from __future__ import absolute_import, print_function

import os

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.hazmat.primitives.asymmetric.utils import (
    encode_dss_signature
)

from tests.utils import (
    load_fips_ecdsa_signing_vectors, load_vectors_from_file
)

CRYPTOGRAPHY_HASH_TYPES = {
    "SHA-1": hashes.SHA1,
    "SHA-224": hashes.SHA224,
    "SHA-256": hashes.SHA256,
    "SHA-384": hashes.SHA384,
    "SHA-512": hashes.SHA512,
}


def verify_one_vector(vector):
    digest_algorithm = vector['digest_algorithm']
    message = vector['message']
    x = vector['x']
    y = vector['y']
    signature = encode_dss_signature(vector['r'], vector['s'])

    numbers = ec.EllipticCurvePublicNumbers(
        x, y,
        ec.SECP256K1()
    )

    key = numbers.public_key(default_backend())

    verifier = key.verifier(
        signature,
        ec.ECDSA(CRYPTOGRAPHY_HASH_TYPES[digest_algorithm]())
    )
    verifier.update(message)
    return verifier.verify()


def verify_vectors(vectors):
    for vector in vectors:
        assert verify_one_vector(vector)


vector_path = os.path.join("asymmetric", "ECDSA", "SECP256K1", "SigGen.txt")

secp256k1_vectors = load_vectors_from_file(
    vector_path,
    load_fips_ecdsa_signing_vectors
)

verify_vectors(secp256k1_vectors)