"""Filename globbing utility."""

import contextlib
import os
import re
import fnmatch
import functools
import itertools
import operator
import stat
import sys


__all__ = ["glob", "iglob", "escape", "translate"]

def glob(pathname, *, root_dir=None, dir_fd=None, recursive=False,
        include_hidden=False):
    """Return a list of paths matching a `pathname` pattern.

    The pattern may contain simple shell-style wildcards a la
    fnmatch. Unlike fnmatch, filenames starting with a
    dot are special cases that are not matched by '*' and '?'
    patterns by default.

    The order of the returned list is undefined. Sort it if you need a
    particular order.

    If `root_dir` is not None, it should be a path-like object specifying
    the root directory for searching.  It has the same effect as changing
    the current directory before calling it (without actually changing it).
    If pathname is relative, the result will contain paths relative to
    `root_dir`.

    If `dir_fd` is not None, it should be a file descriptor referring to a
    directory, and paths will then be relative to that directory.

    If `include_hidden` is true, wildcards can match path segments beginning
    with a dot ('.').

    If `recursive` is true, the pattern '**' will match any files and
    zero or more directories and subdirectories.
    """
    return list(iglob(pathname, root_dir=root_dir, dir_fd=dir_fd, recursive=recursive,
                      include_hidden=include_hidden))

def iglob(pathname, *, root_dir=None, dir_fd=None, recursive=False,
          include_hidden=False):
    """Return an iterator which yields the paths matching a `pathname` pattern.

    The pattern may contain simple shell-style wildcards a la
    fnmatch. However, unlike fnmatch, filenames starting with a
    dot are special cases that are not matched by '*' and '?'
    patterns.

    The order of the returned paths is undefined. Sort them if you need a
    particular order.

    If `root_dir` is not None, it should be a path-like object specifying
    the root directory for searching.  It has the same effect as changing
    the current directory before calling it (without actually changing it).
    If pathname is relative, the result will contain paths relative to
    `root_dir`.

    If `dir_fd` is not None, it should be a file descriptor referring to a
    directory, and paths will then be relative to that directory.

    If `include_hidden` is true, wildcards can match path segments beginning
    with a dot ('.').

    If `recursive` is true, the pattern '**' will match any files and
    zero or more directories and subdirectories.
    """
    sys.audit("glob.glob", pathname, recursive)
    sys.audit("glob.glob/2", pathname, recursive, root_dir, dir_fd)
    if root_dir is not None:
        root_dir = os.fspath(root_dir)
    else:
        root_dir = pathname[:0]
    it = _iglob(pathname, root_dir, dir_fd, recursive, False,
                include_hidden=include_hidden)
    if not pathname or recursive and _isrecursive(pathname[:2]):
        try:
            s = next(it)  # skip empty string
            if s:
                it = itertools.chain((s,), it)
        except StopIteration:
            pass
    return it

def _iglob(pathname, root_dir, dir_fd, recursive, dironly,
           include_hidden=False):
    dirname, basename = os.path.split(pathname)
    if not has_magic(pathname):
        assert not dironly
        if basename:
            if _lexists(_join(root_dir, pathname), dir_fd):
                yield pathname
        else:
            # Patterns ending with a slash should match only directories
            if _isdir(_join(root_dir, dirname), dir_fd):
                yield pathname
        return
    if not dirname:
        if recursive and _isrecursive(basename):
            yield from _glob2(root_dir, basename, dir_fd, dironly,
                             include_hidden=include_hidden)
        else:
            yield from _glob1(root_dir, basename, dir_fd, dironly,
                              include_hidden=include_hidden)
        return
    # `os.path.split()` returns the argument itself as a dirname if it is a
    # drive or UNC path.  Prevent an infinite recursion if a drive or UNC path
    # contains magic characters (i.e. r'\\?\C:').
    if dirname != pathname and has_magic(dirname):
        dirs = _iglob(dirname, root_dir, dir_fd, recursive, True,
                      include_hidden=include_hidden)
    else:
        dirs = [dirname]
    if has_magic(basename):
        if recursive and _isrecursive(basename):
            glob_in_dir = _glob2
        else:
            glob_in_dir = _glob1
    else:
        glob_in_dir = _glob0
    for dirname in dirs:
        for name in glob_in_dir(_join(root_dir, dirname), basename, dir_fd, dironly,
                               include_hidden=include_hidden):
            yield os.path.join(dirname, name)

# These 2 helper functions non-recursively glob inside a literal directory.
# They return a list of basenames.  _glob1 accepts a pattern while _glob0
# takes a literal basename (so it only has to check for its existence).

def _glob1(dirname, pattern, dir_fd, dironly, include_hidden=False):
    names = _listdir(dirname, dir_fd, dironly)
    if not (include_hidden or _ishidden(pattern)):
        names = (x for x in names if not _ishidden(x))
    return fnmatch.filter(names, pattern)

def _glob0(dirname, basename, dir_fd, dironly, include_hidden=False):
    if basename:
        if _lexists(_join(dirname, basename), dir_fd):
            return [basename]
    else:
        # `os.path.split()` returns an empty basename for paths ending with a
        # directory separator.  'q*x/' should match only directories.
        if _isdir(dirname, dir_fd):
            return [basename]
    return []

# This helper function recursively yields relative pathnames inside a literal
# directory.

def _glob2(dirname, pattern, dir_fd, dironly, include_hidden=False):
    assert _isrecursive(pattern)
    if not dirname or _isdir(dirname, dir_fd):
        yield pattern[:0]
    yield from _rlistdir(dirname, dir_fd, dironly,
                         include_hidden=include_hidden)

# If dironly is false, yields all file names inside a directory.
# If dironly is true, yields only directory names.
def _iterdir(dirname, dir_fd, dironly):
    try:
        fd = None
        fsencode = None
        if dir_fd is not None:
            if dirname:
                fd = arg = os.open(dirname, _dir_open_flags, dir_fd=dir_fd)
            else:
                arg = dir_fd
            if isinstance(dirname, bytes):
                fsencode = os.fsencode
        elif dirname:
            arg = dirname
        elif isinstance(dirname, bytes):
            arg = bytes(os.curdir, 'ASCII')
        else:
            arg = os.curdir
        try:
            with os.scandir(arg) as it:
                for entry in it:
                    try:
                        if not dironly or entry.is_dir():
                            if fsencode is not None:
                                yield fsencode(entry.name)
                            else:
                                yield entry.name
                    except OSError:
                        pass
        finally:
            if fd is not None:
                os.close(fd)
    except OSError:
        return

def _listdir(dirname, dir_fd, dironly):
    with contextlib.closing(_iterdir(dirname, dir_fd, dironly)) as it:
        return list(it)

# Recursively yields relative pathnames inside a literal directory.
def _rlistdir(dirname, dir_fd, dironly, include_hidden=False):
    names = _listdir(dirname, dir_fd, dironly)
    for x in names:
        if include_hidden or not _ishidden(x):
            yield x
            path = _join(dirname, x) if dirname else x
            for y in _rlistdir(path, dir_fd, dironly,
                               include_hidden=include_hidden):
                yield _join(x, y)


def _lexists(pathname, dir_fd):
    # Same as os.path.lexists(), but with dir_fd
    if dir_fd is None:
        return os.path.lexists(pathname)
    try:
        os.lstat(pathname, dir_fd=dir_fd)
    except (OSError, ValueError):
        return False
    else:
        return True

def _isdir(pathname, dir_fd):
    # Same as os.path.isdir(), but with dir_fd
    if dir_fd is None:
        return os.path.isdir(pathname)
    try:
        st = os.stat(pathname, dir_fd=dir_fd)
    except (OSError, ValueError):
        return False
    else:
        return stat.S_ISDIR(st.st_mode)

def _join(dirname, basename):
    # It is common if dirname or basename is empty
    if not dirname or not basename:
        return dirname or basename
    return os.path.join(dirname, basename)

magic_check = re.compile('([*?[])')
magic_check_bytes = re.compile(b'([*?[])')

def has_magic(s):
    if isinstance(s, bytes):
        match = magic_check_bytes.search(s)
    else:
        match = magic_check.search(s)
    return match is not None

def _ishidden(path):
    return path[0] in ('.', b'.'[0])

def _isrecursive(pattern):
    if isinstance(pattern, bytes):
        return pattern == b'**'
    else:
        return pattern == '**'

def escape(pathname):
    """Escape all special characters.
    """
    # Escaping is done by wrapping any of "*?[" between square brackets.
    # Metacharacters do not work in the drive part and shouldn't be escaped.
    drive, pathname = os.path.splitdrive(pathname)
    if isinstance(pathname, bytes):
        pathname = magic_check_bytes.sub(br'[\1]', pathname)
    else:
        pathname = magic_check.sub(r'[\1]', pathname)
    return drive + pathname


_special_parts = ('', '.', '..')
_dir_open_flags = os.O_RDONLY | getattr(os, 'O_DIRECTORY', 0)
_no_recurse_symlinks = object()


def translate(pat, *, recursive=False, include_hidden=False, seps=None):
    """Translate a pathname with shell wildcards to a regular expression.

    If `recursive` is true, the pattern segment '**' will match any number
    of path segments.

    If `include_hidden` is true, wildcards can match path segments beginning
    with a dot ('.').

    If a sequence of separator characters is given to `seps`, they will be
    used to split the pattern into segments and match path separators.  If
    not given, os.path.sep and os.path.altsep (where available) are used.
    """
    if not seps:
        if os.path.altsep:
            seps = (os.path.sep, os.path.altsep)
        else:
            seps = os.path.sep
    escaped_seps = ''.join(map(re.escape, seps))
    any_sep = f'[{escaped_seps}]' if len(seps) > 1 else escaped_seps
    not_sep = f'[^{escaped_seps}]'
    if include_hidden:
        one_last_segment = f'{not_sep}+'
        one_segment = f'{one_last_segment}{any_sep}'
        any_segments = f'(?:.+{any_sep})?'
        any_last_segments = '.*'
    else:
        one_last_segment = f'[^{escaped_seps}.]{not_sep}*'
        one_segment = f'{one_last_segment}{any_sep}'
        any_segments = f'(?:{one_segment})*'
        any_last_segments = f'{any_segments}(?:{one_last_segment})?'

    results = []
    parts = re.split(any_sep, pat)
    last_part_idx = len(parts) - 1
    for idx, part in enumerate(parts):
        if part == '*':
            results.append(one_segment if idx < last_part_idx else one_last_segment)
        elif recursive and part == '**':
            if idx < last_part_idx:
                if parts[idx + 1] != '**':
                    results.append(any_segments)
            else:
                results.append(any_last_segments)
        else:
            if part:
                if not include_hidden and part[0] in '*?':
                    results.append(r'(?!\.)')
                results.extend(fnmatch._translate(part, f'{not_sep}*', not_sep)[0])
            if idx < last_part_idx:
                results.append(any_sep)
    res = ''.join(results)
    return fr'(?s:{res})\z'


@functools.lru_cache(maxsize=512)
def _compile_pattern(pat, seps, case_sensitive, recursive=True):
    """Compile given glob pattern to a re.Pattern object (observing case
    sensitivity)."""
    flags = re.NOFLAG if case_sensitive else re.IGNORECASE
    regex = translate(pat, recursive=recursive, include_hidden=True, seps=seps)
    return re.compile(regex, flags=flags).match


class _GlobberBase:
    """Abstract class providing shell-style pattern matching and globbing.
    """

    def __init__(self, sep, case_sensitive, case_pedantic=False, recursive=False):
        self.sep = sep
        self.case_sensitive = case_sensitive
        self.case_pedantic = case_pedantic
        self.recursive = recursive

    # Abstract methods

    @staticmethod
    def lexists(path):
        """Implements os.path.lexists().
        """
        raise NotImplementedError

    @staticmethod
    def scandir(path):
        """Like os.scandir(), but generates (entry, name, path) tuples.
        """
        raise NotImplementedError

    @staticmethod
    def concat_path(path, text):
        """Implements path concatenation.
        """
        raise NotImplementedError

    @staticmethod
    def stringify_path(path):
        """Converts the path to a string object
        """
        raise NotImplementedError

    # High-level methods

    def compile(self, pat, altsep=None):
        seps = (self.sep, altsep) if altsep else self.sep
        return _compile_pattern(pat, seps, self.case_sensitive, self.recursive)

    def selector(self, parts):
        """Returns a function that selects from a given path, walking and
        filtering according to the glob-style pattern parts in *parts*.
        """
        if not parts:
            return self.select_exists
        part = parts.pop()
        if self.recursive and part == '**':
            selector = self.recursive_selector
        elif part in _special_parts:
            selector = self.special_selector
        elif not self.case_pedantic and magic_check.search(part) is None:
            selector = self.literal_selector
        else:
            selector = self.wildcard_selector
        return selector(part, parts)

    def special_selector(self, part, parts):
        """Returns a function that selects special children of the given path.
        """
        if parts:
            part += self.sep
        select_next = self.selector(parts)

        def select_special(path, exists=False):
            path = self.concat_path(path, part)
            return select_next(path, exists)
        return select_special

    def literal_selector(self, part, parts):
        """Returns a function that selects a literal descendant of a path.
        """

        # Optimization: consume and join any subsequent literal parts here,
        # rather than leaving them for the next selector. This reduces the
        # number of string concatenation operations.
        while parts and magic_check.search(parts[-1]) is None:
            part += self.sep + parts.pop()
        if parts:
            part += self.sep

        select_next = self.selector(parts)

        def select_literal(path, exists=False):
            path = self.concat_path(path, part)
            return select_next(path, exists=False)
        return select_literal

    def wildcard_selector(self, part, parts):
        """Returns a function that selects direct children of a given path,
        filtering by pattern.
        """

        match = None if part == '*' else self.compile(part)
        dir_only = bool(parts)
        if dir_only:
            select_next = self.selector(parts)

        def select_wildcard(path, exists=False):
            try:
                entries = self.scandir(path)
            except OSError:
                pass
            else:
                for entry, entry_name, entry_path in entries:
                    if match is None or match(entry_name):
                        if dir_only:
                            try:
                                if not entry.is_dir():
                                    continue
                            except OSError:
                                continue
                            entry_path = self.concat_path(entry_path, self.sep)
                            yield from select_next(entry_path, exists=True)
                        else:
                            yield entry_path
        return select_wildcard

    def recursive_selector(self, part, parts):
        """Returns a function that selects a given path and all its children,
        recursively, filtering by pattern.
        """
        # Optimization: consume following '**' parts, which have no effect.
        while parts and parts[-1] == '**':
            parts.pop()

        # Optimization: consume and join any following non-special parts here,
        # rather than leaving them for the next selector. They're used to
        # build a regular expression, which we use to filter the results of
        # the recursive walk. As a result, non-special pattern segments
        # following a '**' wildcard don't require additional filesystem access
        # to expand.
        follow_symlinks = self.recursive is not _no_recurse_symlinks
        if follow_symlinks:
            while parts and parts[-1] not in _special_parts:
                part += self.sep + parts.pop()

        match = None if part == '**' else self.compile(part)
        dir_only = bool(parts)
        select_next = self.selector(parts)

        def select_recursive(path, exists=False):
            path_str = self.stringify_path(path)
            match_pos = len(path_str)
            if match is None or match(path_str, match_pos):
                yield from select_next(path, exists)
            stack = [path]
            while stack:
                yield from select_recursive_step(stack, match_pos)

        def select_recursive_step(stack, match_pos):
            path = stack.pop()
            try:
                entries = self.scandir(path)
            except OSError:
                pass
            else:
                for entry, _entry_name, entry_path in entries:
                    is_dir = False
                    try:
                        if entry.is_dir(follow_symlinks=follow_symlinks):
                            is_dir = True
                    except OSError:
                        pass

                    if is_dir or not dir_only:
                        entry_path_str = self.stringify_path(entry_path)
                        if dir_only:
                            entry_path = self.concat_path(entry_path, self.sep)
                        if match is None or match(entry_path_str, match_pos):
                            if dir_only:
                                yield from select_next(entry_path, exists=True)
                            else:
                                # Optimization: directly yield the path if this is
                                # last pattern part.
                                yield entry_path
                        if is_dir:
                            stack.append(entry_path)

        return select_recursive

    def select_exists(self, path, exists=False):
        """Yields the given path, if it exists.
        """
        if exists:
            # Optimization: this path is already known to exist, e.g. because
            # it was returned from os.scandir(), so we skip calling lstat().
            yield path
        elif self.lexists(path):
            yield path


class _StringGlobber(_GlobberBase):
    """Provides shell-style pattern matching and globbing for string paths.
    """
    lexists = staticmethod(os.path.lexists)
    concat_path = operator.add

    @staticmethod
    def scandir(path):
        # We must close the scandir() object before proceeding to
        # avoid exhausting file descriptors when globbing deep trees.
        with os.scandir(path) as scandir_it:
            entries = list(scandir_it)
        return ((entry, entry.name, entry.path) for entry in entries)

    @staticmethod
    def stringify_path(path):
        return path  # Already a string.
