this.envConfig = this.validateInput(process.env);
  }

  /**
   * Ensures all needed variables are set, and returns the validated JavaScript object
   * including the applied default values.
   */
  private validateInput(envConfig: EnvConfig): EnvConfig {
    const envVarsSchema: Joi.ObjectSchema = Joi.object({
      NODE_ENV: Joi.string()
        .valid(['development', 'production', 'test', 'provision'])
        .default('development'),
      PORT: Joi.number().default(3000),
      API_HOST: Joi.string().default('localhost'),
      API_PROTOCOL: Joi.string().default('http'),
      LOG_LEVEL: Joi.string()
        .valid(['error', 'warning', 'info', 'debug', 'silly'])
        .default('debug'),
      DATABASE_URL: Joi.string().required(),
      JWT_SECRET: Joi.string()
        .required()
        .default('some_default_jwt_bad_practice_!!'),
      LOG_SQL_REQUEST: Joi.boolean().default(false),
    });

    const { error, value: validatedEnvConfig } = Joi.validate(
      envConfig,
      envVarsSchema,
      {
        stripUnknown: true,
      },
    );
    if (error) {
      throw new Error(`Config validation error: ${error.message}`);
    }
    return validatedEnvConfig;
  }

  get databaseUrl(): string {
    return this.envConfig.DATABASE_URL;
  }

  get jwtSecret(): string {
    return this.envConfig.JWT_SECRET;
  }

  get isLoggingDb(): boolean {
    return false;
  }

  get loggerLevel(): string {
    return this.envConfig.LOG_LEVEL;
  }

  get port(): number {
    return this.envConfig.PORT;
  }
}