"""
Copyright Jason R. Coombs

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to
deal in the Software without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.
"""

import io
import posixpath
import zipfile
import itertools
import contextlib
import pathlib


__all__ = ['Path']


def _parents(path):
    """
    Given a path with elements separated by
    posixpath.sep, generate all parents of that path.

    >>> list(_parents('b/d'))
    ['b']
    >>> list(_parents('/b/d/'))
    ['/b']
    >>> list(_parents('b/d/f/'))
    ['b/d', 'b']
    >>> list(_parents('b'))
    []
    >>> list(_parents(''))
    []
    """
    return itertools.islice(_ancestry(path), 1, None)


def _ancestry(path):
    """
    Given a path with elements separated by
    posixpath.sep, generate all elements of that path

    >>> list(_ancestry('b/d'))
    ['b/d', 'b']
    >>> list(_ancestry('/b/d/'))
    ['/b/d', '/b']
    >>> list(_ancestry('b/d/f/'))
    ['b/d/f', 'b/d', 'b']
    >>> list(_ancestry('b'))
    ['b']
    >>> list(_ancestry(''))
    []
    """
    path = path.rstrip(posixpath.sep)
    while path and path != posixpath.sep:
        yield path
        path, tail = posixpath.split(path)


_dedupe = dict.fromkeys
"""Deduplicate an iterable in original order"""


def _difference(minuend, subtrahend):
    """
    Return items in minuend not in subtrahend, retaining order
    with O(1) lookup.
    """
    return itertools.filterfalse(set(subtrahend).__contains__, minuend)


class CompleteDirs(zipfile.ZipFile):
    """
    A ZipFile subclass that ensures that implied directories
    are always included in the namelist.
    """

    @staticmethod
    def _implied_dirs(names):
        parents = itertools.chain.from_iterable(map(_parents, names))
        as_dirs = (p + posixpath.sep for p in parents)
        return _dedupe(_difference(as_dirs, names))

    def namelist(self):
        names = super(CompleteDirs, self).namelist()
        return names + list(self._implied_dirs(names))

    def _name_set(self):
        return set(self.namelist())

    def resolve_dir(self, name):
        """
        If the name represents a directory, return that name
        as a directory (with the trailing slash).
        """
        names = self._name_set()
        dirname = name + '/'
        dir_match = name not in names and dirname in names
        return dirname if dir_match else name

    @classmethod
    def make(cls, source):
        """
        Given a source (filename or zipfile), return an
        appropriate CompleteDirs subclass.
        """
        if isinstance(source, CompleteDirs):
            return source

        if not isinstance(source, zipfile.ZipFile):
            return cls(source)

        # Only allow for FastLookup when supplied zipfile is read-only
        if 'r' not in source.mode:
            cls = CompleteDirs

        source.__class__ = cls
        return source


class FastLookup(CompleteDirs):
    """
    ZipFile subclass to ensure implicit
    dirs exist and are resolved rapidly.
    """

    def namelist(self):
        with contextlib.suppress(AttributeError):
            return self.__names
        self.__names = super(FastLookup, self).namelist()
        return self.__names

    def _name_set(self):
        with contextlib.suppress(AttributeError):
            return self.__lookup
        self.__lookup = super(FastLookup, self)._name_set()
        return self.__lookup


class Path:
    """
    A pathlib-compatible interface for zip files.

    Consider a zip file with this structure::

        .
        ├── a.txt
        └── b
            ├── c.txt
            └── d
                └── e.txt

    >>> data = io.BytesIO()
    >>> zf = zipfile.ZipFile(data, 'w')
    >>> zf.writestr('a.txt', 'content of a')
    >>> zf.writestr('b/c.txt', 'content of c')
    >>> zf.writestr('b/d/e.txt', 'content of e')
    >>> zf.filename = 'mem/abcde.zip'

    Path accepts the zipfile object itself or a filename

    >>> root = Path(zf)

    From there, several path operations are available.

    Directory iteration (including the zip file itself):

    >>> a, b = root.iterdir()
    >>> a
    Path('mem/abcde.zip', 'a.txt')
    >>> b
    Path('mem/abcde.zip', 'b/')

    name property:

    >>> b.name
    'b'

    join with divide operator:

    >>> c = b / 'c.txt'
    >>> c
    Path('mem/abcde.zip', 'b/c.txt')
    >>> c.name
    'c.txt'

    Read text:

    >>> c.read_text()
    'content of c'

    existence:

    >>> c.exists()
    True
    >>> (b / 'missing.txt').exists()
    False

    Coercion to string:

    >>> import os
    >>> str(c).replace(os.sep, posixpath.sep)
    'mem/abcde.zip/b/c.txt'

    At the root, ``name``, ``filename``, and ``parent``
    resolve to the zipfile. Note these attributes are not
    valid and will raise a ``ValueError`` if the zipfile
    has no filename.

    >>> root.name
    'abcde.zip'
    >>> str(root.filename).replace(os.sep, posixpath.sep)
    'mem/abcde.zip'
    >>> str(root.parent)
    'mem'
    """

    __repr = "{self.__class__.__name__}({self.root.filename!r}, {self.at!r})"

    def __init__(self, root, at=""):
        """
        Construct a Path from a ZipFile or filename.

        Note: When the source is an existing ZipFile object,
        its type (__class__) will be mutated to a
        specialized type. If the caller wishes to retain the
        original type, the caller should either create a
        separate ZipFile object or pass a filename.
        """
        self.root = FastLookup.make(root)
        self.at = at

    def open(self, mode='r', *args, pwd=None, **kwargs):
        """
        Open this entry as text or binary following the semantics
        of ``pathlib.Path.open()`` by passing arguments through
        to io.TextIOWrapper().
        """
        if self.is_dir():
            raise IsADirectoryError(self)
        zip_mode = mode[0]
        if not self.exists() and zip_mode == 'r':
            raise FileNotFoundError(self)
        stream = self.root.open(self.at, zip_mode, pwd=pwd)
        if 'b' in mode:
            if args or kwargs:
                raise ValueError("encoding args invalid for binary operation")
            return stream
        return io.TextIOWrapper(stream, *args, **kwargs)

    @property
    def name(self):
        return pathlib.Path(self.at).name or self.filename.name

    @property
    def suffix(self):
        return pathlib.Path(self.at).suffix or self.filename.suffix

    @property
    def suffixes(self):
        return pathlib.Path(self.at).suffixes or self.filename.suffixes

    @property
    def stem(self):
        return pathlib.Path(self.at).stem or self.filename.stem

    @property
    def filename(self):
        return pathlib.Path(self.root.filename).joinpath(self.at)

    def read_text(self, *args, **kwargs):
        with self.open('r', *args, **kwargs) as strm:
            return strm.read()

    def read_bytes(self):
        with self.open('rb') as strm:
            return strm.read()

    def _is_child(self, path):
        return posixpath.dirname(path.at.rstrip("/")) == self.at.rstrip("/")

    def _next(self, at):
        return self.__class__(self.root, at)

    def is_dir(self):
        return not self.at or self.at.endswith("/")

    def is_file(self):
        return self.exists() and not self.is_dir()

    def exists(self):
        return self.at in self.root._name_set()

    def iterdir(self):
        if not self.is_dir():
            raise ValueError("Can't listdir a file")
        subs = map(self._next, self.root.namelist())
        return filter(self._is_child, subs)

    def __str__(self):
        return posixpath.join(self.root.filename, self.at)

    def __repr__(self):
        return self.__repr.format(self=self)

    def joinpath(self, *other):
        next = posixpath.join(self.at, *other)
        return self._next(self.root.resolve_dir(next))

    __truediv__ = joinpath

    @property
    def parent(self):
        if not self.at:
            return self.filename.parent
        parent_at = posixpath.dirname(self.at.rstrip('/'))
        if parent_at:
            parent_at += '/'
        return self._next(parent_at)