import os
import platform

if os.name == 'nt':
    import sys
    if sys.version_info < (3,):
        import _winreg as winreg
    else:
        import winreg


def _reg_open_key(key, subkey):
    try:
        return winreg.OpenKey(key, subkey)
    except WindowsError, OSError:
        if platform.architecture()[0] == '32bit':
            bitness_sam = winreg.KEY_WOW64_64KEY
        else:
            bitness_sam = winreg.KEY_WOW64_32KEY
        return winreg.OpenKey(key, subkey, 0, winreg.KEY_READ | bitness_sam)


def _reg_open_key_bits(key, subkey, bits):
    sam = winreg.KEY_READ

    if platform.architecture()[0] == '32bit':
        if bits == '64':
            # Force 32bit process to search in 64bit registry
            sam |= winreg.KEY_WOW64_64KEY
    else:
        if bits == '32':
            # Force 64bit process to search in 32bit registry
            sam |= winreg.KEY_WOW64_32KEY

    return winreg.OpenKey(key, subkey, 0, sam)


def _find_mono_in_reg(subkey, bits):
    try:
        with _reg_open_key_bits(winreg.HKEY_LOCAL_MACHINE, subkey, bits) as hKey:
            value, regtype = winreg.QueryValueEx(hKey, 'SdkInstallRoot')
            return value
    except WindowsError, OSError:
        return None


def _find_mono_in_reg_old(subkey, bits):
    try:
        with _reg_open_key_bits(winreg.HKEY_LOCAL_MACHINE, subkey, bits) as hKey:
            default_clr, regtype = winreg.QueryValueEx(hKey, 'DefaultCLR')
            if default_clr:
                return _find_mono_in_reg(subkey + '\\' + default_clr, bits)
            return None
    except (WindowsError, EnvironmentError):
        return None


def find_mono_root_dir(bits):
    root_dir = _find_mono_in_reg(r'SOFTWARE\Mono', bits)
    if root_dir is not None:
        return root_dir
    root_dir = _find_mono_in_reg_old(r'SOFTWARE\Novell\Mono', bits)
    if root_dir is not None:
        return root_dir
    return ''


def find_msbuild_tools_path_reg():
    import subprocess

    vswhere = os.getenv('PROGRAMFILES(X86)')
    if not vswhere:
        vswhere = os.getenv('PROGRAMFILES')
    vswhere += r'\Microsoft Visual Studio\Installer\vswhere.exe'

    vswhere_args = ['-latest', '-requires', 'Microsoft.Component.MSBuild']

    try:
        lines = subprocess.check_output([vswhere] + vswhere_args).splitlines()

        for line in lines:
            parts = line.split(':', 1)

            if len(parts) < 2 or parts[0] != 'installationPath':
                continue

            val = parts[1].strip()

            if not val:
                raise ValueError('Value of `installationPath` entry is empty')

            return os.path.join(val, "MSBuild\\15.0\\Bin")

        raise ValueError('Cannot find `installationPath` entry')
    except ValueError as e:
        print('Error reading output from vswhere: ' + e.message)
    except WindowsError:
        pass # Fine, vswhere not found
    except subprocess.CalledProcessError, OSError:
        pass

    # Try to find 14.0 in the Registry

    try:
        subkey = r'SOFTWARE\Microsoft\MSBuild\ToolsVersions\14.0'
        with _reg_open_key(winreg.HKEY_LOCAL_MACHINE, subkey) as hKey:
            value, regtype = winreg.QueryValueEx(hKey, 'MSBuildToolsPath')
            return value
    except WindowsError, OSError:
        return ''

    return ''