'use strict';

const { generateOTP, getOTPExpiry, isOTPExpired } = require('../../utils/otp.util');

// ── generateOTP ───────────────────────────────────────────────────────────────

describe('generateOTP()', () => {
  test('returns a 6-character string', () => {
    expect(generateOTP()).toHaveLength(6);
  });

  test('contains only digits', () => {
    expect(generateOTP()).toMatch(/^\d{6}$/);
  });

  test('value is within 000000-999999', () => {
    const n = Number(generateOTP());
    expect(n).toBeGreaterThanOrEqual(0);
    expect(n).toBeLessThanOrEqual(999999);
  });

  test('zero-pads values under 100000', () => {
    // Run many samples to catch low values; deterministic check via string length
    for (let i = 0; i < 50; i++) {
      expect(generateOTP()).toHaveLength(6);
    }
  });
});

// ── getOTPExpiry ──────────────────────────────────────────────────────────────

describe('getOTPExpiry()', () => {
  test('returns a Date instance', () => {
    expect(getOTPExpiry()).toBeInstanceOf(Date);
  });

  test('expiry is in the future', () => {
    expect(getOTPExpiry().getTime()).toBeGreaterThan(Date.now());
  });

  test('default offset is approximately 10 minutes', () => {
    const before = Date.now();
    const expiry = getOTPExpiry().getTime();
    const after  = Date.now();
    const tenMin = 10 * 60 * 1000;
    expect(expiry).toBeGreaterThanOrEqual(before + tenMin - 100);
    expect(expiry).toBeLessThanOrEqual(after  + tenMin + 100);
  });

  test('custom minutes are respected', () => {
    const before = Date.now();
    const expiry = getOTPExpiry(5).getTime();
    const fiveMin = 5 * 60 * 1000;
    expect(expiry).toBeGreaterThanOrEqual(before + fiveMin - 100);
  });
});

// ── isOTPExpired ──────────────────────────────────────────────────────────────

describe('isOTPExpired()', () => {
  test('null → expired (true)', () => {
    expect(isOTPExpired(null)).toBe(true);
  });

  test('undefined → expired (true)', () => {
    expect(isOTPExpired(undefined)).toBe(true);
  });

  test('past date → expired (true)', () => {
    const past = new Date(Date.now() - 60_000);
    expect(isOTPExpired(past)).toBe(true);
  });

  test('future date → not expired (false)', () => {
    const future = new Date(Date.now() + 60_000);
    expect(isOTPExpired(future)).toBe(false);
  });

  test('accepts ISO string as well as Date', () => {
    const future = new Date(Date.now() + 60_000).toISOString();
    expect(isOTPExpired(future)).toBe(false);
  });
});