from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.hazmat.primitives.asymmetric.utils import decode_dss_signature
from cryptography.hazmat.primitives.hashes import SHA256

from app.core.security import b64url, canonical_json, verify_signature


def test_verify_es256_signature_der_and_raw():
    private_key = ec.generate_private_key(ec.SECP256R1())
    public_pem = private_key.public_key().public_bytes(
        serialization.Encoding.PEM,
        serialization.PublicFormat.SubjectPublicKeyInfo,
    ).decode("utf-8")
    payload = {"challenge_id": "abc", "nonce": "n", "user_id": "u"}
    der_sig = private_key.sign(canonical_json(payload), ec.ECDSA(SHA256()))
    r, s = decode_dss_signature(der_sig)
    raw_sig = r.to_bytes(32, "big") + s.to_bytes(32, "big")

    assert verify_signature(public_pem, payload, b64url(der_sig))
    assert verify_signature(public_pem, payload, b64url(raw_sig))
    assert not verify_signature(public_pem, payload | {"nonce": "changed"}, b64url(der_sig))