"""
requests.structures
~~~~~~~~~~~~~~~~~~~

Data structures that power Requests.
"""

from collections import OrderedDict

from .compat import Mapping, MutableMapping


class CaseInsensitiveDict(MutableMapping):
    """A case-insensitive ``dict``-like object.

    Implements all methods and operations of
    ``MutableMapping`` as well as dict's ``copy``. Also
    provides ``lower_items``.

    All keys are expected to be strings. The structure remembers the
    case of the last key to be set, and ``iter(instance)``,
    ``keys()``, ``items()``, ``iterkeys()``, and ``iteritems()``
    will contain case-sensitive keys. However, querying and contains
    testing is case insensitive::

        cid = CaseInsensitiveDict()
        cid['Accept'] = 'application/json'
        cid['aCCEPT'] == 'application/json'  # True
        list(cid) == ['Accept']  # True

    For example, ``headers['content-encoding']`` will return the
    value of a ``'Content-Encoding'`` response header, regardless
    of how the header name was originally stored.

    If the constructor, ``.update``, or equality comparison
    operations are given keys that have equal ``.lower()``s, the
    behavior is undefined.
    """

    def __init__(self, data=None, **kwargs):
        self._store = OrderedDict()
        if data is None:
            data = {}
        self.update(data, **kwargs)

    def __setitem__(self, key, value):
        # Use the lowercased key for lookups, but store the actual
        # key alongside the value.
        self._store[key.lower()] = (key, value)

    def __getitem__(self, key):
        return self._store[key.lower()][1]

    def __delitem__(self, key):
        del self._store[key.lower()]

    def __iter__(self):
        return (casedkey for casedkey, mappedvalue in self._store.values())

    def __len__(self):
        return len(self._store)

    def lower_items(self):
        """Like iteritems(), but with all lowercase keys."""
        return ((lowerkey, keyval[1]) for (lowerkey, keyval) in self._store.items())

    def __eq__(self, other):
        if isinstance(other, Mapping):
            other = CaseInsensitiveDict(other)
        else:
            return NotImplemented
        # Compare insensitively
        return dict(self.lower_items()) == dict(other.lower_items())

    # Copy is required
    def copy(self):
        return CaseInsensitiveDict(self._store.values())

    def __repr__(self):
        return str(dict(self.items()))


class LookupDict(dict):
    """Dictionary lookup object."""

    def __init__(self, name=None):
        self.name = name
        super().__init__()

    def __repr__(self):
        return f"<lookup '{self.name}'>"

    def __getitem__(self, key):
        # We allow fall-through here, so values default to None

        return self.__dict__.get(key, None)

    def get(self, key, default=None):
        return self.__dict__.get(key, default)

"""
    pygments.formatters.rtf
    ~~~~~~~~~~~~~~~~~~~~~~~

    A formatter that generates RTF files.

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

from collections import OrderedDict
from pip._vendor.pygments.formatter import Formatter
from pip._vendor.pygments.style import _ansimap
from pip._vendor.pygments.util import get_bool_opt, get_int_opt, get_list_opt, surrogatepair


__all__ = ['RtfFormatter']


class RtfFormatter(Formatter):
    """
    Format tokens as RTF markup. This formatter automatically outputs full RTF
    documents with color information and other useful stuff. Perfect for Copy and
    Paste into Microsoft(R) Word(R) documents.

    Please note that ``encoding`` and ``outencoding`` options are ignored.
    The RTF format is ASCII natively, but handles unicode characters correctly
    thanks to escape sequences.

    .. versionadded:: 0.6

    Additional options accepted:

    `style`
        The style to use, can be a string or a Style subclass (default:
        ``'default'``).

    `fontface`
        The used font family, for example ``Bitstream Vera Sans``. Defaults to
        some generic font which is supposed to have fixed width.

    `fontsize`
        Size of the font used. Size is specified in half points. The
        default is 24 half-points, giving a size 12 font.

        .. versionadded:: 2.0

    `linenos`
        Turn on line numbering (default: ``False``).

        .. versionadded:: 2.18

    `lineno_fontsize`
        Font size for line numbers. Size is specified in half points
        (default: `fontsize`). 

        .. versionadded:: 2.18

    `lineno_padding`
        Number of spaces between the (inline) line numbers and the
        source code (default: ``2``).

        .. versionadded:: 2.18

    `linenostart`
        The line number for the first line (default: ``1``).

        .. versionadded:: 2.18

    `linenostep`
        If set to a number n > 1, only every nth line number is printed.

        .. versionadded:: 2.18

    `lineno_color`
        Color for line numbers specified as a hex triplet, e.g. ``'5e5e5e'``. 
        Defaults to the style's line number color if it is a hex triplet, 
        otherwise ansi bright black.

        .. versionadded:: 2.18

    `hl_lines`
        Specify a list of lines to be highlighted, as line numbers separated by
        spaces, e.g. ``'3 7 8'``. The line numbers are relative to the input 
        (i.e. the first line is line 1) unless `hl_linenostart` is set.

        .. versionadded:: 2.18

    `hl_color`
        Color for highlighting the lines specified in `hl_lines`, specified as 
        a hex triplet (default: style's `highlight_color`).

        .. versionadded:: 2.18

    `hl_linenostart`
        If set to ``True`` line numbers in `hl_lines` are specified
        relative to `linenostart` (default ``False``).

        .. versionadded:: 2.18
    """
    name = 'RTF'
    aliases = ['rtf']
    filenames = ['*.rtf']

    def __init__(self, **options):
        r"""
        Additional options accepted:

        ``fontface``
            Name of the font used. Could for example be ``'Courier New'``
            to further specify the default which is ``'\fmodern'``. The RTF
            specification claims that ``\fmodern`` are "Fixed-pitch serif
            and sans serif fonts". Hope every RTF implementation thinks
            the same about modern...

        """
        Formatter.__init__(self, **options)
        self.fontface = options.get('fontface') or ''
        self.fontsize = get_int_opt(options, 'fontsize', 0)
        self.linenos = get_bool_opt(options, 'linenos', False)
        self.lineno_fontsize = get_int_opt(options, 'lineno_fontsize',
                                           self.fontsize)
        self.lineno_padding = get_int_opt(options, 'lineno_padding', 2)
        self.linenostart = abs(get_int_opt(options, 'linenostart', 1))
        self.linenostep = abs(get_int_opt(options, 'linenostep', 1))
        self.hl_linenostart = get_bool_opt(options, 'hl_linenostart', False)

        self.hl_color = options.get('hl_color', '')
        if not self.hl_color:
            self.hl_color = self.style.highlight_color

        self.hl_lines = []
        for lineno in get_list_opt(options, 'hl_lines', []):
            try:
                lineno = int(lineno)
                if self.hl_linenostart:
                    lineno = lineno - self.linenostart + 1
                self.hl_lines.append(lineno)
            except ValueError:
                pass

        self.lineno_color = options.get('lineno_color', '')
        if not self.lineno_color:
            if  self.style.line_number_color == 'inherit':
                # style color is the css value 'inherit'
                # default to ansi bright-black
                self.lineno_color = _ansimap['ansibrightblack']
            else:
                # style color is assumed to be a hex triplet as other
                # colors in pygments/style.py
                self.lineno_color = self.style.line_number_color

        self.color_mapping = self._create_color_mapping()

    def _escape(self, text):
        return text.replace('\\', '\\\\') \
                   .replace('{', '\\{') \
                   .replace('}', '\\}')

    def _escape_text(self, text):
        # empty strings, should give a small performance improvement
        if not text:
            return ''

        # escape text
        text = self._escape(text)

        buf = []
        for c in text:
            cn = ord(c)
            if cn < (2**7):
                # ASCII character
                buf.append(str(c))
            elif (2**7) <= cn < (2**16):
                # single unicode escape sequence
                buf.append('{\\u%d}' % cn)
            elif (2**16) <= cn:
                # RTF limits unicode to 16 bits.
                # Force surrogate pairs
                buf.append('{\\u%d}{\\u%d}' % surrogatepair(cn))

        return ''.join(buf).replace('\n', '\\par')

    @staticmethod
    def hex_to_rtf_color(hex_color):
        if hex_color[0] == "#":
            hex_color = hex_color[1:]

        return '\\red%d\\green%d\\blue%d;' % (
                        int(hex_color[0:2], 16),
                        int(hex_color[2:4], 16),
                        int(hex_color[4:6], 16)
                    )

    def _split_tokens_on_newlines(self, tokensource):
        """
        Split tokens containing newline characters into multiple token
        each representing a line of the input file. Needed for numbering
        lines of e.g. multiline comments.
        """
        for ttype, value in tokensource:
            if value == '\n':
                yield (ttype, value)
            elif "\n" in value:
                lines = value.split("\n")
                for line in lines[:-1]:
                    yield (ttype, line+"\n")
                if lines[-1]:
                    yield (ttype, lines[-1])
            else:
                yield (ttype, value)

    def _create_color_mapping(self):
        """
        Create a mapping of style hex colors to index/offset in
        the RTF color table.
        """
        color_mapping = OrderedDict()
        offset = 1

        if self.linenos:
            color_mapping[self.lineno_color] = offset
            offset += 1

        if self.hl_lines:
            color_mapping[self.hl_color] = offset
            offset += 1

        for _, style in self.style:
            for color in style['color'], style['bgcolor'], style['border']:
                if color and color not in color_mapping:
                    color_mapping[color] = offset
                    offset += 1

        return color_mapping

    @property
    def _lineno_template(self):
        if self.lineno_fontsize != self.fontsize:
            return '{{\\fs{} \\cf{} %s{}}}'.format(self.lineno_fontsize,
                          self.color_mapping[self.lineno_color],
                          " " * self.lineno_padding)

        return '{{\\cf{} %s{}}}'.format(self.color_mapping[self.lineno_color],
                      " " * self.lineno_padding)

    @property
    def _hl_open_str(self):
        return rf'{{\highlight{self.color_mapping[self.hl_color]} '

    @property
    def _rtf_header(self):
        lines = []
        # rtf 1.8 header
        lines.append('{\\rtf1\\ansi\\uc0\\deff0'
                     '{\\fonttbl{\\f0\\fmodern\\fprq1\\fcharset0%s;}}'
                     % (self.fontface and ' '
                        + self._escape(self.fontface) or ''))

        # color table
        lines.append('{\\colortbl;')
        for color, _ in self.color_mapping.items():
            lines.append(self.hex_to_rtf_color(color))
        lines.append('}')

        # font and fontsize
        lines.append('\\f0\\sa0')
        if self.fontsize:
            lines.append('\\fs%d' % self.fontsize)

        # ensure Libre Office Writer imports and renders consecutive
        # space characters the same width, needed for line numbering.
        # https://bugs.documentfoundation.org/show_bug.cgi?id=144050
        lines.append('\\dntblnsbdb')

        return lines

    def format_unencoded(self, tokensource, outfile):
        for line in self._rtf_header:
            outfile.write(line + "\n")

        tokensource = self._split_tokens_on_newlines(tokensource)

        # first pass of tokens to count lines, needed for line numbering
        if self.linenos:
            line_count = 0
            tokens = [] # for copying the token source generator
            for ttype, value in tokensource:
                tokens.append((ttype, value))
                if value.endswith("\n"):
                    line_count += 1

            # width of line number strings (for padding with spaces)
            linenos_width = len(str(line_count+self.linenostart-1))

            tokensource = tokens

        # highlight stream
        lineno = 1
        start_new_line = True
        for ttype, value in tokensource:
            if start_new_line and lineno in self.hl_lines:
                outfile.write(self._hl_open_str)

            if start_new_line and self.linenos:
                if (lineno-self.linenostart+1)%self.linenostep == 0:
                    current_lineno = lineno + self.linenostart - 1
                    lineno_str = str(current_lineno).rjust(linenos_width)
                else:
                    lineno_str = "".rjust(linenos_width)
                outfile.write(self._lineno_template % lineno_str)

            while not self.style.styles_token(ttype) and ttype.parent:
                ttype = ttype.parent
            style = self.style.style_for_token(ttype)
            buf = []
            if style['bgcolor']:
                buf.append('\\cb%d' % self.color_mapping[style['bgcolor']])
            if style['color']:
                buf.append('\\cf%d' % self.color_mapping[style['color']])
            if style['bold']:
                buf.append('\\b')
            if style['italic']:
                buf.append('\\i')
            if style['underline']:
                buf.append('\\ul')
            if style['border']:
                buf.append('\\chbrdr\\chcfpat%d' %
                           self.color_mapping[style['border']])
            start = ''.join(buf)
            if start:
                outfile.write(f'{{{start} ')
            outfile.write(self._escape_text(value))
            if start:
                outfile.write('}')
            start_new_line = False

            # complete line of input
            if value.endswith("\n"):
                # close line highlighting
                if lineno in self.hl_lines:
                    outfile.write('}')
                # newline in RTF file after closing }
                outfile.write("\n")

                start_new_line = True
                lineno += 1

        outfile.write('}\n')

import functools
import importlib.metadata
import logging
import os
import pathlib
import sys
import zipfile
import zipimport
from typing import Iterator, List, Optional, Sequence, Set, Tuple

from pip._vendor.packaging.utils import NormalizedName, canonicalize_name

from pip._internal.metadata.base import BaseDistribution, BaseEnvironment
from pip._internal.models.wheel import Wheel
from pip._internal.utils.deprecation import deprecated
from pip._internal.utils.filetypes import WHEEL_EXTENSION

from ._compat import BadMetadata, BasePath, get_dist_canonical_name, get_info_location
from ._dists import Distribution

logger = logging.getLogger(__name__)


def _looks_like_wheel(location: str) -> bool:
    if not location.endswith(WHEEL_EXTENSION):
        return False
    if not os.path.isfile(location):
        return False
    if not Wheel.wheel_file_re.match(os.path.basename(location)):
        return False
    return zipfile.is_zipfile(location)


class _DistributionFinder:
    """Finder to locate distributions.

    The main purpose of this class is to memoize found distributions' names, so
    only one distribution is returned for each package name. At lot of pip code
    assumes this (because it is setuptools's behavior), and not doing the same
    can potentially cause a distribution in lower precedence path to override a
    higher precedence one if the caller is not careful.

    Eventually we probably want to make it possible to see lower precedence
    installations as well. It's useful feature, after all.
    """

    FoundResult = Tuple[importlib.metadata.Distribution, Optional[BasePath]]

    def __init__(self) -> None:
        self._found_names: Set[NormalizedName] = set()

    def _find_impl(self, location: str) -> Iterator[FoundResult]:
        """Find distributions in a location."""
        # Skip looking inside a wheel. Since a package inside a wheel is not
        # always valid (due to .data directories etc.), its .dist-info entry
        # should not be considered an installed distribution.
        if _looks_like_wheel(location):
            return
        # To know exactly where we find a distribution, we have to feed in the
        # paths one by one, instead of dumping the list to importlib.metadata.
        for dist in importlib.metadata.distributions(path=[location]):
            info_location = get_info_location(dist)
            try:
                name = get_dist_canonical_name(dist)
            except BadMetadata as e:
                logger.warning("Skipping %s due to %s", info_location, e.reason)
                continue
            if name in self._found_names:
                continue
            self._found_names.add(name)
            yield dist, info_location

    def find(self, location: str) -> Iterator[BaseDistribution]:
        """Find distributions in a location.

        The path can be either a directory, or a ZIP archive.
        """
        for dist, info_location in self._find_impl(location):
            if info_location is None:
                installed_location: Optional[BasePath] = None
            else:
                installed_location = info_location.parent
            yield Distribution(dist, info_location, installed_location)

    def find_linked(self, location: str) -> Iterator[BaseDistribution]:
        """Read location in egg-link files and return distributions in there.

        The path should be a directory; otherwise this returns nothing. This
        follows how setuptools does this for compatibility. The first non-empty
        line in the egg-link is read as a path (resolved against the egg-link's
        containing directory if relative). Distributions found at that linked
        location are returned.
        """
        path = pathlib.Path(location)
        if not path.is_dir():
            return
        for child in path.iterdir():
            if child.suffix != ".egg-link":
                continue
            with child.open() as f:
                lines = (line.strip() for line in f)
                target_rel = next((line for line in lines if line), "")
            if not target_rel:
                continue
            target_location = str(path.joinpath(target_rel))
            for dist, info_location in self._find_impl(target_location):
                yield Distribution(dist, info_location, path)

    def _find_eggs_in_dir(self, location: str) -> Iterator[BaseDistribution]:
        from pip._vendor.pkg_resources import find_distributions

        from pip._internal.metadata import pkg_resources as legacy

        with os.scandir(location) as it:
            for entry in it:
                if not entry.name.endswith(".egg"):
                    continue
                for dist in find_distributions(entry.path):
                    yield legacy.Distribution(dist)

    def _find_eggs_in_zip(self, location: str) -> Iterator[BaseDistribution]:
        from pip._vendor.pkg_resources import find_eggs_in_zip

        from pip._internal.metadata import pkg_resources as legacy

        try:
            importer = zipimport.zipimporter(location)
        except zipimport.ZipImportError:
            return
        for dist in find_eggs_in_zip(importer, location):
            yield legacy.Distribution(dist)

    def find_eggs(self, location: str) -> Iterator[BaseDistribution]:
        """Find eggs in a location.

        This actually uses the old *pkg_resources* backend. We likely want to
        deprecate this so we can eventually remove the *pkg_resources*
        dependency entirely. Before that, this should first emit a deprecation
        warning for some versions when using the fallback since importing
        *pkg_resources* is slow for those who don't need it.
        """
        if os.path.isdir(location):
            yield from self._find_eggs_in_dir(location)
        if zipfile.is_zipfile(location):
            yield from self._find_eggs_in_zip(location)


@functools.lru_cache(maxsize=None)  # Warn a distribution exactly once.
def _emit_egg_deprecation(location: Optional[str]) -> None:
    deprecated(
        reason=f"Loading egg at {location} is deprecated.",
        replacement="to use pip for package installation",
        gone_in="25.1",
        issue=12330,
    )


class Environment(BaseEnvironment):
    def __init__(self, paths: Sequence[str]) -> None:
        self._paths = paths

    @classmethod
    def default(cls) -> BaseEnvironment:
        return cls(sys.path)

    @classmethod
    def from_paths(cls, paths: Optional[List[str]]) -> BaseEnvironment:
        if paths is None:
            return cls(sys.path)
        return cls(paths)

    def _iter_distributions(self) -> Iterator[BaseDistribution]:
        finder = _DistributionFinder()
        for location in self._paths:
            yield from finder.find(location)
            for dist in finder.find_eggs(location):
                _emit_egg_deprecation(dist.location)
                yield dist
            # This must go last because that's how pkg_resources tie-breaks.
            yield from finder.find_linked(location)

    def get_distribution(self, name: str) -> Optional[BaseDistribution]:
        canonical_name = canonicalize_name(name)
        matches = (
            distribution
            for distribution in self.iter_all_distributions()
            if distribution.canonical_name == canonical_name
        )
        return next(matches, None)

import itertools
import logging
import os
import posixpath
import urllib.parse
from dataclasses import dataclass
from typing import List

from pip._vendor.packaging.utils import canonicalize_name

from pip._internal.models.index import PyPI
from pip._internal.utils.compat import has_tls
from pip._internal.utils.misc import normalize_path, redact_auth_from_url

logger = logging.getLogger(__name__)


@dataclass(frozen=True)
class SearchScope:
    """
    Encapsulates the locations that pip is configured to search.
    """

    __slots__ = ["find_links", "index_urls", "no_index"]

    find_links: List[str]
    index_urls: List[str]
    no_index: bool

    @classmethod
    def create(
        cls,
        find_links: List[str],
        index_urls: List[str],
        no_index: bool,
    ) -> "SearchScope":
        """
        Create a SearchScope object after normalizing the `find_links`.
        """
        # Build find_links. If an argument starts with ~, it may be
        # a local file relative to a home directory. So try normalizing
        # it and if it exists, use the normalized version.
        # This is deliberately conservative - it might be fine just to
        # blindly normalize anything starting with a ~...
        built_find_links: List[str] = []
        for link in find_links:
            if link.startswith("~"):
                new_link = normalize_path(link)
                if os.path.exists(new_link):
                    link = new_link
            built_find_links.append(link)

        # If we don't have TLS enabled, then WARN if anyplace we're looking
        # relies on TLS.
        if not has_tls():
            for link in itertools.chain(index_urls, built_find_links):
                parsed = urllib.parse.urlparse(link)
                if parsed.scheme == "https":
                    logger.warning(
                        "pip is configured with locations that require "
                        "TLS/SSL, however the ssl module in Python is not "
                        "available."
                    )
                    break

        return cls(
            find_links=built_find_links,
            index_urls=index_urls,
            no_index=no_index,
        )

    def get_formatted_locations(self) -> str:
        lines = []
        redacted_index_urls = []
        if self.index_urls and self.index_urls != [PyPI.simple_url]:
            for url in self.index_urls:
                redacted_index_url = redact_auth_from_url(url)

                # Parse the URL
                purl = urllib.parse.urlsplit(redacted_index_url)

                # URL is generally invalid if scheme and netloc is missing
                # 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 purl.scheme and not purl.netloc:
                    logger.warning(
                        'The index url "%s" seems invalid, please provide a scheme.',
                        redacted_index_url,
                    )

                redacted_index_urls.append(redacted_index_url)

            lines.append(
                "Looking in indexes: {}".format(", ".join(redacted_index_urls))
            )

        if self.find_links:
            lines.append(
                "Looking in links: {}".format(
                    ", ".join(redact_auth_from_url(url) for url in self.find_links)
                )
            )
        return "\n".join(lines)

    def get_index_urls_locations(self, project_name: str) -> List[str]:
        """Returns the locations found via self.index_urls

        Checks the url_name on the main (first in the list) index and
        use this url_name to produce all locations
        """

        def mkurl_pypi_url(url: str) -> str:
            loc = posixpath.join(
                url, urllib.parse.quote(canonicalize_name(project_name))
            )
            # For maximum compatibility with easy_install, ensure the path
            # ends in a trailing slash.  Although this isn't in the spec
            # (and PyPI can handle it without the slash) some other index
            # implementations might break if they relied on easy_install's
            # behavior.
            if not loc.endswith("/"):
                loc = loc + "/"
            return loc

        return [mkurl_pypi_url(url) for url in self.index_urls]

# -*- coding: utf-8 -*-
#
# Copyright (C) 2012-2023 The Python Software Foundation.
# See LICENSE.txt and CONTRIBUTORS.txt.
#
"""PEP 376 implementation."""

from __future__ import unicode_literals

import base64
import codecs
import contextlib
import hashlib
import logging
import os
import posixpath
import sys
import zipimport

from . import DistlibException, resources
from .compat import StringIO
from .version import get_scheme, UnsupportedVersionError
from .metadata import (Metadata, METADATA_FILENAME, WHEEL_METADATA_FILENAME, LEGACY_METADATA_FILENAME)
from .util import (parse_requirement, cached_property, parse_name_and_version, read_exports, write_exports, CSVReader,
                   CSVWriter)

__all__ = [
    'Distribution', 'BaseInstalledDistribution', 'InstalledDistribution', 'EggInfoDistribution', 'DistributionPath'
]

logger = logging.getLogger(__name__)

EXPORTS_FILENAME = 'pydist-exports.json'
COMMANDS_FILENAME = 'pydist-commands.json'

DIST_FILES = ('INSTALLER', METADATA_FILENAME, 'RECORD', 'REQUESTED', 'RESOURCES', EXPORTS_FILENAME, 'SHARED')

DISTINFO_EXT = '.dist-info'


class _Cache(object):
    """
    A simple cache mapping names and .dist-info paths to distributions
    """

    def __init__(self):
        """
        Initialise an instance. There is normally one for each DistributionPath.
        """
        self.name = {}
        self.path = {}
        self.generated = False

    def clear(self):
        """
        Clear the cache, setting it to its initial state.
        """
        self.name.clear()
        self.path.clear()
        self.generated = False

    def add(self, dist):
        """
        Add a distribution to the cache.
        :param dist: The distribution to add.
        """
        if dist.path not in self.path:
            self.path[dist.path] = dist
            self.name.setdefault(dist.key, []).append(dist)


class DistributionPath(object):
    """
    Represents a set of distributions installed on a path (typically sys.path).
    """

    def __init__(self, path=None, include_egg=False):
        """
        Create an instance from a path, optionally including legacy (distutils/
        setuptools/distribute) distributions.
        :param path: The path to use, as a list of directories. If not specified,
                     sys.path is used.
        :param include_egg: If True, this instance will look for and return legacy
                            distributions as well as those based on PEP 376.
        """
        if path is None:
            path = sys.path
        self.path = path
        self._include_dist = True
        self._include_egg = include_egg

        self._cache = _Cache()
        self._cache_egg = _Cache()
        self._cache_enabled = True
        self._scheme = get_scheme('default')

    def _get_cache_enabled(self):
        return self._cache_enabled

    def _set_cache_enabled(self, value):
        self._cache_enabled = value

    cache_enabled = property(_get_cache_enabled, _set_cache_enabled)

    def clear_cache(self):
        """
        Clears the internal cache.
        """
        self._cache.clear()
        self._cache_egg.clear()

    def _yield_distributions(self):
        """
        Yield .dist-info and/or .egg(-info) distributions.
        """
        # We need to check if we've seen some resources already, because on
        # some Linux systems (e.g. some Debian/Ubuntu variants) there are
        # symlinks which alias other files in the environment.
        seen = set()
        for path in self.path:
            finder = resources.finder_for_path(path)
            if finder is None:
                continue
            r = finder.find('')
            if not r or not r.is_container:
                continue
            rset = sorted(r.resources)
            for entry in rset:
                r = finder.find(entry)
                if not r or r.path in seen:
                    continue
                try:
                    if self._include_dist and entry.endswith(DISTINFO_EXT):
                        possible_filenames = [METADATA_FILENAME, WHEEL_METADATA_FILENAME, LEGACY_METADATA_FILENAME]
                        for metadata_filename in possible_filenames:
                            metadata_path = posixpath.join(entry, metadata_filename)
                            pydist = finder.find(metadata_path)
                            if pydist:
                                break
                        else:
                            continue

                        with contextlib.closing(pydist.as_stream()) as stream:
                            metadata = Metadata(fileobj=stream, scheme='legacy')
                        logger.debug('Found %s', r.path)
                        seen.add(r.path)
                        yield new_dist_class(r.path, metadata=metadata, env=self)
                    elif self._include_egg and entry.endswith(('.egg-info', '.egg')):
                        logger.debug('Found %s', r.path)
                        seen.add(r.path)
                        yield old_dist_class(r.path, self)
                except Exception as e:
                    msg = 'Unable to read distribution at %s, perhaps due to bad metadata: %s'
                    logger.warning(msg, r.path, e)
                    import warnings
                    warnings.warn(msg % (r.path, e), stacklevel=2)

    def _generate_cache(self):
        """
        Scan the path for distributions and populate the cache with
        those that are found.
        """
        gen_dist = not self._cache.generated
        gen_egg = self._include_egg and not self._cache_egg.generated
        if gen_dist or gen_egg:
            for dist in self._yield_distributions():
                if isinstance(dist, InstalledDistribution):
                    self._cache.add(dist)
                else:
                    self._cache_egg.add(dist)

            if gen_dist:
                self._cache.generated = True
            if gen_egg:
                self._cache_egg.generated = True

    @classmethod
    def distinfo_dirname(cls, name, version):
        """
        The *name* and *version* parameters are converted into their
        filename-escaped form, i.e. any ``'-'`` characters are replaced
        with ``'_'`` other than the one in ``'dist-info'`` and the one
        separating the name from the version number.

        :parameter name: is converted to a standard distribution name by replacing
                         any runs of non- alphanumeric characters with a single
                         ``'-'``.
        :type name: string
        :parameter version: is converted to a standard version string. Spaces
                            become dots, and all other non-alphanumeric characters
                            (except dots) become dashes, with runs of multiple
                            dashes condensed to a single dash.
        :type version: string
        :returns: directory name
        :rtype: string"""
        name = name.replace('-', '_')
        return '-'.join([name, version]) + DISTINFO_EXT

    def get_distributions(self):
        """
        Provides an iterator that looks for distributions and returns
        :class:`InstalledDistribution` or
        :class:`EggInfoDistribution` instances for each one of them.

        :rtype: iterator of :class:`InstalledDistribution` and
                :class:`EggInfoDistribution` instances
        """
        if not self._cache_enabled:
            for dist in self._yield_distributions():
                yield dist
        else:
            self._generate_cache()

            for dist in self._cache.path.values():
                yield dist

            if self._include_egg:
                for dist in self._cache_egg.path.values():
                    yield dist

    def get_distribution(self, name):
        """
        Looks for a named distribution on the path.

        This function only returns the first result found, as no more than one
        value is expected. If nothing is found, ``None`` is returned.

        :rtype: :class:`InstalledDistribution`, :class:`EggInfoDistribution`
                or ``None``
        """
        result = None
        name = name.lower()
        if not self._cache_enabled:
            for dist in self._yield_distributions():
                if dist.key == name:
                    result = dist
                    break
        else:
            self._generate_cache()

            if name in self._cache.name:
                result = self._cache.name[name][0]
            elif self._include_egg and name in self._cache_egg.name:
                result = self._cache_egg.name[name][0]
        return result

    def provides_distribution(self, name, version=None):
        """
        Iterates over all distributions to find which distributions provide *name*.
        If a *version* is provided, it will be used to filter the results.

        This function only returns the first result found, since no more than
        one values are expected. If the directory is not found, returns ``None``.

        :parameter version: a version specifier that indicates the version
                            required, conforming to the format in ``PEP-345``

        :type name: string
        :type version: string
        """
        matcher = None
        if version is not None:
            try:
                matcher = self._scheme.matcher('%s (%s)' % (name, version))
            except ValueError:
                raise DistlibException('invalid name or version: %r, %r' % (name, version))

        for dist in self.get_distributions():
            # We hit a problem on Travis where enum34 was installed and doesn't
            # have a provides attribute ...
            if not hasattr(dist, 'provides'):
                logger.debug('No "provides": %s', dist)
            else:
                provided = dist.provides

                for p in provided:
                    p_name, p_ver = parse_name_and_version(p)
                    if matcher is None:
                        if p_name == name:
                            yield dist
                            break
                    else:
                        if p_name == name and matcher.match(p_ver):
                            yield dist
                            break

    def get_file_path(self, name, relative_path):
        """
        Return the path to a resource file.
        """
        dist = self.get_distribution(name)
        if dist is None:
            raise LookupError('no distribution named %r found' % name)
        return dist.get_resource_path(relative_path)

    def get_exported_entries(self, category, name=None):
        """
        Return all of the exported entries in a particular category.

        :param category: The category to search for entries.
        :param name: If specified, only entries with that name are returned.
        """
        for dist in self.get_distributions():
            r = dist.exports
            if category in r:
                d = r[category]
                if name is not None:
                    if name in d:
                        yield d[name]
                else:
                    for v in d.values():
                        yield v


class Distribution(object):
    """
    A base class for distributions, whether installed or from indexes.
    Either way, it must have some metadata, so that's all that's needed
    for construction.
    """

    build_time_dependency = False
    """
    Set to True if it's known to be only a build-time dependency (i.e.
    not needed after installation).
    """

    requested = False
    """A boolean that indicates whether the ``REQUESTED`` metadata file is
    present (in other words, whether the package was installed by user
    request or it was installed as a dependency)."""

    def __init__(self, metadata):
        """
        Initialise an instance.
        :param metadata: The instance of :class:`Metadata` describing this
        distribution.
        """
        self.metadata = metadata
        self.name = metadata.name
        self.key = self.name.lower()  # for case-insensitive comparisons
        self.version = metadata.version
        self.locator = None
        self.digest = None
        self.extras = None  # additional features requested
        self.context = None  # environment marker overrides
        self.download_urls = set()
        self.digests = {}

    @property
    def source_url(self):
        """
        The source archive download URL for this distribution.
        """
        return self.metadata.source_url

    download_url = source_url  # Backward compatibility

    @property
    def name_and_version(self):
        """
        A utility property which displays the name and version in parentheses.
        """
        return '%s (%s)' % (self.name, self.version)

    @property
    def provides(self):
        """
        A set of distribution names and versions provided by this distribution.
        :return: A set of "name (version)" strings.
        """
        plist = self.metadata.provides
        s = '%s (%s)' % (self.name, self.version)
        if s not in plist:
            plist.append(s)
        return plist

    def _get_requirements(self, req_attr):
        md = self.metadata
        reqts = getattr(md, req_attr)
        logger.debug('%s: got requirements %r from metadata: %r', self.name, req_attr, reqts)
        return set(md.get_requirements(reqts, extras=self.extras, env=self.context))

    @property
    def run_requires(self):
        return self._get_requirements('run_requires')

    @property
    def meta_requires(self):
        return self._get_requirements('meta_requires')

    @property
    def build_requires(self):
        return self._get_requirements('build_requires')

    @property
    def test_requires(self):
        return self._get_requirements('test_requires')

    @property
    def dev_requires(self):
        return self._get_requirements('dev_requires')

    def matches_requirement(self, req):
        """
        Say if this instance matches (fulfills) a requirement.
        :param req: The requirement to match.
        :rtype req: str
        :return: True if it matches, else False.
        """
        # Requirement may contain extras - parse to lose those
        # from what's passed to the matcher
        r = parse_requirement(req)
        scheme = get_scheme(self.metadata.scheme)
        try:
            matcher = scheme.matcher(r.requirement)
        except UnsupportedVersionError:
            # XXX compat-mode if cannot read the version
            logger.warning('could not read version %r - using name only', req)
            name = req.split()[0]
            matcher = scheme.matcher(name)

        name = matcher.key  # case-insensitive

        result = False
        for p in self.provides:
            p_name, p_ver = parse_name_and_version(p)
            if p_name != name:
                continue
            try:
                result = matcher.match(p_ver)
                break
            except UnsupportedVersionError:
                pass
        return result

    def __repr__(self):
        """
        Return a textual representation of this instance,
        """
        if self.source_url:
            suffix = ' [%s]' % self.source_url
        else:
            suffix = ''
        return '<Distribution %s (%s)%s>' % (self.name, self.version, suffix)

    def __eq__(self, other):
        """
        See if this distribution is the same as another.
        :param other: The distribution to compare with. To be equal to one
                      another. distributions must have the same type, name,
                      version and source_url.
        :return: True if it is the same, else False.
        """
        if type(other) is not type(self):
            result = False
        else:
            result = (self.name == other.name and self.version == other.version and self.source_url == other.source_url)
        return result

    def __hash__(self):
        """
        Compute hash in a way which matches the equality test.
        """
        return hash(self.name) + hash(self.version) + hash(self.source_url)


class BaseInstalledDistribution(Distribution):
    """
    This is the base class for installed distributions (whether PEP 376 or
    legacy).
    """

    hasher = None

    def __init__(self, metadata, path, env=None):
        """
        Initialise an instance.
        :param metadata: An instance of :class:`Metadata` which describes the
                         distribution. This will normally have been initialised
                         from a metadata file in the ``path``.
        :param path:     The path of the ``.dist-info`` or ``.egg-info``
                         directory for the distribution.
        :param env:      This is normally the :class:`DistributionPath`
                         instance where this distribution was found.
        """
        super(BaseInstalledDistribution, self).__init__(metadata)
        self.path = path
        self.dist_path = env

    def get_hash(self, data, hasher=None):
        """
        Get the hash of some data, using a particular hash algorithm, if
        specified.

        :param data: The data to be hashed.
        :type data: bytes
        :param hasher: The name of a hash implementation, supported by hashlib,
                       or ``None``. Examples of valid values are ``'sha1'``,
                       ``'sha224'``, ``'sha384'``, '``sha256'``, ``'md5'`` and
                       ``'sha512'``. If no hasher is specified, the ``hasher``
                       attribute of the :class:`InstalledDistribution` instance
                       is used. If the hasher is determined to be ``None``, MD5
                       is used as the hashing algorithm.
        :returns: The hash of the data. If a hasher was explicitly specified,
                  the returned hash will be prefixed with the specified hasher
                  followed by '='.
        :rtype: str
        """
        if hasher is None:
            hasher = self.hasher
        if hasher is None:
            hasher = hashlib.md5
            prefix = ''
        else:
            hasher = getattr(hashlib, hasher)
            prefix = '%s=' % self.hasher
        digest = hasher(data).digest()
        digest = base64.urlsafe_b64encode(digest).rstrip(b'=').decode('ascii')
        return '%s%s' % (prefix, digest)


class InstalledDistribution(BaseInstalledDistribution):
    """
    Created with the *path* of the ``.dist-info`` directory provided to the
    constructor. It reads the metadata contained in ``pydist.json`` when it is
    instantiated., or uses a passed in Metadata instance (useful for when
    dry-run mode is being used).
    """

    hasher = 'sha256'

    def __init__(self, path, metadata=None, env=None):
        self.modules = []
        self.finder = finder = resources.finder_for_path(path)
        if finder is None:
            raise ValueError('finder unavailable for %s' % path)
        if env and env._cache_enabled and path in env._cache.path:
            metadata = env._cache.path[path].metadata
        elif metadata is None:
            r = finder.find(METADATA_FILENAME)
            # Temporary - for Wheel 0.23 support
            if r is None:
                r = finder.find(WHEEL_METADATA_FILENAME)
            # Temporary - for legacy support
            if r is None:
                r = finder.find(LEGACY_METADATA_FILENAME)
            if r is None:
                raise ValueError('no %s found in %s' % (METADATA_FILENAME, path))
            with contextlib.closing(r.as_stream()) as stream:
                metadata = Metadata(fileobj=stream, scheme='legacy')

        super(InstalledDistribution, self).__init__(metadata, path, env)

        if env and env._cache_enabled:
            env._cache.add(self)

        r = finder.find('REQUESTED')
        self.requested = r is not None
        p = os.path.join(path, 'top_level.txt')
        if os.path.exists(p):
            with open(p, 'rb') as f:
                data = f.read().decode('utf-8')
            self.modules = data.splitlines()

    def __repr__(self):
        return '<InstalledDistribution %r %s at %r>' % (self.name, self.version, self.path)

    def __str__(self):
        return "%s %s" % (self.name, self.version)

    def _get_records(self):
        """
        Get the list of installed files for the distribution
        :return: A list of tuples of path, hash and size. Note that hash and
                 size might be ``None`` for some entries. The path is exactly
                 as stored in the file (which is as in PEP 376).
        """
        results = []
        r = self.get_distinfo_resource('RECORD')
        with contextlib.closing(r.as_stream()) as stream:
            with CSVReader(stream=stream) as record_reader:
                # Base location is parent dir of .dist-info dir
                # base_location = os.path.dirname(self.path)
                # base_location = os.path.abspath(base_location)
                for row in record_reader:
                    missing = [None for i in range(len(row), 3)]
                    path, checksum, size = row + missing
                    # if not os.path.isabs(path):
                    #     path = path.replace('/', os.sep)
                    #     path = os.path.join(base_location, path)
                    results.append((path, checksum, size))
        return results

    @cached_property
    def exports(self):
        """
        Return the information exported by this distribution.
        :return: A dictionary of exports, mapping an export category to a dict
                 of :class:`ExportEntry` instances describing the individual
                 export entries, and keyed by name.
        """
        result = {}
        r = self.get_distinfo_resource(EXPORTS_FILENAME)
        if r:
            result = self.read_exports()
        return result

    def read_exports(self):
        """
        Read exports data from a file in .ini format.

        :return: A dictionary of exports, mapping an export category to a list
                 of :class:`ExportEntry` instances describing the individual
                 export entries.
        """
        result = {}
        r = self.get_distinfo_resource(EXPORTS_FILENAME)
        if r:
            with contextlib.closing(r.as_stream()) as stream:
                result = read_exports(stream)
        return result

    def write_exports(self, exports):
        """
        Write a dictionary of exports to a file in .ini format.
        :param exports: A dictionary of exports, mapping an export category to
                        a list of :class:`ExportEntry` instances describing the
                        individual export entries.
        """
        rf = self.get_distinfo_file(EXPORTS_FILENAME)
        with open(rf, 'w') as f:
            write_exports(exports, f)

    def get_resource_path(self, relative_path):
        """
        NOTE: This API may change in the future.

        Return the absolute path to a resource file with the given relative
        path.

        :param relative_path: The path, relative to .dist-info, of the resource
                              of interest.
        :return: The absolute path where the resource is to be found.
        """
        r = self.get_distinfo_resource('RESOURCES')
        with contextlib.closing(r.as_stream()) as stream:
            with CSVReader(stream=stream) as resources_reader:
                for relative, destination in resources_reader:
                    if relative == relative_path:
                        return destination
        raise KeyError('no resource file with relative path %r '
                       'is installed' % relative_path)

    def list_installed_files(self):
        """
        Iterates over the ``RECORD`` entries and returns a tuple
        ``(path, hash, size)`` for each line.

        :returns: iterator of (path, hash, size)
        """
        for result in self._get_records():
            yield result

    def write_installed_files(self, paths, prefix, dry_run=False):
        """
        Writes the ``RECORD`` file, using the ``paths`` iterable passed in. Any
        existing ``RECORD`` file is silently overwritten.

        prefix is used to determine when to write absolute paths.
        """
        prefix = os.path.join(prefix, '')
        base = os.path.dirname(self.path)
        base_under_prefix = base.startswith(prefix)
        base = os.path.join(base, '')
        record_path = self.get_distinfo_file('RECORD')
        logger.info('creating %s', record_path)
        if dry_run:
            return None
        with CSVWriter(record_path) as writer:
            for path in paths:
                if os.path.isdir(path) or path.endswith(('.pyc', '.pyo')):
                    # do not put size and hash, as in PEP-376
                    hash_value = size = ''
                else:
                    size = '%d' % os.path.getsize(path)
                    with open(path, 'rb') as fp:
                        hash_value = self.get_hash(fp.read())
                if path.startswith(base) or (base_under_prefix and path.startswith(prefix)):
                    path = os.path.relpath(path, base)
                writer.writerow((path, hash_value, size))

            # add the RECORD file itself
            if record_path.startswith(base):
                record_path = os.path.relpath(record_path, base)
            writer.writerow((record_path, '', ''))
        return record_path

    def check_installed_files(self):
        """
        Checks that the hashes and sizes of the files in ``RECORD`` are
        matched by the files themselves. Returns a (possibly empty) list of
        mismatches. Each entry in the mismatch list will be a tuple consisting
        of the path, 'exists', 'size' or 'hash' according to what didn't match
        (existence is checked first, then size, then hash), the expected
        value and the actual value.
        """
        mismatches = []
        base = os.path.dirname(self.path)
        record_path = self.get_distinfo_file('RECORD')
        for path, hash_value, size in self.list_installed_files():
            if not os.path.isabs(path):
                path = os.path.join(base, path)
            if path == record_path:
                continue
            if not os.path.exists(path):
                mismatches.append((path, 'exists', True, False))
            elif os.path.isfile(path):
                actual_size = str(os.path.getsize(path))
                if size and actual_size != size:
                    mismatches.append((path, 'size', size, actual_size))
                elif hash_value:
                    if '=' in hash_value:
                        hasher = hash_value.split('=', 1)[0]
                    else:
                        hasher = None

                    with open(path, 'rb') as f:
                        actual_hash = self.get_hash(f.read(), hasher)
                        if actual_hash != hash_value:
                            mismatches.append((path, 'hash', hash_value, actual_hash))
        return mismatches

    @cached_property
    def shared_locations(self):
        """
        A dictionary of shared locations whose keys are in the set 'prefix',
        'purelib', 'platlib', 'scripts', 'headers', 'data' and 'namespace'.
        The corresponding value is the absolute path of that category for
        this distribution, and takes into account any paths selected by the
        user at installation time (e.g. via command-line arguments). In the
        case of the 'namespace' key, this would be a list of absolute paths
        for the roots of namespace packages in this distribution.

        The first time this property is accessed, the relevant information is
        read from the SHARED file in the .dist-info directory.
        """
        result = {}
        shared_path = os.path.join(self.path, 'SHARED')
        if os.path.isfile(shared_path):
            with codecs.open(shared_path, 'r', encoding='utf-8') as f:
                lines = f.read().splitlines()
            for line in lines:
                key, value = line.split('=', 1)
                if key == 'namespace':
                    result.setdefault(key, []).append(value)
                else:
                    result[key] = value
        return result

    def write_shared_locations(self, paths, dry_run=False):
        """
        Write shared location information to the SHARED file in .dist-info.
        :param paths: A dictionary as described in the documentation for
        :meth:`shared_locations`.
        :param dry_run: If True, the action is logged but no file is actually
                        written.
        :return: The path of the file written to.
        """
        shared_path = os.path.join(self.path, 'SHARED')
        logger.info('creating %s', shared_path)
        if dry_run:
            return None
        lines = []
        for key in ('prefix', 'lib', 'headers', 'scripts', 'data'):
            path = paths[key]
            if os.path.isdir(paths[key]):
                lines.append('%s=%s' % (key, path))
        for ns in paths.get('namespace', ()):
            lines.append('namespace=%s' % ns)

        with codecs.open(shared_path, 'w', encoding='utf-8') as f:
            f.write('\n'.join(lines))
        return shared_path

    def get_distinfo_resource(self, path):
        if path not in DIST_FILES:
            raise DistlibException('invalid path for a dist-info file: '
                                   '%r at %r' % (path, self.path))
        finder = resources.finder_for_path(self.path)
        if finder is None:
            raise DistlibException('Unable to get a finder for %s' % self.path)
        return finder.find(path)

    def get_distinfo_file(self, path):
        """
        Returns a path located under the ``.dist-info`` directory. Returns a
        string representing the path.

        :parameter path: a ``'/'``-separated path relative to the
                         ``.dist-info`` directory or an absolute path;
                         If *path* is an absolute path and doesn't start
                         with the ``.dist-info`` directory path,
                         a :class:`DistlibException` is raised
        :type path: str
        :rtype: str
        """
        # Check if it is an absolute path  # XXX use relpath, add tests
        if path.find(os.sep) >= 0:
            # it's an absolute path?
            distinfo_dirname, path = path.split(os.sep)[-2:]
            if distinfo_dirname != self.path.split(os.sep)[-1]:
                raise DistlibException('dist-info file %r does not belong to the %r %s '
                                       'distribution' % (path, self.name, self.version))

        # The file must be relative
        if path not in DIST_FILES:
            raise DistlibException('invalid path for a dist-info file: '
                                   '%r at %r' % (path, self.path))

        return os.path.join(self.path, path)

    def list_distinfo_files(self):
        """
        Iterates over the ``RECORD`` entries and returns paths for each line if
        the path is pointing to a file located in the ``.dist-info`` directory
        or one of its subdirectories.

        :returns: iterator of paths
        """
        base = os.path.dirname(self.path)
        for path, checksum, size in self._get_records():
            # XXX add separator or use real relpath algo
            if not os.path.isabs(path):
                path = os.path.join(base, path)
            if path.startswith(self.path):
                yield path

    def __eq__(self, other):
        return (isinstance(other, InstalledDistribution) and self.path == other.path)

    # See http://docs.python.org/reference/datamodel#object.__hash__
    __hash__ = object.__hash__


class EggInfoDistribution(BaseInstalledDistribution):
    """Created with the *path* of the ``.egg-info`` directory or file provided
    to the constructor. It reads the metadata contained in the file itself, or
    if the given path happens to be a directory, the metadata is read from the
    file ``PKG-INFO`` under that directory."""

    requested = True  # as we have no way of knowing, assume it was
    shared_locations = {}

    def __init__(self, path, env=None):

        def set_name_and_version(s, n, v):
            s.name = n
            s.key = n.lower()  # for case-insensitive comparisons
            s.version = v

        self.path = path
        self.dist_path = env
        if env and env._cache_enabled and path in env._cache_egg.path:
            metadata = env._cache_egg.path[path].metadata
            set_name_and_version(self, metadata.name, metadata.version)
        else:
            metadata = self._get_metadata(path)

            # Need to be set before caching
            set_name_and_version(self, metadata.name, metadata.version)

            if env and env._cache_enabled:
                env._cache_egg.add(self)
        super(EggInfoDistribution, self).__init__(metadata, path, env)

    def _get_metadata(self, path):
        requires = None

        def parse_requires_data(data):
            """Create a list of dependencies from a requires.txt file.

            *data*: the contents of a setuptools-produced requires.txt file.
            """
            reqs = []
            lines = data.splitlines()
            for line in lines:
                line = line.strip()
                # sectioned files have bare newlines (separating sections)
                if not line:  # pragma: no cover
                    continue
                if line.startswith('['):  # pragma: no cover
                    logger.warning('Unexpected line: quitting requirement scan: %r', line)
                    break
                r = parse_requirement(line)
                if not r:  # pragma: no cover
                    logger.warning('Not recognised as a requirement: %r', line)
                    continue
                if r.extras:  # pragma: no cover
                    logger.warning('extra requirements in requires.txt are '
                                   'not supported')
                if not r.constraints:
                    reqs.append(r.name)
                else:
                    cons = ', '.join('%s%s' % c for c in r.constraints)
                    reqs.append('%s (%s)' % (r.name, cons))
            return reqs

        def parse_requires_path(req_path):
            """Create a list of dependencies from a requires.txt file.

            *req_path*: the path to a setuptools-produced requires.txt file.
            """

            reqs = []
            try:
                with codecs.open(req_path, 'r', 'utf-8') as fp:
                    reqs = parse_requires_data(fp.read())
            except IOError:
                pass
            return reqs

        tl_path = tl_data = None
        if path.endswith('.egg'):
            if os.path.isdir(path):
                p = os.path.join(path, 'EGG-INFO')
                meta_path = os.path.join(p, 'PKG-INFO')
                metadata = Metadata(path=meta_path, scheme='legacy')
                req_path = os.path.join(p, 'requires.txt')
                tl_path = os.path.join(p, 'top_level.txt')
                requires = parse_requires_path(req_path)
            else:
                # FIXME handle the case where zipfile is not available
                zipf = zipimport.zipimporter(path)
                fileobj = StringIO(zipf.get_data('EGG-INFO/PKG-INFO').decode('utf8'))
                metadata = Metadata(fileobj=fileobj, scheme='legacy')
                try:
                    data = zipf.get_data('EGG-INFO/requires.txt')
                    tl_data = zipf.get_data('EGG-INFO/top_level.txt').decode('utf-8')
                    requires = parse_requires_data(data.decode('utf-8'))
                except IOError:
                    requires = None
        elif path.endswith('.egg-info'):
            if os.path.isdir(path):
                req_path = os.path.join(path, 'requires.txt')
                requires = parse_requires_path(req_path)
                path = os.path.join(path, 'PKG-INFO')
                tl_path = os.path.join(path, 'top_level.txt')
            metadata = Metadata(path=path, scheme='legacy')
        else:
            raise DistlibException('path must end with .egg-info or .egg, '
                                   'got %r' % path)

        if requires:
            metadata.add_requirements(requires)
        # look for top-level modules in top_level.txt, if present
        if tl_data is None:
            if tl_path is not None and os.path.exists(tl_path):
                with open(tl_path, 'rb') as f:
                    tl_data = f.read().decode('utf-8')
        if not tl_data:
            tl_data = []
        else:
            tl_data = tl_data.splitlines()
        self.modules = tl_data
        return metadata

    def __repr__(self):
        return '<EggInfoDistribution %r %s at %r>' % (self.name, self.version, self.path)

    def __str__(self):
        return "%s %s" % (self.name, self.version)

    def check_installed_files(self):
        """
        Checks that the hashes and sizes of the files in ``RECORD`` are
        matched by the files themselves. Returns a (possibly empty) list of
        mismatches. Each entry in the mismatch list will be a tuple consisting
        of the path, 'exists', 'size' or 'hash' according to what didn't match
        (existence is checked first, then size, then hash), the expected
        value and the actual value.
        """
        mismatches = []
        record_path = os.path.join(self.path, 'installed-files.txt')
        if os.path.exists(record_path):
            for path, _, _ in self.list_installed_files():
                if path == record_path:
                    continue
                if not os.path.exists(path):
                    mismatches.append((path, 'exists', True, False))
        return mismatches

    def list_installed_files(self):
        """
        Iterates over the ``installed-files.txt`` entries and returns a tuple
        ``(path, hash, size)`` for each line.

        :returns: a list of (path, hash, size)
        """

        def _md5(path):
            f = open(path, 'rb')
            try:
                content = f.read()
            finally:
                f.close()
            return hashlib.md5(content).hexdigest()

        def _size(path):
            return os.stat(path).st_size

        record_path = os.path.join(self.path, 'installed-files.txt')
        result = []
        if os.path.exists(record_path):
            with codecs.open(record_path, 'r', encoding='utf-8') as f:
                for line in f:
                    line = line.strip()
                    p = os.path.normpath(os.path.join(self.path, line))
                    # "./" is present as a marker between installed files
                    # and installation metadata files
                    if not os.path.exists(p):
                        logger.warning('Non-existent file: %s', p)
                        if p.endswith(('.pyc', '.pyo')):
                            continue
                        # otherwise fall through and fail
                    if not os.path.isdir(p):
                        result.append((p, _md5(p), _size(p)))
            result.append((record_path, None, None))
        return result

    def list_distinfo_files(self, absolute=False):
        """
        Iterates over the ``installed-files.txt`` entries and returns paths for
        each line if the path is pointing to a file located in the
        ``.egg-info`` directory or one of its subdirectories.

        :parameter absolute: If *absolute* is ``True``, each returned path is
                          transformed into a local absolute path. Otherwise the
                          raw value from ``installed-files.txt`` is returned.
        :type absolute: boolean
        :returns: iterator of paths
        """
        record_path = os.path.join(self.path, 'installed-files.txt')
        if os.path.exists(record_path):
            skip = True
            with codecs.open(record_path, 'r', encoding='utf-8') as f:
                for line in f:
                    line = line.strip()
                    if line == './':
                        skip = False
                        continue
                    if not skip:
                        p = os.path.normpath(os.path.join(self.path, line))
                        if p.startswith(self.path):
                            if absolute:
                                yield p
                            else:
                                yield line

    def __eq__(self, other):
        return (isinstance(other, EggInfoDistribution) and self.path == other.path)

    # See http://docs.python.org/reference/datamodel#object.__hash__
    __hash__ = object.__hash__


new_dist_class = InstalledDistribution
old_dist_class = EggInfoDistribution


class DependencyGraph(object):
    """
    Represents a dependency graph between distributions.

    The dependency relationships are stored in an ``adjacency_list`` that maps
    distributions to a list of ``(other, label)`` tuples where  ``other``
    is a distribution and the edge is labeled with ``label`` (i.e. the version
    specifier, if such was provided). Also, for more efficient traversal, for
    every distribution ``x``, a list of predecessors is kept in
    ``reverse_list[x]``. An edge from distribution ``a`` to
    distribution ``b`` means that ``a`` depends on ``b``. If any missing
    dependencies are found, they are stored in ``missing``, which is a
    dictionary that maps distributions to a list of requirements that were not
    provided by any other distributions.
    """

    def __init__(self):
        self.adjacency_list = {}
        self.reverse_list = {}
        self.missing = {}

    def add_distribution(self, distribution):
        """Add the *distribution* to the graph.

        :type distribution: :class:`distutils2.database.InstalledDistribution`
                            or :class:`distutils2.database.EggInfoDistribution`
        """
        self.adjacency_list[distribution] = []
        self.reverse_list[distribution] = []
        # self.missing[distribution] = []

    def add_edge(self, x, y, label=None):
        """Add an edge from distribution *x* to distribution *y* with the given
        *label*.

        :type x: :class:`distutils2.database.InstalledDistribution` or
                 :class:`distutils2.database.EggInfoDistribution`
        :type y: :class:`distutils2.database.InstalledDistribution` or
                 :class:`distutils2.database.EggInfoDistribution`
        :type label: ``str`` or ``None``
        """
        self.adjacency_list[x].append((y, label))
        # multiple edges are allowed, so be careful
        if x not in self.reverse_list[y]:
            self.reverse_list[y].append(x)

    def add_missing(self, distribution, requirement):
        """
        Add a missing *requirement* for the given *distribution*.

        :type distribution: :class:`distutils2.database.InstalledDistribution`
                            or :class:`distutils2.database.EggInfoDistribution`
        :type requirement: ``str``
        """
        logger.debug('%s missing %r', distribution, requirement)
        self.missing.setdefault(distribution, []).append(requirement)

    def _repr_dist(self, dist):
        return '%s %s' % (dist.name, dist.version)

    def repr_node(self, dist, level=1):
        """Prints only a subgraph"""
        output = [self._repr_dist(dist)]
        for other, label in self.adjacency_list[dist]:
            dist = self._repr_dist(other)
            if label is not None:
                dist = '%s [%s]' % (dist, label)
            output.append('    ' * level + str(dist))
            suboutput = self.repr_node(other, level + 1)
            subs = suboutput.split('\n')
            output.extend(subs[1:])
        return '\n'.join(output)

    def to_dot(self, f, skip_disconnected=True):
        """Writes a DOT output for the graph to the provided file *f*.

        If *skip_disconnected* is set to ``True``, then all distributions
        that are not dependent on any other distribution are skipped.

        :type f: has to support ``file``-like operations
        :type skip_disconnected: ``bool``
        """
        disconnected = []

        f.write("digraph dependencies {\n")
        for dist, adjs in self.adjacency_list.items():
            if len(adjs) == 0 and not skip_disconnected:
                disconnected.append(dist)
            for other, label in adjs:
                if label is not None:
                    f.write('"%s" -> "%s" [label="%s"]\n' % (dist.name, other.name, label))
                else:
                    f.write('"%s" -> "%s"\n' % (dist.name, other.name))
        if not skip_disconnected and len(disconnected) > 0:
            f.write('subgraph disconnected {\n')
            f.write('label = "Disconnected"\n')
            f.write('bgcolor = red\n')

            for dist in disconnected:
                f.write('"%s"' % dist.name)
                f.write('\n')
            f.write('}\n')
        f.write('}\n')

    def topological_sort(self):
        """
        Perform a topological sort of the graph.
        :return: A tuple, the first element of which is a topologically sorted
                 list of distributions, and the second element of which is a
                 list of distributions that cannot be sorted because they have
                 circular dependencies and so form a cycle.
        """
        result = []
        # Make a shallow copy of the adjacency list
        alist = {}
        for k, v in self.adjacency_list.items():
            alist[k] = v[:]
        while True:
            # See what we can remove in this run
            to_remove = []
            for k, v in list(alist.items())[:]:
                if not v:
                    to_remove.append(k)
                    del alist[k]
            if not to_remove:
                # What's left in alist (if anything) is a cycle.
                break
            # Remove from the adjacency list of others
            for k, v in alist.items():
                alist[k] = [(d, r) for d, r in v if d not in to_remove]
            logger.debug('Moving to result: %s', ['%s (%s)' % (d.name, d.version) for d in to_remove])
            result.extend(to_remove)
        return result, list(alist.keys())

    def __repr__(self):
        """Representation of the graph"""
        output = []
        for dist, adjs in self.adjacency_list.items():
            output.append(self.repr_node(dist))
        return '\n'.join(output)


def make_graph(dists, scheme='default'):
    """Makes a dependency graph from the given distributions.

    :parameter dists: a list of distributions
    :type dists: list of :class:`distutils2.database.InstalledDistribution` and
                 :class:`distutils2.database.EggInfoDistribution` instances
    :rtype: a :class:`DependencyGraph` instance
    """
    scheme = get_scheme(scheme)
    graph = DependencyGraph()
    provided = {}  # maps names to lists of (version, dist) tuples

    # first, build the graph and find out what's provided
    for dist in dists:
        graph.add_distribution(dist)

        for p in dist.provides:
            name, version = parse_name_and_version(p)
            logger.debug('Add to provided: %s, %s, %s', name, version, dist)
            provided.setdefault(name, []).append((version, dist))

    # now make the edges
    for dist in dists:
        requires = (dist.run_requires | dist.meta_requires | dist.build_requires | dist.dev_requires)
        for req in requires:
            try:
                matcher = scheme.matcher(req)
            except UnsupportedVersionError:
                # XXX compat-mode if cannot read the version
                logger.warning('could not read version %r - using name only', req)
                name = req.split()[0]
                matcher = scheme.matcher(name)

            name = matcher.key  # case-insensitive

            matched = False
            if name in provided:
                for version, provider in provided[name]:
                    try:
                        match = matcher.match(version)
                    except UnsupportedVersionError:
                        match = False

                    if match:
                        graph.add_edge(dist, provider, req)
                        matched = True
                        break
            if not matched:
                graph.add_missing(dist, req)
    return graph


def get_dependent_dists(dists, dist):
    """Recursively generate a list of distributions from *dists* that are
    dependent on *dist*.

    :param dists: a list of distributions
    :param dist: a distribution, member of *dists* for which we are interested
    """
    if dist not in dists:
        raise DistlibException('given distribution %r is not a member '
                               'of the list' % dist.name)
    graph = make_graph(dists)

    dep = [dist]  # dependent distributions
    todo = graph.reverse_list[dist]  # list of nodes we should inspect

    while todo:
        d = todo.pop()
        dep.append(d)
        for succ in graph.reverse_list[d]:
            if succ not in dep:
                todo.append(succ)

    dep.pop(0)  # remove dist from dep, was there to prevent infinite loops
    return dep


def get_required_dists(dists, dist):
    """Recursively generate a list of distributions from *dists* that are
    required by *dist*.

    :param dists: a list of distributions
    :param dist: a distribution, member of *dists* for which we are interested
                 in finding the dependencies.
    """
    if dist not in dists:
        raise DistlibException('given distribution %r is not a member '
                               'of the list' % dist.name)
    graph = make_graph(dists)

    req = set()  # required distributions
    todo = graph.adjacency_list[dist]  # list of nodes we should inspect
    seen = set(t[0] for t in todo)  # already added to todo

    while todo:
        d = todo.pop()[0]
        req.add(d)
        pred_list = graph.adjacency_list[d]
        for pred in pred_list:
            d = pred[0]
            if d not in req and d not in seen:
                seen.add(d)
                todo.append(pred)
    return req


def make_dist(name, version, **kwargs):
    """
    A convenience method for making a dist given just a name and version.
    """
    summary = kwargs.pop('summary', 'Placeholder for summary')
    md = Metadata(**kwargs)
    md.name = name
    md.version = version
    md.summary = summary or 'Placeholder for summary'
    return Distribution(md)

import contextlib
import functools
import os
import sys
from typing import TYPE_CHECKING, List, Optional, Type, cast

from pip._internal.utils.misc import strtobool

from .base import BaseDistribution, BaseEnvironment, FilesystemWheel, MemoryWheel, Wheel

if TYPE_CHECKING:
    from typing import Literal, Protocol
else:
    Protocol = object

__all__ = [
    "BaseDistribution",
    "BaseEnvironment",
    "FilesystemWheel",
    "MemoryWheel",
    "Wheel",
    "get_default_environment",
    "get_environment",
    "get_wheel_distribution",
    "select_backend",
]


def _should_use_importlib_metadata() -> bool:
    """Whether to use the ``importlib.metadata`` or ``pkg_resources`` backend.

    By default, pip uses ``importlib.metadata`` on Python 3.11+, and
    ``pkg_resourcess`` otherwise. This can be overridden by a couple of ways:

    * If environment variable ``_PIP_USE_IMPORTLIB_METADATA`` is set, it
      dictates whether ``importlib.metadata`` is used, regardless of Python
      version.
    * On Python 3.11+, Python distributors can patch ``importlib.metadata``
      to add a global constant ``_PIP_USE_IMPORTLIB_METADATA = False``. This
      makes pip use ``pkg_resources`` (unless the user set the aforementioned
      environment variable to *True*).
    """
    with contextlib.suppress(KeyError, ValueError):
        return bool(strtobool(os.environ["_PIP_USE_IMPORTLIB_METADATA"]))
    if sys.version_info < (3, 11):
        return False
    import importlib.metadata

    return bool(getattr(importlib.metadata, "_PIP_USE_IMPORTLIB_METADATA", True))


class Backend(Protocol):
    NAME: 'Literal["importlib", "pkg_resources"]'
    Distribution: Type[BaseDistribution]
    Environment: Type[BaseEnvironment]


@functools.lru_cache(maxsize=None)
def select_backend() -> Backend:
    if _should_use_importlib_metadata():
        from . import importlib

        return cast(Backend, importlib)
    from . import pkg_resources

    return cast(Backend, pkg_resources)


def get_default_environment() -> BaseEnvironment:
    """Get the default representation for the current environment.

    This returns an Environment instance from the chosen backend. The default
    Environment instance should be built from ``sys.path`` and may use caching
    to share instance state accorss calls.
    """
    return select_backend().Environment.default()


def get_environment(paths: Optional[List[str]]) -> BaseEnvironment:
    """Get a representation of the environment specified by ``paths``.

    This returns an Environment instance from the chosen backend based on the
    given import paths. The backend must build a fresh instance representing
    the state of installed distributions when this function is called.
    """
    return select_backend().Environment.from_paths(paths)


def get_directory_distribution(directory: str) -> BaseDistribution:
    """Get the distribution metadata representation in the specified directory.

    This returns a Distribution instance from the chosen backend based on
    the given on-disk ``.dist-info`` directory.
    """
    return select_backend().Distribution.from_directory(directory)


def get_wheel_distribution(wheel: Wheel, canonical_name: str) -> BaseDistribution:
    """Get the representation of the specified wheel's distribution metadata.

    This returns a Distribution instance from the chosen backend based on
    the given wheel's ``.dist-info`` directory.

    :param canonical_name: Normalized project name of the given wheel.
    """
    return select_backend().Distribution.from_wheel(wheel, canonical_name)


def get_metadata_distribution(
    metadata_contents: bytes,
    filename: str,
    canonical_name: str,
) -> BaseDistribution:
    """Get the dist representation of the specified METADATA file contents.

    This returns a Distribution instance from the chosen backend sourced from the data
    in `metadata_contents`.

    :param metadata_contents: Contents of a METADATA file within a dist, or one served
                              via PEP 658.
    :param filename: Filename for the dist this metadata represents.
    :param canonical_name: Normalized project name of the given dist.
    """
    return select_backend().Distribution.from_metadata_file_contents(
        metadata_contents,
        filename,
        canonical_name,
    )

from pip._internal.distributions.base import AbstractDistribution
from pip._internal.distributions.sdist import SourceDistribution
from pip._internal.distributions.wheel import WheelDistribution
from pip._internal.req.req_install import InstallRequirement


def make_distribution_for_install_requirement(
    install_req: InstallRequirement,
) -> AbstractDistribution:
    """Returns a Distribution for the given InstallRequirement"""
    # Editable requirements will always be source distributions. They use the
    # legacy logic until we create a modern standard for them.
    if install_req.editable:
        return SourceDistribution(install_req)

    # If it's a wheel, it's a WheelDistribution
    if install_req.is_wheel:
        return WheelDistribution(install_req)

    # Otherwise, a SourceDistribution
    return SourceDistribution(install_req)

"""
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."""