"""
Support for installing and building the "wheel" binary package format.
"""
from __future__ import with_statement

import compileall
import csv
import functools
import hashlib
import os
import re
import shutil
import sys

from base64 import urlsafe_b64encode
from email.parser import Parser

from pip.compat import ConfigParser, StringIO, binary
from pip.exceptions import InvalidWheelFilename, UnsupportedWheel
from pip.locations import distutils_scheme
from pip.log import logger
from pip import pep425tags
from pip.util import call_subprocess, normalize_path, make_path_relative
from pip._vendor.distlib.scripts import ScriptMaker
from pip._vendor import pkg_resources


wheel_ext = '.whl'

VERSION_COMPATIBLE = (1, 0)


def rehash(path, algo='sha256', blocksize=1 << 20):
    """Return (hash, length) for path using hashlib.new(algo)"""
    h = hashlib.new(algo)
    length = 0
    with open(path, 'rb') as f:
        block = f.read(blocksize)
        while block:
            length += len(block)
            h.update(block)
            block = f.read(blocksize)
    digest = 'sha256=' + urlsafe_b64encode(
        h.digest()
    ).decode('latin1').rstrip('=')
    return (digest, length)


def open_for_csv(name, mode):
    if sys.version_info[0] < 3:
        nl = {}
        bin = 'b'
    else:
        nl = {'newline': ''}
        bin = ''
    return open(name, mode + bin, **nl)


def fix_script(path):
    """Replace #!python with #!/path/to/python
    Return True if file was changed."""
    # XXX RECORD hashes will need to be updated
    if os.path.isfile(path):
        script = open(path, 'rb')
        try:
            firstline = script.readline()
            if not firstline.startswith(binary('#!python')):
                return False
            exename = sys.executable.encode(sys.getfilesystemencoding())
            firstline = binary('#!') + exename + binary(os.linesep)
            rest = script.read()
        finally:
            script.close()
        script = open(path, 'wb')
        try:
            script.write(firstline)
            script.write(rest)
        finally:
            script.close()
        return True

dist_info_re = re.compile(r"""^(?P<namever>(?P<name>.+?)(-(?P<ver>\d.+?))?)
                                \.dist-info$""", re.VERBOSE)


def root_is_purelib(name, wheeldir):
    """
    Return True if the extracted wheel in wheeldir should go into purelib.
    """
    name_folded = name.replace("-", "_")
    for item in os.listdir(wheeldir):
        match = dist_info_re.match(item)
        if match and match.group('name') == name_folded:
            with open(os.path.join(wheeldir, item, 'WHEEL')) as wheel:
                for line in wheel:
                    line = line.lower().rstrip()
                    if line == "root-is-purelib: true":
                        return True
    return False


def get_entrypoints(filename):
    if not os.path.exists(filename):
        return {}, {}

    # This is done because you can pass a string to entry_points wrappers which
    # means that they may or may not be valid INI files. The attempt here is to
    # strip leading and trailing whitespace in order to make them valid INI
    # files.
    with open(filename) as fp:
        data = StringIO()
        for line in fp:
            data.write(line.strip())
            data.write("\n")
        data.seek(0)

    cp = ConfigParser.RawConfigParser()
    cp.readfp(data)

    console = {}
    gui = {}
    if cp.has_section('console_scripts'):
        console = dict(cp.items('console_scripts'))
    if cp.has_section('gui_scripts'):
        gui = dict(cp.items('gui_scripts'))
    return console, gui


def move_wheel_files(name, req, wheeldir, user=False, home=None, root=None,
                     pycompile=True, scheme=None):
    """Install a wheel"""

    if not scheme:
        scheme = distutils_scheme(name, user=user, home=home, root=root)

    if root_is_purelib(name, wheeldir):
        lib_dir = scheme['purelib']
    else:
        lib_dir = scheme['platlib']

    info_dir = []
    data_dirs = []
    source = wheeldir.rstrip(os.path.sep) + os.path.sep

    # Record details of the files moved
    #   installed = files copied from the wheel to the destination
    #   changed = files changed while installing (scripts #! line typically)
    #   generated = files newly generated during the install (script wrappers)
    installed = {}
    changed = set()
    generated = []

    # Compile all of the pyc files that we're going to be installing
    if pycompile:
        compileall.compile_dir(source, force=True, quiet=True)

    def normpath(src, p):
        return make_path_relative(src, p).replace(os.path.sep, '/')

    def record_installed(srcfile, destfile, modified=False):
        """Map archive RECORD paths to installation RECORD paths."""
        oldpath = normpath(srcfile, wheeldir)
        newpath = normpath(destfile, lib_dir)
        installed[oldpath] = newpath
        if modified:
            changed.add(destfile)

    def clobber(source, dest, is_base, fixer=None, filter=None):
        if not os.path.exists(dest):  # common for the 'include' path
            os.makedirs(dest)

        for dir, subdirs, files in os.walk(source):
            basedir = dir[len(source):].lstrip(os.path.sep)
            destdir = os.path.join(dest, basedir)
            if is_base and basedir.split(os.path.sep, 1)[0].endswith('.data'):
                continue
            for s in subdirs:
                destsubdir = os.path.join(dest, basedir, s)
                if is_base and basedir == '' and destsubdir.endswith('.data'):
                    data_dirs.append(s)
                    continue
                elif (is_base
                        and s.endswith('.dist-info')
                        # is self.req.project_name case preserving?
                        and s.lower().startswith(
                            req.project_name.replace('-', '_').lower())):
                    assert not info_dir, 'Multiple .dist-info directories'
                    info_dir.append(destsubdir)
            for f in files:
                # Skip unwanted files
                if filter and filter(f):
                    continue
                srcfile = os.path.join(dir, f)
                destfile = os.path.join(dest, basedir, f)
                # directory creation is lazy and after the file filtering above
                # to ensure we don't install empty dirs; empty dirs can't be
                # uninstalled.
                if not os.path.exists(destdir):
                    os.makedirs(destdir)
                # use copy2 (not move) to be extra sure we're not moving
                # directories over; copy2 fails for directories.  this would
                # fail tests (not during released/user execution)
                shutil.copy2(srcfile, destfile)
                changed = False
                if fixer:
                    changed = fixer(destfile)
                record_installed(srcfile, destfile, changed)

    clobber(source, lib_dir, True)

    assert info_dir, "%s .dist-info directory not found" % req

    # Get the defined entry points
    ep_file = os.path.join(info_dir[0], 'entry_points.txt')
    console, gui = get_entrypoints(ep_file)

    def is_entrypoint_wrapper(name):
        # EP, EP.exe and EP-script.py are scripts generated for
        # entry point EP by setuptools
        if name.lower().endswith('.exe'):
            matchname = name[:-4]
        elif name.lower().endswith('-script.py'):
            matchname = name[:-10]
        elif name.lower().endswith(".pya"):
            matchname = name[:-4]
        else:
            matchname = name
        # Ignore setuptools-generated scripts
        return (matchname in console or matchname in gui)

    for datadir in data_dirs:
        fixer = None
        filter = None
        for subdir in os.listdir(os.path.join(wheeldir, datadir)):
            fixer = None
            if subdir == 'scripts':
                fixer = fix_script
                filter = is_entrypoint_wrapper
            source = os.path.join(wheeldir, datadir, subdir)
            dest = scheme[subdir]
            clobber(source, dest, False, fixer=fixer, filter=filter)

    maker = ScriptMaker(None, scheme['scripts'])

    # Ensure we don't generate any variants for scripts because this is almost
    # never what somebody wants.
    # See https://bitbucket.org/pypa/distlib/issue/35/
    maker.variants = set(('', ))

    # This is required because otherwise distlib creates scripts that are not
    # executable.
    # See https://bitbucket.org/pypa/distlib/issue/32/
    maker.set_mode = True

    # Simplify the script and fix the fact that the default script swallows
    # every single stack trace.
    # See https://bitbucket.org/pypa/distlib/issue/34/
    # See https://bitbucket.org/pypa/distlib/issue/33/
    def _get_script_text(entry):
        return maker.script_template % {
            "module": entry.prefix,
            "import_name": entry.suffix.split(".")[0],
            "func": entry.suffix,
        }

    maker._get_script_text = _get_script_text
    maker.script_template = """# -*- coding: utf-8 -*-
import re
import sys

from %(module)s import %(import_name)s

if __name__ == '__main__':
    sys.argv[0] = re.sub(r'(-script\.pyw|\.exe)?$', '', sys.argv[0])
    sys.exit(%(func)s())
"""

    # Special case pip and setuptools to generate versioned wrappers
    #
    # The issue is that some projects (specifically, pip and setuptools) use
    # code in setup.py to create "versioned" entry points - pip2.7 on Python
    # 2.7, pip3.3 on Python 3.3, etc. But these entry points are baked into
    # the wheel metadata at build time, and so if the wheel is installed with
    # a *different* version of Python the entry points will be wrong. The
    # correct fix for this is to enhance the metadata to be able to describe
    # such versioned entry points, but that won't happen till Metadata 2.0 is
    # available.
    # In the meantime, projects using versioned entry points will either have
    # incorrect versioned entry points, or they will not be able to distribute
    # "universal" wheels (i.e., they will need a wheel per Python version).
    #
    # Because setuptools and pip are bundled with _ensurepip and virtualenv,
    # we need to use universal wheels. So, as a stopgap until Metadata 2.0, we
    # override the versioned entry points in the wheel and generate the
    # correct ones. This code is purely a short-term measure until Metadat 2.0
    # is available.
    #
    # To add the level of hack in this section of code, in order to support
    # ensurepip this code will look for an ``ENSUREPIP_OPTIONS`` environment
    # variable which will control which version scripts get installed.
    #
    # ENSUREPIP_OPTIONS=altinstall
    #   - Only pipX.Y and easy_install-X.Y will be generated and installed
    # ENSUREPIP_OPTIONS=install
    #   - pipX.Y, pipX, easy_install-X.Y will be generated and installed. Note
    #     that this option is technically if ENSUREPIP_OPTIONS is set and is
    #     not altinstall
    # DEFAULT
    #   - The default behavior is to install pip, pipX, pipX.Y, easy_install
    #     and easy_install-X.Y.
    pip_script = console.pop('pip', None)
    if pip_script:
        if "ENSUREPIP_OPTIONS" not in os.environ:
            spec = 'pip = ' + pip_script
            generated.extend(maker.make(spec))

        if os.environ.get("ENSUREPIP_OPTIONS", "") != "altinstall":
            spec = 'pip%s = %s' % (sys.version[:1], pip_script)
            generated.extend(maker.make(spec))

        spec = 'pip%s = %s' % (sys.version[:3], pip_script)
        generated.extend(maker.make(spec))
        # Delete any other versioned pip entry points
        pip_ep = [k for k in console if re.match(r'pip(\d(\.\d)?)?$', k)]
        for k in pip_ep:
            del console[k]
    easy_install_script = console.pop('easy_install', None)
    if easy_install_script:
        if "ENSUREPIP_OPTIONS" not in os.environ:
            spec = 'easy_install = ' + easy_install_script
            generated.extend(maker.make(spec))

        spec = 'easy_install-%s = %s' % (sys.version[:3], easy_install_script)
        generated.extend(maker.make(spec))
        # Delete any other versioned easy_install entry points
        easy_install_ep = [
            k for k in console if re.match(r'easy_install(-\d\.\d)?$', k)
        ]
        for k in easy_install_ep:
            del console[k]

    # Generate the console and GUI entry points specified in the wheel
    if len(console) > 0:
        generated.extend(
            maker.make_multiple(['%s = %s' % kv for kv in console.items()])
        )
    if len(gui) > 0:
        generated.extend(
            maker.make_multiple(
                ['%s = %s' % kv for kv in gui.items()],
                {'gui': True}
            )
        )

    record = os.path.join(info_dir[0], 'RECORD')
    temp_record = os.path.join(info_dir[0], 'RECORD.pip')
    with open_for_csv(record, 'r') as record_in:
        with open_for_csv(temp_record, 'w+') as record_out:
            reader = csv.reader(record_in)
            writer = csv.writer(record_out)
            for row in reader:
                row[0] = installed.pop(row[0], row[0])
                if row[0] in changed:
                    row[1], row[2] = rehash(row[0])
                writer.writerow(row)
            for f in generated:
                h, l = rehash(f)
                writer.writerow((f, h, l))
            for f in installed:
                writer.writerow((installed[f], '', ''))
    shutil.move(temp_record, record)


def _unique(fn):
    @functools.wraps(fn)
    def unique(*args, **kw):
        seen = set()
        for item in fn(*args, **kw):
            if item not in seen:
                seen.add(item)
                yield item
    return unique


# TODO: this goes somewhere besides the wheel module
@_unique
def uninstallation_paths(dist):
    """
    Yield all the uninstallation paths for dist based on RECORD-without-.pyc

    Yield paths to all the files in RECORD. For each .py file in RECORD, add
    the .pyc in the same directory.

    UninstallPathSet.add() takes care of the __pycache__ .pyc.
    """
    from pip.util import FakeFile  # circular import
    r = csv.reader(FakeFile(dist.get_metadata_lines('RECORD')))
    for row in r:
        path = os.path.join(dist.location, row[0])
        yield path
        if path.endswith('.py'):
            dn, fn = os.path.split(path)
            base = fn[:-3]
            path = os.path.join(dn, base + '.pyc')
            yield path


def wheel_version(source_dir):
    """
    Return the Wheel-Version of an extracted wheel, if possible.

    Otherwise, return False if we couldn't parse / extract it.
    """
    try:
        dist = [d for d in pkg_resources.find_on_path(None, source_dir)][0]

        wheel_data = dist.get_metadata('WHEEL')
        wheel_data = Parser().parsestr(wheel_data)

        version = wheel_data['Wheel-Version'].strip()
        version = tuple(map(int, version.split('.')))
        return version
    except:
        return False


def check_compatibility(version, name):
    """
    Raises errors or warns if called with an incompatible Wheel-Version.

    Pip should refuse to install a Wheel-Version that's a major series
    ahead of what it's compatible with (e.g 2.0 > 1.1); and warn when
    installing a version only minor version ahead (e.g 1.2 > 1.1).

    version: a 2-tuple representing a Wheel-Version (Major, Minor)
    name: name of wheel or package to raise exception about

    :raises UnsupportedWheel: when an incompatible Wheel-Version is given
    """
    if not version:
        raise UnsupportedWheel(
            "%s is in an unsupported or invalid wheel" % name
        )
    if version[0] > VERSION_COMPATIBLE[0]:
        raise UnsupportedWheel(
            "%s's Wheel-Version (%s) is not compatible with this version "
            "of pip" % (name, '.'.join(map(str, version)))
        )
    elif version > VERSION_COMPATIBLE:
        logger.warn('Installing from a newer Wheel-Version (%s)'
                    % '.'.join(map(str, version)))


class Wheel(object):
    """A wheel file"""

    # TODO: maybe move the install code into this class

    wheel_file_re = re.compile(
        r"""^(?P<namever>(?P<name>.+?)-(?P<ver>\d.*?))
        ((-(?P<build>\d.*?))?-(?P<pyver>.+?)-(?P<abi>.+?)-(?P<plat>.+?)
        \.whl|\.dist-info)$""",
        re.VERBOSE
    )

    def __init__(self, filename):
        """
        :raises InvalidWheelFilename: when the filename is invalid for a wheel
        """
        wheel_info = self.wheel_file_re.match(filename)
        if not wheel_info:
            raise InvalidWheelFilename(
                "%s is not a valid wheel filename." % filename
            )
        self.filename = filename
        self.name = wheel_info.group('name').replace('_', '-')
        # we'll assume "_" means "-" due to wheel naming scheme
        # (https://github.com/pypa/pip/issues/1150)
        self.version = wheel_info.group('ver').replace('_', '-')
        self.pyversions = wheel_info.group('pyver').split('.')
        self.abis = wheel_info.group('abi').split('.')
        self.plats = wheel_info.group('plat').split('.')

        # All the tag combinations from this file
        self.file_tags = set(
            (x, y, z) for x in self.pyversions
            for y in self.abis for z in self.plats
        )

    def support_index_min(self, tags=None):
        """
        Return the lowest index that one of the wheel's file_tag combinations
        achieves in the supported_tags list e.g. if there are 8 supported tags,
        and one of the file tags is first in the list, then return 0.  Returns
        None is the wheel is not supported.
        """
        if tags is None:  # for mock
            tags = pep425tags.supported_tags
        indexes = [tags.index(c) for c in self.file_tags if c in tags]
        return min(indexes) if indexes else None

    def supported(self, tags=None):
        """Is this wheel supported on this system?"""
        if tags is None:  # for mock
            tags = pep425tags.supported_tags
        return bool(set(tags).intersection(self.file_tags))


class WheelBuilder(object):
    """Build wheels from a RequirementSet."""

    def __init__(self, requirement_set, finder, wheel_dir, build_options=[],
                 global_options=[]):
        self.requirement_set = requirement_set
        self.finder = finder
        self.wheel_dir = normalize_path(wheel_dir)
        self.build_options = build_options
        self.global_options = global_options

    def _build_one(self, req):
        """Build one wheel."""

        base_args = [
            sys.executable, '-c',
            "import setuptools;__file__=%r;"
            "exec(compile(open(__file__).read().replace('\\r\\n', '\\n'), "
            "__file__, 'exec'))" % req.setup_py
        ] + list(self.global_options)

        logger.notify('Running setup.py bdist_wheel for %s' % req.name)
        logger.notify('Destination directory: %s' % self.wheel_dir)
        wheel_args = base_args + ['bdist_wheel', '-d', self.wheel_dir] \
            + self.build_options
        try:
            call_subprocess(wheel_args, cwd=req.source_dir, show_stdout=False)
            return True
        except:
            logger.error('Failed building wheel for %s' % req.name)
            return False

    def build(self):
        """Build wheels."""

        # unpack and constructs req set
        self.requirement_set.prepare_files(self.finder)

        reqset = self.requirement_set.requirements.values()

        buildset = []
        for req in reqset:
            if req.is_wheel:
                logger.notify(
                    'Skipping %s, due to already being wheel.' % req.name)
            elif req.editable:
                logger.notify(
                    'Skipping %s, due to being editable' % req.name)
            else:
                buildset.append(req)

        if not buildset:
            return True

        # Build the wheels.
        logger.notify(
            'Building wheels for collected packages: %s' %
            ', '.join([req.name for req in buildset])
        )
        logger.indent += 2
        build_success, build_failure = [], []
        for req in buildset:
            if self._build_one(req):
                build_success.append(req)
            else:
                build_failure.append(req)
        logger.indent -= 2

        # notify success/failure
        if build_success:
            logger.notify(
                'Successfully built %s' %
                ' '.join([req.name for req in build_success])
            )
        if build_failure:
            logger.notify(
                'Failed to build %s' %
                ' '.join([req.name for req in build_failure])
            )
        # Return True if all builds were successful
        return len(build_failure) == 0

pip/wheel.py
"""
Support for installing and building the "wheel" binary package format.
"""
from __future__ import with_statement

import compileall
import csv
import functools
import hashlib
import os
import re
import shutil
import sys

from base64 import urlsafe_b64encode
from email.parser import Parser

from pip.compat import ConfigParser, StringIO, binary
from pip.exceptions import InvalidWheelFilename, UnsupportedWheel
from pip.locations import distutils_scheme
from pip.log import logger
from pip import pep425tags
from pip.util import call_subprocess, normalize_path, make_path_relative
from pip._vendor.distlib.scripts import ScriptMaker
from pip._vendor import pkg_resources


wheel_ext = '.whl'

VERSION_COMPATIBLE = (1, 0)


def rehash(path, algo='sha256', blocksize=1 << 20):
    """Return (hash, length) for path using hashlib.new(algo)"""
    h = hashlib.new(algo)
    length = 0
    with open(path, 'rb') as f:
        block = f.read(blocksize)
        while block:
            length += len(block)
            h.update(block)
            block = f.read(blocksize)
    digest = 'sha256=' + urlsafe_b64encode(
        h.digest()
    ).decode('latin1').rstrip('=')
    return (digest, length)


def open_for_csv(name, mode):
    if sys.version_info[0] < 3:
        nl = {}
        bin = 'b'
    else:
        nl = {'newline': ''}
        bin = ''
    return open(name, mode + bin, **nl)


def fix_script(path):
    """Replace #!python with #!/path/to/python
    Return True if file was changed."""
    # XXX RECORD hashes will need to be updated
    if os.path.isfile(path):
        script = open(path, 'rb')
        try:
            firstline = script.readline()
            if not firstline.startswith(binary('#!python')):
                return False
            exename = sys.executable.encode(sys.getfilesystemencoding())
            firstline = binary('#!') + exename + binary(os.linesep)
            rest = script.read()
        finally:
            script.close()
        script = open(path, 'wb')
        try:
            script.write(firstline)
            script.write(rest)
        finally:
            script.close()
        return True

dist_info_re = re.compile(r"""^(?P<namever>(?P<name>.+?)(-(?P<ver>\d.+?))?)
                                \.dist-info$""", re.VERBOSE)


def root_is_purelib(name, wheeldir):
    """
    Return True if the extracted wheel in wheeldir should go into purelib.
    """
    name_folded = name.replace("-", "_")
    for item in os.listdir(wheeldir):
        match = dist_info_re.match(item)
        if match and match.group('name') == name_folded:
            with open(os.path.join(wheeldir, item, 'WHEEL')) as wheel:
                for line in wheel:
                    line = line.lower().rstrip()
                    if line == "root-is-purelib: true":
                        return True
    return False


def get_entrypoints(filename):
    if not os.path.exists(filename):
        return {}, {}

    # This is done because you can pass a string to entry_points wrappers which
    # means that they may or may not be valid INI files. The attempt here is to
    # strip leading and trailing whitespace in order to make them valid INI
    # files.
    with open(filename) as fp:
        data = StringIO()
        for line in fp:
            data.write(line.strip())
            data.write("\n")
        data.seek(0)

    cp = ConfigParser.RawConfigParser()
    cp.readfp(data)

    console = {}
    gui = {}
    if cp.has_section('console_scripts'):
        console = dict(cp.items('console_scripts'))
    if cp.has_section('gui_scripts'):
        gui = dict(cp.items('gui_scripts'))
    return console, gui


def move_wheel_files(name, req, wheeldir, user=False, home=None, root=None,
                     pycompile=True, scheme=None):
    """Install a wheel"""

    if not scheme:
        scheme = distutils_scheme(name, user=user, home=home, root=root)

    if root_is_purelib(name, wheeldir):
        lib_dir = scheme['purelib']
    else:
        lib_dir = scheme['platlib']

    info_dir = []
    data_dirs = []
    source = wheeldir.rstrip(os.path.sep) + os.path.sep

    # Record details of the files moved
    #   installed = files copied from the wheel to the destination
    #   changed = files changed while installing (scripts #! line typically)
    #   generated = files newly generated during the install (script wrappers)
    installed = {}
    changed = set()
    generated = []

    # Compile all of the pyc files that we're going to be installing
    if pycompile:
        compileall.compile_dir(source, force=True, quiet=True)

    def normpath(src, p):
        return make_path_relative(src, p).replace(os.path.sep, '/')

    def record_installed(srcfile, destfile, modified=False):
        """Map archive RECORD paths to installation RECORD paths."""
        oldpath = normpath(srcfile, wheeldir)
        newpath = normpath(destfile, lib_dir)
        installed[oldpath] = newpath
        if modified:
            changed.add(destfile)

    def clobber(source, dest, is_base, fixer=None, filter=None):
        if not os.path.exists(dest):  # common for the 'include' path
            os.makedirs(dest)

        for dir, subdirs, files in os.walk(source):
            basedir = dir[len(source):].lstrip(os.path.sep)
            destdir = os.path.join(dest, basedir)
            if is_base and basedir.split(os.path.sep, 1)[0].endswith('.data'):
                continue
            for s in subdirs:
                destsubdir = os.path.join(dest, basedir, s)
                if is_base and basedir == '' and destsubdir.endswith('.data'):
                    data_dirs.append(s)
                    continue
                elif (is_base
                        and s.endswith('.dist-info')
                        # is self.req.project_name case preserving?
                        and s.lower().startswith(
                            req.project_name.replace('-', '_').lower())):
                    assert not info_dir, 'Multiple .dist-info directories'
                    info_dir.append(destsubdir)
            for f in files:
                # Skip unwanted files
                if filter and filter(f):
                    continue
                srcfile = os.path.join(dir, f)
                destfile = os.path.join(dest, basedir, f)
                # directory creation is lazy and after the file filtering above
                # to ensure we don't install empty dirs; empty dirs can't be
                # uninstalled.
                if not os.path.exists(destdir):
                    os.makedirs(destdir)
                # use copy2 (not move) to be extra sure we're not moving
                # directories over; copy2 fails for directories.  this would
                # fail tests (not during released/user execution)
                shutil.copy2(srcfile, destfile)
                changed = False
                if fixer:
                    changed = fixer(destfile)
                record_installed(srcfile, destfile, changed)

    clobber(source, lib_dir, True)

    assert info_dir, "%s .dist-info directory not found" % req

    # Get the defined entry points
    ep_file = os.path.join(info_dir[0], 'entry_points.txt')
    console, gui = get_entrypoints(ep_file)

    def is_entrypoint_wrapper(name):
        # EP, EP.exe and EP-script.py are scripts generated for
        # entry point EP by setuptools
        if name.lower().endswith('.exe'):
            matchname = name[:-4]
        elif name.lower().endswith('-script.py'):
            matchname = name[:-10]
        elif name.lower().endswith(".pya"):
            matchname = name[:-4]
        else:
            matchname = name
        # Ignore setuptools-generated scripts
        return (matchname in console or matchname in gui)

    for datadir in data_dirs:
        fixer = None
        filter = None
        for subdir in os.listdir(os.path.join(wheeldir, datadir)):
            fixer = None
            if subdir == 'scripts':
                fixer = fix_script
                filter = is_entrypoint_wrapper
            source = os.path.join(wheeldir, datadir, subdir)
            dest = scheme[subdir]
            clobber(source, dest, False, fixer=fixer, filter=filter)

    maker = ScriptMaker(None, scheme['scripts'])

    # Ensure old scripts are overwritten.
    # See https://github.com/pypa/pip/issues/1800
    maker.clobber = True

    # Ensure we don't generate any variants for scripts because this is almost
    # never what somebody wants.
    # See https://bitbucket.org/pypa/distlib/issue/35/
    maker.variants = set(('', ))

    # This is required because otherwise distlib creates scripts that are not
    # executable.
    # See https://bitbucket.org/pypa/distlib/issue/32/
    maker.set_mode = True

    # Simplify the script and fix the fact that the default script swallows
    # every single stack trace.
    # See https://bitbucket.org/pypa/distlib/issue/34/
    # See https://bitbucket.org/pypa/distlib/issue/33/
    def _get_script_text(entry):
        return maker.script_template % {
            "module": entry.prefix,
            "import_name": entry.suffix.split(".")[0],
            "func": entry.suffix,
        }

    maker._get_script_text = _get_script_text
    maker.script_template = """# -*- coding: utf-8 -*-
import re
import sys

from %(module)s import %(import_name)s

if __name__ == '__main__':
    sys.argv[0] = re.sub(r'(-script\.pyw|\.exe)?$', '', sys.argv[0])
    sys.exit(%(func)s())
"""

    # Special case pip and setuptools to generate versioned wrappers
    #
    # The issue is that some projects (specifically, pip and setuptools) use
    # code in setup.py to create "versioned" entry points - pip2.7 on Python
    # 2.7, pip3.3 on Python 3.3, etc. But these entry points are baked into
    # the wheel metadata at build time, and so if the wheel is installed with
    # a *different* version of Python the entry points will be wrong. The
    # correct fix for this is to enhance the metadata to be able to describe
    # such versioned entry points, but that won't happen till Metadata 2.0 is
    # available.
    # In the meantime, projects using versioned entry points will either have
    # incorrect versioned entry points, or they will not be able to distribute
    # "universal" wheels (i.e., they will need a wheel per Python version).
    #
    # Because setuptools and pip are bundled with _ensurepip and virtualenv,
    # we need to use universal wheels. So, as a stopgap until Metadata 2.0, we
    # override the versioned entry points in the wheel and generate the
    # correct ones. This code is purely a short-term measure until Metadat 2.0
    # is available.
    #
    # To add the level of hack in this section of code, in order to support
    # ensurepip this code will look for an ``ENSUREPIP_OPTIONS`` environment
    # variable which will control which version scripts get installed.
    #
    # ENSUREPIP_OPTIONS=altinstall
    #   - Only pipX.Y and easy_install-X.Y will be generated and installed
    # ENSUREPIP_OPTIONS=install
    #   - pipX.Y, pipX, easy_install-X.Y will be generated and installed. Note
    #     that this option is technically if ENSUREPIP_OPTIONS is set and is
    #     not altinstall
    # DEFAULT
    #   - The default behavior is to install pip, pipX, pipX.Y, easy_install
    #     and easy_install-X.Y.
    pip_script = console.pop('pip', None)
    if pip_script:
        if "ENSUREPIP_OPTIONS" not in os.environ:
            spec = 'pip = ' + pip_script
            generated.extend(maker.make(spec))

        if os.environ.get("ENSUREPIP_OPTIONS", "") != "altinstall":
            spec = 'pip%s = %s' % (sys.version[:1], pip_script)
            generated.extend(maker.make(spec))

        spec = 'pip%s = %s' % (sys.version[:3], pip_script)
        generated.extend(maker.make(spec))
        # Delete any other versioned pip entry points
        pip_ep = [k for k in console if re.match(r'pip(\d(\.\d)?)?$', k)]
        for k in pip_ep:
            del console[k]
    easy_install_script = console.pop('easy_install', None)
    if easy_install_script:
        if "ENSUREPIP_OPTIONS" not in os.environ:
            spec = 'easy_install = ' + easy_install_script
            generated.extend(maker.make(spec))

        spec = 'easy_install-%s = %s' % (sys.version[:3], easy_install_script)
        generated.extend(maker.make(spec))
        # Delete any other versioned easy_install entry points
        easy_install_ep = [
            k for k in console if re.match(r'easy_install(-\d\.\d)?$', k)
        ]
        for k in easy_install_ep:
            del console[k]

    # Generate the console and GUI entry points specified in the wheel
    if len(console) > 0:
        generated.extend(
            maker.make_multiple(['%s = %s' % kv for kv in console.items()])
        )
    if len(gui) > 0:
        generated.extend(
            maker.make_multiple(
                ['%s = %s' % kv for kv in gui.items()],
                {'gui': True}
            )
        )

    record = os.path.join(info_dir[0], 'RECORD')
    temp_record = os.path.join(info_dir[0], 'RECORD.pip')
    with open_for_csv(record, 'r') as record_in:
        with open_for_csv(temp_record, 'w+') as record_out:
            reader = csv.reader(record_in)
            writer = csv.writer(record_out)
            for row in reader:
                row[0] = installed.pop(row[0], row[0])
                if row[0] in changed:
                    row[1], row[2] = rehash(row[0])
                writer.writerow(row)
            for f in generated:
                h, l = rehash(f)
                writer.writerow((f, h, l))
            for f in installed:
                writer.writerow((installed[f], '', ''))
    shutil.move(temp_record, record)


def _unique(fn):
    @functools.wraps(fn)
    def unique(*args, **kw):
        seen = set()
        for item in fn(*args, **kw):
            if item not in seen:
                seen.add(item)
                yield item
    return unique


# TODO: this goes somewhere besides the wheel module
@_unique
def uninstallation_paths(dist):
    """
    Yield all the uninstallation paths for dist based on RECORD-without-.pyc

    Yield paths to all the files in RECORD. For each .py file in RECORD, add
    the .pyc in the same directory.

    UninstallPathSet.add() takes care of the __pycache__ .pyc.
    """
    from pip.util import FakeFile  # circular import
    r = csv.reader(FakeFile(dist.get_metadata_lines('RECORD')))
    for row in r:
        path = os.path.join(dist.location, row[0])
        yield path
        if path.endswith('.py'):
            dn, fn = os.path.split(path)
            base = fn[:-3]
            path = os.path.join(dn, base + '.pyc')
            yield path


def wheel_version(source_dir):
    """
    Return the Wheel-Version of an extracted wheel, if possible.

    Otherwise, return False if we couldn't parse / extract it.
    """
    try:
        dist = [d for d in pkg_resources.find_on_path(None, source_dir)][0]

        wheel_data = dist.get_metadata('WHEEL')
        wheel_data = Parser().parsestr(wheel_data)

        version = wheel_data['Wheel-Version'].strip()
        version = tuple(map(int, version.split('.')))
        return version
    except:
        return False


def check_compatibility(version, name):
    """
    Raises errors or warns if called with an incompatible Wheel-Version.

    Pip should refuse to install a Wheel-Version that's a major series
    ahead of what it's compatible with (e.g 2.0 > 1.1); and warn when
    installing a version only minor version ahead (e.g 1.2 > 1.1).

    version: a 2-tuple representing a Wheel-Version (Major, Minor)
    name: name of wheel or package to raise exception about

    :raises UnsupportedWheel: when an incompatible Wheel-Version is given
    """
    if not version:
        raise UnsupportedWheel(
            "%s is in an unsupported or invalid wheel" % name
        )
    if version[0] > VERSION_COMPATIBLE[0]:
        raise UnsupportedWheel(
            "%s's Wheel-Version (%s) is not compatible with this version "
            "of pip" % (name, '.'.join(map(str, version)))
        )
    elif version > VERSION_COMPATIBLE:
        logger.warn('Installing from a newer Wheel-Version (%s)'
                    % '.'.join(map(str, version)))


class Wheel(object):
    """A wheel file"""

    # TODO: maybe move the install code into this class

    wheel_file_re = re.compile(
        r"""^(?P<namever>(?P<name>.+?)-(?P<ver>\d.*?))
        ((-(?P<build>\d.*?))?-(?P<pyver>.+?)-(?P<abi>.+?)-(?P<plat>.+?)
        \.whl|\.dist-info)$""",
        re.VERBOSE
    )

    def __init__(self, filename):
        """
        :raises InvalidWheelFilename: when the filename is invalid for a wheel
        """
        wheel_info = self.wheel_file_re.match(filename)
        if not wheel_info:
            raise InvalidWheelFilename(
                "%s is not a valid wheel filename." % filename
            )
        self.filename = filename
        self.name = wheel_info.group('name').replace('_', '-')
        # we'll assume "_" means "-" due to wheel naming scheme
        # (https://github.com/pypa/pip/issues/1150)
        self.version = wheel_info.group('ver').replace('_', '-')
        self.pyversions = wheel_info.group('pyver').split('.')
        self.abis = wheel_info.group('abi').split('.')
        self.plats = wheel_info.group('plat').split('.')

        # All the tag combinations from this file
        self.file_tags = set(
            (x, y, z) for x in self.pyversions
            for y in self.abis for z in self.plats
        )

    def support_index_min(self, tags=None):
        """
        Return the lowest index that one of the wheel's file_tag combinations
        achieves in the supported_tags list e.g. if there are 8 supported tags,
        and one of the file tags is first in the list, then return 0.  Returns
        None is the wheel is not supported.
        """
        if tags is None:  # for mock
            tags = pep425tags.supported_tags
        indexes = [tags.index(c) for c in self.file_tags if c in tags]
        return min(indexes) if indexes else None

    def supported(self, tags=None):
        """Is this wheel supported on this system?"""
        if tags is None:  # for mock
            tags = pep425tags.supported_tags
        return bool(set(tags).intersection(self.file_tags))


class WheelBuilder(object):
    """Build wheels from a RequirementSet."""

    def __init__(self, requirement_set, finder, wheel_dir, build_options=[],
                 global_options=[]):
        self.requirement_set = requirement_set
        self.finder = finder
        self.wheel_dir = normalize_path(wheel_dir)
        self.build_options = build_options
        self.global_options = global_options

    def _build_one(self, req):
        """Build one wheel."""

        base_args = [
            sys.executable, '-c',
            "import setuptools;__file__=%r;"
            "exec(compile(open(__file__).read().replace('\\r\\n', '\\n'), "
            "__file__, 'exec'))" % req.setup_py
        ] + list(self.global_options)

        logger.notify('Running setup.py bdist_wheel for %s' % req.name)
        logger.notify('Destination directory: %s' % self.wheel_dir)
        wheel_args = base_args + ['bdist_wheel', '-d', self.wheel_dir] \
            + self.build_options
        try:
            call_subprocess(wheel_args, cwd=req.source_dir, show_stdout=False)
            return True
        except:
            logger.error('Failed building wheel for %s' % req.name)
            return False

    def build(self):
        """Build wheels."""

        # unpack and constructs req set
        self.requirement_set.prepare_files(self.finder)

        reqset = self.requirement_set.requirements.values()

        buildset = []
        for req in reqset:
            if req.is_wheel:
                logger.notify(
                    'Skipping %s, due to already being wheel.' % req.name)
            elif req.editable:
                logger.notify(
                    'Skipping %s, due to being editable' % req.name)
            else:
                buildset.append(req)

        if not buildset:
            return True

        # Build the wheels.
        logger.notify(
            'Building wheels for collected packages: %s' %
            ', '.join([req.name for req in buildset])
        )
        logger.indent += 2
        build_success, build_failure = [], []
        for req in buildset:
            if self._build_one(req):
                build_success.append(req)
            else:
                build_failure.append(req)
        logger.indent -= 2

        # notify success/failure
        if build_success:
            logger.notify(
                'Successfully built %s' %
                ' '.join([req.name for req in build_success])
            )
        if build_failure:
            logger.notify(
                'Failed to build %s' %
                ' '.join([req.name for req in build_failure])
            )
        # Return True if all builds were successful
        return len(build_failure) == 0

pip/wheel.py
diff --git a/pip/wheel.py b/pip/wheel.py
index 2d4f4df7570..739eaf9280a 100644
--- a/pip/wheel.py
+++ b/pip/wheel.py
@@ -242,6 +242,10 @@ def is_entrypoint_wrapper(name):
 
     maker = ScriptMaker(None, scheme['scripts'])
 
+    # Ensure old scripts are overwritten.
+    # See https://github.com/pypa/pip/issues/1800
+    maker.clobber = True
+
     # Ensure we don't generate any variants for scripts because this is almost
     # never what somebody wants.
     # See https://bitbucket.org/pypa/distlib/issue/35/

pip fail after upgrade to 1.5.5
```
$ pip install --upgrade pip
Downloading/unpacking pip from https://pypi.python.org/packages/py2.py3/p/pip/pip-1.5.5-py2.py3-none-any.whl#md5=03a932d6f82a3887d8de1cdb837c87ed
  Using download cache from /Users/robinho/Library/Caches/pip-downloads/https%3A%2F%2Fpypi.python.org%2Fpackages%2Fpy2.py3%2Fp%2Fpip%2Fpip-1.5.5-py2.py3-none-any.whl
Installing collected packages: pip
  Found existing installation: pip 1.5.4
    Uninstalling pip:
      Successfully uninstalled pip
Successfully installed pip
Cleaning up...
$ pip
Traceback (most recent call last):
  File "/usr/local/bin/pip", line 5, in <module>
    from pkg_resources import load_entry_point
  File "/usr/local/lib/python2.7/site-packages/pkg_resources.py", line 2749, in <module>
    working_set = WorkingSet._build_master()
  File "/usr/local/lib/python2.7/site-packages/pkg_resources.py", line 446, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/local/lib/python2.7/site-packages/pkg_resources.py", line 459, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/local/lib/python2.7/site-packages/pkg_resources.py", line 628, in resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: pip==1.5.4
```

Using a python installed by homebrew.

```
$ python --version
Python 2.7.6
$ brew --version
0.9.5
$ sw_vers
ProductName:    Mac OS X
ProductVersion: 10.9.2
BuildVersion:   13C1021
```

