import pytest
from core.private_key import PrivateKey
from core.prime_number import PrimeNumber


def test_encrypt_decrypt_cycle():
    """Проверка: сообщение после encrypt → decrypt восстанавливается"""
    p1 = PrimeNumber.from_value(61)
    p2 = PrimeNumber.from_value(53)
    priv = PrivateKey(p1, p2)
    pub = priv.make_public_key()

    messages = [1, 2, 42, 123, priv.n - 1]
    for m in messages:
        c = pub.encrypt(m)
        m_back = priv.decrypt(c)
        assert m == m_back


def test_e_is_prime_and_coprime_with_phi():
    """e должно быть простым и взаимно простым с φ(n)"""
    p1 = PrimeNumber.from_value(61)
    p2 = PrimeNumber.from_value(53)
    priv = PrivateKey(p1, p2)

    assert isinstance(priv.e, PrimeNumber)
    assert (priv.e.value > 1)
    assert (priv.phi % priv.e.value != 0)


def test_d_is_inverse_of_e_mod_phi():
    """e*d ≡ 1 (mod φ(n))"""
    p1 = PrimeNumber.from_value(61)
    p2 = PrimeNumber.from_value(53)
    priv = PrivateKey(p1, p2)

    assert (priv.e.value * priv.d) % priv.phi == 1


def test_decrypt_invalid_inputs():
    """Должны бросаться ошибки при неверных входных данных"""
    p1 = PrimeNumber.from_value(61)
    p2 = PrimeNumber.from_value(53)
    priv = PrivateKey(p1, p2)

    with pytest.raises(ValueError):
        priv.decrypt(-5)

    with pytest.raises(ValueError):
        priv.decrypt("not a number")  # type: ignore