"""tests/test_crypto.py"""

from tuya_re import crypto


def test_crc16_known_answer():
    # CRC-16 with init=0xFFFF, poly 0xA001 (MODBUS variant) — matches the
    # device firmware (verified against ha_tuya_ble's implementation).
    assert crypto.crc16(b"123456789") == 0x4B37


def test_crc16_empty():
    assert crypto.crc16(b"") == 0xFFFF


def test_login_key_uses_first_6_chars_only():
    import hashlib

    key = crypto.login_key("abcdef0123456789")
    assert key == hashlib.md5(b"abcdef").digest()
    assert len(key) == 16


def test_session_key():
    import hashlib

    srand = bytes(range(6))
    key = crypto.session_key("abcdef0123456789", srand)
    assert key == hashlib.md5(b"abcdef" + srand).digest()


def test_encrypt_decrypt_roundtrip():
    key = bytes(16)
    iv = bytes(range(16))
    plain = b"A" * 32  # must be 16-aligned
    ct = crypto.aes_cbc_encrypt(key, iv, plain)
    assert ct != plain
    assert crypto.aes_cbc_decrypt(key, iv, ct) == plain


def test_aes_ecb_known_vector():
    key = b"0123456789abcdef"
    ct = crypto.aes_ecb_encrypt(key, b"hello tuya 12345")
    assert (
        ct.hex() == "892dc5a803b72acfcbacb4f40ace9064377222e061a924c591cd9c27ea163ed4"
    )
    assert crypto.aes_ecb_decrypt(key, ct) == b"hello tuya 12345"


def test_aes_ecb_pkcs7_roundtrip():
    key = bytes(16)
    for n in (0, 1, 15, 16, 17, 32):
        msg = b"x" * n
        assert crypto.aes_ecb_decrypt(key, crypto.aes_ecb_encrypt(key, msg)) == msg


def test_crc32_matches_zlib():
    import zlib

    data = b"\x00\x00\x55\xaa\x00\x00\x00\x01"
    assert crypto.crc32(data) == (zlib.crc32(data) & 0xFFFFFFFF)