import hashlib
import unittest
import unicodedata

from cryptography.hazmat.primitives.ciphers.aead import AESGCM

from secure_sms.core.security import SymmetricCryptoService, b64u_encode


def _encrypt_for_key_text(message: str, key_text: str) -> str:
    key = hashlib.sha256(key_text.encode("utf-8")).digest()
    nonce = bytes(range(12))
    ciphertext = AESGCM(key).encrypt(nonce, message.encode("utf-8"), None)
    return b64u_encode(nonce + ciphertext)


class SymmetricCryptoInteropTests(unittest.TestCase):
    def setUp(self):
        self.service = SymmetricCryptoService()

    def test_encrypts_new_hex_transport(self):
        payload = self.service.encrypt_symmetric("hex transport", "shared-key-123")

        self.assertTrue(payload.startswith("h1:"))
        self.assertEqual(
            self.service.decrypt_symmetric(payload, "shared-key-123"),
            "hex transport",
        )

    def test_decrypts_flutter_style_payload(self):
        key = "  shared-key-123  "
        payload = _encrypt_for_key_text("hello from flutter", key.strip())

        self.assertEqual(
            self.service.decrypt_symmetric(payload, key),
            "hello from flutter",
        )

    def test_decrypts_legacy_python_nfc_payload(self):
        raw_key = "Cafe\u0301-123"
        legacy_python_key = unicodedata.normalize("NFC", raw_key.strip())
        payload = _encrypt_for_key_text("legacy payload", legacy_python_key)

        self.assertEqual(
            self.service.decrypt_symmetric(payload, raw_key),
            "legacy payload",
        )


if __name__ == "__main__":
    unittest.main()