import os
import sys
import operator
import collections
import functools
import stat
from ctypes import (
    POINTER,
    byref,
    cast,
    create_unicode_buffer,
    create_string_buffer,
    windll,
)
from ctypes.wintypes import LPWSTR
import nt
import posixpath
import builtins

from jaraco.structures import binary

from jaraco.windows.error import WindowsError, handle_nonzero_success
import jaraco.windows.api.filesystem as api
from jaraco.windows import reparse


def mklink():
    """
    Like cmd.exe's mklink except it will infer directory status of the
    target.
    """
    from optparse import OptionParser

    parser = OptionParser(usage="usage: %prog [options] link target")
    parser.add_option(
        '-d',
        '--directory',
        help="Target is a directory (only necessary if not present)",
        action="store_true",
    )
    options, args = parser.parse_args()
    try:
        link, target = args
    except ValueError:
        parser.error("incorrect number of arguments")
    symlink(target, link, options.directory)
    sys.stdout.write("Symbolic link created: %(link)s --> %(target)s\n" % vars())


def _is_target_a_directory(link, rel_target):
    """
    If creating a symlink from link to a target, determine if target
    is a directory (relative to dirname(link)).
    """
    target = os.path.join(os.path.dirname(link), rel_target)
    return os.path.isdir(target)


def symlink(target, link, target_is_directory=False):
    """
    An implementation of os.symlink for Windows (Vista and greater)
    """
    target_is_directory = target_is_directory or _is_target_a_directory(link, target)
    # normalize the target (MS symlinks don't respect forward slashes)
    target = os.path.normpath(target)
    flags = target_is_directory | api.SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE
    handle_nonzero_success(api.CreateSymbolicLink(link, target, flags))


def link(target, link):
    """
    Establishes a hard link between an existing file and a new file.
    """
    handle_nonzero_success(api.CreateHardLink(link, target, None))


def is_reparse_point(path):
    """
    Determine if the given path is a reparse point.
    Return False if the file does not exist or the file attributes cannot
    be determined.
    """
    res = api.GetFileAttributes(path)
    return res != api.INVALID_FILE_ATTRIBUTES and bool(
        res & api.FILE_ATTRIBUTE_REPARSE_POINT
    )


def islink(path):
    "Determine if the given path is a symlink"
    return is_reparse_point(path) and is_symlink(path)


def _patch_path(path):
    r"""
    Paths have a max length of api.MAX_PATH characters (260). If a target path
    is longer than that, it needs to be made absolute and prepended with
    \\?\ in order to work with API calls.
    See http://msdn.microsoft.com/en-us/library/aa365247%28v=vs.85%29.aspx for
    details.
    """
    if path.startswith('\\\\?\\'):
        return path
    abs_path = os.path.abspath(path)
    if not abs_path[1] == ':':
        # python doesn't include the drive letter, but \\?\ requires it
        abs_path = os.getcwd()[:2] + abs_path
    return '\\\\?\\' + abs_path


def is_symlink(path):
    """
    Assuming path is a reparse point, determine if it's a symlink.
    """
    path = _patch_path(path)
    try:
        return _is_symlink(next(find_files(path)))
    # comment below workaround for PyCQA/pyflakes#376
    except WindowsError as orig_error:  # noqa: F841
        tmpl = "Error accessing {path}: {orig_error.message}"
        raise builtins.WindowsError(tmpl.format(**locals()))


def _is_symlink(find_data):
    return find_data.reserved[0] == api.IO_REPARSE_TAG_SYMLINK


def find_files(spec):
    r"""
    A pythonic wrapper around the FindFirstFile/FindNextFile win32 api.

    >>> root_files = tuple(find_files(r'c:\*'))
    >>> len(root_files) > 1
    True
    >>> root_files[0].filename == root_files[1].filename
    False

    This test might fail on a non-standard installation
    >>> 'Windows' in (fd.filename for fd in root_files)
    True
    """
    fd = api.WIN32_FIND_DATA()
    handle = api.FindFirstFile(spec, byref(fd))
    while True:
        if handle == api.INVALID_HANDLE_VALUE:
            raise WindowsError()
        yield fd
        fd = api.WIN32_FIND_DATA()
        res = api.FindNextFile(handle, byref(fd))
        if res == 0:  # error
            error = WindowsError()
            if error.code == api.ERROR_NO_MORE_FILES:
                break
            else:
                raise error
    # todo: how to close handle when generator is destroyed?
    # hint: catch GeneratorExit
    windll.kernel32.FindClose(handle)


def get_final_path(path):
    r"""
    For a given path, determine the ultimate location of that path.
    Useful for resolving symlink targets.
    This functions wraps the GetFinalPathNameByHandle from the Windows
    SDK.

    Note, this function fails if a handle cannot be obtained (such as
    for C:\Pagefile.sys on a stock windows system). Consider using
    trace_symlink_target instead.
    """
    desired_access = api.NULL
    share_mode = api.FILE_SHARE_READ | api.FILE_SHARE_WRITE | api.FILE_SHARE_DELETE
    security_attributes = api.LPSECURITY_ATTRIBUTES()  # NULL pointer
    hFile = api.CreateFile(
        path,
        desired_access,
        share_mode,
        security_attributes,
        api.OPEN_EXISTING,
        api.FILE_FLAG_BACKUP_SEMANTICS,
        api.NULL,
    )

    if hFile == api.INVALID_HANDLE_VALUE:
        raise WindowsError()

    buf_size = api.GetFinalPathNameByHandle(hFile, LPWSTR(), 0, api.VOLUME_NAME_DOS)
    handle_nonzero_success(buf_size)
    buf = create_unicode_buffer(buf_size)
    result_length = api.GetFinalPathNameByHandle(
        hFile, buf, len(buf), api.VOLUME_NAME_DOS
    )

    assert result_length < len(buf)
    handle_nonzero_success(result_length)
    handle_nonzero_success(api.CloseHandle(hFile))

    return buf[:result_length]


def compat_stat(path):
    """
    Generate stat as found on Python 3.2 and later.
    """
    stat = os.stat(path)
    info = get_file_info(path)
    # rewrite st_ino, st_dev, and st_nlink based on file info
    return nt.stat_result(
        (stat.st_mode,)
        + (info.file_index, info.volume_serial_number, info.number_of_links)
        + stat[4:]
    )


def samefile(f1, f2):
    """
    Backport of samefile from Python 3.2 with support for Windows.
    """
    return posixpath.samestat(compat_stat(f1), compat_stat(f2))


def get_file_info(path):
    # open the file the same way CPython does in posixmodule.c
    desired_access = api.FILE_READ_ATTRIBUTES
    share_mode = 0
    security_attributes = None
    creation_disposition = api.OPEN_EXISTING
    flags_and_attributes = (
        api.FILE_ATTRIBUTE_NORMAL
        | api.FILE_FLAG_BACKUP_SEMANTICS
        | api.FILE_FLAG_OPEN_REPARSE_POINT
    )
    template_file = None

    handle = api.CreateFile(
        path,
        desired_access,
        share_mode,
        security_attributes,
        creation_disposition,
        flags_and_attributes,
        template_file,
    )

    if handle == api.INVALID_HANDLE_VALUE:
        raise WindowsError()

    info = api.BY_HANDLE_FILE_INFORMATION()
    res = api.GetFileInformationByHandle(handle, info)
    handle_nonzero_success(res)
    handle_nonzero_success(api.CloseHandle(handle))

    return info


def GetBinaryType(filepath):
    res = api.DWORD()
    handle_nonzero_success(api._GetBinaryType(filepath, res))
    return res


def _make_null_terminated_list(obs):
    obs = _makelist(obs)
    if obs is None:
        return
    return u'\x00'.join(obs) + u'\x00\x00'


def _makelist(ob):
    if ob is None:
        return
    if not isinstance(ob, (list, tuple, set)):
        return [ob]
    return ob


def SHFileOperation(operation, from_, to=None, flags=[]):
    flags = functools.reduce(operator.or_, flags, 0)
    from_ = _make_null_terminated_list(from_)
    to = _make_null_terminated_list(to)
    params = api.SHFILEOPSTRUCT(0, operation, from_, to, flags)
    res = api._SHFileOperation(params)
    if res != 0:
        raise RuntimeError("SHFileOperation returned %d" % res)


def join(*paths):
    r"""
    Wrapper around os.path.join that works with Windows drive letters.

    >>> join('d:\\foo', '\\bar')
    'd:\\bar'
    """
    paths_with_drives = map(os.path.splitdrive, paths)
    drives, paths = zip(*paths_with_drives)
    # the drive we care about is the last one in the list
    drive = next(filter(None, reversed(drives)), '')
    return os.path.join(drive, os.path.join(*paths))


def resolve_path(target, start=os.path.curdir):
    r"""
    Find a path from start to target where target is relative to start.

    >>> tmp = str(getfixture('tmpdir_as_cwd'))

    >>> findpath('d:\\')
    'd:\\'

    >>> findpath('d:\\', tmp)
    'd:\\'

    >>> findpath('\\bar', 'd:\\')
    'd:\\bar'

    >>> findpath('\\bar', 'd:\\foo') # fails with '\\bar'
    'd:\\bar'

    >>> findpath('bar', 'd:\\foo')
    'd:\\foo\\bar'

    >>> findpath('\\baz', 'd:\\foo\\bar') # fails with '\\baz'
    'd:\\baz'

    >>> os.path.abspath(findpath('\\bar')).lower()
    'c:\\bar'

    >>> os.path.abspath(findpath('bar'))
    '...\\bar'

    >>> findpath('..', 'd:\\foo\\bar')
    'd:\\foo'

    The parent of the root directory is the root directory.
    >>> findpath('..', 'd:\\')
    'd:\\'
    """
    return os.path.normpath(join(start, target))


findpath = resolve_path


def trace_symlink_target(link):
    """
    Given a file that is known to be a symlink, trace it to its ultimate
    target.

    Raises TargetNotPresent when the target cannot be determined.
    Raises ValueError when the specified link is not a symlink.
    """

    if not is_symlink(link):
        raise ValueError("link must point to a symlink on the system")
    while is_symlink(link):
        orig = os.path.dirname(link)
        link = readlink(link)
        link = resolve_path(link, orig)
    return link


def readlink(link):
    """
    readlink(link) -> target
    Return a string representing the path to which the symbolic link points.
    """
    handle = api.CreateFile(
        link,
        0,
        0,
        None,
        api.OPEN_EXISTING,
        api.FILE_FLAG_OPEN_REPARSE_POINT | api.FILE_FLAG_BACKUP_SEMANTICS,
        None,
    )

    if handle == api.INVALID_HANDLE_VALUE:
        raise WindowsError()

    res = reparse.DeviceIoControl(handle, api.FSCTL_GET_REPARSE_POINT, None, 10240)

    bytes = create_string_buffer(res)
    p_rdb = cast(bytes, POINTER(api.REPARSE_DATA_BUFFER))
    rdb = p_rdb.contents
    if not rdb.tag == api.IO_REPARSE_TAG_SYMLINK:
        raise RuntimeError("Expected IO_REPARSE_TAG_SYMLINK, but got %d" % rdb.tag)

    handle_nonzero_success(api.CloseHandle(handle))
    return rdb.get_substitute_name()


def patch_os_module():
    """
    jaraco.windows provides the os.symlink and os.readlink functions.
    Monkey-patch the os module to include them if not present.
    """
    if not hasattr(os, 'symlink'):
        os.symlink = symlink
        os.path.islink = islink
    if not hasattr(os, 'readlink'):
        os.readlink = readlink


def find_symlinks(root):
    for dirpath, dirnames, filenames in os.walk(root):
        for name in dirnames + filenames:
            pathname = os.path.join(dirpath, name)
            if is_symlink(pathname):
                yield pathname
                # don't traverse symlinks
                if name in dirnames:
                    dirnames.remove(name)


def find_symlinks_cmd():
    """
    %prog [start-path]
    Search the specified path (defaults to the current directory) for symlinks,
    printing the source and target on each line.
    """
    from optparse import OptionParser
    from textwrap import dedent

    parser = OptionParser(usage=dedent(find_symlinks_cmd.__doc__).strip())
    options, args = parser.parse_args()
    if not args:
        args = ['.']
    root = args.pop()
    if args:
        parser.error("unexpected argument(s)")
    try:
        for symlink in find_symlinks(root):
            target = readlink(symlink)
            dir = ['', 'D'][os.path.isdir(symlink)]
            msg = '{dir:2}{symlink} --> {target}'.format(**locals())
            print(msg)
    except KeyboardInterrupt:
        pass


class FileAttributes(int, metaclass=binary.BitMask):

    # extract the values from the stat module on Python 3.5
    # and later.
    locals().update(
        (name.split('FILE_ATTRIBUTES_')[1].lower(), value)
        for name, value in vars(stat).items()
        if name.startswith('FILE_ATTRIBUTES_')
    )

    # For Python 3.4 and earlier, define the constants here
    archive = 0x20
    compressed = 0x800
    hidden = 0x2
    device = 0x40
    directory = 0x10
    encrypted = 0x4000
    normal = 0x80
    not_content_indexed = 0x2000
    offline = 0x1000
    read_only = 0x1
    reparse_point = 0x400
    sparse_file = 0x200
    system = 0x4
    temporary = 0x100
    virtual = 0x10000

    @classmethod
    def get(cls, filepath):
        attrs = api.GetFileAttributes(filepath)
        if attrs == api.INVALID_FILE_ATTRIBUTES:
            raise WindowsError()
        return cls(attrs)


GetFileAttributes = FileAttributes.get


def SetFileAttributes(filepath, *attrs):
    """
    Set file attributes. e.g.:

        SetFileAttributes('C:\\foo', 'hidden')

    Each attr must be either a numeric value, a constant defined in
    jaraco.windows.filesystem.api, or one of the nice names
    defined in this function.
    """
    nice_names = collections.defaultdict(
        lambda key: key,
        hidden='FILE_ATTRIBUTE_HIDDEN',
        read_only='FILE_ATTRIBUTE_READONLY',
    )
    flags = (getattr(api, nice_names[attr], attr) for attr in attrs)
    flags = functools.reduce(operator.or_, flags)
    handle_nonzero_success(api.SetFileAttributes(filepath, flags))