"""
requests.exceptions
~~~~~~~~~~~~~~~~~~~

This module contains the set of Requests' exceptions.
"""
from pip._vendor.urllib3.exceptions import HTTPError as BaseHTTPError

from .compat import JSONDecodeError as CompatJSONDecodeError


class RequestException(IOError):
    """There was an ambiguous exception that occurred while handling your
    request.
    """

    def __init__(self, *args, **kwargs):
        """Initialize RequestException with `request` and `response` objects."""
        response = kwargs.pop("response", None)
        self.response = response
        self.request = kwargs.pop("request", None)
        if response is not None and not self.request and hasattr(response, "request"):
            self.request = self.response.request
        super().__init__(*args, **kwargs)


class InvalidJSONError(RequestException):
    """A JSON error occurred."""


class JSONDecodeError(InvalidJSONError, CompatJSONDecodeError):
    """Couldn't decode the text into json"""

    def __init__(self, *args, **kwargs):
        """
        Construct the JSONDecodeError instance first with all
        args. Then use it's args to construct the IOError so that
        the json specific args aren't used as IOError specific args
        and the error message from JSONDecodeError is preserved.
        """
        CompatJSONDecodeError.__init__(self, *args)
        InvalidJSONError.__init__(self, *self.args, **kwargs)

    def __reduce__(self):
        """
        The __reduce__ method called when pickling the object must
        be the one from the JSONDecodeError (be it json/simplejson)
        as it expects all the arguments for instantiation, not just
        one like the IOError, and the MRO would by default call the
        __reduce__ method from the IOError due to the inheritance order.
        """
        return CompatJSONDecodeError.__reduce__(self)


class HTTPError(RequestException):
    """An HTTP error occurred."""


class ConnectionError(RequestException):
    """A Connection error occurred."""


class ProxyError(ConnectionError):
    """A proxy error occurred."""


class SSLError(ConnectionError):
    """An SSL error occurred."""


class Timeout(RequestException):
    """The request timed out.

    Catching this error will catch both
    :exc:`~requests.exceptions.ConnectTimeout` and
    :exc:`~requests.exceptions.ReadTimeout` errors.
    """


class ConnectTimeout(ConnectionError, Timeout):
    """The request timed out while trying to connect to the remote server.

    Requests that produced this error are safe to retry.
    """


class ReadTimeout(Timeout):
    """The server did not send any data in the allotted amount of time."""


class URLRequired(RequestException):
    """A valid URL is required to make a request."""


class TooManyRedirects(RequestException):
    """Too many redirects."""


class MissingSchema(RequestException, ValueError):
    """The URL scheme (e.g. http or https) is missing."""


class InvalidSchema(RequestException, ValueError):
    """The URL scheme provided is either invalid or unsupported."""


class InvalidURL(RequestException, ValueError):
    """The URL provided was somehow invalid."""


class InvalidHeader(RequestException, ValueError):
    """The header value provided was somehow invalid."""


class InvalidProxyURL(InvalidURL):
    """The proxy URL provided is invalid."""


class ChunkedEncodingError(RequestException):
    """The server declared chunked encoding but sent an invalid chunk."""


class ContentDecodingError(RequestException, BaseHTTPError):
    """Failed to decode response content."""


class StreamConsumedError(RequestException, TypeError):
    """The content for this response was already consumed."""


class RetryError(RequestException):
    """Custom retries logic failed"""


class UnrewindableBodyError(RequestException):
    """Requests encountered an error when trying to rewind a body."""


# Warnings


class RequestsWarning(Warning):
    """Base warning for Requests."""


class FileModeWarning(RequestsWarning, DeprecationWarning):
    """A file was opened in text mode, but Requests determined its binary length."""


class RequestsDependencyWarning(RequestsWarning):
    """An imported dependency doesn't match the expected version range."""

from __future__ import annotations

import contextlib
import re
from dataclasses import dataclass
from typing import Iterator, NoReturn

from .specifiers import Specifier


@dataclass
class Token:
    name: str
    text: str
    position: int


class ParserSyntaxError(Exception):
    """The provided source text could not be parsed correctly."""

    def __init__(
        self,
        message: str,
        *,
        source: str,
        span: tuple[int, int],
    ) -> None:
        self.span = span
        self.message = message
        self.source = source

        super().__init__()

    def __str__(self) -> str:
        marker = " " * self.span[0] + "~" * (self.span[1] - self.span[0]) + "^"
        return "\n    ".join([self.message, self.source, marker])


DEFAULT_RULES: dict[str, str | re.Pattern[str]] = {
    "LEFT_PARENTHESIS": r"\(",
    "RIGHT_PARENTHESIS": r"\)",
    "LEFT_BRACKET": r"\[",
    "RIGHT_BRACKET": r"\]",
    "SEMICOLON": r";",
    "COMMA": r",",
    "QUOTED_STRING": re.compile(
        r"""
            (
                ('[^']*')
                |
                ("[^"]*")
            )
        """,
        re.VERBOSE,
    ),
    "OP": r"(===|==|~=|!=|<=|>=|<|>)",
    "BOOLOP": r"\b(or|and)\b",
    "IN": r"\bin\b",
    "NOT": r"\bnot\b",
    "VARIABLE": re.compile(
        r"""
            \b(
                python_version
                |python_full_version
                |os[._]name
                |sys[._]platform
                |platform_(release|system)
                |platform[._](version|machine|python_implementation)
                |python_implementation
                |implementation_(name|version)
                |extra
            )\b
        """,
        re.VERBOSE,
    ),
    "SPECIFIER": re.compile(
        Specifier._operator_regex_str + Specifier._version_regex_str,
        re.VERBOSE | re.IGNORECASE,
    ),
    "AT": r"\@",
    "URL": r"[^ \t]+",
    "IDENTIFIER": r"\b[a-zA-Z0-9][a-zA-Z0-9._-]*\b",
    "VERSION_PREFIX_TRAIL": r"\.\*",
    "VERSION_LOCAL_LABEL_TRAIL": r"\+[a-z0-9]+(?:[-_\.][a-z0-9]+)*",
    "WS": r"[ \t]+",
    "END": r"$",
}


class Tokenizer:
    """Context-sensitive token parsing.

    Provides methods to examine the input stream to check whether the next token
    matches.
    """

    def __init__(
        self,
        source: str,
        *,
        rules: dict[str, str | re.Pattern[str]],
    ) -> None:
        self.source = source
        self.rules: dict[str, re.Pattern[str]] = {
            name: re.compile(pattern) for name, pattern in rules.items()
        }
        self.next_token: Token | None = None
        self.position = 0

    def consume(self, name: str) -> None:
        """Move beyond provided token name, if at current position."""
        if self.check(name):
            self.read()

    def check(self, name: str, *, peek: bool = False) -> bool:
        """Check whether the next token has the provided name.

        By default, if the check succeeds, the token *must* be read before
        another check. If `peek` is set to `True`, the token is not loaded and
        would need to be checked again.
        """
        assert (
            self.next_token is None
        ), f"Cannot check for {name!r}, already have {self.next_token!r}"
        assert name in self.rules, f"Unknown token name: {name!r}"

        expression = self.rules[name]

        match = expression.match(self.source, self.position)
        if match is None:
            return False
        if not peek:
            self.next_token = Token(name, match[0], self.position)
        return True

    def expect(self, name: str, *, expected: str) -> Token:
        """Expect a certain token name next, failing with a syntax error otherwise.

        The token is *not* read.
        """
        if not self.check(name):
            raise self.raise_syntax_error(f"Expected {expected}")
        return self.read()

    def read(self) -> Token:
        """Consume the next token and return it."""
        token = self.next_token
        assert token is not None

        self.position += len(token.text)
        self.next_token = None

        return token

    def raise_syntax_error(
        self,
        message: str,
        *,
        span_start: int | None = None,
        span_end: int | None = None,
    ) -> NoReturn:
        """Raise ParserSyntaxError at the given position."""
        span = (
            self.position if span_start is None else span_start,
            self.position if span_end is None else span_end,
        )
        raise ParserSyntaxError(
            message,
            source=self.source,
            span=span,
        )

    @contextlib.contextmanager
    def enclosing_tokens(
        self, open_token: str, close_token: str, *, around: str
    ) -> Iterator[None]:
        if self.check(open_token):
            open_position = self.position
            self.read()
        else:
            open_position = None

        yield

        if open_position is None:
            return

        if not self.check(close_token):
            self.raise_syntax_error(
                f"Expected matching {close_token} for {open_token}, after {around}",
                span_start=open_position,
            )

        self.read()

# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
"""
.. testsetup::

    from pip._vendor.packaging.version import parse, Version
"""

from __future__ import annotations

import itertools
import re
from typing import Any, Callable, NamedTuple, SupportsInt, Tuple, Union

from ._structures import Infinity, InfinityType, NegativeInfinity, NegativeInfinityType

__all__ = ["VERSION_PATTERN", "parse", "Version", "InvalidVersion"]

LocalType = Tuple[Union[int, str], ...]

CmpPrePostDevType = Union[InfinityType, NegativeInfinityType, Tuple[str, int]]
CmpLocalType = Union[
    NegativeInfinityType,
    Tuple[Union[Tuple[int, str], Tuple[NegativeInfinityType, Union[int, str]]], ...],
]
CmpKey = Tuple[
    int,
    Tuple[int, ...],
    CmpPrePostDevType,
    CmpPrePostDevType,
    CmpPrePostDevType,
    CmpLocalType,
]
VersionComparisonMethod = Callable[[CmpKey, CmpKey], bool]


class _Version(NamedTuple):
    epoch: int
    release: tuple[int, ...]
    dev: tuple[str, int] | None
    pre: tuple[str, int] | None
    post: tuple[str, int] | None
    local: LocalType | None


def parse(version: str) -> Version:
    """Parse the given version string.

    >>> parse('1.0.dev1')
    <Version('1.0.dev1')>

    :param version: The version string to parse.
    :raises InvalidVersion: When the version string is not a valid version.
    """
    return Version(version)


class InvalidVersion(ValueError):
    """Raised when a version string is not a valid version.

    >>> Version("invalid")
    Traceback (most recent call last):
        ...
    packaging.version.InvalidVersion: Invalid version: 'invalid'
    """


class _BaseVersion:
    _key: tuple[Any, ...]

    def __hash__(self) -> int:
        return hash(self._key)

    # Please keep the duplicated `isinstance` check
    # in the six comparisons hereunder
    # unless you find a way to avoid adding overhead function calls.
    def __lt__(self, other: _BaseVersion) -> bool:
        if not isinstance(other, _BaseVersion):
            return NotImplemented

        return self._key < other._key

    def __le__(self, other: _BaseVersion) -> bool:
        if not isinstance(other, _BaseVersion):
            return NotImplemented

        return self._key <= other._key

    def __eq__(self, other: object) -> bool:
        if not isinstance(other, _BaseVersion):
            return NotImplemented

        return self._key == other._key

    def __ge__(self, other: _BaseVersion) -> bool:
        if not isinstance(other, _BaseVersion):
            return NotImplemented

        return self._key >= other._key

    def __gt__(self, other: _BaseVersion) -> bool:
        if not isinstance(other, _BaseVersion):
            return NotImplemented

        return self._key > other._key

    def __ne__(self, other: object) -> bool:
        if not isinstance(other, _BaseVersion):
            return NotImplemented

        return self._key != other._key


# Deliberately not anchored to the start and end of the string, to make it
# easier for 3rd party code to reuse
_VERSION_PATTERN = r"""
    v?
    (?:
        (?:(?P<epoch>[0-9]+)!)?                           # epoch
        (?P<release>[0-9]+(?:\.[0-9]+)*)                  # release segment
        (?P<pre>                                          # pre-release
            [-_\.]?
            (?P<pre_l>alpha|a|beta|b|preview|pre|c|rc)
            [-_\.]?
            (?P<pre_n>[0-9]+)?
        )?
        (?P<post>                                         # post release
            (?:-(?P<post_n1>[0-9]+))
            |
            (?:
                [-_\.]?
                (?P<post_l>post|rev|r)
                [-_\.]?
                (?P<post_n2>[0-9]+)?
            )
        )?
        (?P<dev>                                          # dev release
            [-_\.]?
            (?P<dev_l>dev)
            [-_\.]?
            (?P<dev_n>[0-9]+)?
        )?
    )
    (?:\+(?P<local>[a-z0-9]+(?:[-_\.][a-z0-9]+)*))?       # local version
"""

VERSION_PATTERN = _VERSION_PATTERN
"""
A string containing the regular expression used to match a valid version.

The pattern is not anchored at either end, and is intended for embedding in larger
expressions (for example, matching a version number as part of a file name). The
regular expression should be compiled with the ``re.VERBOSE`` and ``re.IGNORECASE``
flags set.

:meta hide-value:
"""


class Version(_BaseVersion):
    """This class abstracts handling of a project's versions.

    A :class:`Version` instance is comparison aware and can be compared and
    sorted using the standard Python interfaces.

    >>> v1 = Version("1.0a5")
    >>> v2 = Version("1.0")
    >>> v1
    <Version('1.0a5')>
    >>> v2
    <Version('1.0')>
    >>> v1 < v2
    True
    >>> v1 == v2
    False
    >>> v1 > v2
    False
    >>> v1 >= v2
    False
    >>> v1 <= v2
    True
    """

    _regex = re.compile(r"^\s*" + VERSION_PATTERN + r"\s*$", re.VERBOSE | re.IGNORECASE)
    _key: CmpKey

    def __init__(self, version: str) -> None:
        """Initialize a Version object.

        :param version:
            The string representation of a version which will be parsed and normalized
            before use.
        :raises InvalidVersion:
            If the ``version`` does not conform to PEP 440 in any way then this
            exception will be raised.
        """

        # Validate the version and parse it into pieces
        match = self._regex.search(version)
        if not match:
            raise InvalidVersion(f"Invalid version: '{version}'")

        # Store the parsed out pieces of the version
        self._version = _Version(
            epoch=int(match.group("epoch")) if match.group("epoch") else 0,
            release=tuple(int(i) for i in match.group("release").split(".")),
            pre=_parse_letter_version(match.group("pre_l"), match.group("pre_n")),
            post=_parse_letter_version(
                match.group("post_l"), match.group("post_n1") or match.group("post_n2")
            ),
            dev=_parse_letter_version(match.group("dev_l"), match.group("dev_n")),
            local=_parse_local_version(match.group("local")),
        )

        # Generate a key which will be used for sorting
        self._key = _cmpkey(
            self._version.epoch,
            self._version.release,
            self._version.pre,
            self._version.post,
            self._version.dev,
            self._version.local,
        )

    def __repr__(self) -> str:
        """A representation of the Version that shows all internal state.

        >>> Version('1.0.0')
        <Version('1.0.0')>
        """
        return f"<Version('{self}')>"

    def __str__(self) -> str:
        """A string representation of the version that can be rounded-tripped.

        >>> str(Version("1.0a5"))
        '1.0a5'
        """
        parts = []

        # Epoch
        if self.epoch != 0:
            parts.append(f"{self.epoch}!")

        # Release segment
        parts.append(".".join(str(x) for x in self.release))

        # Pre-release
        if self.pre is not None:
            parts.append("".join(str(x) for x in self.pre))

        # Post-release
        if self.post is not None:
            parts.append(f".post{self.post}")

        # Development release
        if self.dev is not None:
            parts.append(f".dev{self.dev}")

        # Local version segment
        if self.local is not None:
            parts.append(f"+{self.local}")

        return "".join(parts)

    @property
    def epoch(self) -> int:
        """The epoch of the version.

        >>> Version("2.0.0").epoch
        0
        >>> Version("1!2.0.0").epoch
        1
        """
        return self._version.epoch

    @property
    def release(self) -> tuple[int, ...]:
        """The components of the "release" segment of the version.

        >>> Version("1.2.3").release
        (1, 2, 3)
        >>> Version("2.0.0").release
        (2, 0, 0)
        >>> Version("1!2.0.0.post0").release
        (2, 0, 0)

        Includes trailing zeroes but not the epoch or any pre-release / development /
        post-release suffixes.
        """
        return self._version.release

    @property
    def pre(self) -> tuple[str, int] | None:
        """The pre-release segment of the version.

        >>> print(Version("1.2.3").pre)
        None
        >>> Version("1.2.3a1").pre
        ('a', 1)
        >>> Version("1.2.3b1").pre
        ('b', 1)
        >>> Version("1.2.3rc1").pre
        ('rc', 1)
        """
        return self._version.pre

    @property
    def post(self) -> int | None:
        """The post-release number of the version.

        >>> print(Version("1.2.3").post)
        None
        >>> Version("1.2.3.post1").post
        1
        """
        return self._version.post[1] if self._version.post else None

    @property
    def dev(self) -> int | None:
        """The development number of the version.

        >>> print(Version("1.2.3").dev)
        None
        >>> Version("1.2.3.dev1").dev
        1
        """
        return self._version.dev[1] if self._version.dev else None

    @property
    def local(self) -> str | None:
        """The local version segment of the version.

        >>> print(Version("1.2.3").local)
        None
        >>> Version("1.2.3+abc").local
        'abc'
        """
        if self._version.local:
            return ".".join(str(x) for x in self._version.local)
        else:
            return None

    @property
    def public(self) -> str:
        """The public portion of the version.

        >>> Version("1.2.3").public
        '1.2.3'
        >>> Version("1.2.3+abc").public
        '1.2.3'
        >>> Version("1.2.3+abc.dev1").public
        '1.2.3'
        """
        return str(self).split("+", 1)[0]

    @property
    def base_version(self) -> str:
        """The "base version" of the version.

        >>> Version("1.2.3").base_version
        '1.2.3'
        >>> Version("1.2.3+abc").base_version
        '1.2.3'
        >>> Version("1!1.2.3+abc.dev1").base_version
        '1!1.2.3'

        The "base version" is the public version of the project without any pre or post
        release markers.
        """
        parts = []

        # Epoch
        if self.epoch != 0:
            parts.append(f"{self.epoch}!")

        # Release segment
        parts.append(".".join(str(x) for x in self.release))

        return "".join(parts)

    @property
    def is_prerelease(self) -> bool:
        """Whether this version is a pre-release.

        >>> Version("1.2.3").is_prerelease
        False
        >>> Version("1.2.3a1").is_prerelease
        True
        >>> Version("1.2.3b1").is_prerelease
        True
        >>> Version("1.2.3rc1").is_prerelease
        True
        >>> Version("1.2.3dev1").is_prerelease
        True
        """
        return self.dev is not None or self.pre is not None

    @property
    def is_postrelease(self) -> bool:
        """Whether this version is a post-release.

        >>> Version("1.2.3").is_postrelease
        False
        >>> Version("1.2.3.post1").is_postrelease
        True
        """
        return self.post is not None

    @property
    def is_devrelease(self) -> bool:
        """Whether this version is a development release.

        >>> Version("1.2.3").is_devrelease
        False
        >>> Version("1.2.3.dev1").is_devrelease
        True
        """
        return self.dev is not None

    @property
    def major(self) -> int:
        """The first item of :attr:`release` or ``0`` if unavailable.

        >>> Version("1.2.3").major
        1
        """
        return self.release[0] if len(self.release) >= 1 else 0

    @property
    def minor(self) -> int:
        """The second item of :attr:`release` or ``0`` if unavailable.

        >>> Version("1.2.3").minor
        2
        >>> Version("1").minor
        0
        """
        return self.release[1] if len(self.release) >= 2 else 0

    @property
    def micro(self) -> int:
        """The third item of :attr:`release` or ``0`` if unavailable.

        >>> Version("1.2.3").micro
        3
        >>> Version("1").micro
        0
        """
        return self.release[2] if len(self.release) >= 3 else 0


def _parse_letter_version(
    letter: str | None, number: str | bytes | SupportsInt | None
) -> tuple[str, int] | None:
    if letter:
        # We consider there to be an implicit 0 in a pre-release if there is
        # not a numeral associated with it.
        if number is None:
            number = 0

        # We normalize any letters to their lower case form
        letter = letter.lower()

        # We consider some words to be alternate spellings of other words and
        # in those cases we want to normalize the spellings to our preferred
        # spelling.
        if letter == "alpha":
            letter = "a"
        elif letter == "beta":
            letter = "b"
        elif letter in ["c", "pre", "preview"]:
            letter = "rc"
        elif letter in ["rev", "r"]:
            letter = "post"

        return letter, int(number)
    if not letter and number:
        # We assume if we are given a number, but we are not given a letter
        # then this is using the implicit post release syntax (e.g. 1.0-1)
        letter = "post"

        return letter, int(number)

    return None


_local_version_separators = re.compile(r"[\._-]")


def _parse_local_version(local: str | None) -> LocalType | None:
    """
    Takes a string like abc.1.twelve and turns it into ("abc", 1, "twelve").
    """
    if local is not None:
        return tuple(
            part.lower() if not part.isdigit() else int(part)
            for part in _local_version_separators.split(local)
        )
    return None


def _cmpkey(
    epoch: int,
    release: tuple[int, ...],
    pre: tuple[str, int] | None,
    post: tuple[str, int] | None,
    dev: tuple[str, int] | None,
    local: LocalType | None,
) -> CmpKey:
    # When we compare a release version, we want to compare it with all of the
    # trailing zeros removed. So we'll use a reverse the list, drop all the now
    # leading zeros until we come to something non zero, then take the rest
    # re-reverse it back into the correct order and make it a tuple and use
    # that for our sorting key.
    _release = tuple(
        reversed(list(itertools.dropwhile(lambda x: x == 0, reversed(release))))
    )

    # We need to "trick" the sorting algorithm to put 1.0.dev0 before 1.0a0.
    # We'll do this by abusing the pre segment, but we _only_ want to do this
    # if there is not a pre or a post segment. If we have one of those then
    # the normal sorting rules will handle this case correctly.
    if pre is None and post is None and dev is not None:
        _pre: CmpPrePostDevType = NegativeInfinity
    # Versions without a pre-release (except as noted above) should sort after
    # those with one.
    elif pre is None:
        _pre = Infinity
    else:
        _pre = pre

    # Versions without a post segment should sort before those with one.
    if post is None:
        _post: CmpPrePostDevType = NegativeInfinity

    else:
        _post = post

    # Versions without a development segment should sort after those with one.
    if dev is None:
        _dev: CmpPrePostDevType = Infinity

    else:
        _dev = dev

    if local is None:
        # Versions without a local segment should sort before those with one.
        _local: CmpLocalType = NegativeInfinity
    else:
        # Versions with a local segment need that segment parsed to implement
        # the sorting rules in PEP440.
        # - Alpha numeric segments sort before numeric segments
        # - Alpha numeric segments sort lexicographically
        # - Numeric segments sort numerically
        # - Shorter versions sort before longer versions when the prefixes
        #   match exactly
        _local = tuple(
            (i, "") if isinstance(i, int) else (NegativeInfinity, i) for i in local
        )

    return epoch, _release, _pre, _post, _dev, _local

"""Legacy editable installation process, i.e. `setup.py develop`.
"""

import logging
from typing import Optional, Sequence

from pip._internal.build_env import BuildEnvironment
from pip._internal.utils.logging import indent_log
from pip._internal.utils.setuptools_build import make_setuptools_develop_args
from pip._internal.utils.subprocess import call_subprocess

logger = logging.getLogger(__name__)


def install_editable(
    *,
    global_options: Sequence[str],
    prefix: Optional[str],
    home: Optional[str],
    use_user_site: bool,
    name: str,
    setup_py_path: str,
    isolated: bool,
    build_env: BuildEnvironment,
    unpacked_source_directory: str,
) -> None:
    """Install a package in editable mode. Most arguments are pass-through
    to setuptools.
    """
    logger.info("Running setup.py develop for %s", name)

    args = make_setuptools_develop_args(
        setup_py_path,
        global_options=global_options,
        no_user_config=isolated,
        prefix=prefix,
        home=home,
        use_user_site=use_user_site,
    )

    with indent_log():
        with build_env:
            call_subprocess(
                args,
                command_desc="python setup.py develop",
                cwd=unpacked_source_directory,
            )

__version__ = '3.7'

from typing import Iterable, Tuple, TypeVar

T = TypeVar("T")


def loop_first(values: Iterable[T]) -> Iterable[Tuple[bool, T]]:
    """Iterate and generate a tuple with a flag for first value."""
    iter_values = iter(values)
    try:
        value = next(iter_values)
    except StopIteration:
        return
    yield True, value
    for value in iter_values:
        yield False, value


def loop_last(values: Iterable[T]) -> Iterable[Tuple[bool, T]]:
    """Iterate and generate a tuple with a flag for last value."""
    iter_values = iter(values)
    try:
        previous_value = next(iter_values)
    except StopIteration:
        return
    for value in iter_values:
        yield False, previous_value
        previous_value = value
    yield True, previous_value


def loop_first_last(values: Iterable[T]) -> Iterable[Tuple[bool, bool, T]]:
    """Iterate and generate a tuple with a flag for first and last value."""
    iter_values = iter(values)
    try:
        previous_value = next(iter_values)
    except StopIteration:
        return
    first = True
    for value in iter_values:
        yield first, False, previous_value
        first = False
        previous_value = value
    yield first, True, previous_value

"""
    pygments.token
    ~~~~~~~~~~~~~~

    Basic token types and the standard tokens.

    :copyright: Copyright 2006-2024 by the Pygments team, see AUTHORS.
    :license: BSD, see LICENSE for details.
"""


class _TokenType(tuple):
    parent = None

    def split(self):
        buf = []
        node = self
        while node is not None:
            buf.append(node)
            node = node.parent
        buf.reverse()
        return buf

    def __init__(self, *args):
        # no need to call super.__init__
        self.subtypes = set()

    def __contains__(self, val):
        return self is val or (
            type(val) is self.__class__ and
            val[:len(self)] == self
        )

    def __getattr__(self, val):
        if not val or not val[0].isupper():
            return tuple.__getattribute__(self, val)
        new = _TokenType(self + (val,))
        setattr(self, val, new)
        self.subtypes.add(new)
        new.parent = self
        return new

    def __repr__(self):
        return 'Token' + (self and '.' or '') + '.'.join(self)

    def __copy__(self):
        # These instances are supposed to be singletons
        return self

    def __deepcopy__(self, memo):
        # These instances are supposed to be singletons
        return self


Token = _TokenType()

# Special token types
Text = Token.Text
Whitespace = Text.Whitespace
Escape = Token.Escape
Error = Token.Error
# Text that doesn't belong to this lexer (e.g. HTML in PHP)
Other = Token.Other

# Common token types for source code
Keyword = Token.Keyword
Name = Token.Name
Literal = Token.Literal
String = Literal.String
Number = Literal.Number
Punctuation = Token.Punctuation
Operator = Token.Operator
Comment = Token.Comment

# Generic types for non-source code
Generic = Token.Generic

# String and some others are not direct children of Token.
# alias them:
Token.Token = Token
Token.String = String
Token.Number = Number


def is_token_subtype(ttype, other):
    """
    Return True if ``ttype`` is a subtype of ``other``.

    exists for backwards compatibility. use ``ttype in other`` now.
    """
    return ttype in other


def string_to_tokentype(s):
    """
    Convert a string into a token type::

        >>> string_to_token('String.Double')
        Token.Literal.String.Double
        >>> string_to_token('Token.Literal.Number')
        Token.Literal.Number
        >>> string_to_token('')
        Token

    Tokens that are already tokens are returned unchanged:

        >>> string_to_token(String)
        Token.Literal.String
    """
    if isinstance(s, _TokenType):
        return s
    if not s:
        return Token
    node = Token
    for item in s.split('.'):
        node = getattr(node, item)
    return node


# Map standard token types to short names, used in CSS class naming.
# If you add a new item, please be sure to run this file to perform
# a consistency check for duplicate values.
STANDARD_TYPES = {
    Token:                         '',

    Text:                          '',
    Whitespace:                    'w',
    Escape:                        'esc',
    Error:                         'err',
    Other:                         'x',

    Keyword:                       'k',
    Keyword.Constant:              'kc',
    Keyword.Declaration:           'kd',
    Keyword.Namespace:             'kn',
    Keyword.Pseudo:                'kp',
    Keyword.Reserved:              'kr',
    Keyword.Type:                  'kt',

    Name:                          'n',
    Name.Attribute:                'na',
    Name.Builtin:                  'nb',
    Name.Builtin.Pseudo:           'bp',
    Name.Class:                    'nc',
    Name.Constant:                 'no',
    Name.Decorator:                'nd',
    Name.Entity:                   'ni',
    Name.Exception:                'ne',
    Name.Function:                 'nf',
    Name.Function.Magic:           'fm',
    Name.Property:                 'py',
    Name.Label:                    'nl',
    Name.Namespace:                'nn',
    Name.Other:                    'nx',
    Name.Tag:                      'nt',
    Name.Variable:                 'nv',
    Name.Variable.Class:           'vc',
    Name.Variable.Global:          'vg',
    Name.Variable.Instance:        'vi',
    Name.Variable.Magic:           'vm',

    Literal:                       'l',
    Literal.Date:                  'ld',

    String:                        's',
    String.Affix:                  'sa',
    String.Backtick:               'sb',
    String.Char:                   'sc',
    String.Delimiter:              'dl',
    String.Doc:                    'sd',
    String.Double:                 's2',
    String.Escape:                 'se',
    String.Heredoc:                'sh',
    String.Interpol:               'si',
    String.Other:                  'sx',
    String.Regex:                  'sr',
    String.Single:                 's1',
    String.Symbol:                 'ss',

    Number:                        'm',
    Number.Bin:                    'mb',
    Number.Float:                  'mf',
    Number.Hex:                    'mh',
    Number.Integer:                'mi',
    Number.Integer.Long:           'il',
    Number.Oct:                    'mo',

    Operator:                      'o',
    Operator.Word:                 'ow',

    Punctuation:                   'p',
    Punctuation.Marker:            'pm',

    Comment:                       'c',
    Comment.Hashbang:              'ch',
    Comment.Multiline:             'cm',
    Comment.Preproc:               'cp',
    Comment.PreprocFile:           'cpf',
    Comment.Single:                'c1',
    Comment.Special:               'cs',

    Generic:                       'g',
    Generic.Deleted:               'gd',
    Generic.Emph:                  'ge',
    Generic.Error:                 'gr',
    Generic.Heading:               'gh',
    Generic.Inserted:              'gi',
    Generic.Output:                'go',
    Generic.Prompt:                'gp',
    Generic.Strong:                'gs',
    Generic.Subheading:            'gu',
    Generic.EmphStrong:            'ges',
    Generic.Traceback:             'gt',
}

"""
requests.api
~~~~~~~~~~~~

This module implements the Requests API.

:copyright: (c) 2012 by Kenneth Reitz.
:license: Apache2, see LICENSE for more details.
"""

from . import sessions


def request(method, url, **kwargs):
    """Constructs and sends a :class:`Request <Request>`.

    :param method: method for the new :class:`Request` object: ``GET``, ``OPTIONS``, ``HEAD``, ``POST``, ``PUT``, ``PATCH``, or ``DELETE``.
    :param url: URL for the new :class:`Request` object.
    :param params: (optional) Dictionary, list of tuples or bytes to send
        in the query string for the :class:`Request`.
    :param data: (optional) Dictionary, list of tuples, bytes, or file-like
        object to send in the body of the :class:`Request`.
    :param json: (optional) A JSON serializable Python object to send in the body of the :class:`Request`.
    :param headers: (optional) Dictionary of HTTP Headers to send with the :class:`Request`.
    :param cookies: (optional) Dict or CookieJar object to send with the :class:`Request`.
    :param files: (optional) Dictionary of ``'name': file-like-objects`` (or ``{'name': file-tuple}``) for multipart encoding upload.
        ``file-tuple`` can be a 2-tuple ``('filename', fileobj)``, 3-tuple ``('filename', fileobj, 'content_type')``
        or a 4-tuple ``('filename', fileobj, 'content_type', custom_headers)``, where ``'content_type'`` is a string
        defining the content type of the given file and ``custom_headers`` a dict-like object containing additional headers
        to add for the file.
    :param auth: (optional) Auth tuple to enable Basic/Digest/Custom HTTP Auth.
    :param timeout: (optional) How many seconds to wait for the server to send data
        before giving up, as a float, or a :ref:`(connect timeout, read
        timeout) <timeouts>` tuple.
    :type timeout: float or tuple
    :param allow_redirects: (optional) Boolean. Enable/disable GET/OPTIONS/POST/PUT/PATCH/DELETE/HEAD redirection. Defaults to ``True``.
    :type allow_redirects: bool
    :param proxies: (optional) Dictionary mapping protocol to the URL of the proxy.
    :param verify: (optional) Either a boolean, in which case it controls whether we verify
            the server's TLS certificate, or a string, in which case it must be a path
            to a CA bundle to use. Defaults to ``True``.
    :param stream: (optional) if ``False``, the response content will be immediately downloaded.
    :param cert: (optional) if String, path to ssl client cert file (.pem). If Tuple, ('cert', 'key') pair.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response

    Usage::

      >>> import requests
      >>> req = requests.request('GET', 'https://httpbin.org/get')
      >>> req
      <Response [200]>
    """

    # By using the 'with' statement we are sure the session is closed, thus we
    # avoid leaving sockets open which can trigger a ResourceWarning in some
    # cases, and look like a memory leak in others.
    with sessions.Session() as session:
        return session.request(method=method, url=url, **kwargs)


def get(url, params=None, **kwargs):
    r"""Sends a GET request.

    :param url: URL for the new :class:`Request` object.
    :param params: (optional) Dictionary, list of tuples or bytes to send
        in the query string for the :class:`Request`.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    return request("get", url, params=params, **kwargs)


def options(url, **kwargs):
    r"""Sends an OPTIONS request.

    :param url: URL for the new :class:`Request` object.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    return request("options", url, **kwargs)


def head(url, **kwargs):
    r"""Sends a HEAD request.

    :param url: URL for the new :class:`Request` object.
    :param \*\*kwargs: Optional arguments that ``request`` takes. If
        `allow_redirects` is not provided, it will be set to `False` (as
        opposed to the default :meth:`request` behavior).
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    kwargs.setdefault("allow_redirects", False)
    return request("head", url, **kwargs)


def post(url, data=None, json=None, **kwargs):
    r"""Sends a POST request.

    :param url: URL for the new :class:`Request` object.
    :param data: (optional) Dictionary, list of tuples, bytes, or file-like
        object to send in the body of the :class:`Request`.
    :param json: (optional) A JSON serializable Python object to send in the body of the :class:`Request`.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    return request("post", url, data=data, json=json, **kwargs)


def put(url, data=None, **kwargs):
    r"""Sends a PUT request.

    :param url: URL for the new :class:`Request` object.
    :param data: (optional) Dictionary, list of tuples, bytes, or file-like
        object to send in the body of the :class:`Request`.
    :param json: (optional) A JSON serializable Python object to send in the body of the :class:`Request`.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    return request("put", url, data=data, **kwargs)


def patch(url, data=None, **kwargs):
    r"""Sends a PATCH request.

    :param url: URL for the new :class:`Request` object.
    :param data: (optional) Dictionary, list of tuples, bytes, or file-like
        object to send in the body of the :class:`Request`.
    :param json: (optional) A JSON serializable Python object to send in the body of the :class:`Request`.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    return request("patch", url, data=data, **kwargs)


def delete(url, **kwargs):
    r"""Sends a DELETE request.

    :param url: URL for the new :class:`Request` object.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    return request("delete", url, **kwargs)

CONSOLE_HTML_FORMAT = """\
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<style>
{stylesheet}
body {{
    color: {foreground};
    background-color: {background};
}}
</style>
</head>
<body>
    <pre style="font-family:Menlo,'DejaVu Sans Mono',consolas,'Courier New',monospace"><code style="font-family:inherit">{code}</code></pre>
</body>
</html>
"""

CONSOLE_SVG_FORMAT = """\
<svg class="rich-terminal" viewBox="0 0 {width} {height}" xmlns="http://www.w3.org/2000/svg">
    <!-- Generated with Rich https://www.textualize.io -->
    <style>

    @font-face {{
        font-family: "Fira Code";
        src: local("FiraCode-Regular"),
                url("https://cdnjs.cloudflare.com/ajax/libs/firacode/6.2.0/woff2/FiraCode-Regular.woff2") format("woff2"),
                url("https://cdnjs.cloudflare.com/ajax/libs/firacode/6.2.0/woff/FiraCode-Regular.woff") format("woff");
        font-style: normal;
        font-weight: 400;
    }}
    @font-face {{
        font-family: "Fira Code";
        src: local("FiraCode-Bold"),
                url("https://cdnjs.cloudflare.com/ajax/libs/firacode/6.2.0/woff2/FiraCode-Bold.woff2") format("woff2"),
                url("https://cdnjs.cloudflare.com/ajax/libs/firacode/6.2.0/woff/FiraCode-Bold.woff") format("woff");
        font-style: bold;
        font-weight: 700;
    }}

    .{unique_id}-matrix {{
        font-family: Fira Code, monospace;
        font-size: {char_height}px;
        line-height: {line_height}px;
        font-variant-east-asian: full-width;
    }}

    .{unique_id}-title {{
        font-size: 18px;
        font-weight: bold;
        font-family: arial;
    }}

    {styles}
    </style>

    <defs>
    <clipPath id="{unique_id}-clip-terminal">
      <rect x="0" y="0" width="{terminal_width}" height="{terminal_height}" />
    </clipPath>
    {lines}
    </defs>

    {chrome}
    <g transform="translate({terminal_x}, {terminal_y})" clip-path="url(#{unique_id}-clip-terminal)">
    {backgrounds}
    <g class="{unique_id}-matrix">
    {matrix}
    </g>
    </g>
</svg>
"""

_SVG_FONT_FAMILY = "Rich Fira Code"
_SVG_CLASSES_PREFIX = "rich-svg"

"""Prepares a distribution for installation
"""

# The following comment should be removed at some point in the future.
# mypy: strict-optional=False

import mimetypes
import os
import shutil
from dataclasses import dataclass
from pathlib import Path
from typing import Dict, Iterable, List, Optional

from pip._vendor.packaging.utils import canonicalize_name

from pip._internal.distributions import make_distribution_for_install_requirement
from pip._internal.distributions.installed import InstalledDistribution
from pip._internal.exceptions import (
    DirectoryUrlHashUnsupported,
    HashMismatch,
    HashUnpinned,
    InstallationError,
    MetadataInconsistent,
    NetworkConnectionError,
    VcsHashUnsupported,
)
from pip._internal.index.package_finder import PackageFinder
from pip._internal.metadata import BaseDistribution, get_metadata_distribution
from pip._internal.models.direct_url import ArchiveInfo
from pip._internal.models.link import Link
from pip._internal.models.wheel import Wheel
from pip._internal.network.download import BatchDownloader, Downloader
from pip._internal.network.lazy_wheel import (
    HTTPRangeRequestUnsupported,
    dist_from_wheel_url,
)
from pip._internal.network.session import PipSession
from pip._internal.operations.build.build_tracker import BuildTracker
from pip._internal.req.req_install import InstallRequirement
from pip._internal.utils._log import getLogger
from pip._internal.utils.direct_url_helpers import (
    direct_url_for_editable,
    direct_url_from_link,
)
from pip._internal.utils.hashes import Hashes, MissingHashes
from pip._internal.utils.logging import indent_log
from pip._internal.utils.misc import (
    display_path,
    hash_file,
    hide_url,
    redact_auth_from_requirement,
)
from pip._internal.utils.temp_dir import TempDirectory
from pip._internal.utils.unpacking import unpack_file
from pip._internal.vcs import vcs

logger = getLogger(__name__)


def _get_prepared_distribution(
    req: InstallRequirement,
    build_tracker: BuildTracker,
    finder: PackageFinder,
    build_isolation: bool,
    check_build_deps: bool,
) -> BaseDistribution:
    """Prepare a distribution for installation."""
    abstract_dist = make_distribution_for_install_requirement(req)
    tracker_id = abstract_dist.build_tracker_id
    if tracker_id is not None:
        with build_tracker.track(req, tracker_id):
            abstract_dist.prepare_distribution_metadata(
                finder, build_isolation, check_build_deps
            )
    return abstract_dist.get_metadata_distribution()


def unpack_vcs_link(link: Link, location: str, verbosity: int) -> None:
    vcs_backend = vcs.get_backend_for_scheme(link.scheme)
    assert vcs_backend is not None
    vcs_backend.unpack(location, url=hide_url(link.url), verbosity=verbosity)


@dataclass
class File:
    path: str
    content_type: Optional[str] = None

    def __post_init__(self) -> None:
        if self.content_type is None:
            self.content_type = mimetypes.guess_type(self.path)[0]


def get_http_url(
    link: Link,
    download: Downloader,
    download_dir: Optional[str] = None,
    hashes: Optional[Hashes] = None,
) -> File:
    temp_dir = TempDirectory(kind="unpack", globally_managed=True)
    # If a download dir is specified, is the file already downloaded there?
    already_downloaded_path = None
    if download_dir:
        already_downloaded_path = _check_download_dir(link, download_dir, hashes)

    if already_downloaded_path:
        from_path = already_downloaded_path
        content_type = None
    else:
        # let's download to a tmp dir
        from_path, content_type = download(link, temp_dir.path)
        if hashes:
            hashes.check_against_path(from_path)

    return File(from_path, content_type)


def get_file_url(
    link: Link, download_dir: Optional[str] = None, hashes: Optional[Hashes] = None
) -> File:
    """Get file and optionally check its hash."""
    # If a download dir is specified, is the file already there and valid?
    already_downloaded_path = None
    if download_dir:
        already_downloaded_path = _check_download_dir(link, download_dir, hashes)

    if already_downloaded_path:
        from_path = already_downloaded_path
    else:
        from_path = link.file_path

    # If --require-hashes is off, `hashes` is either empty, the
    # link's embedded hash, or MissingHashes; it is required to
    # match. If --require-hashes is on, we are satisfied by any
    # hash in `hashes` matching: a URL-based or an option-based
    # one; no internet-sourced hash will be in `hashes`.
    if hashes:
        hashes.check_against_path(from_path)
    return File(from_path, None)


def unpack_url(
    link: Link,
    location: str,
    download: Downloader,
    verbosity: int,
    download_dir: Optional[str] = None,
    hashes: Optional[Hashes] = None,
) -> Optional[File]:
    """Unpack link into location, downloading if required.

    :param hashes: A Hashes object, one of whose embedded hashes must match,
        or HashMismatch will be raised. If the Hashes is empty, no matches are
        required, and unhashable types of requirements (like VCS ones, which
        would ordinarily raise HashUnsupported) are allowed.
    """
    # non-editable vcs urls
    if link.is_vcs:
        unpack_vcs_link(link, location, verbosity=verbosity)
        return None

    assert not link.is_existing_dir()

    # file urls
    if link.is_file:
        file = get_file_url(link, download_dir, hashes=hashes)

    # http urls
    else:
        file = get_http_url(
            link,
            download,
            download_dir,
            hashes=hashes,
        )

    # unpack the archive to the build dir location. even when only downloading
    # archives, they have to be unpacked to parse dependencies, except wheels
    if not link.is_wheel:
        unpack_file(file.path, location, file.content_type)

    return file


def _check_download_dir(
    link: Link,
    download_dir: str,
    hashes: Optional[Hashes],
    warn_on_hash_mismatch: bool = True,
) -> Optional[str]:
    """Check download_dir for previously downloaded file with correct hash
    If a correct file is found return its path else None
    """
    download_path = os.path.join(download_dir, link.filename)

    if not os.path.exists(download_path):
        return None

    # If already downloaded, does its hash match?
    logger.info("File was already downloaded %s", download_path)
    if hashes:
        try:
            hashes.check_against_path(download_path)
        except HashMismatch:
            if warn_on_hash_mismatch:
                logger.warning(
                    "Previously-downloaded file %s has bad hash. Re-downloading.",
                    download_path,
                )
            os.unlink(download_path)
            return None
    return download_path


class RequirementPreparer:
    """Prepares a Requirement"""

    def __init__(
        self,
        build_dir: str,
        download_dir: Optional[str],
        src_dir: str,
        build_isolation: bool,
        check_build_deps: bool,
        build_tracker: BuildTracker,
        session: PipSession,
        progress_bar: str,
        finder: PackageFinder,
        require_hashes: bool,
        use_user_site: bool,
        lazy_wheel: bool,
        verbosity: int,
        legacy_resolver: bool,
    ) -> None:
        super().__init__()

        self.src_dir = src_dir
        self.build_dir = build_dir
        self.build_tracker = build_tracker
        self._session = session
        self._download = Downloader(session, progress_bar)
        self._batch_download = BatchDownloader(session, progress_bar)
        self.finder = finder

        # Where still-packed archives should be written to. If None, they are
        # not saved, and are deleted immediately after unpacking.
        self.download_dir = download_dir

        # Is build isolation allowed?
        self.build_isolation = build_isolation

        # Should check build dependencies?
        self.check_build_deps = check_build_deps

        # Should hash-checking be required?
        self.require_hashes = require_hashes

        # Should install in user site-packages?
        self.use_user_site = use_user_site

        # Should wheels be downloaded lazily?
        self.use_lazy_wheel = lazy_wheel

        # How verbose should underlying tooling be?
        self.verbosity = verbosity

        # Are we using the legacy resolver?
        self.legacy_resolver = legacy_resolver

        # Memoized downloaded files, as mapping of url: path.
        self._downloaded: Dict[str, str] = {}

        # Previous "header" printed for a link-based InstallRequirement
        self._previous_requirement_header = ("", "")

    def _log_preparing_link(self, req: InstallRequirement) -> None:
        """Provide context for the requirement being prepared."""
        if req.link.is_file and not req.is_wheel_from_cache:
            message = "Processing %s"
            information = str(display_path(req.link.file_path))
        else:
            message = "Collecting %s"
            information = redact_auth_from_requirement(req.req) if req.req else str(req)

        # If we used req.req, inject requirement source if available (this
        # would already be included if we used req directly)
        if req.req and req.comes_from:
            if isinstance(req.comes_from, str):
                comes_from: Optional[str] = req.comes_from
            else:
                comes_from = req.comes_from.from_path()
            if comes_from:
                information += f" (from {comes_from})"

        if (message, information) != self._previous_requirement_header:
            self._previous_requirement_header = (message, information)
            logger.info(message, information)

        if req.is_wheel_from_cache:
            with indent_log():
                logger.info("Using cached %s", req.link.filename)

    def _ensure_link_req_src_dir(
        self, req: InstallRequirement, parallel_builds: bool
    ) -> None:
        """Ensure source_dir of a linked InstallRequirement."""
        # Since source_dir is only set for editable requirements.
        if req.link.is_wheel:
            # We don't need to unpack wheels, so no need for a source
            # directory.
            return
        assert req.source_dir is None
        if req.link.is_existing_dir():
            # build local directories in-tree
            req.source_dir = req.link.file_path
            return

        # We always delete unpacked sdists after pip runs.
        req.ensure_has_source_dir(
            self.build_dir,
            autodelete=True,
            parallel_builds=parallel_builds,
        )
        req.ensure_pristine_source_checkout()

    def _get_linked_req_hashes(self, req: InstallRequirement) -> Hashes:
        # By the time this is called, the requirement's link should have
        # been checked so we can tell what kind of requirements req is
        # and raise some more informative errors than otherwise.
        # (For example, we can raise VcsHashUnsupported for a VCS URL
        # rather than HashMissing.)
        if not self.require_hashes:
            return req.hashes(trust_internet=True)

        # We could check these first 2 conditions inside unpack_url
        # and save repetition of conditions, but then we would
        # report less-useful error messages for unhashable
        # requirements, complaining that there's no hash provided.
        if req.link.is_vcs:
            raise VcsHashUnsupported()
        if req.link.is_existing_dir():
            raise DirectoryUrlHashUnsupported()

        # Unpinned packages are asking for trouble when a new version
        # is uploaded.  This isn't a security check, but it saves users
        # a surprising hash mismatch in the future.
        # file:/// URLs aren't pinnable, so don't complain about them
        # not being pinned.
        if not req.is_direct and not req.is_pinned:
            raise HashUnpinned()

        # If known-good hashes are missing for this requirement,
        # shim it with a facade object that will provoke hash
        # computation and then raise a HashMissing exception
        # showing the user what the hash should be.
        return req.hashes(trust_internet=False) or MissingHashes()

    def _fetch_metadata_only(
        self,
        req: InstallRequirement,
    ) -> Optional[BaseDistribution]:
        if self.legacy_resolver:
            logger.debug(
                "Metadata-only fetching is not used in the legacy resolver",
            )
            return None
        if self.require_hashes:
            logger.debug(
                "Metadata-only fetching is not used as hash checking is required",
            )
            return None
        # Try PEP 658 metadata first, then fall back to lazy wheel if unavailable.
        return self._fetch_metadata_using_link_data_attr(
            req
        ) or self._fetch_metadata_using_lazy_wheel(req.link)

    def _fetch_metadata_using_link_data_attr(
        self,
        req: InstallRequirement,
    ) -> Optional[BaseDistribution]:
        """Fetch metadata from the data-dist-info-metadata attribute, if possible."""
        # (1) Get the link to the metadata file, if provided by the backend.
        metadata_link = req.link.metadata_link()
        if metadata_link is None:
            return None
        assert req.req is not None
        logger.verbose(
            "Obtaining dependency information for %s from %s",
            req.req,
            metadata_link,
        )
        # (2) Download the contents of the METADATA file, separate from the dist itself.
        metadata_file = get_http_url(
            metadata_link,
            self._download,
            hashes=metadata_link.as_hashes(),
        )
        with open(metadata_file.path, "rb") as f:
            metadata_contents = f.read()
        # (3) Generate a dist just from those file contents.
        metadata_dist = get_metadata_distribution(
            metadata_contents,
            req.link.filename,
            req.req.name,
        )
        # (4) Ensure the Name: field from the METADATA file matches the name from the
        #     install requirement.
        #
        #     NB: raw_name will fall back to the name from the install requirement if
        #     the Name: field is not present, but it's noted in the raw_name docstring
        #     that that should NEVER happen anyway.
        if canonicalize_name(metadata_dist.raw_name) != canonicalize_name(req.req.name):
            raise MetadataInconsistent(
                req, "Name", req.req.name, metadata_dist.raw_name
            )
        return metadata_dist

    def _fetch_metadata_using_lazy_wheel(
        self,
        link: Link,
    ) -> Optional[BaseDistribution]:
        """Fetch metadata using lazy wheel, if possible."""
        # --use-feature=fast-deps must be provided.
        if not self.use_lazy_wheel:
            return None
        if link.is_file or not link.is_wheel:
            logger.debug(
                "Lazy wheel is not used as %r does not point to a remote wheel",
                link,
            )
            return None

        wheel = Wheel(link.filename)
        name = canonicalize_name(wheel.name)
        logger.info(
            "Obtaining dependency information from %s %s",
            name,
            wheel.version,
        )
        url = link.url.split("#", 1)[0]
        try:
            return dist_from_wheel_url(name, url, self._session)
        except HTTPRangeRequestUnsupported:
            logger.debug("%s does not support range requests", url)
            return None

    def _complete_partial_requirements(
        self,
        partially_downloaded_reqs: Iterable[InstallRequirement],
        parallel_builds: bool = False,
    ) -> None:
        """Download any requirements which were only fetched by metadata."""
        # Download to a temporary directory. These will be copied over as
        # needed for downstream 'download', 'wheel', and 'install' commands.
        temp_dir = TempDirectory(kind="unpack", globally_managed=True).path

        # Map each link to the requirement that owns it. This allows us to set
        # `req.local_file_path` on the appropriate requirement after passing
        # all the links at once into BatchDownloader.
        links_to_fully_download: Dict[Link, InstallRequirement] = {}
        for req in partially_downloaded_reqs:
            assert req.link
            links_to_fully_download[req.link] = req

        batch_download = self._batch_download(
            links_to_fully_download.keys(),
            temp_dir,
        )
        for link, (filepath, _) in batch_download:
            logger.debug("Downloading link %s to %s", link, filepath)
            req = links_to_fully_download[link]
            # Record the downloaded file path so wheel reqs can extract a Distribution
            # in .get_dist().
            req.local_file_path = filepath
            # Record that the file is downloaded so we don't do it again in
            # _prepare_linked_requirement().
            self._downloaded[req.link.url] = filepath

            # If this is an sdist, we need to unpack it after downloading, but the
            # .source_dir won't be set up until we are in _prepare_linked_requirement().
            # Add the downloaded archive to the install requirement to unpack after
            # preparing the source dir.
            if not req.is_wheel:
                req.needs_unpacked_archive(Path(filepath))

        # This step is necessary to ensure all lazy wheels are processed
        # successfully by the 'download', 'wheel', and 'install' commands.
        for req in partially_downloaded_reqs:
            self._prepare_linked_requirement(req, parallel_builds)

    def prepare_linked_requirement(
        self, req: InstallRequirement, parallel_builds: bool = False
    ) -> BaseDistribution:
        """Prepare a requirement to be obtained from req.link."""
        assert req.link
        self._log_preparing_link(req)
        with indent_log():
            # Check if the relevant file is already available
            # in the download directory
            file_path = None
            if self.download_dir is not None and req.link.is_wheel:
                hashes = self._get_linked_req_hashes(req)
                file_path = _check_download_dir(
                    req.link,
                    self.download_dir,
                    hashes,
                    # When a locally built wheel has been found in cache, we don't warn
                    # about re-downloading when the already downloaded wheel hash does
                    # not match. This is because the hash must be checked against the
                    # original link, not the cached link. It that case the already
                    # downloaded file will be removed and re-fetched from cache (which
                    # implies a hash check against the cache entry's origin.json).
                    warn_on_hash_mismatch=not req.is_wheel_from_cache,
                )

            if file_path is not None:
                # The file is already available, so mark it as downloaded
                self._downloaded[req.link.url] = file_path
            else:
                # The file is not available, attempt to fetch only metadata
                metadata_dist = self._fetch_metadata_only(req)
                if metadata_dist is not None:
                    req.needs_more_preparation = True
                    return metadata_dist

            # None of the optimizations worked, fully prepare the requirement
            return self._prepare_linked_requirement(req, parallel_builds)

    def prepare_linked_requirements_more(
        self, reqs: Iterable[InstallRequirement], parallel_builds: bool = False
    ) -> None:
        """Prepare linked requirements more, if needed."""
        reqs = [req for req in reqs if req.needs_more_preparation]
        for req in reqs:
            # Determine if any of these requirements were already downloaded.
            if self.download_dir is not None and req.link.is_wheel:
                hashes = self._get_linked_req_hashes(req)
                file_path = _check_download_dir(req.link, self.download_dir, hashes)
                if file_path is not None:
                    self._downloaded[req.link.url] = file_path
                    req.needs_more_preparation = False

        # Prepare requirements we found were already downloaded for some
        # reason. The other downloads will be completed separately.
        partially_downloaded_reqs: List[InstallRequirement] = []
        for req in reqs:
            if req.needs_more_preparation:
                partially_downloaded_reqs.append(req)
            else:
                self._prepare_linked_requirement(req, parallel_builds)

        # TODO: separate this part out from RequirementPreparer when the v1
        # resolver can be removed!
        self._complete_partial_requirements(
            partially_downloaded_reqs,
            parallel_builds=parallel_builds,
        )

    def _prepare_linked_requirement(
        self, req: InstallRequirement, parallel_builds: bool
    ) -> BaseDistribution:
        assert req.link
        link = req.link

        hashes = self._get_linked_req_hashes(req)

        if hashes and req.is_wheel_from_cache:
            assert req.download_info is not None
            assert link.is_wheel
            assert link.is_file
            # We need to verify hashes, and we have found the requirement in the cache
            # of locally built wheels.
            if (
                isinstance(req.download_info.info, ArchiveInfo)
                and req.download_info.info.hashes
                and hashes.has_one_of(req.download_info.info.hashes)
            ):
                # At this point we know the requirement was built from a hashable source
                # artifact, and we verified that the cache entry's hash of the original
                # artifact matches one of the hashes we expect. We don't verify hashes
                # against the cached wheel, because the wheel is not the original.
                hashes = None
            else:
                logger.warning(
                    "The hashes of the source archive found in cache entry "
                    "don't match, ignoring cached built wheel "
                    "and re-downloading source."
                )
                req.link = req.cached_wheel_source_link
                link = req.link

        self._ensure_link_req_src_dir(req, parallel_builds)

        if link.is_existing_dir():
            local_file = None
        elif link.url not in self._downloaded:
            try:
                local_file = unpack_url(
                    link,
                    req.source_dir,
                    self._download,
                    self.verbosity,
                    self.download_dir,
                    hashes,
                )
            except NetworkConnectionError as exc:
                raise InstallationError(
                    f"Could not install requirement {req} because of HTTP "
                    f"error {exc} for URL {link}"
                )
        else:
            file_path = self._downloaded[link.url]
            if hashes:
                hashes.check_against_path(file_path)
            local_file = File(file_path, content_type=None)

        # If download_info is set, we got it from the wheel cache.
        if req.download_info is None:
            # Editables don't go through this function (see
            # prepare_editable_requirement).
            assert not req.editable
            req.download_info = direct_url_from_link(link, req.source_dir)
            # Make sure we have a hash in download_info. If we got it as part of the
            # URL, it will have been verified and we can rely on it. Otherwise we
            # compute it from the downloaded file.
            # FIXME: https://github.com/pypa/pip/issues/11943
            if (
                isinstance(req.download_info.info, ArchiveInfo)
                and not req.download_info.info.hashes
                and local_file
            ):
                hash = hash_file(local_file.path)[0].hexdigest()
                # We populate info.hash for backward compatibility.
                # This will automatically populate info.hashes.
                req.download_info.info.hash = f"sha256={hash}"

        # For use in later processing,
        # preserve the file path on the requirement.
        if local_file:
            req.local_file_path = local_file.path

        dist = _get_prepared_distribution(
            req,
            self.build_tracker,
            self.finder,
            self.build_isolation,
            self.check_build_deps,
        )
        return dist

    def save_linked_requirement(self, req: InstallRequirement) -> None:
        assert self.download_dir is not None
        assert req.link is not None
        link = req.link
        if link.is_vcs or (link.is_existing_dir() and req.editable):
            # Make a .zip of the source_dir we already created.
            req.archive(self.download_dir)
            return

        if link.is_existing_dir():
            logger.debug(
                "Not copying link to destination directory "
                "since it is a directory: %s",
                link,
            )
            return
        if req.local_file_path is None:
            # No distribution was downloaded for this requirement.
            return

        download_location = os.path.join(self.download_dir, link.filename)
        if not os.path.exists(download_location):
            shutil.copy(req.local_file_path, download_location)
            download_path = display_path(download_location)
            logger.info("Saved %s", download_path)

    def prepare_editable_requirement(
        self,
        req: InstallRequirement,
    ) -> BaseDistribution:
        """Prepare an editable requirement."""
        assert req.editable, "cannot prepare a non-editable req as editable"

        logger.info("Obtaining %s", req)

        with indent_log():
            if self.require_hashes:
                raise InstallationError(
                    f"The editable requirement {req} cannot be installed when "
                    "requiring hashes, because there is no single file to "
                    "hash."
                )
            req.ensure_has_source_dir(self.src_dir)
            req.update_editable()
            assert req.source_dir
            req.download_info = direct_url_for_editable(req.unpacked_source_directory)

            dist = _get_prepared_distribution(
                req,
                self.build_tracker,
                self.finder,
                self.build_isolation,
                self.check_build_deps,
            )

            req.check_if_exists(self.use_user_site)

        return dist

    def prepare_installed_requirement(
        self,
        req: InstallRequirement,
        skip_reason: str,
    ) -> BaseDistribution:
        """Prepare an already-installed requirement."""
        assert req.satisfied_by, "req should have been satisfied but isn't"
        assert skip_reason is not None, (
            "did not get skip reason skipped but req.satisfied_by "
            f"is set to {req.satisfied_by}"
        )
        logger.info(
            "Requirement %s: %s (%s)", skip_reason, req, req.satisfied_by.version
        )
        with indent_log():
            if self.require_hashes:
                logger.debug(
                    "Since it is already installed, we are trusting this "
                    "package without checking its hash. To ensure a "
                    "completely repeatable environment, install into an "
                    "empty virtualenv."
                )
            return InstalledDistribution(req).get_metadata_distribution()

# -*- coding: utf-8 -*-
#
# Copyright (C) 2012-2023 Vinay Sajip.
# Licensed to the Python Software Foundation under a contributor agreement.
# See LICENSE.txt and CONTRIBUTORS.txt.
#
import logging

__version__ = '0.3.9'


class DistlibException(Exception):
    pass


try:
    from logging import NullHandler
except ImportError:  # pragma: no cover

    class NullHandler(logging.Handler):

        def handle(self, record):
            pass

        def emit(self, record):
            pass

        def createLock(self):
            self.lock = None


logger = logging.getLogger(__name__)
logger.addHandler(NullHandler())

"""
    pygments.scanner
    ~~~~~~~~~~~~~~~~

    This library implements a regex based scanner. Some languages
    like Pascal are easy to parse but have some keywords that
    depend on the context. Because of this it's impossible to lex
    that just by using a regular expression lexer like the
    `RegexLexer`.

    Have a look at the `DelphiLexer` to get an idea of how to use
    this scanner.

    :copyright: Copyright 2006-2024 by the Pygments team, see AUTHORS.
    :license: BSD, see LICENSE for details.
"""
import re


class EndOfText(RuntimeError):
    """
    Raise if end of text is reached and the user
    tried to call a match function.
    """


class Scanner:
    """
    Simple scanner

    All method patterns are regular expression strings (not
    compiled expressions!)
    """

    def __init__(self, text, flags=0):
        """
        :param text:    The text which should be scanned
        :param flags:   default regular expression flags
        """
        self.data = text
        self.data_length = len(text)
        self.start_pos = 0
        self.pos = 0
        self.flags = flags
        self.last = None
        self.match = None
        self._re_cache = {}

    def eos(self):
        """`True` if the scanner reached the end of text."""
        return self.pos >= self.data_length
    eos = property(eos, eos.__doc__)

    def check(self, pattern):
        """
        Apply `pattern` on the current position and return
        the match object. (Doesn't touch pos). Use this for
        lookahead.
        """
        if self.eos:
            raise EndOfText()
        if pattern not in self._re_cache:
            self._re_cache[pattern] = re.compile(pattern, self.flags)
        return self._re_cache[pattern].match(self.data, self.pos)

    def test(self, pattern):
        """Apply a pattern on the current position and check
        if it patches. Doesn't touch pos.
        """
        return self.check(pattern) is not None

    def scan(self, pattern):
        """
        Scan the text for the given pattern and update pos/match
        and related fields. The return value is a boolean that
        indicates if the pattern matched. The matched value is
        stored on the instance as ``match``, the last value is
        stored as ``last``. ``start_pos`` is the position of the
        pointer before the pattern was matched, ``pos`` is the
        end position.
        """
        if self.eos:
            raise EndOfText()
        if pattern not in self._re_cache:
            self._re_cache[pattern] = re.compile(pattern, self.flags)
        self.last = self.match
        m = self._re_cache[pattern].match(self.data, self.pos)
        if m is None:
            return False
        self.start_pos = m.start()
        self.pos = m.end()
        self.match = m.group()
        return True

    def get_char(self):
        """Scan exactly one char."""
        self.scan('.')

    def __repr__(self):
        return '<%s %d/%d>' % (
            self.__class__.__name__,
            self.pos,
            self.data_length
        )

#
# Copyright (C) 2012-2023 The Python Software Foundation.
# See LICENSE.txt and CONTRIBUTORS.txt.
#
import codecs
from collections import deque
import contextlib
import csv
from glob import iglob as std_iglob
import io
import json
import logging
import os
import py_compile
import re
import socket
try:
    import ssl
except ImportError:  # pragma: no cover
    ssl = None
import subprocess
import sys
import tarfile
import tempfile
import textwrap

try:
    import threading
except ImportError:  # pragma: no cover
    import dummy_threading as threading
import time

from . import DistlibException
from .compat import (string_types, text_type, shutil, raw_input, StringIO, cache_from_source, urlopen, urljoin, httplib,
                     xmlrpclib, HTTPHandler, BaseConfigurator, valid_ident, Container, configparser, URLError, ZipFile,
                     fsdecode, unquote, urlparse)

logger = logging.getLogger(__name__)

#
# Requirement parsing code as per PEP 508
#

IDENTIFIER = re.compile(r'^([\w\.-]+)\s*')
VERSION_IDENTIFIER = re.compile(r'^([\w\.*+-]+)\s*')
COMPARE_OP = re.compile(r'^(<=?|>=?|={2,3}|[~!]=)\s*')
MARKER_OP = re.compile(r'^((<=?)|(>=?)|={2,3}|[~!]=|in|not\s+in)\s*')
OR = re.compile(r'^or\b\s*')
AND = re.compile(r'^and\b\s*')
NON_SPACE = re.compile(r'(\S+)\s*')
STRING_CHUNK = re.compile(r'([\s\w\.{}()*+#:;,/?!~`@$%^&=|<>\[\]-]+)')


def parse_marker(marker_string):
    """
    Parse a marker string and return a dictionary containing a marker expression.

    The dictionary will contain keys "op", "lhs" and "rhs" for non-terminals in
    the expression grammar, or strings. A string contained in quotes is to be
    interpreted as a literal string, and a string not contained in quotes is a
    variable (such as os_name).
    """

    def marker_var(remaining):
        # either identifier, or literal string
        m = IDENTIFIER.match(remaining)
        if m:
            result = m.groups()[0]
            remaining = remaining[m.end():]
        elif not remaining:
            raise SyntaxError('unexpected end of input')
        else:
            q = remaining[0]
            if q not in '\'"':
                raise SyntaxError('invalid expression: %s' % remaining)
            oq = '\'"'.replace(q, '')
            remaining = remaining[1:]
            parts = [q]
            while remaining:
                # either a string chunk, or oq, or q to terminate
                if remaining[0] == q:
                    break
                elif remaining[0] == oq:
                    parts.append(oq)
                    remaining = remaining[1:]
                else:
                    m = STRING_CHUNK.match(remaining)
                    if not m:
                        raise SyntaxError('error in string literal: %s' % remaining)
                    parts.append(m.groups()[0])
                    remaining = remaining[m.end():]
            else:
                s = ''.join(parts)
                raise SyntaxError('unterminated string: %s' % s)
            parts.append(q)
            result = ''.join(parts)
            remaining = remaining[1:].lstrip()  # skip past closing quote
        return result, remaining

    def marker_expr(remaining):
        if remaining and remaining[0] == '(':
            result, remaining = marker(remaining[1:].lstrip())
            if remaining[0] != ')':
                raise SyntaxError('unterminated parenthesis: %s' % remaining)
            remaining = remaining[1:].lstrip()
        else:
            lhs, remaining = marker_var(remaining)
            while remaining:
                m = MARKER_OP.match(remaining)
                if not m:
                    break
                op = m.groups()[0]
                remaining = remaining[m.end():]
                rhs, remaining = marker_var(remaining)
                lhs = {'op': op, 'lhs': lhs, 'rhs': rhs}
            result = lhs
        return result, remaining

    def marker_and(remaining):
        lhs, remaining = marker_expr(remaining)
        while remaining:
            m = AND.match(remaining)
            if not m:
                break
            remaining = remaining[m.end():]
            rhs, remaining = marker_expr(remaining)
            lhs = {'op': 'and', 'lhs': lhs, 'rhs': rhs}
        return lhs, remaining

    def marker(remaining):
        lhs, remaining = marker_and(remaining)
        while remaining:
            m = OR.match(remaining)
            if not m:
                break
            remaining = remaining[m.end():]
            rhs, remaining = marker_and(remaining)
            lhs = {'op': 'or', 'lhs': lhs, 'rhs': rhs}
        return lhs, remaining

    return marker(marker_string)


def parse_requirement(req):
    """
    Parse a requirement passed in as a string. Return a Container
    whose attributes contain the various parts of the requirement.
    """
    remaining = req.strip()
    if not remaining or remaining.startswith('#'):
        return None
    m = IDENTIFIER.match(remaining)
    if not m:
        raise SyntaxError('name expected: %s' % remaining)
    distname = m.groups()[0]
    remaining = remaining[m.end():]
    extras = mark_expr = versions = uri = None
    if remaining and remaining[0] == '[':
        i = remaining.find(']', 1)
        if i < 0:
            raise SyntaxError('unterminated extra: %s' % remaining)
        s = remaining[1:i]
        remaining = remaining[i + 1:].lstrip()
        extras = []
        while s:
            m = IDENTIFIER.match(s)
            if not m:
                raise SyntaxError('malformed extra: %s' % s)
            extras.append(m.groups()[0])
            s = s[m.end():]
            if not s:
                break
            if s[0] != ',':
                raise SyntaxError('comma expected in extras: %s' % s)
            s = s[1:].lstrip()
        if not extras:
            extras = None
    if remaining:
        if remaining[0] == '@':
            # it's a URI
            remaining = remaining[1:].lstrip()
            m = NON_SPACE.match(remaining)
            if not m:
                raise SyntaxError('invalid URI: %s' % remaining)
            uri = m.groups()[0]
            t = urlparse(uri)
            # there are issues with Python and URL parsing, so this test
            # is a bit crude. See bpo-20271, bpo-23505. Python doesn't
            # always parse invalid URLs correctly - it should raise
            # exceptions for malformed URLs
            if not (t.scheme and t.netloc):
                raise SyntaxError('Invalid URL: %s' % uri)
            remaining = remaining[m.end():].lstrip()
        else:

            def get_versions(ver_remaining):
                """
                Return a list of operator, version tuples if any are
                specified, else None.
                """
                m = COMPARE_OP.match(ver_remaining)
                versions = None
                if m:
                    versions = []
                    while True:
                        op = m.groups()[0]
                        ver_remaining = ver_remaining[m.end():]
                        m = VERSION_IDENTIFIER.match(ver_remaining)
                        if not m:
                            raise SyntaxError('invalid version: %s' % ver_remaining)
                        v = m.groups()[0]
                        versions.append((op, v))
                        ver_remaining = ver_remaining[m.end():]
                        if not ver_remaining or ver_remaining[0] != ',':
                            break
                        ver_remaining = ver_remaining[1:].lstrip()
                        # Some packages have a trailing comma which would break things
                        # See issue #148
                        if not ver_remaining:
                            break
                        m = COMPARE_OP.match(ver_remaining)
                        if not m:
                            raise SyntaxError('invalid constraint: %s' % ver_remaining)
                    if not versions:
                        versions = None
                return versions, ver_remaining

            if remaining[0] != '(':
                versions, remaining = get_versions(remaining)
            else:
                i = remaining.find(')', 1)
                if i < 0:
                    raise SyntaxError('unterminated parenthesis: %s' % remaining)
                s = remaining[1:i]
                remaining = remaining[i + 1:].lstrip()
                # As a special diversion from PEP 508, allow a version number
                # a.b.c in parentheses as a synonym for ~= a.b.c (because this
                # is allowed in earlier PEPs)
                if COMPARE_OP.match(s):
                    versions, _ = get_versions(s)
                else:
                    m = VERSION_IDENTIFIER.match(s)
                    if not m:
                        raise SyntaxError('invalid constraint: %s' % s)
                    v = m.groups()[0]
                    s = s[m.end():].lstrip()
                    if s:
                        raise SyntaxError('invalid constraint: %s' % s)
                    versions = [('~=', v)]

    if remaining:
        if remaining[0] != ';':
            raise SyntaxError('invalid requirement: %s' % remaining)
        remaining = remaining[1:].lstrip()

        mark_expr, remaining = parse_marker(remaining)

    if remaining and remaining[0] != '#':
        raise SyntaxError('unexpected trailing data: %s' % remaining)

    if not versions:
        rs = distname
    else:
        rs = '%s %s' % (distname, ', '.join(['%s %s' % con for con in versions]))
    return Container(name=distname, extras=extras, constraints=versions, marker=mark_expr, url=uri, requirement=rs)


def get_resources_dests(resources_root, rules):
    """Find destinations for resources files"""

    def get_rel_path(root, path):
        # normalizes and returns a lstripped-/-separated path
        root = root.replace(os.path.sep, '/')
        path = path.replace(os.path.sep, '/')
        assert path.startswith(root)
        return path[len(root):].lstrip('/')

    destinations = {}
    for base, suffix, dest in rules:
        prefix = os.path.join(resources_root, base)
        for abs_base in iglob(prefix):
            abs_glob = os.path.join(abs_base, suffix)
            for abs_path in iglob(abs_glob):
                resource_file = get_rel_path(resources_root, abs_path)
                if dest is None:  # remove the entry if it was here
                    destinations.pop(resource_file, None)
                else:
                    rel_path = get_rel_path(abs_base, abs_path)
                    rel_dest = dest.replace(os.path.sep, '/').rstrip('/')
                    destinations[resource_file] = rel_dest + '/' + rel_path
    return destinations


def in_venv():
    if hasattr(sys, 'real_prefix'):
        # virtualenv venvs
        result = True
    else:
        # PEP 405 venvs
        result = sys.prefix != getattr(sys, 'base_prefix', sys.prefix)
    return result


def get_executable():
    # The __PYVENV_LAUNCHER__ dance is apparently no longer needed, as
    # changes to the stub launcher mean that sys.executable always points
    # to the stub on OS X
    #    if sys.platform == 'darwin' and ('__PYVENV_LAUNCHER__'
    #                                     in os.environ):
    #        result =  os.environ['__PYVENV_LAUNCHER__']
    #    else:
    #        result = sys.executable
    #    return result
    # Avoid normcasing: see issue #143
    # result = os.path.normcase(sys.executable)
    result = sys.executable
    if not isinstance(result, text_type):
        result = fsdecode(result)
    return result


def proceed(prompt, allowed_chars, error_prompt=None, default=None):
    p = prompt
    while True:
        s = raw_input(p)
        p = prompt
        if not s and default:
            s = default
        if s:
            c = s[0].lower()
            if c in allowed_chars:
                break
            if error_prompt:
                p = '%c: %s\n%s' % (c, error_prompt, prompt)
    return c


def extract_by_key(d, keys):
    if isinstance(keys, string_types):
        keys = keys.split()
    result = {}
    for key in keys:
        if key in d:
            result[key] = d[key]
    return result


def read_exports(stream):
    if sys.version_info[0] >= 3:
        # needs to be a text stream
        stream = codecs.getreader('utf-8')(stream)
    # Try to load as JSON, falling back on legacy format
    data = stream.read()
    stream = StringIO(data)
    try:
        jdata = json.load(stream)
        result = jdata['extensions']['python.exports']['exports']
        for group, entries in result.items():
            for k, v in entries.items():
                s = '%s = %s' % (k, v)
                entry = get_export_entry(s)
                assert entry is not None
                entries[k] = entry
        return result
    except Exception:
        stream.seek(0, 0)

    def read_stream(cp, stream):
        if hasattr(cp, 'read_file'):
            cp.read_file(stream)
        else:
            cp.readfp(stream)

    cp = configparser.ConfigParser()
    try:
        read_stream(cp, stream)
    except configparser.MissingSectionHeaderError:
        stream.close()
        data = textwrap.dedent(data)
        stream = StringIO(data)
        read_stream(cp, stream)

    result = {}
    for key in cp.sections():
        result[key] = entries = {}
        for name, value in cp.items(key):
            s = '%s = %s' % (name, value)
            entry = get_export_entry(s)
            assert entry is not None
            # entry.dist = self
            entries[name] = entry
    return result


def write_exports(exports, stream):
    if sys.version_info[0] >= 3:
        # needs to be a text stream
        stream = codecs.getwriter('utf-8')(stream)
    cp = configparser.ConfigParser()
    for k, v in exports.items():
        # TODO check k, v for valid values
        cp.add_section(k)
        for entry in v.values():
            if entry.suffix is None:
                s = entry.prefix
            else:
                s = '%s:%s' % (entry.prefix, entry.suffix)
            if entry.flags:
                s = '%s [%s]' % (s, ', '.join(entry.flags))
            cp.set(k, entry.name, s)
    cp.write(stream)


@contextlib.contextmanager
def tempdir():
    td = tempfile.mkdtemp()
    try:
        yield td
    finally:
        shutil.rmtree(td)


@contextlib.contextmanager
def chdir(d):
    cwd = os.getcwd()
    try:
        os.chdir(d)
        yield
    finally:
        os.chdir(cwd)


@contextlib.contextmanager
def socket_timeout(seconds=15):
    cto = socket.getdefaulttimeout()
    try:
        socket.setdefaulttimeout(seconds)
        yield
    finally:
        socket.setdefaulttimeout(cto)


class cached_property(object):

    def __init__(self, func):
        self.func = func
        # for attr in ('__name__', '__module__', '__doc__'):
        #     setattr(self, attr, getattr(func, attr, None))

    def __get__(self, obj, cls=None):
        if obj is None:
            return self
        value = self.func(obj)
        object.__setattr__(obj, self.func.__name__, value)
        # obj.__dict__[self.func.__name__] = value = self.func(obj)
        return value


def convert_path(pathname):
    """Return 'pathname' as a name that will work on the native filesystem.

    The path is split on '/' and put back together again using the current
    directory separator.  Needed because filenames in the setup script are
    always supplied in Unix style, and have to be converted to the local
    convention before we can actually use them in the filesystem.  Raises
    ValueError on non-Unix-ish systems if 'pathname' either starts or
    ends with a slash.
    """
    if os.sep == '/':
        return pathname
    if not pathname:
        return pathname
    if pathname[0] == '/':
        raise ValueError("path '%s' cannot be absolute" % pathname)
    if pathname[-1] == '/':
        raise ValueError("path '%s' cannot end with '/'" % pathname)

    paths = pathname.split('/')
    while os.curdir in paths:
        paths.remove(os.curdir)
    if not paths:
        return os.curdir
    return os.path.join(*paths)


class FileOperator(object):

    def __init__(self, dry_run=False):
        self.dry_run = dry_run
        self.ensured = set()
        self._init_record()

    def _init_record(self):
        self.record = False
        self.files_written = set()
        self.dirs_created = set()

    def record_as_written(self, path):
        if self.record:
            self.files_written.add(path)

    def newer(self, source, target):
        """Tell if the target is newer than the source.

        Returns true if 'source' exists and is more recently modified than
        'target', or if 'source' exists and 'target' doesn't.

        Returns false if both exist and 'target' is the same age or younger
        than 'source'. Raise PackagingFileError if 'source' does not exist.

        Note that this test is not very accurate: files created in the same
        second will have the same "age".
        """
        if not os.path.exists(source):
            raise DistlibException("file '%r' does not exist" % os.path.abspath(source))
        if not os.path.exists(target):
            return True

        return os.stat(source).st_mtime > os.stat(target).st_mtime

    def copy_file(self, infile, outfile, check=True):
        """Copy a file respecting dry-run and force flags.
        """
        self.ensure_dir(os.path.dirname(outfile))
        logger.info('Copying %s to %s', infile, outfile)
        if not self.dry_run:
            msg = None
            if check:
                if os.path.islink(outfile):
                    msg = '%s is a symlink' % outfile
                elif os.path.exists(outfile) and not os.path.isfile(outfile):
                    msg = '%s is a non-regular file' % outfile
            if msg:
                raise ValueError(msg + ' which would be overwritten')
            shutil.copyfile(infile, outfile)
        self.record_as_written(outfile)

    def copy_stream(self, instream, outfile, encoding=None):
        assert not os.path.isdir(outfile)
        self.ensure_dir(os.path.dirname(outfile))
        logger.info('Copying stream %s to %s', instream, outfile)
        if not self.dry_run:
            if encoding is None:
                outstream = open(outfile, 'wb')
            else:
                outstream = codecs.open(outfile, 'w', encoding=encoding)
            try:
                shutil.copyfileobj(instream, outstream)
            finally:
                outstream.close()
        self.record_as_written(outfile)

    def write_binary_file(self, path, data):
        self.ensure_dir(os.path.dirname(path))
        if not self.dry_run:
            if os.path.exists(path):
                os.remove(path)
            with open(path, 'wb') as f:
                f.write(data)
        self.record_as_written(path)

    def write_text_file(self, path, data, encoding):
        self.write_binary_file(path, data.encode(encoding))

    def set_mode(self, bits, mask, files):
        if os.name == 'posix' or (os.name == 'java' and os._name == 'posix'):
            # Set the executable bits (owner, group, and world) on
            # all the files specified.
            for f in files:
                if self.dry_run:
                    logger.info("changing mode of %s", f)
                else:
                    mode = (os.stat(f).st_mode | bits) & mask
                    logger.info("changing mode of %s to %o", f, mode)
                    os.chmod(f, mode)

    set_executable_mode = lambda s, f: s.set_mode(0o555, 0o7777, f)

    def ensure_dir(self, path):
        path = os.path.abspath(path)
        if path not in self.ensured and not os.path.exists(path):
            self.ensured.add(path)
            d, f = os.path.split(path)
            self.ensure_dir(d)
            logger.info('Creating %s' % path)
            if not self.dry_run:
                os.mkdir(path)
            if self.record:
                self.dirs_created.add(path)

    def byte_compile(self, path, optimize=False, force=False, prefix=None, hashed_invalidation=False):
        dpath = cache_from_source(path, not optimize)
        logger.info('Byte-compiling %s to %s', path, dpath)
        if not self.dry_run:
            if force or self.newer(path, dpath):
                if not prefix:
                    diagpath = None
                else:
                    assert path.startswith(prefix)
                    diagpath = path[len(prefix):]
            compile_kwargs = {}
            if hashed_invalidation and hasattr(py_compile, 'PycInvalidationMode'):
                if not isinstance(hashed_invalidation, py_compile.PycInvalidationMode):
                    hashed_invalidation = py_compile.PycInvalidationMode.CHECKED_HASH
                compile_kwargs['invalidation_mode'] = hashed_invalidation
            py_compile.compile(path, dpath, diagpath, True, **compile_kwargs)  # raise error
        self.record_as_written(dpath)
        return dpath

    def ensure_removed(self, path):
        if os.path.exists(path):
            if os.path.isdir(path) and not os.path.islink(path):
                logger.debug('Removing directory tree at %s', path)
                if not self.dry_run:
                    shutil.rmtree(path)
                if self.record:
                    if path in self.dirs_created:
                        self.dirs_created.remove(path)
            else:
                if os.path.islink(path):
                    s = 'link'
                else:
                    s = 'file'
                logger.debug('Removing %s %s', s, path)
                if not self.dry_run:
                    os.remove(path)
                if self.record:
                    if path in self.files_written:
                        self.files_written.remove(path)

    def is_writable(self, path):
        result = False
        while not result:
            if os.path.exists(path):
                result = os.access(path, os.W_OK)
                break
            parent = os.path.dirname(path)
            if parent == path:
                break
            path = parent
        return result

    def commit(self):
        """
        Commit recorded changes, turn off recording, return
        changes.
        """
        assert self.record
        result = self.files_written, self.dirs_created
        self._init_record()
        return result

    def rollback(self):
        if not self.dry_run:
            for f in list(self.files_written):
                if os.path.exists(f):
                    os.remove(f)
            # dirs should all be empty now, except perhaps for
            # __pycache__ subdirs
            # reverse so that subdirs appear before their parents
            dirs = sorted(self.dirs_created, reverse=True)
            for d in dirs:
                flist = os.listdir(d)
                if flist:
                    assert flist == ['__pycache__']
                    sd = os.path.join(d, flist[0])
                    os.rmdir(sd)
                os.rmdir(d)  # should fail if non-empty
        self._init_record()


def resolve(module_name, dotted_path):
    if module_name in sys.modules:
        mod = sys.modules[module_name]
    else:
        mod = __import__(module_name)
    if dotted_path is None:
        result = mod
    else:
        parts = dotted_path.split('.')
        result = getattr(mod, parts.pop(0))
        for p in parts:
            result = getattr(result, p)
    return result


class ExportEntry(object):

    def __init__(self, name, prefix, suffix, flags):
        self.name = name
        self.prefix = prefix
        self.suffix = suffix
        self.flags = flags

    @cached_property
    def value(self):
        return resolve(self.prefix, self.suffix)

    def __repr__(self):  # pragma: no cover
        return '<ExportEntry %s = %s:%s %s>' % (self.name, self.prefix, self.suffix, self.flags)

    def __eq__(self, other):
        if not isinstance(other, ExportEntry):
            result = False
        else:
            result = (self.name == other.name and self.prefix == other.prefix and self.suffix == other.suffix and
                      self.flags == other.flags)
        return result

    __hash__ = object.__hash__


ENTRY_RE = re.compile(
    r'''(?P<name>([^\[]\S*))
                      \s*=\s*(?P<callable>(\w+)([:\.]\w+)*)
                      \s*(\[\s*(?P<flags>[\w-]+(=\w+)?(,\s*\w+(=\w+)?)*)\s*\])?
                      ''', re.VERBOSE)


def get_export_entry(specification):
    m = ENTRY_RE.search(specification)
    if not m:
        result = None
        if '[' in specification or ']' in specification:
            raise DistlibException("Invalid specification "
                                   "'%s'" % specification)
    else:
        d = m.groupdict()
        name = d['name']
        path = d['callable']
        colons = path.count(':')
        if colons == 0:
            prefix, suffix = path, None
        else:
            if colons != 1:
                raise DistlibException("Invalid specification "
                                       "'%s'" % specification)
            prefix, suffix = path.split(':')
        flags = d['flags']
        if flags is None:
            if '[' in specification or ']' in specification:
                raise DistlibException("Invalid specification "
                                       "'%s'" % specification)
            flags = []
        else:
            flags = [f.strip() for f in flags.split(',')]
        result = ExportEntry(name, prefix, suffix, flags)
    return result


def get_cache_base(suffix=None):
    """
    Return the default base location for distlib caches. If the directory does
    not exist, it is created. Use the suffix provided for the base directory,
    and default to '.distlib' if it isn't provided.

    On Windows, if LOCALAPPDATA is defined in the environment, then it is
    assumed to be a directory, and will be the parent directory of the result.
    On POSIX, and on Windows if LOCALAPPDATA is not defined, the user's home
    directory - using os.expanduser('~') - will be the parent directory of
    the result.

    The result is just the directory '.distlib' in the parent directory as
    determined above, or with the name specified with ``suffix``.
    """
    if suffix is None:
        suffix = '.distlib'
    if os.name == 'nt' and 'LOCALAPPDATA' in os.environ:
        result = os.path.expandvars('$localappdata')
    else:
        # Assume posix, or old Windows
        result = os.path.expanduser('~')
    # we use 'isdir' instead of 'exists', because we want to
    # fail if there's a file with that name
    if os.path.isdir(result):
        usable = os.access(result, os.W_OK)
        if not usable:
            logger.warning('Directory exists but is not writable: %s', result)
    else:
        try:
            os.makedirs(result)
            usable = True
        except OSError:
            logger.warning('Unable to create %s', result, exc_info=True)
            usable = False
    if not usable:
        result = tempfile.mkdtemp()
        logger.warning('Default location unusable, using %s', result)
    return os.path.join(result, suffix)


def path_to_cache_dir(path, use_abspath=True):
    """
    Convert an absolute path to a directory name for use in a cache.

    The algorithm used is:

    #. On Windows, any ``':'`` in the drive is replaced with ``'---'``.
    #. Any occurrence of ``os.sep`` is replaced with ``'--'``.
    #. ``'.cache'`` is appended.
    """
    d, p = os.path.splitdrive(os.path.abspath(path) if use_abspath else path)
    if d:
        d = d.replace(':', '---')
    p = p.replace(os.sep, '--')
    return d + p + '.cache'


def ensure_slash(s):
    if not s.endswith('/'):
        return s + '/'
    return s


def parse_credentials(netloc):
    username = password = None
    if '@' in netloc:
        prefix, netloc = netloc.rsplit('@', 1)
        if ':' not in prefix:
            username = prefix
        else:
            username, password = prefix.split(':', 1)
    if username:
        username = unquote(username)
    if password:
        password = unquote(password)
    return username, password, netloc


def get_process_umask():
    result = os.umask(0o22)
    os.umask(result)
    return result


def is_string_sequence(seq):
    result = True
    i = None
    for i, s in enumerate(seq):
        if not isinstance(s, string_types):
            result = False
            break
    assert i is not None
    return result


PROJECT_NAME_AND_VERSION = re.compile('([a-z0-9_]+([.-][a-z_][a-z0-9_]*)*)-'
                                      '([a-z0-9_.+-]+)', re.I)
PYTHON_VERSION = re.compile(r'-py(\d\.?\d?)')


def split_filename(filename, project_name=None):
    """
    Extract name, version, python version from a filename (no extension)

    Return name, version, pyver or None
    """
    result = None
    pyver = None
    filename = unquote(filename).replace(' ', '-')
    m = PYTHON_VERSION.search(filename)
    if m:
        pyver = m.group(1)
        filename = filename[:m.start()]
    if project_name and len(filename) > len(project_name) + 1:
        m = re.match(re.escape(project_name) + r'\b', filename)
        if m:
            n = m.end()
            result = filename[:n], filename[n + 1:], pyver
    if result is None:
        m = PROJECT_NAME_AND_VERSION.match(filename)
        if m:
            result = m.group(1), m.group(3), pyver
    return result


# Allow spaces in name because of legacy dists like "Twisted Core"
NAME_VERSION_RE = re.compile(r'(?P<name>[\w .-]+)\s*'
                             r'\(\s*(?P<ver>[^\s)]+)\)$')


def parse_name_and_version(p):
    """
    A utility method used to get name and version from a string.

    From e.g. a Provides-Dist value.

    :param p: A value in a form 'foo (1.0)'
    :return: The name and version as a tuple.
    """
    m = NAME_VERSION_RE.match(p)
    if not m:
        raise DistlibException('Ill-formed name/version string: \'%s\'' % p)
    d = m.groupdict()
    return d['name'].strip().lower(), d['ver']


def get_extras(requested, available):
    result = set()
    requested = set(requested or [])
    available = set(available or [])
    if '*' in requested:
        requested.remove('*')
        result |= available
    for r in requested:
        if r == '-':
            result.add(r)
        elif r.startswith('-'):
            unwanted = r[1:]
            if unwanted not in available:
                logger.warning('undeclared extra: %s' % unwanted)
            if unwanted in result:
                result.remove(unwanted)
        else:
            if r not in available:
                logger.warning('undeclared extra: %s' % r)
            result.add(r)
    return result


#
# Extended metadata functionality
#


def _get_external_data(url):
    result = {}
    try:
        # urlopen might fail if it runs into redirections,
        # because of Python issue #13696. Fixed in locators
        # using a custom redirect handler.
        resp = urlopen(url)
        headers = resp.info()
        ct = headers.get('Content-Type')
        if not ct.startswith('application/json'):
            logger.debug('Unexpected response for JSON request: %s', ct)
        else:
            reader = codecs.getreader('utf-8')(resp)
            # data = reader.read().decode('utf-8')
            # result = json.loads(data)
            result = json.load(reader)
    except Exception as e:
        logger.exception('Failed to get external data for %s: %s', url, e)
    return result


_external_data_base_url = 'https://www.red-dove.com/pypi/projects/'


def get_project_data(name):
    url = '%s/%s/project.json' % (name[0].upper(), name)
    url = urljoin(_external_data_base_url, url)
    result = _get_external_data(url)
    return result


def get_package_data(name, version):
    url = '%s/%s/package-%s.json' % (name[0].upper(), name, version)
    url = urljoin(_external_data_base_url, url)
    return _get_external_data(url)


class Cache(object):
    """
    A class implementing a cache for resources that need to live in the file system
    e.g. shared libraries. This class was moved from resources to here because it
    could be used by other modules, e.g. the wheel module.
    """

    def __init__(self, base):
        """
        Initialise an instance.

        :param base: The base directory where the cache should be located.
        """
        # we use 'isdir' instead of 'exists', because we want to
        # fail if there's a file with that name
        if not os.path.isdir(base):  # pragma: no cover
            os.makedirs(base)
        if (os.stat(base).st_mode & 0o77) != 0:
            logger.warning('Directory \'%s\' is not private', base)
        self.base = os.path.abspath(os.path.normpath(base))

    def prefix_to_dir(self, prefix, use_abspath=True):
        """
        Converts a resource prefix to a directory name in the cache.
        """
        return path_to_cache_dir(prefix, use_abspath=use_abspath)

    def clear(self):
        """
        Clear the cache.
        """
        not_removed = []
        for fn in os.listdir(self.base):
            fn = os.path.join(self.base, fn)
            try:
                if os.path.islink(fn) or os.path.isfile(fn):
                    os.remove(fn)
                elif os.path.isdir(fn):
                    shutil.rmtree(fn)
            except Exception:
                not_removed.append(fn)
        return not_removed


class EventMixin(object):
    """
    A very simple publish/subscribe system.
    """

    def __init__(self):
        self._subscribers = {}

    def add(self, event, subscriber, append=True):
        """
        Add a subscriber for an event.

        :param event: The name of an event.
        :param subscriber: The subscriber to be added (and called when the
                           event is published).
        :param append: Whether to append or prepend the subscriber to an
                       existing subscriber list for the event.
        """
        subs = self._subscribers
        if event not in subs:
            subs[event] = deque([subscriber])
        else:
            sq = subs[event]
            if append:
                sq.append(subscriber)
            else:
                sq.appendleft(subscriber)

    def remove(self, event, subscriber):
        """
        Remove a subscriber for an event.

        :param event: The name of an event.
        :param subscriber: The subscriber to be removed.
        """
        subs = self._subscribers
        if event not in subs:
            raise ValueError('No subscribers: %r' % event)
        subs[event].remove(subscriber)

    def get_subscribers(self, event):
        """
        Return an iterator for the subscribers for an event.
        :param event: The event to return subscribers for.
        """
        return iter(self._subscribers.get(event, ()))

    def publish(self, event, *args, **kwargs):
        """
        Publish a event and return a list of values returned by its
        subscribers.

        :param event: The event to publish.
        :param args: The positional arguments to pass to the event's
                     subscribers.
        :param kwargs: The keyword arguments to pass to the event's
                       subscribers.
        """
        result = []
        for subscriber in self.get_subscribers(event):
            try:
                value = subscriber(event, *args, **kwargs)
            except Exception:
                logger.exception('Exception during event publication')
                value = None
            result.append(value)
        logger.debug('publish %s: args = %s, kwargs = %s, result = %s', event, args, kwargs, result)
        return result


#
# Simple sequencing
#
class Sequencer(object):

    def __init__(self):
        self._preds = {}
        self._succs = {}
        self._nodes = set()  # nodes with no preds/succs

    def add_node(self, node):
        self._nodes.add(node)

    def remove_node(self, node, edges=False):
        if node in self._nodes:
            self._nodes.remove(node)
        if edges:
            for p in set(self._preds.get(node, ())):
                self.remove(p, node)
            for s in set(self._succs.get(node, ())):
                self.remove(node, s)
            # Remove empties
            for k, v in list(self._preds.items()):
                if not v:
                    del self._preds[k]
            for k, v in list(self._succs.items()):
                if not v:
                    del self._succs[k]

    def add(self, pred, succ):
        assert pred != succ
        self._preds.setdefault(succ, set()).add(pred)
        self._succs.setdefault(pred, set()).add(succ)

    def remove(self, pred, succ):
        assert pred != succ
        try:
            preds = self._preds[succ]
            succs = self._succs[pred]
        except KeyError:  # pragma: no cover
            raise ValueError('%r not a successor of anything' % succ)
        try:
            preds.remove(pred)
            succs.remove(succ)
        except KeyError:  # pragma: no cover
            raise ValueError('%r not a successor of %r' % (succ, pred))

    def is_step(self, step):
        return (step in self._preds or step in self._succs or step in self._nodes)

    def get_steps(self, final):
        if not self.is_step(final):
            raise ValueError('Unknown: %r' % final)
        result = []
        todo = []
        seen = set()
        todo.append(final)
        while todo:
            step = todo.pop(0)
            if step in seen:
                # if a step was already seen,
                # move it to the end (so it will appear earlier
                # when reversed on return) ... but not for the
                # final step, as that would be confusing for
                # users
                if step != final:
                    result.remove(step)
                    result.append(step)
            else:
                seen.add(step)
                result.append(step)
                preds = self._preds.get(step, ())
                todo.extend(preds)
        return reversed(result)

    @property
    def strong_connections(self):
        # http://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm
        index_counter = [0]
        stack = []
        lowlinks = {}
        index = {}
        result = []

        graph = self._succs

        def strongconnect(node):
            # set the depth index for this node to the smallest unused index
            index[node] = index_counter[0]
            lowlinks[node] = index_counter[0]
            index_counter[0] += 1
            stack.append(node)

            # Consider successors
            try:
                successors = graph[node]
            except Exception:
                successors = []
            for successor in successors:
                if successor not in lowlinks:
                    # Successor has not yet been visited
                    strongconnect(successor)
                    lowlinks[node] = min(lowlinks[node], lowlinks[successor])
                elif successor in stack:
                    # the successor is in the stack and hence in the current
                    # strongly connected component (SCC)
                    lowlinks[node] = min(lowlinks[node], index[successor])

            # If `node` is a root node, pop the stack and generate an SCC
            if lowlinks[node] == index[node]:
                connected_component = []

                while True:
                    successor = stack.pop()
                    connected_component.append(successor)
                    if successor == node:
                        break
                component = tuple(connected_component)
                # storing the result
                result.append(component)

        for node in graph:
            if node not in lowlinks:
                strongconnect(node)

        return result

    @property
    def dot(self):
        result = ['digraph G {']
        for succ in self._preds:
            preds = self._preds[succ]
            for pred in preds:
                result.append('  %s -> %s;' % (pred, succ))
        for node in self._nodes:
            result.append('  %s;' % node)
        result.append('}')
        return '\n'.join(result)


#
# Unarchiving functionality for zip, tar, tgz, tbz, whl
#

ARCHIVE_EXTENSIONS = ('.tar.gz', '.tar.bz2', '.tar', '.zip', '.tgz', '.tbz', '.whl')


def unarchive(archive_filename, dest_dir, format=None, check=True):

    def check_path(path):
        if not isinstance(path, text_type):
            path = path.decode('utf-8')
        p = os.path.abspath(os.path.join(dest_dir, path))
        if not p.startswith(dest_dir) or p[plen] != os.sep:
            raise ValueError('path outside destination: %r' % p)

    dest_dir = os.path.abspath(dest_dir)
    plen = len(dest_dir)
    archive = None
    if format is None:
        if archive_filename.endswith(('.zip', '.whl')):
            format = 'zip'
        elif archive_filename.endswith(('.tar.gz', '.tgz')):
            format = 'tgz'
            mode = 'r:gz'
        elif archive_filename.endswith(('.tar.bz2', '.tbz')):
            format = 'tbz'
            mode = 'r:bz2'
        elif archive_filename.endswith('.tar'):
            format = 'tar'
            mode = 'r'
        else:  # pragma: no cover
            raise ValueError('Unknown format for %r' % archive_filename)
    try:
        if format == 'zip':
            archive = ZipFile(archive_filename, 'r')
            if check:
                names = archive.namelist()
                for name in names:
                    check_path(name)
        else:
            archive = tarfile.open(archive_filename, mode)
            if check:
                names = archive.getnames()
                for name in names:
                    check_path(name)
        if format != 'zip' and sys.version_info[0] < 3:
            # See Python issue 17153. If the dest path contains Unicode,
            # tarfile extraction fails on Python 2.x if a member path name
            # contains non-ASCII characters - it leads to an implicit
            # bytes -> unicode conversion using ASCII to decode.
            for tarinfo in archive.getmembers():
                if not isinstance(tarinfo.name, text_type):
                    tarinfo.name = tarinfo.name.decode('utf-8')

        # Limit extraction of dangerous items, if this Python
        # allows it easily. If not, just trust the input.
        # See: https://docs.python.org/3/library/tarfile.html#extraction-filters
        def extraction_filter(member, path):
            """Run tarfile.tar_filter, but raise the expected ValueError"""
            # This is only called if the current Python has tarfile filters
            try:
                return tarfile.tar_filter(member, path)
            except tarfile.FilterError as exc:
                raise ValueError(str(exc))

        archive.extraction_filter = extraction_filter

        archive.extractall(dest_dir)

    finally:
        if archive:
            archive.close()


def zip_dir(directory):
    """zip a directory tree into a BytesIO object"""
    result = io.BytesIO()
    dlen = len(directory)
    with ZipFile(result, "w") as zf:
        for root, dirs, files in os.walk(directory):
            for name in files:
                full = os.path.join(root, name)
                rel = root[dlen:]
                dest = os.path.join(rel, name)
                zf.write(full, dest)
    return result


#
# Simple progress bar
#

UNITS = ('', 'K', 'M', 'G', 'T', 'P')


class Progress(object):
    unknown = 'UNKNOWN'

    def __init__(self, minval=0, maxval=100):
        assert maxval is None or maxval >= minval
        self.min = self.cur = minval
        self.max = maxval
        self.started = None
        self.elapsed = 0
        self.done = False

    def update(self, curval):
        assert self.min <= curval
        assert self.max is None or curval <= self.max
        self.cur = curval
        now = time.time()
        if self.started is None:
            self.started = now
        else:
            self.elapsed = now - self.started

    def increment(self, incr):
        assert incr >= 0
        self.update(self.cur + incr)

    def start(self):
        self.update(self.min)
        return self

    def stop(self):
        if self.max is not None:
            self.update(self.max)
        self.done = True

    @property
    def maximum(self):
        return self.unknown if self.max is None else self.max

    @property
    def percentage(self):
        if self.done:
            result = '100 %'
        elif self.max is None:
            result = ' ?? %'
        else:
            v = 100.0 * (self.cur - self.min) / (self.max - self.min)
            result = '%3d %%' % v
        return result

    def format_duration(self, duration):
        if (duration <= 0) and self.max is None or self.cur == self.min:
            result = '??:??:??'
        # elif duration < 1:
        #     result = '--:--:--'
        else:
            result = time.strftime('%H:%M:%S', time.gmtime(duration))
        return result

    @property
    def ETA(self):
        if self.done:
            prefix = 'Done'
            t = self.elapsed
            # import pdb; pdb.set_trace()
        else:
            prefix = 'ETA '
            if self.max is None:
                t = -1
            elif self.elapsed == 0 or (self.cur == self.min):
                t = 0
            else:
                # import pdb; pdb.set_trace()
                t = float(self.max - self.min)
                t /= self.cur - self.min
                t = (t - 1) * self.elapsed
        return '%s: %s' % (prefix, self.format_duration(t))

    @property
    def speed(self):
        if self.elapsed == 0:
            result = 0.0
        else:
            result = (self.cur - self.min) / self.elapsed
        for unit in UNITS:
            if result < 1000:
                break
            result /= 1000.0
        return '%d %sB/s' % (result, unit)


#
# Glob functionality
#

RICH_GLOB = re.compile(r'\{([^}]*)\}')
_CHECK_RECURSIVE_GLOB = re.compile(r'[^/\\,{]\*\*|\*\*[^/\\,}]')
_CHECK_MISMATCH_SET = re.compile(r'^[^{]*\}|\{[^}]*$')


def iglob(path_glob):
    """Extended globbing function that supports ** and {opt1,opt2,opt3}."""
    if _CHECK_RECURSIVE_GLOB.search(path_glob):
        msg = """invalid glob %r: recursive glob "**" must be used alone"""
        raise ValueError(msg % path_glob)
    if _CHECK_MISMATCH_SET.search(path_glob):
        msg = """invalid glob %r: mismatching set marker '{' or '}'"""
        raise ValueError(msg % path_glob)
    return _iglob(path_glob)


def _iglob(path_glob):
    rich_path_glob = RICH_GLOB.split(path_glob, 1)
    if len(rich_path_glob) > 1:
        assert len(rich_path_glob) == 3, rich_path_glob
        prefix, set, suffix = rich_path_glob
        for item in set.split(','):
            for path in _iglob(''.join((prefix, item, suffix))):
                yield path
    else:
        if '**' not in path_glob:
            for item in std_iglob(path_glob):
                yield item
        else:
            prefix, radical = path_glob.split('**', 1)
            if prefix == '':
                prefix = '.'
            if radical == '':
                radical = '*'
            else:
                # we support both
                radical = radical.lstrip('/')
                radical = radical.lstrip('\\')
            for path, dir, files in os.walk(prefix):
                path = os.path.normpath(path)
                for fn in _iglob(os.path.join(path, radical)):
                    yield fn


if ssl:
    from .compat import (HTTPSHandler as BaseHTTPSHandler, match_hostname, CertificateError)

    #
    # HTTPSConnection which verifies certificates/matches domains
    #

    class HTTPSConnection(httplib.HTTPSConnection):
        ca_certs = None  # set this to the path to the certs file (.pem)
        check_domain = True  # only used if ca_certs is not None

        # noinspection PyPropertyAccess
        def connect(self):
            sock = socket.create_connection((self.host, self.port), self.timeout)
            if getattr(self, '_tunnel_host', False):
                self.sock = sock
                self._tunnel()

            context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
            if hasattr(ssl, 'OP_NO_SSLv2'):
                context.options |= ssl.OP_NO_SSLv2
            if getattr(self, 'cert_file', None):
                context.load_cert_chain(self.cert_file, self.key_file)
            kwargs = {}
            if self.ca_certs:
                context.verify_mode = ssl.CERT_REQUIRED
                context.load_verify_locations(cafile=self.ca_certs)
                if getattr(ssl, 'HAS_SNI', False):
                    kwargs['server_hostname'] = self.host

            self.sock = context.wrap_socket(sock, **kwargs)
            if self.ca_certs and self.check_domain:
                try:
                    match_hostname(self.sock.getpeercert(), self.host)
                    logger.debug('Host verified: %s', self.host)
                except CertificateError:  # pragma: no cover
                    self.sock.shutdown(socket.SHUT_RDWR)
                    self.sock.close()
                    raise

    class HTTPSHandler(BaseHTTPSHandler):

        def __init__(self, ca_certs, check_domain=True):
            BaseHTTPSHandler.__init__(self)
            self.ca_certs = ca_certs
            self.check_domain = check_domain

        def _conn_maker(self, *args, **kwargs):
            """
            This is called to create a connection instance. Normally you'd
            pass a connection class to do_open, but it doesn't actually check for
            a class, and just expects a callable. As long as we behave just as a
            constructor would have, we should be OK. If it ever changes so that
            we *must* pass a class, we'll create an UnsafeHTTPSConnection class
            which just sets check_domain to False in the class definition, and
            choose which one to pass to do_open.
            """
            result = HTTPSConnection(*args, **kwargs)
            if self.ca_certs:
                result.ca_certs = self.ca_certs
                result.check_domain = self.check_domain
            return result

        def https_open(self, req):
            try:
                return self.do_open(self._conn_maker, req)
            except URLError as e:
                if 'certificate verify failed' in str(e.reason):
                    raise CertificateError('Unable to verify server certificate '
                                           'for %s' % req.host)
                else:
                    raise

    #
    # To prevent against mixing HTTP traffic with HTTPS (examples: A Man-In-The-
    # Middle proxy using HTTP listens on port 443, or an index mistakenly serves
    # HTML containing a http://xyz link when it should be https://xyz),
    # you can use the following handler class, which does not allow HTTP traffic.
    #
    # It works by inheriting from HTTPHandler - so build_opener won't add a
    # handler for HTTP itself.
    #
    class HTTPSOnlyHandler(HTTPSHandler, HTTPHandler):

        def http_open(self, req):
            raise URLError('Unexpected HTTP request on what should be a secure '
                           'connection: %s' % req)


#
# XML-RPC with timeouts
#
class Transport(xmlrpclib.Transport):

    def __init__(self, timeout, use_datetime=0):
        self.timeout = timeout
        xmlrpclib.Transport.__init__(self, use_datetime)

    def make_connection(self, host):
        h, eh, x509 = self.get_host_info(host)
        if not self._connection or host != self._connection[0]:
            self._extra_headers = eh
            self._connection = host, httplib.HTTPConnection(h)
        return self._connection[1]


if ssl:

    class SafeTransport(xmlrpclib.SafeTransport):

        def __init__(self, timeout, use_datetime=0):
            self.timeout = timeout
            xmlrpclib.SafeTransport.__init__(self, use_datetime)

        def make_connection(self, host):
            h, eh, kwargs = self.get_host_info(host)
            if not kwargs:
                kwargs = {}
            kwargs['timeout'] = self.timeout
            if not self._connection or host != self._connection[0]:
                self._extra_headers = eh
                self._connection = host, httplib.HTTPSConnection(h, None, **kwargs)
            return self._connection[1]


class ServerProxy(xmlrpclib.ServerProxy):

    def __init__(self, uri, **kwargs):
        self.timeout = timeout = kwargs.pop('timeout', None)
        # The above classes only come into play if a timeout
        # is specified
        if timeout is not None:
            # scheme = splittype(uri)  # deprecated as of Python 3.8
            scheme = urlparse(uri)[0]
            use_datetime = kwargs.get('use_datetime', 0)
            if scheme == 'https':
                tcls = SafeTransport
            else:
                tcls = Transport
            kwargs['transport'] = t = tcls(timeout, use_datetime=use_datetime)
            self.transport = t
        xmlrpclib.ServerProxy.__init__(self, uri, **kwargs)


#
# CSV functionality. This is provided because on 2.x, the csv module can't
# handle Unicode. However, we need to deal with Unicode in e.g. RECORD files.
#


def _csv_open(fn, mode, **kwargs):
    if sys.version_info[0] < 3:
        mode += 'b'
    else:
        kwargs['newline'] = ''
        # Python 3 determines encoding from locale. Force 'utf-8'
        # file encoding to match other forced utf-8 encoding
        kwargs['encoding'] = 'utf-8'
    return open(fn, mode, **kwargs)


class CSVBase(object):
    defaults = {
        'delimiter': str(','),  # The strs are used because we need native
        'quotechar': str('"'),  # str in the csv API (2.x won't take
        'lineterminator': str('\n')  # Unicode)
    }

    def __enter__(self):
        return self

    def __exit__(self, *exc_info):
        self.stream.close()


class CSVReader(CSVBase):

    def __init__(self, **kwargs):
        if 'stream' in kwargs:
            stream = kwargs['stream']
            if sys.version_info[0] >= 3:
                # needs to be a text stream
                stream = codecs.getreader('utf-8')(stream)
            self.stream = stream
        else:
            self.stream = _csv_open(kwargs['path'], 'r')
        self.reader = csv.reader(self.stream, **self.defaults)

    def __iter__(self):
        return self

    def next(self):
        result = next(self.reader)
        if sys.version_info[0] < 3:
            for i, item in enumerate(result):
                if not isinstance(item, text_type):
                    result[i] = item.decode('utf-8')
        return result

    __next__ = next


class CSVWriter(CSVBase):

    def __init__(self, fn, **kwargs):
        self.stream = _csv_open(fn, 'w')
        self.writer = csv.writer(self.stream, **self.defaults)

    def writerow(self, row):
        if sys.version_info[0] < 3:
            r = []
            for item in row:
                if isinstance(item, text_type):
                    item = item.encode('utf-8')
                r.append(item)
            row = r
        self.writer.writerow(row)


#
#   Configurator functionality
#


class Configurator(BaseConfigurator):

    value_converters = dict(BaseConfigurator.value_converters)
    value_converters['inc'] = 'inc_convert'

    def __init__(self, config, base=None):
        super(Configurator, self).__init__(config)
        self.base = base or os.getcwd()

    def configure_custom(self, config):

        def convert(o):
            if isinstance(o, (list, tuple)):
                result = type(o)([convert(i) for i in o])
            elif isinstance(o, dict):
                if '()' in o:
                    result = self.configure_custom(o)
                else:
                    result = {}
                    for k in o:
                        result[k] = convert(o[k])
            else:
                result = self.convert(o)
            return result

        c = config.pop('()')
        if not callable(c):
            c = self.resolve(c)
        props = config.pop('.', None)
        # Check for valid identifiers
        args = config.pop('[]', ())
        if args:
            args = tuple([convert(o) for o in args])
        items = [(k, convert(config[k])) for k in config if valid_ident(k)]
        kwargs = dict(items)
        result = c(*args, **kwargs)
        if props:
            for n, v in props.items():
                setattr(result, n, convert(v))
        return result

    def __getitem__(self, key):
        result = self.config[key]
        if isinstance(result, dict) and '()' in result:
            self.config[key] = result = self.configure_custom(result)
        return result

    def inc_convert(self, value):
        """Default converter for the inc:// protocol."""
        if not os.path.isabs(value):
            value = os.path.join(self.base, value)
        with codecs.open(value, 'r', encoding='utf-8') as f:
            result = json.load(f)
        return result


class SubprocessMixin(object):
    """
    Mixin for running subprocesses and capturing their output
    """

    def __init__(self, verbose=False, progress=None):
        self.verbose = verbose
        self.progress = progress

    def reader(self, stream, context):
        """
        Read lines from a subprocess' output stream and either pass to a progress
        callable (if specified) or write progress information to sys.stderr.
        """
        progress = self.progress
        verbose = self.verbose
        while True:
            s = stream.readline()
            if not s:
                break
            if progress is not None:
                progress(s, context)
            else:
                if not verbose:
                    sys.stderr.write('.')
                else:
                    sys.stderr.write(s.decode('utf-8'))
                sys.stderr.flush()
        stream.close()

    def run_command(self, cmd, **kwargs):
        p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, **kwargs)
        t1 = threading.Thread(target=self.reader, args=(p.stdout, 'stdout'))
        t1.start()
        t2 = threading.Thread(target=self.reader, args=(p.stderr, 'stderr'))
        t2.start()
        p.wait()
        t1.join()
        t2.join()
        if self.progress is not None:
            self.progress('done.', 'main')
        elif self.verbose:
            sys.stderr.write('done.\n')
        return p


def normalize_name(name):
    """Normalize a python package name a la PEP 503"""
    # https://www.python.org/dev/peps/pep-0503/#normalized-names
    return re.sub('[-_.]+', '-', name).lower()


# def _get_pypirc_command():
# """
# Get the distutils command for interacting with PyPI configurations.
# :return: the command.
# """
# from distutils.core import Distribution
# from distutils.config import PyPIRCCommand
# d = Distribution()
# return PyPIRCCommand(d)


class PyPIRCFile(object):

    DEFAULT_REPOSITORY = 'https://upload.pypi.org/legacy/'
    DEFAULT_REALM = 'pypi'

    def __init__(self, fn=None, url=None):
        if fn is None:
            fn = os.path.join(os.path.expanduser('~'), '.pypirc')
        self.filename = fn
        self.url = url

    def read(self):
        result = {}

        if os.path.exists(self.filename):
            repository = self.url or self.DEFAULT_REPOSITORY

            config = configparser.RawConfigParser()
            config.read(self.filename)
            sections = config.sections()
            if 'distutils' in sections:
                # let's get the list of servers
                index_servers = config.get('distutils', 'index-servers')
                _servers = [server.strip() for server in index_servers.split('\n') if server.strip() != '']
                if _servers == []:
                    # nothing set, let's try to get the default pypi
                    if 'pypi' in sections:
                        _servers = ['pypi']
                else:
                    for server in _servers:
                        result = {'server': server}
                        result['username'] = config.get(server, 'username')

                        # optional params
                        for key, default in (('repository', self.DEFAULT_REPOSITORY), ('realm', self.DEFAULT_REALM),
                                             ('password', None)):
                            if config.has_option(server, key):
                                result[key] = config.get(server, key)
                            else:
                                result[key] = default

                        # work around people having "repository" for the "pypi"
                        # section of their config set to the HTTP (rather than
                        # HTTPS) URL
                        if (server == 'pypi' and repository in (self.DEFAULT_REPOSITORY, 'pypi')):
                            result['repository'] = self.DEFAULT_REPOSITORY
                        elif (result['server'] != repository and result['repository'] != repository):
                            result = {}
            elif 'server-login' in sections:
                # old format
                server = 'server-login'
                if config.has_option(server, 'repository'):
                    repository = config.get(server, 'repository')
                else:
                    repository = self.DEFAULT_REPOSITORY
                result = {
                    'username': config.get(server, 'username'),
                    'password': config.get(server, 'password'),
                    'repository': repository,
                    'server': server,
                    'realm': self.DEFAULT_REALM
                }
        return result

    def update(self, username, password):
        # import pdb; pdb.set_trace()
        config = configparser.RawConfigParser()
        fn = self.filename
        config.read(fn)
        if not config.has_section('pypi'):
            config.add_section('pypi')
        config.set('pypi', 'username', username)
        config.set('pypi', 'password', password)
        with open(fn, 'w') as f:
            config.write(f)


def _load_pypirc(index):
    """
    Read the PyPI access configuration as supported by distutils.
    """
    return PyPIRCFile(url=index.url).read()


def _store_pypirc(index):
    PyPIRCFile().update(index.username, index.password)


#
# get_platform()/get_host_platform() copied from Python 3.10.a0 source, with some minor
# tweaks
#


def get_host_platform():
    """Return a string that identifies the current platform.  This is used mainly to
    distinguish platform-specific build directories and platform-specific built
    distributions.  Typically includes the OS name and version and the
    architecture (as supplied by 'os.uname()'), although the exact information
    included depends on the OS; eg. on Linux, the kernel version isn't
    particularly important.

    Examples of returned values:
       linux-i586
       linux-alpha (?)
       solaris-2.6-sun4u

    Windows will return one of:
       win-amd64 (64bit Windows on AMD64 (aka x86_64, Intel64, EM64T, etc)
       win32 (all others - specifically, sys.platform is returned)

    For other non-POSIX platforms, currently just returns 'sys.platform'.

    """
    if os.name == 'nt':
        if 'amd64' in sys.version.lower():
            return 'win-amd64'
        if '(arm)' in sys.version.lower():
            return 'win-arm32'
        if '(arm64)' in sys.version.lower():
            return 'win-arm64'
        return sys.platform

    # Set for cross builds explicitly
    if "_PYTHON_HOST_PLATFORM" in os.environ:
        return os.environ["_PYTHON_HOST_PLATFORM"]

    if os.name != 'posix' or not hasattr(os, 'uname'):
        # XXX what about the architecture? NT is Intel or Alpha,
        # Mac OS is M68k or PPC, etc.
        return sys.platform

    # Try to distinguish various flavours of Unix

    (osname, host, release, version, machine) = os.uname()

    # Convert the OS name to lowercase, remove '/' characters, and translate
    # spaces (for "Power Macintosh")
    osname = osname.lower().replace('/', '')
    machine = machine.replace(' ', '_').replace('/', '-')

    if osname[:5] == 'linux':
        # At least on Linux/Intel, 'machine' is the processor --
        # i386, etc.
        # XXX what about Alpha, SPARC, etc?
        return "%s-%s" % (osname, machine)

    elif osname[:5] == 'sunos':
        if release[0] >= '5':  # SunOS 5 == Solaris 2
            osname = 'solaris'
            release = '%d.%s' % (int(release[0]) - 3, release[2:])
            # We can't use 'platform.architecture()[0]' because a
            # bootstrap problem. We use a dict to get an error
            # if some suspicious happens.
            bitness = {2147483647: '32bit', 9223372036854775807: '64bit'}
            machine += '.%s' % bitness[sys.maxsize]
        # fall through to standard osname-release-machine representation
    elif osname[:3] == 'aix':
        from _aix_support import aix_platform
        return aix_platform()
    elif osname[:6] == 'cygwin':
        osname = 'cygwin'
        rel_re = re.compile(r'[\d.]+', re.ASCII)
        m = rel_re.match(release)
        if m:
            release = m.group()
    elif osname[:6] == 'darwin':
        import _osx_support
        try:
            from distutils import sysconfig
        except ImportError:
            import sysconfig
        osname, release, machine = _osx_support.get_platform_osx(sysconfig.get_config_vars(), osname, release, machine)

    return '%s-%s-%s' % (osname, release, machine)


_TARGET_TO_PLAT = {
    'x86': 'win32',
    'x64': 'win-amd64',
    'arm': 'win-arm32',
}


def get_platform():
    if os.name != 'nt':
        return get_host_platform()
    cross_compilation_target = os.environ.get('VSCMD_ARG_TGT_ARCH')
    if cross_compilation_target not in _TARGET_TO_PLAT:
        return get_host_platform()
    return _TARGET_TO_PLAT[cross_compilation_target]

#   __
#  /__)  _  _     _   _ _/   _
# / (   (- (/ (/ (- _)  /  _)
#          /

"""
Requests HTTP Library
~~~~~~~~~~~~~~~~~~~~~

Requests is an HTTP library, written in Python, for human beings.
Basic GET usage:

   >>> import requests
   >>> r = requests.get('https://www.python.org')
   >>> r.status_code
   200
   >>> b'Python is a programming language' in r.content
   True

... or POST:

   >>> payload = dict(key1='value1', key2='value2')
   >>> r = requests.post('https://httpbin.org/post', data=payload)
   >>> print(r.text)
   {
     ...
     "form": {
       "key1": "value1",
       "key2": "value2"
     },
     ...
   }

The other HTTP methods are supported - see `requests.api`. Full documentation
is at <https://requests.readthedocs.io>.

:copyright: (c) 2017 by Kenneth Reitz.
:license: Apache 2.0, see LICENSE for more details.
"""

import warnings

from pip._vendor import urllib3

from .exceptions import RequestsDependencyWarning

charset_normalizer_version = None
chardet_version = None


def check_compatibility(urllib3_version, chardet_version, charset_normalizer_version):
    urllib3_version = urllib3_version.split(".")
    assert urllib3_version != ["dev"]  # Verify urllib3 isn't installed from git.

    # Sometimes, urllib3 only reports its version as 16.1.
    if len(urllib3_version) == 2:
        urllib3_version.append("0")

    # Check urllib3 for compatibility.
    major, minor, patch = urllib3_version  # noqa: F811
    major, minor, patch = int(major), int(minor), int(patch)
    # urllib3 >= 1.21.1
    assert major >= 1
    if major == 1:
        assert minor >= 21

    # Check charset_normalizer for compatibility.
    if chardet_version:
        major, minor, patch = chardet_version.split(".")[:3]
        major, minor, patch = int(major), int(minor), int(patch)
        # chardet_version >= 3.0.2, < 6.0.0
        assert (3, 0, 2) <= (major, minor, patch) < (6, 0, 0)
    elif charset_normalizer_version:
        major, minor, patch = charset_normalizer_version.split(".")[:3]
        major, minor, patch = int(major), int(minor), int(patch)
        # charset_normalizer >= 2.0.0 < 4.0.0
        assert (2, 0, 0) <= (major, minor, patch) < (4, 0, 0)
    else:
        # pip does not need or use character detection
        pass


def _check_cryptography(cryptography_version):
    # cryptography < 1.3.4
    try:
        cryptography_version = list(map(int, cryptography_version.split(".")))
    except ValueError:
        return

    if cryptography_version < [1, 3, 4]:
        warning = "Old version of cryptography ({}) may cause slowdown.".format(
            cryptography_version
        )
        warnings.warn(warning, RequestsDependencyWarning)


# Check imported dependencies for compatibility.
try:
    check_compatibility(
        urllib3.__version__, chardet_version, charset_normalizer_version
    )
except (AssertionError, ValueError):
    warnings.warn(
        "urllib3 ({}) or chardet ({})/charset_normalizer ({}) doesn't match a supported "
        "version!".format(
            urllib3.__version__, chardet_version, charset_normalizer_version
        ),
        RequestsDependencyWarning,
    )

# Attempt to enable urllib3's fallback for SNI support
# if the standard library doesn't support SNI or the
# 'ssl' library isn't available.
try:
    # Note: This logic prevents upgrading cryptography on Windows, if imported
    #       as part of pip.
    from pip._internal.utils.compat import WINDOWS
    if not WINDOWS:
        raise ImportError("pip internals: don't import cryptography on Windows")
    try:
        import ssl
    except ImportError:
        ssl = None

    if not getattr(ssl, "HAS_SNI", False):
        from pip._vendor.urllib3.contrib import pyopenssl

        pyopenssl.inject_into_urllib3()

        # Check cryptography version
        from cryptography import __version__ as cryptography_version

        _check_cryptography(cryptography_version)
except ImportError:
    pass

# urllib3's DependencyWarnings should be silenced.
from pip._vendor.urllib3.exceptions import DependencyWarning

warnings.simplefilter("ignore", DependencyWarning)

# Set default logging handler to avoid "No handler found" warnings.
import logging
from logging import NullHandler

from . import packages, utils
from .__version__ import (
    __author__,
    __author_email__,
    __build__,
    __cake__,
    __copyright__,
    __description__,
    __license__,
    __title__,
    __url__,
    __version__,
)
from .api import delete, get, head, options, patch, post, put, request
from .exceptions import (
    ConnectionError,
    ConnectTimeout,
    FileModeWarning,
    HTTPError,
    JSONDecodeError,
    ReadTimeout,
    RequestException,
    Timeout,
    TooManyRedirects,
    URLRequired,
)
from .models import PreparedRequest, Request, Response
from .sessions import Session, session
from .status_codes import codes

logging.getLogger(__name__).addHandler(NullHandler())

# FileModeWarnings go off per the default.
warnings.simplefilter("default", FileModeWarning, append=True)