from __future__ import annotations

import hmac
import os
import socket
import sys
import typing
import warnings
from binascii import unhexlify
from hashlib import md5, sha1, sha256

from ..exceptions import ProxySchemeUnsupported, SSLError
from .url import _BRACELESS_IPV6_ADDRZ_RE, _IPV4_RE

SSLContext = None
SSLTransport = None
HAS_NEVER_CHECK_COMMON_NAME = False
IS_PYOPENSSL = False
IS_SECURETRANSPORT = False
ALPN_PROTOCOLS = ["http/1.1"]

_TYPE_VERSION_INFO = typing.Tuple[int, int, int, str, int]

# Maps the length of a digest to a possible hash function producing this digest
HASHFUNC_MAP = {32: md5, 40: sha1, 64: sha256}


def _is_bpo_43522_fixed(
    implementation_name: str, version_info: _TYPE_VERSION_INFO
) -> bool:
    """Return True for CPython 3.8.9+, 3.9.3+ or 3.10+ where setting
    SSLContext.hostname_checks_common_name to False works.

    PyPy 7.3.7 doesn't work as it doesn't ship with OpenSSL 1.1.1l+
    so we're waiting for a version of PyPy that works before
    allowing this function to return 'True'.

    Outside of CPython and PyPy we don't know which implementations work
    or not so we conservatively use our hostname matching as we know that works
    on all implementations.

    https://github.com/urllib3/urllib3/issues/2192#issuecomment-821832963
    https://foss.heptapod.net/pypy/pypy/-/issues/3539#
    """
    if implementation_name != "cpython":
        return False

    major_minor = version_info[:2]
    micro = version_info[2]
    return (
        (major_minor == (3, 8) and micro >= 9)
        or (major_minor == (3, 9) and micro >= 3)
        or major_minor >= (3, 10)
    )


def _is_has_never_check_common_name_reliable(
    openssl_version: str,
    openssl_version_number: int,
    implementation_name: str,
    version_info: _TYPE_VERSION_INFO,
) -> bool:
    # As of May 2023, all released versions of LibreSSL fail to reject certificates with
    # only common names, see https://github.com/urllib3/urllib3/pull/3024
    is_openssl = openssl_version.startswith("OpenSSL ")
    # Before fixing OpenSSL issue #14579, the SSL_new() API was not copying hostflags
    # like X509_CHECK_FLAG_NEVER_CHECK_SUBJECT, which tripped up CPython.
    # https://github.com/openssl/openssl/issues/14579
    # This was released in OpenSSL 1.1.1l+ (>=0x101010cf)
    is_openssl_issue_14579_fixed = openssl_version_number >= 0x101010CF

    return is_openssl and (
        is_openssl_issue_14579_fixed
        or _is_bpo_43522_fixed(implementation_name, version_info)
    )


if typing.TYPE_CHECKING:
    from ssl import VerifyMode

    from typing_extensions import Literal, TypedDict

    from .ssltransport import SSLTransport as SSLTransportType

    class _TYPE_PEER_CERT_RET_DICT(TypedDict, total=False):
        subjectAltName: tuple[tuple[str, str], ...]
        subject: tuple[tuple[tuple[str, str], ...], ...]
        serialNumber: str


# Mapping from 'ssl.PROTOCOL_TLSX' to 'TLSVersion.X'
_SSL_VERSION_TO_TLS_VERSION: dict[int, int] = {}

try:  # Do we have ssl at all?
    import ssl
    from ssl import (  # type: ignore[assignment]
        CERT_REQUIRED,
        HAS_NEVER_CHECK_COMMON_NAME,
        OP_NO_COMPRESSION,
        OP_NO_TICKET,
        OPENSSL_VERSION,
        OPENSSL_VERSION_NUMBER,
        PROTOCOL_TLS,
        PROTOCOL_TLS_CLIENT,
        OP_NO_SSLv2,
        OP_NO_SSLv3,
        SSLContext,
        TLSVersion,
    )

    PROTOCOL_SSLv23 = PROTOCOL_TLS

    # Setting SSLContext.hostname_checks_common_name = False didn't work before CPython
    # 3.8.9, 3.9.3, and 3.10 (but OK on PyPy) or OpenSSL 1.1.1l+
    if HAS_NEVER_CHECK_COMMON_NAME and not _is_has_never_check_common_name_reliable(
        OPENSSL_VERSION,
        OPENSSL_VERSION_NUMBER,
        sys.implementation.name,
        sys.version_info,
    ):
        HAS_NEVER_CHECK_COMMON_NAME = False

    # Need to be careful here in case old TLS versions get
    # removed in future 'ssl' module implementations.
    for attr in ("TLSv1", "TLSv1_1", "TLSv1_2"):
        try:
            _SSL_VERSION_TO_TLS_VERSION[getattr(ssl, f"PROTOCOL_{attr}")] = getattr(
                TLSVersion, attr
            )
        except AttributeError:  # Defensive:
            continue

    from .ssltransport import SSLTransport  # type: ignore[assignment]
except ImportError:
    OP_NO_COMPRESSION = 0x20000  # type: ignore[assignment]
    OP_NO_TICKET = 0x4000  # type: ignore[assignment]
    OP_NO_SSLv2 = 0x1000000  # type: ignore[assignment]
    OP_NO_SSLv3 = 0x2000000  # type: ignore[assignment]
    PROTOCOL_SSLv23 = PROTOCOL_TLS = 2  # type: ignore[assignment]
    PROTOCOL_TLS_CLIENT = 16  # type: ignore[assignment]


_TYPE_PEER_CERT_RET = typing.Union["_TYPE_PEER_CERT_RET_DICT", bytes, None]


def assert_fingerprint(cert: bytes | None, fingerprint: str) -> None:
    """
    Checks if given fingerprint matches the supplied certificate.

    :param cert:
        Certificate as bytes object.
    :param fingerprint:
        Fingerprint as string of hexdigits, can be interspersed by colons.
    """

    if cert is None:
        raise SSLError("No certificate for the peer.")

    fingerprint = fingerprint.replace(":", "").lower()
    digest_length = len(fingerprint)
    hashfunc = HASHFUNC_MAP.get(digest_length)
    if not hashfunc:
        raise SSLError(f"Fingerprint of invalid length: {fingerprint}")

    # We need encode() here for py32; works on py2 and p33.
    fingerprint_bytes = unhexlify(fingerprint.encode())

    cert_digest = hashfunc(cert).digest()

    if not hmac.compare_digest(cert_digest, fingerprint_bytes):
        raise SSLError(
            f'Fingerprints did not match. Expected "{fingerprint}", got "{cert_digest.hex()}"'
        )


def resolve_cert_reqs(candidate: None | int | str) -> VerifyMode:
    """
    Resolves the argument to a numeric constant, which can be passed to
    the wrap_socket function/method from the ssl module.
    Defaults to :data:`ssl.CERT_REQUIRED`.
    If given a string it is assumed to be the name of the constant in the
    :mod:`ssl` module or its abbreviation.
    (So you can specify `REQUIRED` instead of `CERT_REQUIRED`.
    If it's neither `None` nor a string we assume it is already the numeric
    constant which can directly be passed to wrap_socket.
    """
    if candidate is None:
        return CERT_REQUIRED

    if isinstance(candidate, str):
        res = getattr(ssl, candidate, None)
        if res is None:
            res = getattr(ssl, "CERT_" + candidate)
        return res  # type: ignore[no-any-return]

    return candidate  # type: ignore[return-value]


def resolve_ssl_version(candidate: None | int | str) -> int:
    """
    like resolve_cert_reqs
    """
    if candidate is None:
        return PROTOCOL_TLS

    if isinstance(candidate, str):
        res = getattr(ssl, candidate, None)
        if res is None:
            res = getattr(ssl, "PROTOCOL_" + candidate)
        return typing.cast(int, res)

    return candidate


def create_urllib3_context(
    ssl_version: int | None = None,
    cert_reqs: int | None = None,
    options: int | None = None,
    ciphers: str | None = None,
    ssl_minimum_version: int | None = None,
    ssl_maximum_version: int | None = None,
) -> ssl.SSLContext:
    """Creates and configures an :class:`ssl.SSLContext` instance for use with urllib3.

    :param ssl_version:
        The desired protocol version to use. This will default to
        PROTOCOL_SSLv23 which will negotiate the highest protocol that both
        the server and your installation of OpenSSL support.

        This parameter is deprecated instead use 'ssl_minimum_version'.
    :param ssl_minimum_version:
        The minimum version of TLS to be used. Use the 'ssl.TLSVersion' enum for specifying the value.
    :param ssl_maximum_version:
        The maximum version of TLS to be used. Use the 'ssl.TLSVersion' enum for specifying the value.
        Not recommended to set to anything other than 'ssl.TLSVersion.MAXIMUM_SUPPORTED' which is the
        default value.
    :param cert_reqs:
        Whether to require the certificate verification. This defaults to
        ``ssl.CERT_REQUIRED``.
    :param options:
        Specific OpenSSL options. These default to ``ssl.OP_NO_SSLv2``,
        ``ssl.OP_NO_SSLv3``, ``ssl.OP_NO_COMPRESSION``, and ``ssl.OP_NO_TICKET``.
    :param ciphers:
        Which cipher suites to allow the server to select. Defaults to either system configured
        ciphers if OpenSSL 1.1.1+, otherwise uses a secure default set of ciphers.
    :returns:
        Constructed SSLContext object with specified options
    :rtype: SSLContext
    """
    if SSLContext is None:
        raise TypeError("Can't create an SSLContext object without an ssl module")

    # This means 'ssl_version' was specified as an exact value.
    if ssl_version not in (None, PROTOCOL_TLS, PROTOCOL_TLS_CLIENT):
        # Disallow setting 'ssl_version' and 'ssl_minimum|maximum_version'
        # to avoid conflicts.
        if ssl_minimum_version is not None or ssl_maximum_version is not None:
            raise ValueError(
                "Can't specify both 'ssl_version' and either "
                "'ssl_minimum_version' or 'ssl_maximum_version'"
            )

        # 'ssl_version' is deprecated and will be removed in the future.
        else:
            # Use 'ssl_minimum_version' and 'ssl_maximum_version' instead.
            ssl_minimum_version = _SSL_VERSION_TO_TLS_VERSION.get(
                ssl_version, TLSVersion.MINIMUM_SUPPORTED
            )
            ssl_maximum_version = _SSL_VERSION_TO_TLS_VERSION.get(
                ssl_version, TLSVersion.MAXIMUM_SUPPORTED
            )

            # This warning message is pushing users to use 'ssl_minimum_version'
            # instead of both min/max. Best practice is to only set the minimum version and
            # keep the maximum version to be it's default value: 'TLSVersion.MAXIMUM_SUPPORTED'
            warnings.warn(
                "'ssl_version' option is deprecated and will be "
                "removed in urllib3 v2.1.0. Instead use 'ssl_minimum_version'",
                category=DeprecationWarning,
                stacklevel=2,
            )

    # PROTOCOL_TLS is deprecated in Python 3.10 so we always use PROTOCOL_TLS_CLIENT
    context = SSLContext(PROTOCOL_TLS_CLIENT)

    if ssl_minimum_version is not None:
        context.minimum_version = ssl_minimum_version
    else:  # Python <3.10 defaults to 'MINIMUM_SUPPORTED' so explicitly set TLSv1.2 here
        context.minimum_version = TLSVersion.TLSv1_2

    if ssl_maximum_version is not None:
        context.maximum_version = ssl_maximum_version

    # Unless we're given ciphers defer to either system ciphers in
    # the case of OpenSSL 1.1.1+ or use our own secure default ciphers.
    if ciphers:
        context.set_ciphers(ciphers)

    # Setting the default here, as we may have no ssl module on import
    cert_reqs = ssl.CERT_REQUIRED if cert_reqs is None else cert_reqs

    if options is None:
        options = 0
        # SSLv2 is easily broken and is considered harmful and dangerous
        options |= OP_NO_SSLv2
        # SSLv3 has several problems and is now dangerous
        options |= OP_NO_SSLv3
        # Disable compression to prevent CRIME attacks for OpenSSL 1.0+
        # (issue #309)
        options |= OP_NO_COMPRESSION
        # TLSv1.2 only. Unless set explicitly, do not request tickets.
        # This may save some bandwidth on wire, and although the ticket is encrypted,
        # there is a risk associated with it being on wire,
        # if the server is not rotating its ticketing keys properly.
        options |= OP_NO_TICKET

    context.options |= options

    # Enable post-handshake authentication for TLS 1.3, see GH #1634. PHA is
    # necessary for conditional client cert authentication with TLS 1.3.
    # The attribute is None for OpenSSL <= 1.1.0 or does not exist in older
    # versions of Python.  We only enable on Python 3.7.4+ or if certificate
    # verification is enabled to work around Python issue #37428
    # See: https://bugs.python.org/issue37428
    if (cert_reqs == ssl.CERT_REQUIRED or sys.version_info >= (3, 7, 4)) and getattr(
        context, "post_handshake_auth", None
    ) is not None:
        context.post_handshake_auth = True

    # The order of the below lines setting verify_mode and check_hostname
    # matter due to safe-guards SSLContext has to prevent an SSLContext with
    # check_hostname=True, verify_mode=NONE/OPTIONAL.
    # We always set 'check_hostname=False' for pyOpenSSL so we rely on our own
    # 'ssl.match_hostname()' implementation.
    if cert_reqs == ssl.CERT_REQUIRED and not IS_PYOPENSSL:
        context.verify_mode = cert_reqs
        context.check_hostname = True
    else:
        context.check_hostname = False
        context.verify_mode = cert_reqs

    try:
        context.hostname_checks_common_name = False
    except AttributeError:
        pass

    # Enable logging of TLS session keys via defacto standard environment variable
    # 'SSLKEYLOGFILE', if the feature is available (Python 3.8+). Skip empty values.
    if hasattr(context, "keylog_filename"):
        sslkeylogfile = os.environ.get("SSLKEYLOGFILE")
        if sslkeylogfile:
            context.keylog_filename = sslkeylogfile

    return context


@typing.overload
def ssl_wrap_socket(
    sock: socket.socket,
    keyfile: str | None = ...,
    certfile: str | None = ...,
    cert_reqs: int | None = ...,
    ca_certs: str | None = ...,
    server_hostname: str | None = ...,
    ssl_version: int | None = ...,
    ciphers: str | None = ...,
    ssl_context: ssl.SSLContext | None = ...,
    ca_cert_dir: str | None = ...,
    key_password: str | None = ...,
    ca_cert_data: None | str | bytes = ...,
    tls_in_tls: Literal[False] = ...,
) -> ssl.SSLSocket:
    ...


@typing.overload
def ssl_wrap_socket(
    sock: socket.socket,
    keyfile: str | None = ...,
    certfile: str | None = ...,
    cert_reqs: int | None = ...,
    ca_certs: str | None = ...,
    server_hostname: str | None = ...,
    ssl_version: int | None = ...,
    ciphers: str | None = ...,
    ssl_context: ssl.SSLContext | None = ...,
    ca_cert_dir: str | None = ...,
    key_password: str | None = ...,
    ca_cert_data: None | str | bytes = ...,
    tls_in_tls: bool = ...,
) -> ssl.SSLSocket | SSLTransportType:
    ...


def ssl_wrap_socket(
    sock: socket.socket,
    keyfile: str | None = None,
    certfile: str | None = None,
    cert_reqs: int | None = None,
    ca_certs: str | None = None,
    server_hostname: str | None = None,
    ssl_version: int | None = None,
    ciphers: str | None = None,
    ssl_context: ssl.SSLContext | None = None,
    ca_cert_dir: str | None = None,
    key_password: str | None = None,
    ca_cert_data: None | str | bytes = None,
    tls_in_tls: bool = False,
) -> ssl.SSLSocket | SSLTransportType:
    """
    All arguments except for server_hostname, ssl_context, and ca_cert_dir have
    the same meaning as they do when using :func:`ssl.wrap_socket`.

    :param server_hostname:
        When SNI is supported, the expected hostname of the certificate
    :param ssl_context:
        A pre-made :class:`SSLContext` object. If none is provided, one will
        be created using :func:`create_urllib3_context`.
    :param ciphers:
        A string of ciphers we wish the client to support.
    :param ca_cert_dir:
        A directory containing CA certificates in multiple separate files, as
        supported by OpenSSL's -CApath flag or the capath argument to
        SSLContext.load_verify_locations().
    :param key_password:
        Optional password if the keyfile is encrypted.
    :param ca_cert_data:
        Optional string containing CA certificates in PEM format suitable for
        passing as the cadata parameter to SSLContext.load_verify_locations()
    :param tls_in_tls:
        Use SSLTransport to wrap the existing socket.
    """
    context = ssl_context
    if context is None:
        # Note: This branch of code and all the variables in it are only used in tests.
        # We should consider deprecating and removing this code.
        context = create_urllib3_context(ssl_version, cert_reqs, ciphers=ciphers)

    if ca_certs or ca_cert_dir or ca_cert_data:
        try:
            context.load_verify_locations(ca_certs, ca_cert_dir, ca_cert_data)
        except OSError as e:
            raise SSLError(e) from e

    elif ssl_context is None and hasattr(context, "load_default_certs"):
        # try to load OS default certs; works well on Windows.
        context.load_default_certs()

    # Attempt to detect if we get the goofy behavior of the
    # keyfile being encrypted and OpenSSL asking for the
    # passphrase via the terminal and instead error out.
    if keyfile and key_password is None and _is_key_file_encrypted(keyfile):
        raise SSLError("Client private key is encrypted, password is required")

    if certfile:
        if key_password is None:
            context.load_cert_chain(certfile, keyfile)
        else:
            context.load_cert_chain(certfile, keyfile, key_password)

    try:
        context.set_alpn_protocols(ALPN_PROTOCOLS)
    except NotImplementedError:  # Defensive: in CI, we always have set_alpn_protocols
        pass

    ssl_sock = _ssl_wrap_socket_impl(sock, context, tls_in_tls, server_hostname)
    return ssl_sock


def is_ipaddress(hostname: str | bytes) -> bool:
    """Detects whether the hostname given is an IPv4 or IPv6 address.
    Also detects IPv6 addresses with Zone IDs.

    :param str hostname: Hostname to examine.
    :return: True if the hostname is an IP address, False otherwise.
    """
    if isinstance(hostname, bytes):
        # IDN A-label bytes are ASCII compatible.
        hostname = hostname.decode("ascii")
    return bool(_IPV4_RE.match(hostname) or _BRACELESS_IPV6_ADDRZ_RE.match(hostname))


def _is_key_file_encrypted(key_file: str) -> bool:
    """Detects if a key file is encrypted or not."""
    with open(key_file) as f:
        for line in f:
            # Look for Proc-Type: 4,ENCRYPTED
            if "ENCRYPTED" in line:
                return True

    return False


def _ssl_wrap_socket_impl(
    sock: socket.socket,
    ssl_context: ssl.SSLContext,
    tls_in_tls: bool,
    server_hostname: str | None = None,
) -> ssl.SSLSocket | SSLTransportType:
    if tls_in_tls:
        if not SSLTransport:
            # Import error, ssl is not available.
            raise ProxySchemeUnsupported(
                "TLS in TLS requires support for the 'ssl' module"
            )

        SSLTransport._validate_ssl_context_for_tls_in_tls(ssl_context)
        return SSLTransport(sock, ssl_context, server_hostname)

    return ssl_context.wrap_socket(sock, server_hostname=server_hostname)
