"""Manage the filesystem in a Zip archive.
"""

from __future__ import print_function
from __future__ import unicode_literals

import zipfile

from datetime import datetime

import six
from six import PY2

from . import errors
from .base import FS
from .compress import write_zip
from .enums import ResourceType, Seek
from .info import Info
from .iotools import RawWrapper
from .permissions import Permissions
from .memoryfs import MemoryFS
from .opener import open_fs
from .path import dirname, normpath, relpath
from .time import datetime_to_epoch
from .wrapfs import WrapFS


class _ZipExtFile(RawWrapper):

    def __init__(self, fs, name):
        self._zip = _zip = fs._zip
        self._end = _zip.getinfo(name).file_size
        self._pos = 0
        super(_ZipExtFile, self).__init__(_zip.open(name), 'r', name)

    def read(self, size=-1):
        buf = self._f.read(-1 if size is None else size)
        self._pos += len(buf)
        return buf

    def read1(self, size=-1):
        buf = self._f.read1(-1 if size is None else size)
        self._pos += len(buf)
        return buf

    def seek(self, offset, whence=Seek.set):
        """Change stream position.

        Change the stream position to the given byte offset. The
        offset is interpreted relative to the position indicated by
        ``whence``.

        Arguments:
            offset (int): the offset to the new position, in bytes.
            whence (int): the position reference. Possible values are:
                * `Seek.set`: start of stream (the default).
                * `Seek.current`: current position; offset may be negative.
                * `Seek.end`: end of stream; offset must be negative.

        Returns:
            int: the new absolute position.

        Raises:
            ValueError: when ``whence`` is not known, or ``offset``
                is invalid.

        Note:
            Zip compression does not support seeking, so the seeking
            is emulated. Seeking somewhere else than the current position
            will need to either:
                * reopen the file and restart decompression
                * read and discard data to advance in the file

        """
        if whence == Seek.current:
            offset += self._pos
        if whence == Seek.current or whence == Seek.set:
            if offset < 0:
                raise ValueError("Negative seek position {}".format(offset))
        elif whence == Seek.end:
            if offset > 0:
                raise ValueError("Positive seek position {}".format(offset))
            offset += self._end
        else:
            raise ValueError(
                "Invalid whence ({}, should be {}, {} or {})".format(
                    whence, Seek.set, Seek.current, Seek.end
                )
            )

        if offset < self._pos:
            self._f = self._zip.open(self.name)
            self._pos = 0
        self.read(offset - self._pos)
        return self._pos

    def tell(self):
        return self._pos


class ZipFS(WrapFS):
    """Read and write zip files.

    There are two ways to open a ZipFS for the use cases of reading
    a zip file, and creating a new one.

    If you open the ZipFS with  ``write`` set to `False` (the default)
    then the filesystem will be a read only filesystem which maps to
    the files and directories within the zip file. Files are
    decompressed on the fly when you open them.

    Here's how you might extract and print a readme from a zip file::

        with ZipFS('foo.zip') as zip_fs:
            readme = zip_fs.gettext('readme.txt')

    If you open the ZipFS with ``write`` set to `True`, then the ZipFS
    will be a empty temporary filesystem. Any files / directories you
    create in the ZipFS will be written in to a zip file when the ZipFS
    is closed.

    Here's how you might write a new zip file containing a readme.txt
    file::

        with ZipFS('foo.zip', write=True) as new_zip:
            new_zip.settext(
                'readme.txt',
                'This zip file was written by PyFilesystem'
            )


    Arguments:
        file (str or io.IOBase): An OS filename, or an open file object.
        write (bool, optional): Set to `True` to write a new zip file, or
            `False` (default) to read an existing zip file.
        compression (str, optional): Compression to use (one of the constants
            defined in the `zipfile` module in the stdlib).
        temp_fs (str, optional): An FS URL for the temporary
            filesystem used to store data prior to zipping.

    """

    def __new__(cls,
                file,
                write=False,
                compression=zipfile.ZIP_DEFLATED,
                encoding="utf-8",
                temp_fs="temp://__ziptemp__"):
        # This magic returns a different class instance based on the
        # value of the ``write`` parameter.
        if write:
            return WriteZipFS(file,
                              compression=compression,
                              encoding=encoding,
                              temp_fs=temp_fs)
        else:
            return ReadZipFS(file, encoding=encoding)


@six.python_2_unicode_compatible
class WriteZipFS(WrapFS):
    """A writable zip file.
    """

    def __init__(self,
                 file,
                 compression=zipfile.ZIP_DEFLATED,
                 encoding="utf-8",
                 temp_fs="temp://__ziptemp__"):
        self._file = file
        self.compression = compression
        self.encoding = encoding
        self._temp_fs_url = temp_fs
        self._temp_fs = open_fs(temp_fs)
        self._meta = self._temp_fs.getmeta().copy()
        super(WriteZipFS, self).__init__(self._temp_fs)

    def __repr__(self):
        t = "WriteZipFS({!r}, compression={!r}, encoding={!r}, temp_fs={!r})"
        return t.format(
            self._file,
            self.compression,
            self.encoding,
            self._temp_fs_url
        )

    def __str__(self):
        return "<zipfs-write '{}'>".format(self._file)

    def delegate_path(self, path):
        return self._temp_fs, path

    def delegate_fs(self):
        return self._temp_fs

    def close(self):
        if not self.isclosed():
            try:
                self.write_zip()
            finally:
                self._temp_fs.close()
        super(WriteZipFS, self).close()

    def write_zip(self, file=None, compression=None, encoding=None):
        """Write zip to a file.

        Arguments:
            file (str or io.IOBase, optional): Destination file, may be
                a file name or an open file handle.
            compression (str, optional): Compression to use (one of the
                constants defined in the `zipfile` module in the stdlib).
            encoding (str, optional): The character encoding to use
                (default uses the encoding defined in
                `~WriteZipFS.__init__`).

        Note:
            This is called automatically when the ZipFS is closed.

        """
        if not self.isclosed():
            write_zip(
                self._temp_fs,
                file or self._file,
                compression=compression or self.compression,
                encoding=encoding or self.encoding
            )


@six.python_2_unicode_compatible
class ReadZipFS(FS):
    """A readable zip file.
    """

    _meta = {
        'case_insensitive': True,
        'network': False,
        'read_only': True,
        'supports_rename': False,
        'thread_safe': True,
        'unicode_paths': True,
        'virtual': False,
    }

    @errors.CreateFailed.catch_all
    def __init__(self, file, encoding='utf-8'):
        super(ReadZipFS, self).__init__()
        self._file = file
        self.encoding = encoding
        self._zip = zipfile.ZipFile(file, 'r')
        self._directory_fs = None

    def __repr__(self):
        return "ReadZipFS({!r})".format(self._file)

    def __str__(self):
        return "<zipfs '{}'>".format(self._file)

    def _path_to_zip_name(self, path):
        """Convert a path to a zip file name.
        """
        if self._directory.isdir(path):
            _path = relpath(normpath(path)) + '/'
        else:
            _path = relpath(normpath(path))
        return (
            _path.encode(self.encoding)
            if PY2 else
            _path
        )

    @property
    def _directory(self):
        """`MemoryFS`: a filesystem with the same folder hierarchy as the zip.
        """
        self.check()
        with self._lock:
            if self._directory_fs is None:
                self._directory_fs = _fs = MemoryFS()
                for zip_name in self._zip.namelist():
                    resource_name = zip_name
                    if six.PY2:
                        resource_name =\
                            resource_name.decode(self.encoding, 'replace')
                    if resource_name.endswith('/'):
                        _fs.makedirs(resource_name, recreate=True)
                    else:
                        _fs.makedirs(dirname(resource_name), recreate=True)
                        _fs.create(resource_name)
            return self._directory_fs

    def getinfo(self, path, namespaces=None):
        _path = self.validatepath(path)
        namespaces = namespaces or ()
        raw_info = {}

        if _path == '/':
            raw_info["basic"] = {
                "name": "",
                "is_dir": True,
            }
            if "details" in namespaces:
                raw_info["details"] = {
                    "type": int(ResourceType.directory)
                }

        else:
            basic_info = self._directory.getinfo(_path)
            raw_info["basic"] = {
                "name": basic_info.name,
                "is_dir": basic_info.is_dir,
            }

            if not {"details", "access", "zip"}.isdisjoint(namespaces):
                zip_name = self._path_to_zip_name(path)
                try:
                    zip_info = self._zip.getinfo(zip_name)
                except KeyError:
                    # Can occur if there is an implied directory in the zip
                    pass
                else:
                    if "details" in namespaces:
                        raw_info["details"] = {
                            "size": zip_info.file_size,
                            "type": int(
                                ResourceType.directory
                                if basic_info.is_dir else
                                ResourceType.file
                            ),
                            "modified": datetime_to_epoch(
                                datetime(*zip_info.date_time)
                            )
                        }
                    if "zip" in namespaces:
                        raw_info["zip"] = {
                            k: getattr(zip_info, k)
                            for k in zip_info.__slots__
                            if not k.startswith('_')
                        }
                    if "access" in namespaces:
                        # check the zip was created on UNIX to get permissions
                        if zip_info.external_attr \
                                and zip_info.create_system == 3:
                            raw_info["access"] = {
                                "permissions": Permissions(
                                    mode=zip_info.external_attr >> 16 & 0xFFF
                                ).dump(),
                            }

        return Info(raw_info)

    def setinfo(self, path, info):
        self.check()
        raise errors.ResourceReadOnly(path)

    def listdir(self, path):
        self.check()
        return self._directory.listdir(path)

    def makedir(self, path, permissions=None, recreate=False):
        self.check()
        raise errors.ResourceReadOnly(path)

    def openbin(self, path, mode="r", buffering=-1, **kwargs):
        self.check()
        if 'w' in mode or '+' in mode or 'a' in mode:
            raise errors.ResourceReadOnly(path)

        if not self._directory.exists(path):
            raise errors.ResourceNotFound(path)
        elif self._directory.isdir(path):
            raise errors.FileExpected(path)

        zip_name = self._path_to_zip_name(path)
        return _ZipExtFile(self, zip_name)

    def remove(self, path):
        self.check()
        raise errors.ResourceReadOnly(path)

    def removedir(self, path):
        self.check()
        raise errors.ResourceReadOnly(path)

    def close(self):
        super(ReadZipFS, self).close()
        self._zip.close()

    def getbytes(self, path):
        self.check()
        if not self._directory.isfile(path):
            raise errors.ResourceNotFound(path)
        zip_name = self._path_to_zip_name(path)
        zip_bytes = self._zip.read(zip_name)
        return zip_bytes
