import { describe, it, expect, beforeEach, afterEach } from 'vitest';
import { loadConfig } from '../src/config.js';

const REQUIRED_VARS = ['STORAGE_DIR', 'DB_HOST', 'DB_USER', 'DB_PASSWORD', 'DB_NAME'];
let savedEnv;

beforeEach(() => {
  savedEnv = { ...process.env };
});

afterEach(() => {
  process.env = savedEnv;
});

describe('loadConfig', () => {
  it('returns parsed config when all required vars are set', () => {
    process.env.STORAGE_DIR = './storage';
    process.env.DB_HOST = 'localhost';
    process.env.DB_USER = 'user';
    process.env.DB_PASSWORD = 'pass';
    process.env.DB_NAME = 'db';
    process.env.PORT = '4000';
    process.env.MAX_FILE_SIZE_MB = '50';

    const config = loadConfig();

    expect(config.port).toBe(4000);
    expect(config.storageDir).toBe('./storage');
    expect(config.db).toEqual({ host: 'localhost', user: 'user', password: 'pass', database: 'db' });
    expect(config.maxFileSizeMb).toBe(50);
  });

  it('applies defaults for optional vars', () => {
    process.env.STORAGE_DIR = './storage';
    process.env.DB_HOST = 'localhost';
    process.env.DB_USER = 'user';
    process.env.DB_PASSWORD = 'pass';
    process.env.DB_NAME = 'db';
    delete process.env.PORT;
    delete process.env.MAX_FILE_SIZE_MB;
    delete process.env.RETENTION_HOURS;
    delete process.env.WORKER_CONCURRENCY;

    const config = loadConfig();

    expect(config.port).toBe(3000);
    expect(config.maxFileSizeMb).toBe(100);
    expect(config.retentionHours).toBe(1);
    expect(config.workerConcurrency).toBe(3);
  });

  it('throws listing every missing required variable', () => {
    for (const key of REQUIRED_VARS) delete process.env[key];

    expect(() => loadConfig()).toThrowError(/STORAGE_DIR.*DB_HOST.*DB_USER.*DB_PASSWORD.*DB_NAME/s);
  });
});