# 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 packaging.specifiers import Specifier, SpecifierSet, InvalidSpecifier
    from packaging.version import Version
"""

from __future__ import annotations

import abc
import itertools
import re
from typing import Callable, Final, Iterable, Iterator, TypeVar, Union

from .utils import canonicalize_version
from .version import InvalidVersion, Version

UnparsedVersion = Union[Version, str]
UnparsedVersionVar = TypeVar("UnparsedVersionVar", bound=UnparsedVersion)
CallableOperator = Callable[[Version, str], bool]


def _coerce_version(version: UnparsedVersion) -> Version | None:
    if not isinstance(version, Version):
        try:
            version = Version(version)
        except InvalidVersion:
            return None
    return version


def _public_version(version: Version) -> Version:
    return version.__replace__(local=None)


def _base_version(version: Version) -> Version:
    return version.__replace__(pre=None, post=None, dev=None, local=None)


class InvalidSpecifier(ValueError):
    """
    Raised when attempting to create a :class:`Specifier` with a specifier
    string that is invalid.

    >>> Specifier("lolwat")
    Traceback (most recent call last):
        ...
    packaging.specifiers.InvalidSpecifier: Invalid specifier: 'lolwat'
    """


class BaseSpecifier(metaclass=abc.ABCMeta):
    __slots__ = ()
    __match_args__ = ("_str",)

    @property
    def _str(self) -> str:
        """Internal property for match_args"""
        return str(self)

    @abc.abstractmethod
    def __str__(self) -> str:
        """
        Returns the str representation of this Specifier-like object. This
        should be representative of the Specifier itself.
        """

    @abc.abstractmethod
    def __hash__(self) -> int:
        """
        Returns a hash value for this Specifier-like object.
        """

    @abc.abstractmethod
    def __eq__(self, other: object) -> bool:
        """
        Returns a boolean representing whether or not the two Specifier-like
        objects are equal.

        :param other: The other object to check against.
        """

    @property
    @abc.abstractmethod
    def prereleases(self) -> bool | None:
        """Whether or not pre-releases as a whole are allowed.

        This can be set to either ``True`` or ``False`` to explicitly enable or disable
        prereleases or it can be set to ``None`` (the default) to use default semantics.
        """

    @prereleases.setter  # noqa: B027
    def prereleases(self, value: bool) -> None:
        """Setter for :attr:`prereleases`.

        :param value: The value to set.
        """

    @abc.abstractmethod
    def contains(self, item: str, prereleases: bool | None = None) -> bool:
        """
        Determines if the given item is contained within this specifier.
        """

    @abc.abstractmethod
    def filter(
        self, iterable: Iterable[UnparsedVersionVar], prereleases: bool | None = None
    ) -> Iterator[UnparsedVersionVar]:
        """
        Takes an iterable of items and filters them so that only items which
        are contained within this specifier are allowed in it.
        """


class Specifier(BaseSpecifier):
    """This class abstracts handling of version specifiers.

    .. tip::

        It is generally not required to instantiate this manually. You should instead
        prefer to work with :class:`SpecifierSet` instead, which can parse
        comma-separated version specifiers (which is what package metadata contains).
    """

    __slots__ = ("_prereleases", "_spec", "_spec_version")

    _operator_regex_str = r"""
        (?P<operator>(~=|==|!=|<=|>=|<|>|===))
        """
    _version_regex_str = r"""
        (?P<version>
            (?:
                # The identity operators allow for an escape hatch that will
                # do an exact string match of the version you wish to install.
                # This will not be parsed by PEP 440 and we cannot determine
                # any semantic meaning from it. This operator is discouraged
                # but included entirely as an escape hatch.
                (?<====)  # Only match for the identity operator
                \s*
                [^\s;)]*  # The arbitrary version can be just about anything,
                          # we match everything except for whitespace, a
                          # semi-colon for marker support, and a closing paren
                          # since versions can be enclosed in them.
            )
            |
            (?:
                # The (non)equality operators allow for wild card and local
                # versions to be specified so we have to define these two
                # operators separately to enable that.
                (?<===|!=)            # Only match for equals and not equals

                \s*
                v?
                (?:[0-9]+!)?          # epoch
                [0-9]+(?:\.[0-9]+)*   # release

                # You cannot use a wild card and a pre-release, post-release, a dev or
                # local version together so group them with a | and make them optional.
                (?:
                    \.\*  # Wild card syntax of .*
                    |
                    (?:                                  # pre release
                        [-_\.]?
                        (alpha|beta|preview|pre|a|b|c|rc)
                        [-_\.]?
                        [0-9]*
                    )?
                    (?:                                  # post release
                        (?:-[0-9]+)|(?:[-_\.]?(post|rev|r)[-_\.]?[0-9]*)
                    )?
                    (?:[-_\.]?dev[-_\.]?[0-9]*)?         # dev release
                    (?:\+[a-z0-9]+(?:[-_\.][a-z0-9]+)*)? # local
                )?
            )
            |
            (?:
                # The compatible operator requires at least two digits in the
                # release segment.
                (?<=~=)               # Only match for the compatible operator

                \s*
                v?
                (?:[0-9]+!)?          # epoch
                [0-9]+(?:\.[0-9]+)+   # release  (We have a + instead of a *)
                (?:                   # pre release
                    [-_\.]?
                    (alpha|beta|preview|pre|a|b|c|rc)
                    [-_\.]?
                    [0-9]*
                )?
                (?:                                   # post release
                    (?:-[0-9]+)|(?:[-_\.]?(post|rev|r)[-_\.]?[0-9]*)
                )?
                (?:[-_\.]?dev[-_\.]?[0-9]*)?          # dev release
            )
            |
            (?:
                # All other operators only allow a sub set of what the
                # (non)equality operators do. Specifically they do not allow
                # local versions to be specified nor do they allow the prefix
                # matching wild cards.
                (?<!==|!=|~=)         # We have special cases for these
                                      # operators so we want to make sure they
                                      # don't match here.

                \s*
                v?
                (?:[0-9]+!)?          # epoch
                [0-9]+(?:\.[0-9]+)*   # release
                (?:                   # pre release
                    [-_\.]?
                    (alpha|beta|preview|pre|a|b|c|rc)
                    [-_\.]?
                    [0-9]*
                )?
                (?:                                   # post release
                    (?:-[0-9]+)|(?:[-_\.]?(post|rev|r)[-_\.]?[0-9]*)
                )?
                (?:[-_\.]?dev[-_\.]?[0-9]*)?          # dev release
            )
        )
        """

    _regex = re.compile(
        r"\s*" + _operator_regex_str + _version_regex_str + r"\s*",
        re.VERBOSE | re.IGNORECASE,
    )

    _operators: Final = {
        "~=": "compatible",
        "==": "equal",
        "!=": "not_equal",
        "<=": "less_than_equal",
        ">=": "greater_than_equal",
        "<": "less_than",
        ">": "greater_than",
        "===": "arbitrary",
    }

    def __init__(self, spec: str = "", prereleases: bool | None = None) -> None:
        """Initialize a Specifier instance.

        :param spec:
            The string representation of a specifier which will be parsed and
            normalized before use.
        :param prereleases:
            This tells the specifier if it should accept prerelease versions if
            applicable or not. The default of ``None`` will autodetect it from the
            given specifiers.
        :raises InvalidSpecifier:
            If the given specifier is invalid (i.e. bad syntax).
        """
        match = self._regex.fullmatch(spec)
        if not match:
            raise InvalidSpecifier(f"Invalid specifier: {spec!r}")

        self._spec: tuple[str, str] = (
            match.group("operator").strip(),
            match.group("version").strip(),
        )

        # Store whether or not this Specifier should accept prereleases
        self._prereleases = prereleases

        # Specifier version cache
        self._spec_version: tuple[str, Version] | None = None

    def _get_spec_version(self, version: str) -> Version | None:
        """One element cache, as only one spec Version is needed per Specifier."""
        if self._spec_version is not None and self._spec_version[0] == version:
            return self._spec_version[1]

        version_specifier = _coerce_version(version)
        if version_specifier is None:
            return None

        self._spec_version = (version, version_specifier)
        return version_specifier

    def _require_spec_version(self, version: str) -> Version:
        """Get spec version, asserting it's valid (not for === operator).

        This method should only be called for operators where version
        strings are guaranteed to be valid PEP 440 versions (not ===).
        """
        spec_version = self._get_spec_version(version)
        assert spec_version is not None
        return spec_version

    @property
    def prereleases(self) -> bool | None:
        # If there is an explicit prereleases set for this, then we'll just
        # blindly use that.
        if self._prereleases is not None:
            return self._prereleases

        # Only the "!=" operator does not imply prereleases when
        # the version in the specifier is a prerelease.
        operator, version_str = self._spec
        if operator != "!=":
            # The == specifier with trailing .* cannot include prereleases
            # e.g. "==1.0a1.*" is not valid.
            if operator == "==" and version_str.endswith(".*"):
                return False

            # "===" can have arbitrary string versions, so we cannot parse
            # those, we take prereleases as unknown (None) for those.
            version = self._get_spec_version(version_str)
            if version is None:
                return None

            # For all other operators, use the check if spec Version
            # object implies pre-releases.
            if version.is_prerelease:
                return True

        return False

    @prereleases.setter
    def prereleases(self, value: bool | None) -> None:
        self._prereleases = value

    @property
    def operator(self) -> str:
        """The operator of this specifier.

        >>> Specifier("==1.2.3").operator
        '=='
        """
        return self._spec[0]

    @property
    def version(self) -> str:
        """The version of this specifier.

        >>> Specifier("==1.2.3").version
        '1.2.3'
        """
        return self._spec[1]

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

        >>> Specifier('>=1.0.0')
        <Specifier('>=1.0.0')>
        >>> Specifier('>=1.0.0', prereleases=False)
        <Specifier('>=1.0.0', prereleases=False)>
        >>> Specifier('>=1.0.0', prereleases=True)
        <Specifier('>=1.0.0', prereleases=True)>
        """
        pre = (
            f", prereleases={self.prereleases!r}"
            if self._prereleases is not None
            else ""
        )

        return f"<{self.__class__.__name__}({str(self)!r}{pre})>"

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

        >>> str(Specifier('>=1.0.0'))
        '>=1.0.0'
        >>> str(Specifier('>=1.0.0', prereleases=False))
        '>=1.0.0'
        """
        return "{}{}".format(*self._spec)

    @property
    def _canonical_spec(self) -> tuple[str, str]:
        operator, version = self._spec
        if operator == "===" or version.endswith(".*"):
            return operator, version

        spec_version = self._require_spec_version(version)

        canonical_version = canonicalize_version(
            spec_version, strip_trailing_zero=(operator != "~=")
        )

        return operator, canonical_version

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

    def __eq__(self, other: object) -> bool:
        """Whether or not the two Specifier-like objects are equal.

        :param other: The other object to check against.

        The value of :attr:`prereleases` is ignored.

        >>> Specifier("==1.2.3") == Specifier("== 1.2.3.0")
        True
        >>> (Specifier("==1.2.3", prereleases=False) ==
        ...  Specifier("==1.2.3", prereleases=True))
        True
        >>> Specifier("==1.2.3") == "==1.2.3"
        True
        >>> Specifier("==1.2.3") == Specifier("==1.2.4")
        False
        >>> Specifier("==1.2.3") == Specifier("~=1.2.3")
        False
        """
        if isinstance(other, str):
            try:
                other = self.__class__(str(other))
            except InvalidSpecifier:
                return NotImplemented
        elif not isinstance(other, self.__class__):
            return NotImplemented

        return self._canonical_spec == other._canonical_spec

    def _get_operator(self, op: str) -> CallableOperator:
        operator_callable: CallableOperator = getattr(
            self, f"_compare_{self._operators[op]}"
        )
        return operator_callable

    def _compare_compatible(self, prospective: Version, spec: str) -> bool:
        # Compatible releases have an equivalent combination of >= and ==. That
        # is that ~=2.2 is equivalent to >=2.2,==2.*. This allows us to
        # implement this in terms of the other specifiers instead of
        # implementing it ourselves. The only thing we need to do is construct
        # the other specifiers.

        # We want everything but the last item in the version, but we want to
        # ignore suffix segments.
        prefix = _version_join(
            list(itertools.takewhile(_is_not_suffix, _version_split(spec)))[:-1]
        )

        # Add the prefix notation to the end of our string
        prefix += ".*"

        return self._get_operator(">=")(prospective, spec) and self._get_operator("==")(
            prospective, prefix
        )

    def _compare_equal(self, prospective: Version, spec: str) -> bool:
        # We need special logic to handle prefix matching
        if spec.endswith(".*"):
            # In the case of prefix matching we want to ignore local segment.
            normalized_prospective = canonicalize_version(
                _public_version(prospective), strip_trailing_zero=False
            )
            # Get the normalized version string ignoring the trailing .*
            normalized_spec = canonicalize_version(spec[:-2], strip_trailing_zero=False)
            # Split the spec out by bangs and dots, and pretend that there is
            # an implicit dot in between a release segment and a pre-release segment.
            split_spec = _version_split(normalized_spec)

            # Split the prospective version out by bangs and dots, and pretend
            # that there is an implicit dot in between a release segment and
            # a pre-release segment.
            split_prospective = _version_split(normalized_prospective)

            # 0-pad the prospective version before shortening it to get the correct
            # shortened version.
            padded_prospective, _ = _pad_version(split_prospective, split_spec)

            # Shorten the prospective version to be the same length as the spec
            # so that we can determine if the specifier is a prefix of the
            # prospective version or not.
            shortened_prospective = padded_prospective[: len(split_spec)]

            return shortened_prospective == split_spec
        else:
            # Convert our spec string into a Version
            spec_version = self._require_spec_version(spec)

            # If the specifier does not have a local segment, then we want to
            # act as if the prospective version also does not have a local
            # segment.
            if not spec_version.local:
                prospective = _public_version(prospective)

            return prospective == spec_version

    def _compare_not_equal(self, prospective: Version, spec: str) -> bool:
        return not self._compare_equal(prospective, spec)

    def _compare_less_than_equal(self, prospective: Version, spec: str) -> bool:
        # NB: Local version identifiers are NOT permitted in the version
        # specifier, so local version labels can be universally removed from
        # the prospective version.
        return _public_version(prospective) <= self._require_spec_version(spec)

    def _compare_greater_than_equal(self, prospective: Version, spec: str) -> bool:
        # NB: Local version identifiers are NOT permitted in the version
        # specifier, so local version labels can be universally removed from
        # the prospective version.
        return _public_version(prospective) >= self._require_spec_version(spec)

    def _compare_less_than(self, prospective: Version, spec_str: str) -> bool:
        # Convert our spec to a Version instance, since we'll want to work with
        # it as a version.
        spec = self._require_spec_version(spec_str)

        # Check to see if the prospective version is less than the spec
        # version. If it's not we can short circuit and just return False now
        # instead of doing extra unneeded work.
        if not prospective < spec:
            return False

        # This special case is here so that, unless the specifier itself
        # includes is a pre-release version, that we do not accept pre-release
        # versions for the version mentioned in the specifier (e.g. <3.1 should
        # not match 3.1.dev0, but should match 3.0.dev0).
        if (
            not spec.is_prerelease
            and prospective.is_prerelease
            and _base_version(prospective) == _base_version(spec)
        ):
            return False

        # If we've gotten to here, it means that prospective version is both
        # less than the spec version *and* it's not a pre-release of the same
        # version in the spec.
        return True

    def _compare_greater_than(self, prospective: Version, spec_str: str) -> bool:
        # Convert our spec to a Version instance, since we'll want to work with
        # it as a version.
        spec = self._require_spec_version(spec_str)

        # Check to see if the prospective version is greater than the spec
        # version. If it's not we can short circuit and just return False now
        # instead of doing extra unneeded work.
        if not prospective > spec:
            return False

        # This special case is here so that, unless the specifier itself
        # includes is a post-release version, that we do not accept
        # post-release versions for the version mentioned in the specifier
        # (e.g. >3.1 should not match 3.0.post0, but should match 3.2.post0).
        if (
            not spec.is_postrelease
            and prospective.is_postrelease
            and _base_version(prospective) == _base_version(spec)
        ):
            return False

        # Ensure that we do not allow a local version of the version mentioned
        # in the specifier, which is technically greater than, to match.
        if prospective.local is not None and _base_version(
            prospective
        ) == _base_version(spec):
            return False

        # If we've gotten to here, it means that prospective version is both
        # greater than the spec version *and* it's not a pre-release of the
        # same version in the spec.
        return True

    def _compare_arbitrary(self, prospective: Version | str, spec: str) -> bool:
        return str(prospective).lower() == str(spec).lower()

    def __contains__(self, item: str | Version) -> bool:
        """Return whether or not the item is contained in this specifier.

        :param item: The item to check for.

        This is used for the ``in`` operator and behaves the same as
        :meth:`contains` with no ``prereleases`` argument passed.

        >>> "1.2.3" in Specifier(">=1.2.3")
        True
        >>> Version("1.2.3") in Specifier(">=1.2.3")
        True
        >>> "1.0.0" in Specifier(">=1.2.3")
        False
        >>> "1.3.0a1" in Specifier(">=1.2.3")
        True
        >>> "1.3.0a1" in Specifier(">=1.2.3", prereleases=True)
        True
        """
        return self.contains(item)

    def contains(self, item: UnparsedVersion, prereleases: bool | None = None) -> bool:
        """Return whether or not the item is contained in this specifier.

        :param item:
            The item to check for, which can be a version string or a
            :class:`Version` instance.
        :param prereleases:
            Whether or not to match prereleases with this Specifier. If set to
            ``None`` (the default), it will follow the recommendation from
            :pep:`440` and match prereleases, as there are no other versions.

        >>> Specifier(">=1.2.3").contains("1.2.3")
        True
        >>> Specifier(">=1.2.3").contains(Version("1.2.3"))
        True
        >>> Specifier(">=1.2.3").contains("1.0.0")
        False
        >>> Specifier(">=1.2.3").contains("1.3.0a1")
        True
        >>> Specifier(">=1.2.3", prereleases=False).contains("1.3.0a1")
        False
        >>> Specifier(">=1.2.3").contains("1.3.0a1")
        True
        """

        return bool(list(self.filter([item], prereleases=prereleases)))

    def filter(
        self, iterable: Iterable[UnparsedVersionVar], prereleases: bool | None = None
    ) -> Iterator[UnparsedVersionVar]:
        """Filter items in the given iterable, that match the specifier.

        :param iterable:
            An iterable that can contain version strings and :class:`Version` instances.
            The items in the iterable will be filtered according to the specifier.
        :param prereleases:
            Whether or not to allow prereleases in the returned iterator. If set to
            ``None`` (the default), it will follow the recommendation from :pep:`440`
            and match prereleases if there are no other versions.

        >>> list(Specifier(">=1.2.3").filter(["1.2", "1.3", "1.5a1"]))
        ['1.3']
        >>> list(Specifier(">=1.2.3").filter(["1.2", "1.2.3", "1.3", Version("1.4")]))
        ['1.2.3', '1.3', <Version('1.4')>]
        >>> list(Specifier(">=1.2.3").filter(["1.2", "1.5a1"]))
        ['1.5a1']
        >>> list(Specifier(">=1.2.3").filter(["1.3", "1.5a1"], prereleases=True))
        ['1.3', '1.5a1']
        >>> list(Specifier(">=1.2.3", prereleases=True).filter(["1.3", "1.5a1"]))
        ['1.3', '1.5a1']
        """
        prereleases_versions = []
        found_non_prereleases = False

        # Determine if to include prereleases by default
        include_prereleases = (
            prereleases if prereleases is not None else self.prereleases
        )

        # Get the matching operator
        operator_callable = self._get_operator(self.operator)

        # Filter versions
        for version in iterable:
            parsed_version = _coerce_version(version)
            if parsed_version is None:
                # === operator can match arbitrary (non-version) strings
                if self.operator == "===" and self._compare_arbitrary(
                    version, self.version
                ):
                    yield version
            elif operator_callable(parsed_version, self.version):
                # If it's not a prerelease or prereleases are allowed, yield it directly
                if not parsed_version.is_prerelease or include_prereleases:
                    found_non_prereleases = True
                    yield version
                # Otherwise collect prereleases for potential later use
                elif prereleases is None and self._prereleases is not False:
                    prereleases_versions.append(version)

        # If no non-prereleases were found and prereleases weren't
        # explicitly forbidden, yield the collected prereleases
        if (
            not found_non_prereleases
            and prereleases is None
            and self._prereleases is not False
        ):
            yield from prereleases_versions


_prefix_regex = re.compile(r"([0-9]+)((?:a|b|c|rc)[0-9]+)")


def _version_split(version: str) -> list[str]:
    """Split version into components.

    The split components are intended for version comparison. The logic does
    not attempt to retain the original version string, so joining the
    components back with :func:`_version_join` may not produce the original
    version string.
    """
    result: list[str] = []

    epoch, _, rest = version.rpartition("!")
    result.append(epoch or "0")

    for item in rest.split("."):
        match = _prefix_regex.fullmatch(item)
        if match:
            result.extend(match.groups())
        else:
            result.append(item)
    return result


def _version_join(components: list[str]) -> str:
    """Join split version components into a version string.

    This function assumes the input came from :func:`_version_split`, where the
    first component must be the epoch (either empty or numeric), and all other
    components numeric.
    """
    epoch, *rest = components
    return f"{epoch}!{'.'.join(rest)}"


def _is_not_suffix(segment: str) -> bool:
    return not any(
        segment.startswith(prefix) for prefix in ("dev", "a", "b", "rc", "post")
    )


def _pad_version(left: list[str], right: list[str]) -> tuple[list[str], list[str]]:
    left_split, right_split = [], []

    # Get the release segment of our versions
    left_split.append(list(itertools.takewhile(lambda x: x.isdigit(), left)))
    right_split.append(list(itertools.takewhile(lambda x: x.isdigit(), right)))

    # Get the rest of our versions
    left_split.append(left[len(left_split[0]) :])
    right_split.append(right[len(right_split[0]) :])

    # Insert our padding
    left_split.insert(1, ["0"] * max(0, len(right_split[0]) - len(left_split[0])))
    right_split.insert(1, ["0"] * max(0, len(left_split[0]) - len(right_split[0])))

    return (
        list(itertools.chain.from_iterable(left_split)),
        list(itertools.chain.from_iterable(right_split)),
    )


class SpecifierSet(BaseSpecifier):
    """This class abstracts handling of a set of version specifiers.

    It can be passed a single specifier (``>=3.0``), a comma-separated list of
    specifiers (``>=3.0,!=3.1``), or no specifier at all.
    """

    __slots__ = ("_prereleases", "_specs")

    def __init__(
        self,
        specifiers: str | Iterable[Specifier] = "",
        prereleases: bool | None = None,
    ) -> None:
        """Initialize a SpecifierSet instance.

        :param specifiers:
            The string representation of a specifier or a comma-separated list of
            specifiers which will be parsed and normalized before use.
            May also be an iterable of ``Specifier`` instances, which will be used
            as is.
        :param prereleases:
            This tells the SpecifierSet if it should accept prerelease versions if
            applicable or not. The default of ``None`` will autodetect it from the
            given specifiers.

        :raises InvalidSpecifier:
            If the given ``specifiers`` are not parseable than this exception will be
            raised.
        """

        if isinstance(specifiers, str):
            # Split on `,` to break each individual specifier into its own item, and
            # strip each item to remove leading/trailing whitespace.
            split_specifiers = [s.strip() for s in specifiers.split(",") if s.strip()]

            # Make each individual specifier a Specifier and save in a frozen set
            # for later.
            self._specs = frozenset(map(Specifier, split_specifiers))
        else:
            # Save the supplied specifiers in a frozen set.
            self._specs = frozenset(specifiers)

        # Store our prereleases value so we can use it later to determine if
        # we accept prereleases or not.
        self._prereleases = prereleases

    @property
    def prereleases(self) -> bool | None:
        # If we have been given an explicit prerelease modifier, then we'll
        # pass that through here.
        if self._prereleases is not None:
            return self._prereleases

        # If we don't have any specifiers, and we don't have a forced value,
        # then we'll just return None since we don't know if this should have
        # pre-releases or not.
        if not self._specs:
            return None

        # Otherwise we'll see if any of the given specifiers accept
        # prereleases, if any of them do we'll return True, otherwise False.
        if any(s.prereleases for s in self._specs):
            return True

        return None

    @prereleases.setter
    def prereleases(self, value: bool | None) -> None:
        self._prereleases = value

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

        Note that the ordering of the individual specifiers within the set may not
        match the input string.

        >>> SpecifierSet('>=1.0.0,!=2.0.0')
        <SpecifierSet('!=2.0.0,>=1.0.0')>
        >>> SpecifierSet('>=1.0.0,!=2.0.0', prereleases=False)
        <SpecifierSet('!=2.0.0,>=1.0.0', prereleases=False)>
        >>> SpecifierSet('>=1.0.0,!=2.0.0', prereleases=True)
        <SpecifierSet('!=2.0.0,>=1.0.0', prereleases=True)>
        """
        pre = (
            f", prereleases={self.prereleases!r}"
            if self._prereleases is not None
            else ""
        )

        return f"<SpecifierSet({str(self)!r}{pre})>"

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

        Note that the ordering of the individual specifiers within the set may not
        match the input string.

        >>> str(SpecifierSet(">=1.0.0,!=1.0.1"))
        '!=1.0.1,>=1.0.0'
        >>> str(SpecifierSet(">=1.0.0,!=1.0.1", prereleases=False))
        '!=1.0.1,>=1.0.0'
        """
        return ",".join(sorted(str(s) for s in self._specs))

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

    def __and__(self, other: SpecifierSet | str) -> SpecifierSet:
        """Return a SpecifierSet which is a combination of the two sets.

        :param other: The other object to combine with.

        >>> SpecifierSet(">=1.0.0,!=1.0.1") & '<=2.0.0,!=2.0.1'
        <SpecifierSet('!=1.0.1,!=2.0.1,<=2.0.0,>=1.0.0')>
        >>> SpecifierSet(">=1.0.0,!=1.0.1") & SpecifierSet('<=2.0.0,!=2.0.1')
        <SpecifierSet('!=1.0.1,!=2.0.1,<=2.0.0,>=1.0.0')>
        """
        if isinstance(other, str):
            other = SpecifierSet(other)
        elif not isinstance(other, SpecifierSet):
            return NotImplemented

        specifier = SpecifierSet()
        specifier._specs = frozenset(self._specs | other._specs)

        if self._prereleases is None and other._prereleases is not None:
            specifier._prereleases = other._prereleases
        elif (
            self._prereleases is not None and other._prereleases is None
        ) or self._prereleases == other._prereleases:
            specifier._prereleases = self._prereleases
        else:
            raise ValueError(
                "Cannot combine SpecifierSets with True and False prerelease overrides."
            )

        return specifier

    def __eq__(self, other: object) -> bool:
        """Whether or not the two SpecifierSet-like objects are equal.

        :param other: The other object to check against.

        The value of :attr:`prereleases` is ignored.

        >>> SpecifierSet(">=1.0.0,!=1.0.1") == SpecifierSet(">=1.0.0,!=1.0.1")
        True
        >>> (SpecifierSet(">=1.0.0,!=1.0.1", prereleases=False) ==
        ...  SpecifierSet(">=1.0.0,!=1.0.1", prereleases=True))
        True
        >>> SpecifierSet(">=1.0.0,!=1.0.1") == ">=1.0.0,!=1.0.1"
        True
        >>> SpecifierSet(">=1.0.0,!=1.0.1") == SpecifierSet(">=1.0.0")
        False
        >>> SpecifierSet(">=1.0.0,!=1.0.1") == SpecifierSet(">=1.0.0,!=1.0.2")
        False
        """
        if isinstance(other, (str, Specifier)):
            other = SpecifierSet(str(other))
        elif not isinstance(other, SpecifierSet):
            return NotImplemented

        return self._specs == other._specs

    def __len__(self) -> int:
        """Returns the number of specifiers in this specifier set."""
        return len(self._specs)

    def __iter__(self) -> Iterator[Specifier]:
        """
        Returns an iterator over all the underlying :class:`Specifier` instances
        in this specifier set.

        >>> sorted(SpecifierSet(">=1.0.0,!=1.0.1"), key=str)
        [<Specifier('!=1.0.1')>, <Specifier('>=1.0.0')>]
        """
        return iter(self._specs)

    def __contains__(self, item: UnparsedVersion) -> bool:
        """Return whether or not the item is contained in this specifier.

        :param item: The item to check for.

        This is used for the ``in`` operator and behaves the same as
        :meth:`contains` with no ``prereleases`` argument passed.

        >>> "1.2.3" in SpecifierSet(">=1.0.0,!=1.0.1")
        True
        >>> Version("1.2.3") in SpecifierSet(">=1.0.0,!=1.0.1")
        True
        >>> "1.0.1" in SpecifierSet(">=1.0.0,!=1.0.1")
        False
        >>> "1.3.0a1" in SpecifierSet(">=1.0.0,!=1.0.1")
        True
        >>> "1.3.0a1" in SpecifierSet(">=1.0.0,!=1.0.1", prereleases=True)
        True
        """
        return self.contains(item)

    def contains(
        self,
        item: UnparsedVersion,
        prereleases: bool | None = None,
        installed: bool | None = None,
    ) -> bool:
        """Return whether or not the item is contained in this SpecifierSet.

        :param item:
            The item to check for, which can be a version string or a
            :class:`Version` instance.
        :param prereleases:
            Whether or not to match prereleases with this SpecifierSet. If set to
            ``None`` (the default), it will follow the recommendation from :pep:`440`
            and match prereleases, as there are no other versions.
        :param installed:
            Whether or not the item is installed. If set to ``True``, it will
            accept prerelease versions even if the specifier does not allow them.

        >>> SpecifierSet(">=1.0.0,!=1.0.1").contains("1.2.3")
        True
        >>> SpecifierSet(">=1.0.0,!=1.0.1").contains(Version("1.2.3"))
        True
        >>> SpecifierSet(">=1.0.0,!=1.0.1").contains("1.0.1")
        False
        >>> SpecifierSet(">=1.0.0,!=1.0.1").contains("1.3.0a1")
        True
        >>> SpecifierSet(">=1.0.0,!=1.0.1", prereleases=False).contains("1.3.0a1")
        False
        >>> SpecifierSet(">=1.0.0,!=1.0.1").contains("1.3.0a1", prereleases=True)
        True
        """
        version = _coerce_version(item)

        if version is not None and installed and version.is_prerelease:
            prereleases = True

        check_item = item if version is None else version
        return bool(list(self.filter([check_item], prereleases=prereleases)))

    def filter(
        self, iterable: Iterable[UnparsedVersionVar], prereleases: bool | None = None
    ) -> Iterator[UnparsedVersionVar]:
        """Filter items in the given iterable, that match the specifiers in this set.

        :param iterable:
            An iterable that can contain version strings and :class:`Version` instances.
            The items in the iterable will be filtered according to the specifier.
        :param prereleases:
            Whether or not to allow prereleases in the returned iterator. If set to
            ``None`` (the default), it will follow the recommendation from :pep:`440`
            and match prereleases if there are no other versions.

        >>> list(SpecifierSet(">=1.2.3").filter(["1.2", "1.3", "1.5a1"]))
        ['1.3']
        >>> list(SpecifierSet(">=1.2.3").filter(["1.2", "1.3", Version("1.4")]))
        ['1.3', <Version('1.4')>]
        >>> list(SpecifierSet(">=1.2.3").filter(["1.2", "1.5a1"]))
        ['1.5a1']
        >>> list(SpecifierSet(">=1.2.3").filter(["1.3", "1.5a1"], prereleases=True))
        ['1.3', '1.5a1']
        >>> list(SpecifierSet(">=1.2.3", prereleases=True).filter(["1.3", "1.5a1"]))
        ['1.3', '1.5a1']

        An "empty" SpecifierSet will filter items based on the presence of prerelease
        versions in the set.

        >>> list(SpecifierSet("").filter(["1.3", "1.5a1"]))
        ['1.3']
        >>> list(SpecifierSet("").filter(["1.5a1"]))
        ['1.5a1']
        >>> list(SpecifierSet("", prereleases=True).filter(["1.3", "1.5a1"]))
        ['1.3', '1.5a1']
        >>> list(SpecifierSet("").filter(["1.3", "1.5a1"], prereleases=True))
        ['1.3', '1.5a1']
        """
        # Determine if we're forcing a prerelease or not, if we're not forcing
        # one for this particular filter call, then we'll use whatever the
        # SpecifierSet thinks for whether or not we should support prereleases.
        if prereleases is None and self.prereleases is not None:
            prereleases = self.prereleases

        # If we have any specifiers, then we want to wrap our iterable in the
        # filter method for each one, this will act as a logical AND amongst
        # each specifier.
        if self._specs:
            # When prereleases is None, we need to let all versions through
            # the individual filters, then decide about prereleases at the end
            # based on whether any non-prereleases matched ALL specs.
            for spec in self._specs:
                iterable = spec.filter(
                    iterable, prereleases=True if prereleases is None else prereleases
                )

            if prereleases is not None:
                # If we have a forced prereleases value,
                # we can immediately return the iterator.
                return iter(iterable)
        else:
            # Handle empty SpecifierSet cases where prereleases is not None.
            if prereleases is True:
                return iter(iterable)

            if prereleases is False:
                return (
                    item
                    for item in iterable
                    if (version := _coerce_version(item)) is None
                    or not version.is_prerelease
                )

        # Finally if prereleases is None, apply PEP 440 logic:
        # exclude prereleases unless there are no final releases that matched.
        filtered_items: list[UnparsedVersionVar] = []
        found_prereleases: list[UnparsedVersionVar] = []
        found_final_release = False

        for item in iterable:
            parsed_version = _coerce_version(item)
            # Arbitrary strings are always included as it is not
            # possible to determine if they are prereleases,
            # and they have already passed all specifiers.
            if parsed_version is None:
                filtered_items.append(item)
                found_prereleases.append(item)
            elif parsed_version.is_prerelease:
                found_prereleases.append(item)
            else:
                filtered_items.append(item)
                found_final_release = True

        return iter(filtered_items if found_final_release else found_prereleases)