# Copyright (c) 2016-2017, Yanis Guenane <yanis+ansible@guenane.org>
# Copyright (c) 2017, Markus Teufelberger <mteufelberger+ansible@mgit.at>
# Copyright (c) 2020, Felix Fontein <felix@fontein.de>
# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
# SPDX-License-Identifier: GPL-3.0-or-later

from __future__ import annotations

import abc
import traceback

from ansible.module_utils import six
from ansible.module_utils.basic import missing_required_lib
from ansible.module_utils.common.text.converters import to_bytes, to_native
from ansible_collections.community.crypto.plugins.module_utils.crypto.basic import (
    CRYPTOGRAPHY_HAS_ED448,
    CRYPTOGRAPHY_HAS_ED25519,
    OpenSSLObjectError,
)
from ansible_collections.community.crypto.plugins.module_utils.crypto.math import (
    binary_exp_mod,
    quick_is_not_prime,
)
from ansible_collections.community.crypto.plugins.module_utils.crypto.module_backends.publickey_info import (
    _get_cryptography_public_key_info,
)
from ansible_collections.community.crypto.plugins.module_utils.crypto.support import (
    get_fingerprint_of_bytes,
    load_privatekey,
)
from ansible_collections.community.crypto.plugins.module_utils.version import (
    LooseVersion,
)


MINIMAL_CRYPTOGRAPHY_VERSION = "1.2.3"

CRYPTOGRAPHY_IMP_ERR = None
try:
    import cryptography
    from cryptography.hazmat.primitives import serialization

    CRYPTOGRAPHY_VERSION = LooseVersion(cryptography.__version__)
except ImportError:
    CRYPTOGRAPHY_IMP_ERR = traceback.format_exc()
    CRYPTOGRAPHY_FOUND = False
else:
    CRYPTOGRAPHY_FOUND = True

SIGNATURE_TEST_DATA = b"1234"


def _get_cryptography_private_key_info(key, need_private_key_data=False):
    key_type, key_public_data = _get_cryptography_public_key_info(key.public_key())
    key_private_data = dict()
    if need_private_key_data:
        if isinstance(key, cryptography.hazmat.primitives.asymmetric.rsa.RSAPrivateKey):
            private_numbers = key.private_numbers()
            key_private_data["p"] = private_numbers.p
            key_private_data["q"] = private_numbers.q
            key_private_data["exponent"] = private_numbers.d
        elif isinstance(
            key, cryptography.hazmat.primitives.asymmetric.dsa.DSAPrivateKey
        ):
            private_numbers = key.private_numbers()
            key_private_data["x"] = private_numbers.x
        elif isinstance(
            key, cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePrivateKey
        ):
            private_numbers = key.private_numbers()
            key_private_data["multiplier"] = private_numbers.private_value
    return key_type, key_public_data, key_private_data


def _check_dsa_consistency(key_public_data, key_private_data):
    # Get parameters
    p = key_public_data.get("p")
    q = key_public_data.get("q")
    g = key_public_data.get("g")
    y = key_public_data.get("y")
    x = key_private_data.get("x")
    for v in (p, q, g, y, x):
        if v is None:
            return None
    # Make sure that g is not 0, 1 or -1 in Z/pZ
    if g < 2 or g >= p - 1:
        return False
    # Make sure that x is in range
    if x < 1 or x >= q:
        return False
    # Check whether q divides p-1
    if (p - 1) % q != 0:
        return False
    # Check that g**q mod p == 1
    if binary_exp_mod(g, q, p) != 1:
        return False
    # Check whether g**x mod p == y
    if binary_exp_mod(g, x, p) != y:
        return False
    # Check (quickly) whether p or q are not primes
    if quick_is_not_prime(q) or quick_is_not_prime(p):
        return False
    return True


def _is_cryptography_key_consistent(
    key, key_public_data, key_private_data, warn_func=None
):
    if isinstance(key, cryptography.hazmat.primitives.asymmetric.rsa.RSAPrivateKey):
        # key._backend was removed in cryptography 42.0.0
        backend = getattr(key, "_backend", None)
        if backend is not None:
            return bool(backend._lib.RSA_check_key(key._rsa_cdata))
    if isinstance(key, cryptography.hazmat.primitives.asymmetric.dsa.DSAPrivateKey):
        result = _check_dsa_consistency(key_public_data, key_private_data)
        if result is not None:
            return result
        try:
            signature = key.sign(
                SIGNATURE_TEST_DATA, cryptography.hazmat.primitives.hashes.SHA256()
            )
        except AttributeError:
            # sign() was added in cryptography 1.5, but we support older versions
            return None
        try:
            key.public_key().verify(
                signature,
                SIGNATURE_TEST_DATA,
                cryptography.hazmat.primitives.hashes.SHA256(),
            )
            return True
        except cryptography.exceptions.InvalidSignature:
            return False
    if isinstance(
        key, cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePrivateKey
    ):
        try:
            signature = key.sign(
                SIGNATURE_TEST_DATA,
                cryptography.hazmat.primitives.asymmetric.ec.ECDSA(
                    cryptography.hazmat.primitives.hashes.SHA256()
                ),
            )
        except AttributeError:
            # sign() was added in cryptography 1.5, but we support older versions
            return None
        try:
            key.public_key().verify(
                signature,
                SIGNATURE_TEST_DATA,
                cryptography.hazmat.primitives.asymmetric.ec.ECDSA(
                    cryptography.hazmat.primitives.hashes.SHA256()
                ),
            )
            return True
        except cryptography.exceptions.InvalidSignature:
            return False
    has_simple_sign_function = False
    if CRYPTOGRAPHY_HAS_ED25519 and isinstance(
        key, cryptography.hazmat.primitives.asymmetric.ed25519.Ed25519PrivateKey
    ):
        has_simple_sign_function = True
    if CRYPTOGRAPHY_HAS_ED448 and isinstance(
        key, cryptography.hazmat.primitives.asymmetric.ed448.Ed448PrivateKey
    ):
        has_simple_sign_function = True
    if has_simple_sign_function:
        signature = key.sign(SIGNATURE_TEST_DATA)
        try:
            key.public_key().verify(signature, SIGNATURE_TEST_DATA)
            return True
        except cryptography.exceptions.InvalidSignature:
            return False
    # For X25519 and X448, there's no test yet.
    if warn_func is not None:
        warn_func("Cannot determine consistency for key of type %s" % type(key))
    return None


class PrivateKeyConsistencyError(OpenSSLObjectError):
    def __init__(self, msg, result):
        super(PrivateKeyConsistencyError, self).__init__(msg)
        self.error_message = msg
        self.result = result


class PrivateKeyParseError(OpenSSLObjectError):
    def __init__(self, msg, result):
        super(PrivateKeyParseError, self).__init__(msg)
        self.error_message = msg
        self.result = result


@six.add_metaclass(abc.ABCMeta)
class PrivateKeyInfoRetrieval:
    def __init__(
        self,
        module,
        backend,
        content,
        passphrase=None,
        return_private_key_data=False,
        check_consistency=False,
    ):
        # content must be a bytes string
        self.module = module
        self.backend = backend
        self.content = content
        self.passphrase = passphrase
        self.return_private_key_data = return_private_key_data
        self.check_consistency = check_consistency

    @abc.abstractmethod
    def _get_public_key(self, binary):
        pass

    @abc.abstractmethod
    def _get_key_info(self, need_private_key_data=False):
        pass

    @abc.abstractmethod
    def _is_key_consistent(self, key_public_data, key_private_data):
        pass

    def get_info(self, prefer_one_fingerprint=False):
        result = dict(
            can_parse_key=False,
            key_is_consistent=None,
        )
        priv_key_detail = self.content
        try:
            self.key = load_privatekey(
                path=None,
                content=priv_key_detail,
                passphrase=(
                    to_bytes(self.passphrase)
                    if self.passphrase is not None
                    else self.passphrase
                ),
                backend=self.backend,
            )
            result["can_parse_key"] = True
        except OpenSSLObjectError as exc:
            raise PrivateKeyParseError(to_native(exc), result)

        result["public_key"] = to_native(self._get_public_key(binary=False))
        pk = self._get_public_key(binary=True)
        result["public_key_fingerprints"] = (
            get_fingerprint_of_bytes(pk, prefer_one=prefer_one_fingerprint)
            if pk is not None
            else dict()
        )

        key_type, key_public_data, key_private_data = self._get_key_info(
            need_private_key_data=self.return_private_key_data or self.check_consistency
        )
        result["type"] = key_type
        result["public_data"] = key_public_data
        if self.return_private_key_data:
            result["private_data"] = key_private_data

        if self.check_consistency:
            result["key_is_consistent"] = self._is_key_consistent(
                key_public_data, key_private_data
            )
            if result["key_is_consistent"] is False:
                # Only fail when it is False, to avoid to fail on None (which means "we do not know")
                msg = (
                    "Private key is not consistent! (See "
                    "https://blog.hboeck.de/archives/888-How-I-tricked-Symantec-with-a-Fake-Private-Key.html)"
                )
                raise PrivateKeyConsistencyError(msg, result)
        return result


class PrivateKeyInfoRetrievalCryptography(PrivateKeyInfoRetrieval):
    """Validate the supplied private key, using the cryptography backend"""

    def __init__(self, module, content, **kwargs):
        super(PrivateKeyInfoRetrievalCryptography, self).__init__(
            module, "cryptography", content, **kwargs
        )

    def _get_public_key(self, binary):
        return self.key.public_key().public_bytes(
            serialization.Encoding.DER if binary else serialization.Encoding.PEM,
            serialization.PublicFormat.SubjectPublicKeyInfo,
        )

    def _get_key_info(self, need_private_key_data=False):
        return _get_cryptography_private_key_info(
            self.key, need_private_key_data=need_private_key_data
        )

    def _is_key_consistent(self, key_public_data, key_private_data):
        return _is_cryptography_key_consistent(
            self.key, key_public_data, key_private_data, warn_func=self.module.warn
        )


def get_privatekey_info(
    module,
    backend,
    content,
    passphrase=None,
    return_private_key_data=False,
    prefer_one_fingerprint=False,
):
    if backend == "cryptography":
        info = PrivateKeyInfoRetrievalCryptography(
            module,
            content,
            passphrase=passphrase,
            return_private_key_data=return_private_key_data,
        )
    return info.get_info(prefer_one_fingerprint=prefer_one_fingerprint)


def select_backend(
    module,
    backend,
    content,
    passphrase=None,
    return_private_key_data=False,
    check_consistency=False,
):
    if backend == "auto":
        # Detection what is possible
        can_use_cryptography = (
            CRYPTOGRAPHY_FOUND
            and CRYPTOGRAPHY_VERSION >= LooseVersion(MINIMAL_CRYPTOGRAPHY_VERSION)
        )

        # Try cryptography
        if can_use_cryptography:
            backend = "cryptography"

        # Success?
        if backend == "auto":
            module.fail_json(
                msg=(
                    "Cannot detect the required Python library " "cryptography (>= {0})"
                ).format(MINIMAL_CRYPTOGRAPHY_VERSION)
            )

    if backend == "cryptography":
        if not CRYPTOGRAPHY_FOUND:
            module.fail_json(
                msg=missing_required_lib(
                    "cryptography >= {0}".format(MINIMAL_CRYPTOGRAPHY_VERSION)
                ),
                exception=CRYPTOGRAPHY_IMP_ERR,
            )
        return backend, PrivateKeyInfoRetrievalCryptography(
            module,
            content,
            passphrase=passphrase,
            return_private_key_data=return_private_key_data,
            check_consistency=check_consistency,
        )
    else:
        raise ValueError("Unsupported value for backend: {0}".format(backend))