import pytest

from algorithms import Algorithm, get_algorithm


def test_algorithm_has_required_methods():
    """Verify Algorithm protocol defines required methods."""
    algo = get_algorithm("pbkdf2")
    assert hasattr(algo, "hash")
    assert hasattr(algo, "verify")
    assert hasattr(algo, "identifier")


def test_get_algorithm_returns_pbkdf2():
    """Verify default algorithm is PBKDF2."""
    algo = get_algorithm("pbkdf2")
    assert algo.identifier == "pbkdf2"


def test_get_algorithm_unknown_raises_error():
    """Verify unknown algorithm raises ValueError."""
    with pytest.raises(ValueError, match="Unknown algorithm"):
        get_algorithm("unknown")


def test_pbkdf2_algorithm_hash_round_trip():
    """Verify PBKDF2 algorithm can hash and verify passwords."""
    algo = get_algorithm("pbkdf2")
    salt, hashed = algo.hash("test password")
    assert algo.verify("test password", salt, hashed)
    assert not algo.verify("wrong password", salt, hashed)


def test_pbkdf2_algorithm_respects_iterations():
    """Verify PBKDF2 algorithm respects custom iterations."""
    algo = get_algorithm("pbkdf2")
    salt1, hash1 = algo.hash("test", iterations=100000)
    salt2, hash2 = algo.hash("test", iterations=200000)
    # Different iterations should produce different hashes even with same password
    assert hash1 != hash2