"""
Improved support for Microsoft Visual C++ compilers.

Known supported compilers:
--------------------------
Microsoft Visual C++ 9.0:
    Microsoft Visual C++ Compiler for Python 2.7 (x86, amd64)
    Microsoft Windows SDK 6.1 (x86, x64, ia64)
    Microsoft Windows SDK 7.0 (x86, x64, ia64)

Microsoft Visual C++ 10.0:
    Microsoft Windows SDK 7.1 (x86, x64, ia64)

Microsoft Visual C++ 14.0:
    Microsoft Visual C++ Build Tools 2015 (x86, x64, arm)
    Microsoft Visual Studio 2017 (x86, x64, arm, arm64)
    Microsoft Visual Studio Build Tools 2017 (x86, x64, arm, arm64)
"""

import os
import sys
import platform
import itertools
import distutils.errors
from packaging.version import LegacyVersion

from six.moves import filterfalse

from .monkey import get_unpatched

if platform.system() == 'Windows':
    from six.moves import winreg
    safe_env = os.environ
else:
    """
    Mock winreg and environ so the module can be imported
    on this platform.
    """

    class winreg:
        HKEY_USERS = None
        HKEY_CURRENT_USER = None
        HKEY_LOCAL_MACHINE = None
        HKEY_CLASSES_ROOT = None

    safe_env = dict()

_msvc9_suppress_errors = (
    # msvc9compiler isn't available on some platforms
    ImportError,

    # msvc9compiler raises DistutilsPlatformError in some
    # environments. See #1118.
    distutils.errors.DistutilsPlatformError,
)

try:
    from distutils.msvc9compiler import Reg
except _msvc9_suppress_errors:
    pass


def msvc9_find_vcvarsall(version):
    """
    Patched "distutils.msvc9compiler.find_vcvarsall" to use the standalone
    compiler build for Python (VCForPython). Fall back to original behavior
    when the standalone compiler is not available.

    Redirect the path of "vcvarsall.bat".

    Known supported compilers
    -------------------------
    Microsoft Visual C++ 9.0:
        Microsoft Visual C++ Compiler for Python 2.7 (x86, amd64)

    Parameters
    ----------
    version: float
        Required Microsoft Visual C++ version.

    Return
    ------
    vcvarsall.bat path: str
    """
    VC_BASE = r'Software\%sMicrosoft\DevDiv\VCForPython\%0.1f'
    key = VC_BASE % ('', version)
    try:
        # Per-user installs register the compiler path here
        productdir = Reg.get_value(key, "installdir")
    except KeyError:
        try:
            # All-user installs on a 64-bit system register here
            key = VC_BASE % ('Wow6432Node\\', version)
            productdir = Reg.get_value(key, "installdir")
        except KeyError:
            productdir = None

    if productdir:
        vcvarsall = os.path.os.path.join(productdir, "vcvarsall.bat")
        if os.path.isfile(vcvarsall):
            return vcvarsall

    return get_unpatched(msvc9_find_vcvarsall)(version)


def msvc9_query_vcvarsall(ver, arch='x86', *args, **kwargs):
    """
    Patched "distutils.msvc9compiler.query_vcvarsall" for support extra
    compilers.

    Set environment without use of "vcvarsall.bat".

    Known supported compilers
    -------------------------
    Microsoft Visual C++ 9.0:
        Microsoft Visual C++ Compiler for Python 2.7 (x86, amd64)
        Microsoft Windows SDK 6.1 (x86, x64, ia64)
        Microsoft Windows SDK 7.0 (x86, x64, ia64)

    Microsoft Visual C++ 10.0:
        Microsoft Windows SDK 7.1 (x86, x64, ia64)

    Parameters
    ----------
    ver: float
        Required Microsoft Visual C++ version.
    arch: str
        Target architecture.

    Return
    ------
    environment: dict
    """
    # Try to get environement from vcvarsall.bat (Classical way)
    try:
        orig = get_unpatched(msvc9_query_vcvarsall)
        return orig(ver, arch, *args, **kwargs)
    except distutils.errors.DistutilsPlatformError:
        # Pass error if Vcvarsall.bat is missing
        pass
    except ValueError:
        # Pass error if environment not set after executing vcvarsall.bat
        pass

    # If error, try to set environment directly
    try:
        return EnvironmentInfo(arch, ver).return_env()
    except distutils.errors.DistutilsPlatformError as exc:
        _augment_exception(exc, ver, arch)
        raise


def msvc14_get_vc_env(plat_spec):
    """
    Patched "distutils._msvccompiler._get_vc_env" for support extra
    compilers.

    Set environment without use of "vcvarsall.bat".

    Known supported compilers
    -------------------------
    Microsoft Visual C++ 14.0:
        Microsoft Visual C++ Build Tools 2015 (x86, x64, arm)
        Microsoft Visual Studio 2017 (x86, x64, arm, arm64)
        Microsoft Visual Studio Build Tools 2017 (x86, x64, arm, arm64)

    Parameters
    ----------
    plat_spec: str
        Target architecture.

    Return
    ------
    environment: dict
    """
    # Try to get environment from vcvarsall.bat (Classical way)
    try:
        return get_unpatched(msvc14_get_vc_env)(plat_spec)
    except distutils.errors.DistutilsPlatformError:
        # Pass error Vcvarsall.bat is missing
        pass

    # If error, try to set environment directly
    try:
        return EnvironmentInfo(plat_spec, vc_min_ver=14.0).return_env()
    except distutils.errors.DistutilsPlatformError as exc:
        _augment_exception(exc, 14.0)
        raise


def msvc14_gen_lib_options(*args, **kwargs):
    """
    Patched "distutils._msvccompiler.gen_lib_options" for fix
    compatibility between "numpy.distutils" and "distutils._msvccompiler"
    (for Numpy < 1.11.2)
    """
    if "numpy.distutils" in sys.modules:
        import numpy as np
        if LegacyVersion(np.__version__) < LegacyVersion('1.11.2'):
            return np.distutils.ccompiler.gen_lib_options(*args, **kwargs)
    return get_unpatched(msvc14_gen_lib_options)(*args, **kwargs)


def _augment_exception(exc, version, arch=''):
    """
    Add details to the exception message to help guide the user
    as to what action will resolve it.
    """
    # Error if MSVC++ directory not found or environment not set
    message = exc.args[0]

    if "vcvarsall" in message.lower() or "visual c" in message.lower():
        # Special error message if MSVC++ not installed
        tmpl = 'Microsoft Visual C++ {version:0.1f} is required.'
        message = tmpl.format(**locals())
        msdownload = 'www.microsoft.com/download/details.aspx?id=%d'
        if version == 9.0:
            if arch.lower().find('ia64') > -1:
                # For VC++ 9.0, if IA64 support is needed, redirect user
                # to Windows SDK 7.0
                message += ' Get it with "Microsoft Windows SDK 7.0": '
                message += msdownload % 3138
            else:
                # For VC++ 9.0 redirect user to Vc++ for Python 2.7 :
                # This redirection link is maintained by Microsoft.
                # Contact vspython@microsoft.com if it needs updating.
                message += ' Get it from http://aka.ms/vcpython27'
        elif version == 10.0:
            # For VC++ 10.0 Redirect user to Windows SDK 7.1
            message += ' Get it with "Microsoft Windows SDK 7.1": '
            message += msdownload % 8279
        elif version >= 14.0:
            # For VC++ 14.0 Redirect user to Visual C++ Build Tools
            message += (' Get it with "Microsoft Visual C++ Build Tools": '
                        r'http://landinghub.visualstudio.com/'
                        'visual-cpp-build-tools')

    exc.args = (message, )


class PlatformInfo:
    """
    Current and Target Architectures informations.

    Parameters
    ----------
    arch: str
        Target architecture.
    """
    current_cpu = safe_env.get('processor_architecture', '').lower()

    def __init__(self, arch):
        self.arch = arch.lower().replace('x64', 'amd64')

    @property
    def target_cpu(self):
        return self.arch[self.arch.find('_') + 1:]

    def target_is_x86(self):
        return self.target_cpu == 'x86'

    def current_is_x86(self):
        return self.current_cpu == 'x86'

    def current_dir(self, hidex86=False, x64=False):
        """
        Current platform specific subfolder.

        Parameters
        ----------
        hidex86: bool
            return '' and not '\x86' if architecture is x86.
        x64: bool
            return '\x64' and not '\amd64' if architecture is amd64.

        Return
        ------
        subfolder: str
            '\target', or '' (see hidex86 parameter)
        """
        return (
            '' if (self.current_cpu == 'x86' and hidex86) else
            r'\x64' if (self.current_cpu == 'amd64' and x64) else
            r'\%s' % self.current_cpu
        )

    def target_dir(self, hidex86=False, x64=False):
        r"""
        Target platform specific subfolder.

        Parameters
        ----------
        hidex86: bool
            return '' and not '\x86' if architecture is x86.
        x64: bool
            return '\x64' and not '\amd64' if architecture is amd64.

        Return
        ------
        subfolder: str
            '\current', or '' (see hidex86 parameter)
        """
        return (
            '' if (self.target_cpu == 'x86' and hidex86) else
            r'\x64' if (self.target_cpu == 'amd64' and x64) else
            r'\%s' % self.target_cpu
        )

    def cross_dir(self, forcex86=False):
        r"""
        Cross platform specific subfolder.

        Parameters
        ----------
        forcex86: bool
            Use 'x86' as current architecture even if current acritecture is
            not x86.

        Return
        ------
        subfolder: str
            '' if target architecture is current architecture,
            '\current_target' if not.
        """
        current = 'x86' if forcex86 else self.current_cpu
        return (
            '' if self.target_cpu == current else
            self.target_dir().replace('\\', '\\%s_' % current)
        )


class RegistryInfo:
    """
    Microsoft Visual Studio related registry informations.

    Parameters
    ----------
    platform_info: PlatformInfo
        "PlatformInfo" instance.
    """
    HKEYS = (winreg.HKEY_USERS,
             winreg.HKEY_CURRENT_USER,
             winreg.HKEY_LOCAL_MACHINE,
             winreg.HKEY_CLASSES_ROOT)

    def __init__(self, platform_info):
        self.pi = platform_info

    @property
    def visualstudio(self):
        """
        Microsoft Visual Studio root registry key.
        """
        return 'VisualStudio'

    @property
    def sxs(self):
        """
        Microsoft Visual Studio SxS registry key.
        """
        return os.path.join(self.visualstudio, 'SxS')

    @property
    def vc(self):
        """
        Microsoft Visual C++ VC7 registry key.
        """
        return os.path.join(self.sxs, 'VC7')

    @property
    def vs(self):
        """
        Microsoft Visual Studio VS7 registry key.
        """
        return os.path.join(self.sxs, 'VS7')

    @property
    def vc_for_python(self):
        """
        Microsoft Visual C++ for Python registry key.
        """
        return r'DevDiv\VCForPython'

    @property
    def microsoft_sdk(self):
        """
        Microsoft SDK registry key.
        """
        return 'Microsoft SDKs'

    @property
    def windows_sdk(self):
        """
        Microsoft Windows/Platform SDK registry key.
        """
        return os.path.join(self.microsoft_sdk, 'Windows')

    @property
    def netfx_sdk(self):
        """
        Microsoft .NET Framework SDK registry key.
        """
        return os.path.join(self.microsoft_sdk, 'NETFXSDK')

    @property
    def windows_kits_roots(self):
        """
        Microsoft Windows Kits Roots registry key.
        """
        return r'Windows Kits\Installed Roots'

    def microsoft(self, key, x86=False):
        """
        Return key in Microsoft software registry.

        Parameters
        ----------
        key: str
            Registry key path where look.
        x86: str
            Force x86 software registry.

        Return
        ------
        str: value
        """
        node64 = '' if self.pi.current_is_x86() or x86 else 'Wow6432Node'
        return os.path.join('Software', node64, 'Microsoft', key)

    def lookup(self, key, name):
        """
        Look for values in registry in Microsoft software registry.

        Parameters
        ----------
        key: str
            Registry key path where look.
        name: str
            Value name to find.

        Return
        ------
        str: value
        """
        KEY_READ = winreg.KEY_READ
        openkey = winreg.OpenKey
        ms = self.microsoft
        for hkey in self.HKEYS:
            try:
                bkey = openkey(hkey, ms(key), 0, KEY_READ)
            except (OSError, IOError):
                if not self.pi.current_is_x86():
                    try:
                        bkey = openkey(hkey, ms(key, True), 0, KEY_READ)
                    except (OSError, IOError):
                        continue
                else:
                    continue
            try:
                return winreg.QueryValueEx(bkey, name)[0]
            except (OSError, IOError):
                pass


class SystemInfo:
    """
    Microsoft Windows and Visual Studio related system inormations.

    Parameters
    ----------
    registry_info: RegistryInfo
        "RegistryInfo" instance.
    vc_ver: float
        Required Microsoft Visual C++ version.
    """

    # Variables and properties in this class use originals CamelCase variables
    # names from Microsoft source files for more easy comparaison.
    WinDir = safe_env.get('WinDir', '')
    ProgramFiles = safe_env.get('ProgramFiles', '')
    ProgramFilesx86 = safe_env.get('ProgramFiles(x86)', ProgramFiles)

    def __init__(self, registry_info, vc_ver=None):
        self.ri = registry_info
        self.pi = self.ri.pi
        self.vc_ver = vc_ver or self._find_latest_available_vc_ver()

    def _find_latest_available_vc_ver(self):
        try:
            return self.find_available_vc_vers()[-1]
        except IndexError:
            err = 'No Microsoft Visual C++ version found'
            raise distutils.errors.DistutilsPlatformError(err)

    def find_available_vc_vers(self):
        """
        Find all available Microsoft Visual C++ versions.
        """
        ms = self.ri.microsoft
        vckeys = (self.ri.vc, self.ri.vc_for_python, self.ri.vs)
        vc_vers = []
        for hkey in self.ri.HKEYS:
            for key in vckeys:
                try:
                    bkey = winreg.OpenKey(hkey, ms(key), 0, winreg.KEY_READ)
                except (OSError, IOError):
                    continue
                subkeys, values, _ = winreg.QueryInfoKey(bkey)
                for i in range(values):
                    try:
                        ver = float(winreg.EnumValue(bkey, i)[0])
                        if ver not in vc_vers:
                            vc_vers.append(ver)
                    except ValueError:
                        pass
                for i in range(subkeys):
                    try:
                        ver = float(winreg.EnumKey(bkey, i))
                        if ver not in vc_vers:
                            vc_vers.append(ver)
                    except ValueError:
                        pass
        return sorted(vc_vers)

    @property
    def VSInstallDir(self):
        """
        Microsoft Visual Studio directory.
        """
        # Default path
        name = 'Microsoft Visual Studio %0.1f' % self.vc_ver
        default = os.path.join(self.ProgramFilesx86, name)

        # Try to get path from registry, if fail use default path
        return self.ri.lookup(self.ri.vs, '%0.1f' % self.vc_ver) or default

    @property
    def VCInstallDir(self):
        """
        Microsoft Visual C++ directory.
        """
        self.VSInstallDir

        guess_vc = self._guess_vc() or self._guess_vc_legacy()

        # Try to get "VC++ for Python" path from registry as default path
        reg_path = os.path.join(self.ri.vc_for_python, '%0.1f' % self.vc_ver)
        python_vc = self.ri.lookup(reg_path, 'installdir')
        default_vc = os.path.join(python_vc, 'VC') if python_vc else guess_vc

        # Try to get path from registry, if fail use default path
        path = self.ri.lookup(self.ri.vc, '%0.1f' % self.vc_ver) or default_vc

        if not os.path.isdir(path):
            msg = 'Microsoft Visual C++ directory not found'
            raise distutils.errors.DistutilsPlatformError(msg)

        return path

    def _guess_vc(self):
        """
        Locate Visual C for 2017
        """
        if self.vc_ver <= 14.0:
            return

        default = r'VC\Tools\MSVC'
        guess_vc = os.path.join(self.VSInstallDir, default)
        # Subdir with VC exact version as name
        try:
            vc_exact_ver = os.listdir(guess_vc)[-1]
            return os.path.join(guess_vc, vc_exact_ver)
        except (OSError, IOError, IndexError):
            pass

    def _guess_vc_legacy(self):
        """
        Locate Visual C for versions prior to 2017
        """
        default = r'Microsoft Visual Studio %0.1f\VC' % self.vc_ver
        return os.path.join(self.ProgramFilesx86, default)

    @property
    def WindowsSdkVersion(self):
        """
        Microsoft Windows SDK versions for specified MSVC++ version.
        """
        if self.vc_ver <= 9.0:
            return ('7.0', '6.1', '6.0a')
        elif self.vc_ver == 10.0:
            return ('7.1', '7.0a')
        elif self.vc_ver == 11.0:
            return ('8.0', '8.0a')
        elif self.vc_ver == 12.0:
            return ('8.1', '8.1a')
        elif self.vc_ver >= 14.0:
            return ('10.0', '8.1')

    @property
    def WindowsSdkLastVersion(self):
        """
        Microsoft Windows SDK last version
        """
        return self._use_last_dir_name(os.path.join(
            self.WindowsSdkDir, 'lib'))

    @property
    def WindowsSdkDir(self):
        """
        Microsoft Windows SDK directory.
        """
        sdkdir = ''
        for ver in self.WindowsSdkVersion:
            # Try to get it from registry
            loc = os.path.join(self.ri.windows_sdk, 'v%s' % ver)
            sdkdir = self.ri.lookup(loc, 'installationfolder')
            if sdkdir:
                break
        if not sdkdir or not os.path.isdir(sdkdir):
            # Try to get "VC++ for Python" version from registry
            path = os.path.join(self.ri.vc_for_python, '%0.1f' % self.vc_ver)
            install_base = self.ri.lookup(path, 'installdir')
            if install_base:
                sdkdir = os.path.join(install_base, 'WinSDK')
        if not sdkdir or not os.path.isdir(sdkdir):
            # If fail, use default new path
            for ver in self.WindowsSdkVersion:
                intver = ver[:ver.rfind('.')]
                path = r'Microsoft SDKs\Windows Kits\%s' % (intver)
                d = os.path.join(self.ProgramFiles, path)
                if os.path.isdir(d):
                    sdkdir = d
        if not sdkdir or not os.path.isdir(sdkdir):
            # If fail, use default old path
            for ver in self.WindowsSdkVersion:
                path = r'Microsoft SDKs\Windows\v%s' % ver
                d = os.path.join(self.ProgramFiles, path)
                if os.path.isdir(d):
                    sdkdir = d
        if not sdkdir:
            # If fail, use Platform SDK
            sdkdir = os.path.join(self.VCInstallDir, 'PlatformSDK')
        return sdkdir

    @property
    def WindowsSDKExecutablePath(self):
        """
        Microsoft Windows SDK executable directory.
        """
        # Find WinSDK NetFx Tools registry dir name
        if self.vc_ver <= 11.0:
            netfxver = 35
            arch = ''
        else:
            netfxver = 40
            hidex86 = True if self.vc_ver <= 12.0 else False
            arch = self.pi.current_dir(x64=True, hidex86=hidex86)
        fx = 'WinSDK-NetFx%dTools%s' % (netfxver, arch.replace('\\', '-'))

        # liste all possibles registry paths
        regpaths = []
        if self.vc_ver >= 14.0:
            for ver in self.NetFxSdkVersion:
                regpaths += [os.path.join(self.ri.netfx_sdk, ver, fx)]

        for ver in self.WindowsSdkVersion:
            regpaths += [os.path.join(self.ri.windows_sdk, 'v%sA' % ver, fx)]

        # Return installation folder from the more recent path
        for path in regpaths:
            execpath = self.ri.lookup(path, 'installationfolder')
            if execpath:
                break
        return execpath

    @property
    def FSharpInstallDir(self):
        """
        Microsoft Visual F# directory.
        """
        path = r'%0.1f\Setup\F#' % self.vc_ver
        path = os.path.join(self.ri.visualstudio, path)
        return self.ri.lookup(path, 'productdir') or ''

    @property
    def UniversalCRTSdkDir(self):
        """
        Microsoft Universal CRT SDK directory.
        """
        # Set Kit Roots versions for specified MSVC++ version
        if self.vc_ver >= 14.0:
            vers = ('10', '81')
        else:
            vers = ()

        # Find path of the more recent Kit
        for ver in vers:
            sdkdir = self.ri.lookup(self.ri.windows_kits_roots,
                                    'kitsroot%s' % ver)
            if sdkdir:
                break
        return sdkdir or ''

    @property
    def UniversalCRTSdkLastVersion(self):
        """
        Microsoft Universal C Runtime SDK last version
        """
        return self._use_last_dir_name(os.path.join(
            self.UniversalCRTSdkDir, 'lib'))

    @property
    def NetFxSdkVersion(self):
        """
        Microsoft .NET Framework SDK versions.
        """
        # Set FxSdk versions for specified MSVC++ version
        if self.vc_ver >= 14.0:
            return ('4.6.1', '4.6')
        else:
            return ()

    @property
    def NetFxSdkDir(self):
        """
        Microsoft .NET Framework SDK directory.
        """
        for ver in self.NetFxSdkVersion:
            loc = os.path.join(self.ri.netfx_sdk, ver)
            sdkdir = self.ri.lookup(loc, 'kitsinstallationfolder')
            if sdkdir:
                break
        return sdkdir or ''

    @property
    def FrameworkDir32(self):
        """
        Microsoft .NET Framework 32bit directory.
        """
        # Default path
        guess_fw = os.path.join(self.WinDir, r'Microsoft.NET\Framework')

        # Try to get path from registry, if fail use default path
        return self.ri.lookup(self.ri.vc, 'frameworkdir32') or guess_fw

    @property
    def FrameworkDir64(self):
        """
        Microsoft .NET Framework 64bit directory.
        """
        # Default path
        guess_fw = os.path.join(self.WinDir, r'Microsoft.NET\Framework64')

        # Try to get path from registry, if fail use default path
        return self.ri.lookup(self.ri.vc, 'frameworkdir64') or guess_fw

    @property
    def FrameworkVersion32(self):
        """
        Microsoft .NET Framework 32bit versions.
        """
        return self._find_dot_net_versions(32)

    @property
    def FrameworkVersion64(self):
        """
        Microsoft .NET Framework 64bit versions.
        """
        return self._find_dot_net_versions(64)

    def _find_dot_net_versions(self, bits):
        """
        Find Microsoft .NET Framework versions.

        Parameters
        ----------
        bits: int
            Platform number of bits: 32 or 64.
        """
        # Find actual .NET version in registry
        reg_ver = self.ri.lookup(self.ri.vc, 'frameworkver%d' % bits)
        dot_net_dir = getattr(self, 'FrameworkDir%d' % bits)
        ver = reg_ver or self._use_last_dir_name(dot_net_dir, 'v') or ''

        # Set .NET versions for specified MSVC++ version
        if self.vc_ver >= 12.0:
            frameworkver = (ver, 'v4.0')
        elif self.vc_ver >= 10.0:
            frameworkver = ('v4.0.30319' if ver.lower()[:2] != 'v4' else ver,
                            'v3.5')
        elif self.vc_ver == 9.0:
            frameworkver = ('v3.5', 'v2.0.50727')
        if self.vc_ver == 8.0:
            frameworkver = ('v3.0', 'v2.0.50727')
        return frameworkver

    def _use_last_dir_name(self, path, prefix=''):
        """
        Return name of the last dir in path or '' if no dir found.

        Parameters
        ----------
        path: str
            Use dirs in this path
        prefix: str
            Use only dirs startings by this prefix
        """
        matching_dirs = (
            dir_name
            for dir_name in reversed(os.listdir(path))
            if os.path.isdir(os.path.join(path, dir_name)) and
            dir_name.startswith(prefix)
        )
        return next(matching_dirs, None) or ''


class EnvironmentInfo:
    """
    Return environment variables for specified Microsoft Visual C++ version
    and platform : Lib, Include, Path and libpath.

    This function is compatible with Microsoft Visual C++ 9.0 to 14.0.

    Script created by analysing Microsoft environment configuration files like
    "vcvars[...].bat", "SetEnv.Cmd", "vcbuildtools.bat", ...

    Parameters
    ----------
    arch: str
        Target architecture.
    vc_ver: float
        Required Microsoft Visual C++ version. If not set, autodetect the last
        version.
    vc_min_ver: float
        Minimum Microsoft Visual C++ version.
    """

    # Variables and properties in this class use originals CamelCase variables
    # names from Microsoft source files for more easy comparaison.

    def __init__(self, arch, vc_ver=None, vc_min_ver=0):
        self.pi = PlatformInfo(arch)
        self.ri = RegistryInfo(self.pi)
        self.si = SystemInfo(self.ri, vc_ver)

        if self.vc_ver < vc_min_ver:
            err = 'No suitable Microsoft Visual C++ version found'
            raise distutils.errors.DistutilsPlatformError(err)

    @property
    def vc_ver(self):
        """
        Microsoft Visual C++ version.
        """
        return self.si.vc_ver

    @property
    def VSTools(self):
        """
        Microsoft Visual Studio Tools
        """
        paths = [r'Common7\IDE', r'Common7\Tools']

        if self.vc_ver >= 14.0:
            arch_subdir = self.pi.current_dir(hidex86=True, x64=True)
            paths += [r'Common7\IDE\CommonExtensions\Microsoft\TestWindow']
            paths += [r'Team Tools\Performance Tools']
            paths += [r'Team Tools\Performance Tools%s' % arch_subdir]

        return [os.path.join(self.si.VSInstallDir, path) for path in paths]

    @property
    def VCIncludes(self):
        """
        Microsoft Visual C++ & Microsoft Foundation Class Includes
        """
        return [os.path.join(self.si.VCInstallDir, 'Include'),
                os.path.join(self.si.VCInstallDir, r'ATLMFC\Include')]

    @property
    def VCLibraries(self):
        """
        Microsoft Visual C++ & Microsoft Foundation Class Libraries
        """
        if self.vc_ver >= 15.0:
            arch_subdir = self.pi.target_dir(x64=True)
        else:
            arch_subdir = self.pi.target_dir(hidex86=True)
        paths = ['Lib%s' % arch_subdir, r'ATLMFC\Lib%s' % arch_subdir]

        if self.vc_ver >= 14.0:
            paths += [r'Lib\store%s' % arch_subdir]

        return [os.path.join(self.si.VCInstallDir, path) for path in paths]

    @property
    def VCStoreRefs(self):
        """
        Microsoft Visual C++ store references Libraries
        """
        if self.vc_ver < 14.0:
            return []
        return [os.path.join(self.si.VCInstallDir, r'Lib\store\references')]

    @property
    def VCTools(self):
        """
        Microsoft Visual C++ Tools
        """
        si = self.si
        tools = [os.path.join(si.VCInstallDir, 'VCPackages')]

        forcex86 = True if self.vc_ver <= 10.0 else False
        arch_subdir = self.pi.cross_dir(forcex86)
        if arch_subdir:
            tools += [os.path.join(si.VCInstallDir, 'Bin%s' % arch_subdir)]

        if self.vc_ver == 14.0:
            path = 'Bin%s' % self.pi.current_dir(hidex86=True)
            tools += [os.path.join(si.VCInstallDir, path)]

        elif self.vc_ver >= 15.0:
            host_dir = (r'bin\HostX86%s' if self.pi.current_is_x86() else
                        r'bin\HostX64%s')
            tools += [os.path.join(
                si.VCInstallDir, host_dir % self.pi.target_dir(x64=True))]

            if self.pi.current_cpu != self.pi.target_cpu:
                tools += [os.path.join(
                    si.VCInstallDir, host_dir % self.pi.current_dir(x64=True))]

        else:
            tools += [os.path.join(si.VCInstallDir, 'Bin')]

        return tools

    @property
    def OSLibraries(self):
        """
        Microsoft Windows SDK Libraries
        """
        if self.vc_ver <= 10.0:
            arch_subdir = self.pi.target_dir(hidex86=True, x64=True)
            return [os.path.join(self.si.WindowsSdkDir, 'Lib%s' % arch_subdir)]

        else:
            arch_subdir = self.pi.target_dir(x64=True)
            lib = os.path.join(self.si.WindowsSdkDir, 'lib')
            libver = self._sdk_subdir
            return [os.path.join(lib, '%sum%s' % (libver , arch_subdir))]

    @property
    def OSIncludes(self):
        """
        Microsoft Windows SDK Include
        """
        include = os.path.join(self.si.WindowsSdkDir, 'include')

        if self.vc_ver <= 10.0:
            return [include, os.path.join(include, 'gl')]

        else:
            if self.vc_ver >= 14.0:
                sdkver = self._sdk_subdir
            else:
                sdkver = ''
            return [os.path.join(include, '%sshared' % sdkver),
                    os.path.join(include, '%sum' % sdkver),
                    os.path.join(include, '%swinrt' % sdkver)]

    @property
    def OSLibpath(self):
        """
        Microsoft Windows SDK Libraries Paths
        """
        ref = os.path.join(self.si.WindowsSdkDir, 'References')
        libpath = []

        if self.vc_ver <= 9.0:
            libpath += self.OSLibraries

        if self.vc_ver >= 11.0:
            libpath += [os.path.join(ref, r'CommonConfiguration\Neutral')]

        if self.vc_ver >= 14.0:
            libpath += [
                ref,
                os.path.join(self.si.WindowsSdkDir, 'UnionMetadata'),
                os.path.join(
                    ref,
                    'Windows.Foundation.UniversalApiContract',
                    '1.0.0.0',
                ),
                os.path.join(
                    ref,
                    'Windows.Foundation.FoundationContract',
                    '1.0.0.0',
                ),
                os.path.join(
                    ref,
                    'Windows.Networking.Connectivity.WwanContract',
                    '1.0.0.0',
                ),
                os.path.join(
                    self.si.WindowsSdkDir,
                    'ExtensionSDKs',
                    'Microsoft.VCLibs',
                    '%0.1f' % self.vc_ver,
                    'References',
                    'CommonConfiguration',
                    'neutral',
                ),
            ]
        return libpath

    @property
    def SdkTools(self):
        """
        Microsoft Windows SDK Tools
        """
        return list(self._sdk_tools())

    def _sdk_tools(self):
        """
        Microsoft Windows SDK Tools paths generator
        """
        if self.vc_ver < 15.0:
            bin_dir = 'Bin' if self.vc_ver <= 11.0 else r'Bin\x86'
            yield os.path.join(self.si.WindowsSdkDir, bin_dir)

        if not self.pi.current_is_x86():
            arch_subdir = self.pi.current_dir(x64=True)
            path = 'Bin%s' % arch_subdir
            yield os.path.join(self.si.WindowsSdkDir, path)

        if self.vc_ver == 10.0 or self.vc_ver == 11.0:
            if self.pi.target_is_x86():
                arch_subdir = ''
            else:
                arch_subdir = self.pi.current_dir(hidex86=True, x64=True)
            path = r'Bin\NETFX 4.0 Tools%s' % arch_subdir
            yield os.path.join(self.si.WindowsSdkDir, path)

        elif self.vc_ver >= 15.0:
            path = os.path.join(self.si.WindowsSdkDir, 'Bin')
            arch_subdir = self.pi.current_dir(x64=True)
            sdkver = self.si.WindowsSdkLastVersion
            yield os.path.join(path, '%s%s' % (sdkver, arch_subdir))

        if self.si.WindowsSDKExecutablePath:
            yield self.si.WindowsSDKExecutablePath

    @property
    def _sdk_subdir(self):
        """
        Microsoft Windows SDK version subdir
        """
        ucrtver = self.si.WindowsSdkLastVersion
        return ('%s\\' % ucrtver) if ucrtver else ''

    @property
    def SdkSetup(self):
        """
        Microsoft Windows SDK Setup
        """
        if self.vc_ver > 9.0:
            return []

        return [os.path.join(self.si.WindowsSdkDir, 'Setup')]

    @property
    def FxTools(self):
        """
        Microsoft .NET Framework Tools
        """
        pi = self.pi
        si = self.si

        if self.vc_ver <= 10.0:
            include32 = True
            include64 = not pi.target_is_x86() and not pi.current_is_x86()
        else:
            include32 = pi.target_is_x86() or pi.current_is_x86()
            include64 = pi.current_cpu == 'amd64' or pi.target_cpu == 'amd64'

        tools = []
        if include32:
            tools += [os.path.join(si.FrameworkDir32, ver)
                      for ver in si.FrameworkVersion32]
        if include64:
            tools += [os.path.join(si.FrameworkDir64, ver)
                      for ver in si.FrameworkVersion64]
        return tools

    @property
    def NetFxSDKLibraries(self):
        """
        Microsoft .Net Framework SDK Libraries
        """
        if self.vc_ver < 14.0 or not self.si.NetFxSdkDir:
            return []

        arch_subdir = self.pi.target_dir(x64=True)
        return [os.path.join(self.si.NetFxSdkDir, r'lib\um%s' % arch_subdir)]

    @property
    def NetFxSDKIncludes(self):
        """
        Microsoft .Net Framework SDK Includes
        """
        if self.vc_ver < 14.0 or not self.si.NetFxSdkDir:
            return []

        return [os.path.join(self.si.NetFxSdkDir, r'include\um')]

    @property
    def VsTDb(self):
        """
        Microsoft Visual Studio Team System Database
        """
        return [os.path.join(self.si.VSInstallDir, r'VSTSDB\Deploy')]

    @property
    def MSBuild(self):
        """
        Microsoft Build Engine
        """
        if self.vc_ver < 12.0:
            return []
        elif self.vc_ver < 15.0:
            base_path = self.si.ProgramFilesx86
            arch_subdir = self.pi.current_dir(hidex86=True)
        else:
            base_path = self.si.VSInstallDir
            arch_subdir = ''

        path = r'MSBuild\%0.1f\bin%s' % (self.vc_ver, arch_subdir)
        build = [os.path.join(base_path, path)]

        if self.vc_ver >= 15.0:
            # Add Roslyn C# & Visual Basic Compiler
            build += [os.path.join(base_path, path, 'Roslyn')]

        return build

    @property
    def HTMLHelpWorkshop(self):
        """
        Microsoft HTML Help Workshop
        """
        if self.vc_ver < 11.0:
            return []

        return [os.path.join(self.si.ProgramFilesx86, 'HTML Help Workshop')]

    @property
    def UCRTLibraries(self):
        """
        Microsoft Universal C Runtime SDK Libraries
        """
        if self.vc_ver < 14.0:
            return []

        arch_subdir = self.pi.target_dir(x64=True)
        lib = os.path.join(self.si.UniversalCRTSdkDir, 'lib')
        ucrtver = self._ucrt_subdir
        return [os.path.join(lib, '%sucrt%s' % (ucrtver, arch_subdir))]

    @property
    def UCRTIncludes(self):
        """
        Microsoft Universal C Runtime SDK Include
        """
        if self.vc_ver < 14.0:
            return []

        include = os.path.join(self.si.UniversalCRTSdkDir, 'include')
        return [os.path.join(include, '%sucrt' % self._ucrt_subdir)]

    @property
    def _ucrt_subdir(self):
        """
        Microsoft Universal C Runtime SDK version subdir
        """
        ucrtver = self.si.UniversalCRTSdkLastVersion
        return ('%s\\' % ucrtver) if ucrtver else ''

    @property
    def FSharp(self):
        """
        Microsoft Visual F#
        """
        if self.vc_ver < 11.0 and self.vc_ver > 12.0:
            return []

        return self.si.FSharpInstallDir

    @property
    def VCRuntimeRedist(self):
        """
        Microsoft Visual C++ runtime redistribuable dll
        """
        arch_subdir = self.pi.target_dir(x64=True)
        if self.vc_ver < 15:
            redist_path = self.si.VCInstallDir
            vcruntime = 'redist%s\\Microsoft.VC%d0.CRT\\vcruntime%d0.dll'
        else:
            redist_path = self.si.VCInstallDir.replace('\\Tools', '\\Redist')
            vcruntime = 'onecore%s\\Microsoft.VC%d0.CRT\\vcruntime%d0.dll'

        # Visual Studio 2017  is still Visual C++ 14.0
        dll_ver = 14.0 if self.vc_ver == 15 else self.vc_ver

        vcruntime = vcruntime % (arch_subdir, self.vc_ver, dll_ver)
        return os.path.join(redist_path, vcruntime)

    def return_env(self, exists=True):
        """
        Return environment dict.

        Parameters
        ----------
        exists: bool
            It True, only return existing paths.
        """
        env = dict(
            include=self._build_paths('include',
                                      [self.VCIncludes,
                                       self.OSIncludes,
                                       self.UCRTIncludes,
                                       self.NetFxSDKIncludes],
                                      exists),
            lib=self._build_paths('lib',
                                  [self.VCLibraries,
                                   self.OSLibraries,
                                   self.FxTools,
                                   self.UCRTLibraries,
                                   self.NetFxSDKLibraries],
                                  exists),
            libpath=self._build_paths('libpath',
                                      [self.VCLibraries,
                                       self.FxTools,
                                       self.VCStoreRefs,
                                       self.OSLibpath],
                                      exists),
            path=self._build_paths('path',
                                   [self.VCTools,
                                    self.VSTools,
                                    self.VsTDb,
                                    self.SdkTools,
                                    self.SdkSetup,
                                    self.FxTools,
                                    self.MSBuild,
                                    self.HTMLHelpWorkshop,
                                    self.FSharp],
                                   exists),
        )
        if self.vc_ver >= 14 and os.path.isfile(self.VCRuntimeRedist):
            env['py_vcruntime_redist'] = self.VCRuntimeRedist
        return env

    def _build_paths(self, name, spec_path_lists, exists):
        """
        Given an environment variable name and specified paths,
        return a pathsep-separated string of paths containing
        unique, extant, directories from those paths and from
        the environment variable. Raise an error if no paths
        are resolved.
        """
        # flatten spec_path_lists
        spec_paths = itertools.chain.from_iterable(spec_path_lists)
        env_paths = safe_env.get(name, '').split(os.pathsep)
        paths = itertools.chain(spec_paths, env_paths)
        extant_paths = list(filter(os.path.isdir, paths)) if exists else paths
        if not extant_paths:
            msg = "%s environment variable is empty" % name.upper()
            raise distutils.errors.DistutilsPlatformError(msg)
        unique_paths = self._unique_everseen(extant_paths)
        return os.pathsep.join(unique_paths)

    # from Python docs
    def _unique_everseen(self, iterable, key=None):
        """
        List unique elements, preserving order.
        Remember all elements ever seen.

        _unique_everseen('AAAABBBCCDAABBB') --> A B C D

        _unique_everseen('ABBCcAD', str.lower) --> A B C D
        """
        seen = set()
        seen_add = seen.add
        if key is None:
            for element in filterfalse(seen.__contains__, iterable):
                seen_add(element)
                yield element
        else:
            for element in iterable:
                k = key(element)
                if k not in seen:
                    seen_add(k)
                    yield element
