from __future__ import annotations

import hashlib
import hmac
import os
import socket
import sys
import typing
import warnings
from binascii import unhexlify

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
ALPN_PROTOCOLS = ["http/1.1"]

_TYPE_VERSION_INFO = tuple[int, int, int, str, int]

# Maps the length of a digest to a possible hash function producing this digest
HASHFUNC_MAP = {
    length: getattr(hashlib, algorithm, None)
    for length, algorithm in ((32, "md5"), (40, "sha1"), (64, "sha256"))
}


def _is_has_never_check_common_name_reliable(
    openssl_version: str,
) -> 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 ")

    return is_openssl


if typing.TYPE_CHECKING:
    from ssl import VerifyMode
    from typing import 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,
        PROTOCOL_TLS,
        PROTOCOL_TLS_CLIENT,
        VERIFY_X509_PARTIAL_CHAIN,
        VERIFY_X509_STRICT,
        OP_NO_SSLv2,
        OP_NO_SSLv3,
        SSLContext,
        TLSVersion,
    )

    PROTOCOL_SSLv23 = PROTOCOL_TLS

    # Setting SSLContext.hostname_checks_common_name = False didn't work with
    # LibreSSL, check details in the used function.
    if HAS_NEVER_CHECK_COMMON_NAME and not _is_has_never_check_common_name_reliable(
        OPENSSL_VERSION,
    ):  # Defensive:
        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, misc]
    OP_NO_TICKET = 0x4000  # type: ignore[assignment, misc]
    OP_NO_SSLv2 = 0x1000000  # type: ignore[assignment, misc]
    OP_NO_SSLv3 = 0x2000000  # type: ignore[assignment, misc]
    PROTOCOL_SSLv23 = PROTOCOL_TLS = 2  # type: ignore[assignment, misc]
    PROTOCOL_TLS_CLIENT = 16  # type: ignore[assignment, misc]
    VERIFY_X509_PARTIAL_CHAIN = 0x80000  # type: ignore[assignment,misc]
    VERIFY_X509_STRICT = 0x20  # type: ignore[assignment, misc]


_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)
    if digest_length not in HASHFUNC_MAP:
        raise SSLError(f"Fingerprint of invalid length: {fingerprint}")
    hashfunc = HASHFUNC_MAP.get(digest_length)
    if hashfunc is None:
        raise SSLError(
            f"Hash function implementation unavailable for fingerprint length: {digest_length}"
        )

    # 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,
    verify_flags: 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.
    :param verify_flags:
        The flags for certificate verification operations. These default to
        ``ssl.VERIFY_X509_PARTIAL_CHAIN`` and ``ssl.VERIFY_X509_STRICT`` for Python 3.13+.
    :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 v3.0. Instead use 'ssl_minimum_version'",
                category=FutureWarning,
                stacklevel=2,
            )

    context = SSLContext(PROTOCOL_TLS_CLIENT)
    if ssl_minimum_version is not None:
        context.minimum_version = ssl_minimum_version
    else:  # pyOpenSSL 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

    if verify_flags is None:
        verify_flags = 0
        # In Python 3.13+ ssl.create_default_context() sets VERIFY_X509_PARTIAL_CHAIN
        # and VERIFY_X509_STRICT so we do the same
        if sys.version_info >= (3, 13):
            verify_flags |= VERIFY_X509_PARTIAL_CHAIN
            verify_flags |= VERIFY_X509_STRICT

    context.verify_flags |= verify_flags

    # 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 when using
    # an SSLContext created by pyOpenSSL.
    if 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

    context.hostname_checks_common_name = False

    if "SSLKEYLOGFILE" in os.environ:
        sslkeylogfile = os.path.expandvars(os.environ.get("SSLKEYLOGFILE"))
    else:
        sslkeylogfile = None
    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: typing.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, tls_in_tls, ca_cert_data and
    ca_cert_dir have the same meaning as they do when using
    :func:`ssl.create_default_context`, :meth:`ssl.SSLContext.load_cert_chain`,
    :meth:`ssl.SSLContext.set_ciphers` and :meth:`ssl.SSLContext.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)

    context.set_alpn_protocols(ALPN_PROTOCOLS)

    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)