"""Manage filesystems on remote FTP servers.
"""

from __future__ import print_function
from __future__ import unicode_literals

import calendar
import ftplib
import io
import itertools
import socket
import threading
import typing
from collections import OrderedDict
from contextlib import contextmanager
from ftplib import FTP
from ftplib import error_perm
from ftplib import error_temp

from six import PY2
from six import text_type

from . import errors
from .base import FS
from .constants import DEFAULT_CHUNK_SIZE
from .enums import ResourceType
from .enums import Seek
from .info import Info
from .iotools import line_iterator
from .mode import Mode
from .path import abspath
from .path import dirname
from .path import basename
from .path import normpath
from .path import split
from . import _ftp_parse as ftp_parse

if False:  # typing.TYPE_CHECKING
    import ftplib
    from typing import (
        Any, BinaryIO, ByteString, ContextManager,
        Iterable, Iterator, Collection, Container,
        Dict, List, Optional, SupportsInt, Text,
        Tuple, Union)
    from .base import _OpendirFactory
    from .info import RawInfo
    from .permissions import Permissions
    from .subfs import SubFS


_F = typing.TypeVar('_F', bound='FTPFS')


__all__ = ['FTPFS']


@contextmanager
def ftp_errors(fs, path=None):
    # type: (FTPFS, Optional[Text]) -> Iterator[None]
    try:
        with fs._lock:
            yield
    except socket.error:
        raise errors.RemoteConnectionError(
            msg='unable to connect to {}'.format(fs.host)
        )
    except error_temp as error:
        if path is not None:
            raise errors.ResourceError(
                path,
                msg="ftp error on resource '{}' ({})".format(path, error)
            )
        else:
            raise errors.OperationFailed(
                msg='ftp error ({})'.format(error)
            )
    except error_perm as error:
        code, message = _parse_ftp_error(error)
        if code == '552':
            raise errors.InsufficientStorage(
                path=path,
                msg=message
            )
        elif code in ('501', '550'):
            raise errors.ResourceNotFound(path=path)
        raise errors.PermissionDenied(
            msg=message
        )


@contextmanager
def manage_ftp(ftp):
    # type: (FTP) -> Iterator[FTP]
    try:
        yield ftp
    finally:
        try:
            ftp.quit()
        except:  # pragma: no cover
            pass


def _parse_ftp_error(error):
    # type: (ftplib.Error) -> Tuple[Text, Text]
    """Extract code and message from ftp error."""
    code, _, message = text_type(error).partition(' ')
    return code, message


if PY2:
    def _encode(st, encoding):
        # type: (Union[Text, bytes], Text) -> str
        return st.encode(encoding) if isinstance(st, text_type) else st
    def _decode(st, encoding):
        # type: (Union[Text, bytes], Text) -> Text
        return st.decode(encoding, 'replace') if isinstance(st, bytes) else st
else:
    def _encode(st, _):
        # type: (str, str) -> str
        return st
    def _decode(st, _):
        # type: (str, str) -> str
        return st


class FTPFile(io.RawIOBase):

    def __init__(self, ftpfs, path, mode):
        # type: (FTPFS, Text, Text) -> None
        super(FTPFile, self).__init__()
        self.fs = ftpfs
        self.path = path
        self.mode = Mode(mode)
        self.pos = 0
        self._lock = threading.Lock()
        self.ftp = self._open_ftp()
        self._read_conn = None          # type: Optional[socket.socket]
        self._write_conn = None         # type: Optional[socket.socket]

    def _open_ftp(self):
        # type: () -> FTP
        """Open an ftp object for the file."""
        ftp = self.fs._open_ftp()
        ftp.voidcmd(str('TYPE I'))
        return ftp

    @property
    def read_conn(self):
        # type: () -> socket.socket
        if self._read_conn is None:
            self._read_conn = self.ftp.transfercmd(
                str('RETR ') + _encode(self.path, self.ftp.encoding),
                self.pos
            )
        return self._read_conn

    @property
    def write_conn(self):
        # type: () -> socket.socket
        if self._write_conn is None:
            if self.mode.appending:
                self._write_conn = self.ftp.transfercmd(
                    str('APPE ') + _encode(self.path, self.ftp.encoding)
                )
            else:
                self._write_conn = self.ftp.transfercmd(
                    str('STOR ') + _encode(self.path, self.ftp.encoding),
                    self.pos
                )
        return self._write_conn

    def __repr__(self):
        # type: () -> str
        _repr = "<ftpfile {!r} {!r} {!r}>"
        return _repr.format(self.fs.ftp_url, self.path, self.mode)

    def close(self):
        # type: () -> None
        if not self.closed:
            with self._lock:
                try:
                    if self._write_conn is not None:
                        self._write_conn.close()
                        self._write_conn = None
                    if self._read_conn is not None:
                        self._read_conn.close()
                        self._read_conn = None
                    try:
                        self.ftp.quit()
                    except error_temp:  # pragma: no cover
                        pass
                finally:
                    super(FTPFile, self).close()

    def tell(self):
        # type: () -> int
        return self.pos

    def readable(self):
        # type: () -> bool
        return self.mode.reading

    def read(self, size=-1):
        # type: (int) -> bytes
        if not self.mode.reading:
            raise IOError('File not open for reading')

        chunks = []
        remaining = size

        conn = self.read_conn
        with self._lock:
            while remaining:
                if remaining < 0:
                    read_size = DEFAULT_CHUNK_SIZE
                else:
                    read_size = min(DEFAULT_CHUNK_SIZE, remaining)
                try:
                    chunk = conn.recv(read_size)
                except socket.error:  # pragma: no cover
                    break
                if not chunk:
                    break
                chunks.append(chunk)
                self.pos += len(chunk)
                remaining -= len(chunk)
        return b''.join(chunks)

    def readline(self, size=-1):
        # type: (int) -> bytes
        return next(line_iterator(self, size))    # type: ignore

    def readlines(self, hint=-1):
        # type: (int) -> List[bytes]
        lines = []
        size = 0
        for line in line_iterator(self):          # type: ignore
            lines.append(line)
            size += len(line)
            if hint != -1 and size > hint:
                break
        return lines

    def writable(self):
        # type: () -> bool
        return self.mode.writing

    def write(self, data):
        # type: (bytes) -> int
        if not self.mode.writing:
            raise IOError('File not open for writing')

        with self._lock:
            conn = self.write_conn
            data_pos = 0
            remaining_data = len(data)

            while remaining_data:
                chunk_size = min(remaining_data, DEFAULT_CHUNK_SIZE)
                sent_size = conn.send(data[data_pos:data_pos + chunk_size])
                data_pos += sent_size
                remaining_data -= sent_size
                self.pos += sent_size

        return data_pos

    def writelines(self, lines):
        # type: (Iterable[bytes]) -> None
        self.write(b''.join(lines))

    def truncate(self, size=None):
        # type: (Optional[int]) -> int
        # Inefficient, but I don't know if truncate is possible with ftp
        with self._lock:
            if size is None:
                size = self.tell()
            with self.fs.openbin(self.path) as f:
                data = f.read(size)
            with self.fs.openbin(self.path, 'w') as f:
                f.write(data)
                if len(data) < size:
                    f.write(b'\0' * (size - len(data)))
        return size

    def seekable(self):
        # type: () -> bool
        return True

    def seek(self, pos, whence=Seek.set):
        # type: (int, SupportsInt) -> int
        _whence = int(whence)
        if _whence not in (Seek.set, Seek.current, Seek.end):
            raise ValueError('invalid value for whence')
        with self._lock:
            if _whence == Seek.set:
                new_pos = pos
            elif _whence == Seek.current:
                new_pos = self.pos + pos
            elif _whence == Seek.end:
                file_size = self.fs.getsize(self.path)
                new_pos = file_size + pos
            self.pos = max(0, new_pos)

            self.ftp.quit()
            self.ftp = self._open_ftp()

            if self._read_conn:
                self._read_conn.close()
                self._read_conn = None
            if self._write_conn:
                self._write_conn.close()
                self._write_conn = None
        return self.tell()


class FTPFS(FS):
    """A FTP (File Transport Protocol) Filesystem.

    Arguments:
        host (str): A FTP host, e.g. ``'ftp.mirror.nl'``.
        user (str): A username (default is ``'anonymous'``).
        passwd (str): Password for the server, or `None` for anon.
        acct (str): FTP account.
        timeout (int): Timeout for contacting server (in seconds,
            defaults to 10).
        port (int): FTP port number (default 21).
        proxy (str, optional): An FTP proxy, or ``None`` (default)
            for no proxy.

    """

    _meta = {
        'invalid_path_chars': '\0',
        'network': True,
        'read_only': False,
        'thread_safe': True,
        'unicode_paths': True,
        'virtual': False,
    }

    def __init__(self,
                 host,                  # type: Text
                 user='anonymous',      # type: Text
                 passwd='',             # type: Text
                 acct='',               # type: Text
                 timeout=10,            # type: int
                 port=21,               # type: int
                 proxy=None             # type: Optional[Text]
                 ):
        # type: (...) -> None
        super(FTPFS, self).__init__()
        self._host = host
        self._user = user
        self.passwd = passwd
        self.acct = acct
        self.timeout = timeout
        self.port = port
        self.proxy = proxy

        self.encoding = 'latin-1'
        self._ftp = None            # type: Optional[FTP]
        self._welcome = None        # type: Optional[Text]
        self._features = {}         # type: Dict[Text, Text]

    def __repr__(self):
        # type: (...) -> Text
        return "FTPFS({!r}, port={!r})".format(self.host, self.port)

    def __str__(self):
        # type: (...) -> Text
        _fmt = (
            "<ftpfs '{host}'>"
            if self.port == 21
            else "<ftpfs '{host}:{port}'>"
        )
        return _fmt.format(host=self.host, port=self.port)

    @property
    def user(self):
        # type: () -> Text
        return (
            self._user
            if self.proxy is None else
            '{}@{}'.format(self._user, self._host)
        )

    @property
    def host(self):
        # type: () -> Text
        return (
            self._host
            if self.proxy is None else
            self.proxy
        )

    @classmethod
    def _parse_features(cls, feat_response):
        # type: (Text) -> Dict[Text, Text]
        """Parse a dict of features from FTP feat response.
        """
        features = {}
        if feat_response.split('-')[0] == '211':
            for line in feat_response.splitlines():
                if line.startswith(' '):
                    key, _, value = line[1:].partition(' ')
                    features[key] = value
        return features

    def _open_ftp(self):
        # type: () -> FTP
        """Open a new ftp object.
        """
        _ftp = FTP()
        _ftp.set_debuglevel(0)
        with ftp_errors(self):
            _ftp.connect(self.host, self.port, self.timeout)
            _ftp.login(self.user, self.passwd, self.acct)
            self._features = {}
            try:
                feat_response = _decode(_ftp.sendcmd("FEAT"), 'latin-1')
            except error_perm:  # pragma: no cover
                self.encoding = 'latin-1'
            else:
                self._features = self._parse_features(feat_response)
                self.encoding = (
                    'utf-8'
                    if 'UTF8' in self._features
                    else 'latin-1'
                )
                if not PY2:
                    _ftp.file = _ftp.sock.makefile(  # type: ignore
                        'r',
                        encoding=self.encoding
                    )
        _ftp.encoding = self.encoding
        self._welcome = _ftp.welcome
        return _ftp

    def _manage_ftp(self):
        # type: () -> ContextManager[FTP]
        ftp = self._open_ftp()
        return manage_ftp(ftp)

    @property
    def ftp_url(self):
        # type: () -> Text
        """Get the FTP url this filesystem will open."""
        url = (
            "ftp://{}".format(self.host)
            if self.port == 21
            else "ftp://{}:{}".format(self.host, self.port)
        )
        return url

    @property
    def ftp(self):
        # type: () -> FTP
        """~ftplib.FTP: the underlying FTP client.
        """
        return self._get_ftp()

    def _get_ftp(self):
        # type: () -> FTP
        if self._ftp is None:
            self._ftp = self._open_ftp()
        return self._ftp

    @property
    def features(self):
        # type: () -> Dict[Text, Text]
        """dict: features of the remote FTP server.
        """
        self._get_ftp()
        return self._features

    def _read_dir(self, path):
        # type: (Text) -> Dict[Text, Info]
        _path = abspath(normpath(path))
        lines = []  # type: List[Union[ByteString, Text]]
        with ftp_errors(self, path=path):
            self.ftp.retrlines(
                str('LIST ') + _encode(_path, self.ftp.encoding),
                lines.append
            )
        lines = [
            line.decode('utf-8') if isinstance(line, bytes) else line
            for line in lines
        ]
        _list = [Info(raw_info) for raw_info in ftp_parse.parse(lines)]
        dir_listing = OrderedDict({info.name: info for info in _list})
        return dir_listing

    @property
    def supports_mlst(self):
        # type: () -> bool
        """bool: whether the server supports MLST feature.
        """
        return 'MLST' in self.features

    def create(self, path, wipe=False):
        # type: (Text, bool) -> bool
        _path = self.validatepath(path)
        with ftp_errors(self, path):
            if wipe or not self.isfile(path):
                empty_file = io.BytesIO()
                self.ftp.storbinary(
                    str("STOR ") + _encode(_path, self.ftp.encoding),
                    empty_file
                )
                return True
        return False

    @classmethod
    def _parse_ftp_time(cls, time_text):
        # type: (Text) -> Optional[int]
        """Parse a time from an ftp directory listing.
        """
        try:
            tm_year = int(time_text[0:4])
            tm_month = int(time_text[4:6])
            tm_day = int(time_text[6:8])
            tm_hour = int(time_text[8:10])
            tm_min = int(time_text[10:12])
            tm_sec = int(time_text[12:14])
        except ValueError:
            return None
        epoch_time = calendar.timegm((
            tm_year,
            tm_month,
            tm_day,
            tm_hour,
            tm_min,
            tm_sec
        ))
        return epoch_time

    @classmethod
    def _parse_facts(cls, line):
        # type: (Text) -> Tuple[Optional[Text], Dict[Text, Text]]
        name = None
        facts = {}
        for fact in line.split(';'):
            key, sep, value = fact.partition('=')
            if sep:
                key = key.strip().lower()
                value = value.strip()
                facts[key] = value
            else:
                name = basename(fact.rstrip('/').strip())
        return name if name not in ('.', '..') else None, facts

    @classmethod
    def _parse_mlsx(cls, lines):
        # type: (Iterable[Text]) -> Iterator[RawInfo]
        for line in lines:
            name, facts = cls._parse_facts(line.strip())
            if name is None:
                continue
            is_dir = facts.get('type', None) in ('dir', 'cdir', 'pdir')
            raw_info = {} # type: Dict[Text, Dict[Text, object]]

            raw_info["basic"] = {"name": name, "is_dir": is_dir}
            raw_info["ftp"] = facts  # type: ignore
            raw_info["details"] = {"type": (
                int(ResourceType.directory)
                if is_dir else int(ResourceType.file)
            )}

            details = raw_info['details']
            size_str = facts.get('size', facts.get('sizd', '0'))
            size = 0
            if size_str.isdigit():
                size = int(size_str)
            details['size'] = size
            if 'modify' in facts:
                details['modified'] = cls._parse_ftp_time(facts['modify'])
            if 'create' in facts:
                details['created'] = cls._parse_ftp_time(facts['create'])
            yield raw_info

    if False:  # typing.TYPE_CHECKING
        def opendir(self, path, factory=None):
            # type: (_F, Text, Optional[_OpendirFactory]) -> SubFS[_F]
            pass

    def getinfo(self, path, namespaces=None):
        # type: (Text, Optional[Container[Text]]) -> Info
        _path = self.validatepath(path)
        namespaces = namespaces or ()

        if _path == '/':
            return Info({
                "basic":
                {
                    "name": "",
                    "is_dir": True
                },
                "details":
                {
                    "type": int(ResourceType.directory)
                }
            })

        if self.supports_mlst:
            with self._lock:
                with ftp_errors(self, path=path):
                    response = self.ftp.sendcmd(
                        str('MLST ') + _encode(_path, self.ftp.encoding)
                    )
                lines = _decode(response, self.ftp.encoding).splitlines()[1:-1]
                for raw_info in self._parse_mlsx(lines):
                    return Info(raw_info)

        with ftp_errors(self, path=path):
            dir_name, file_name = split(_path)
            directory = self._read_dir(dir_name)
            if file_name not in directory:
                raise errors.ResourceNotFound(path)
            info = directory[file_name]
            return info

    def getmeta(self, namespace="standard"):
        # type: (Text) -> Dict[Text, object]
        _meta = {}  # type: Dict[Text, object]
        self._get_ftp()
        if namespace == "standard":
            _meta = self._meta.copy()
            _meta['unicode_paths'] = "UTF8" in self.features
        return _meta

    def listdir(self, path):
        # type: (Text) -> List[Text]
        _path = self.validatepath(path)
        with self._lock:
            dir_list = [
                info.name
                for info in self.scandir(_path)
            ]
        return dir_list

    def makedir(self,               # type: _F
                path,               # type: Text
                permissions=None,   # type: Optional[Permissions]
                recreate=False      # type: bool
                ):
        # type: (...) -> SubFS[_F]
        _path = self.validatepath(path)

        with ftp_errors(self, path=path):
            if _path == '/':
                if recreate:
                    return self.opendir(path)
                else:
                    raise errors.DirectoryExists(path)

            if not (recreate and self.isdir(path)):
                try:
                    self.ftp.mkd(_encode(_path, self.ftp.encoding))
                except error_perm as error:
                    code, _ = _parse_ftp_error(error)
                    if code == '550':
                        if self.isdir(path):
                            raise errors.DirectoryExists(path)
                        else:
                            if self.exists(path):
                                raise errors.DirectoryExists(path)
                    raise errors.ResourceNotFound(path)
        return self.opendir(path)

    def openbin(self, path, mode="r", buffering=-1, **options):
        # type: (Text, Text, int, **Any) -> BinaryIO
        _mode = Mode(mode)
        _mode.validate_bin()
        _path = self.validatepath(path)

        with self._lock:
            try:
                info = self.getinfo(_path)
            except errors.ResourceNotFound:
                if _mode.reading:
                    raise errors.ResourceNotFound(path)
                if _mode.writing and not self.isdir(dirname(_path)):
                    raise errors.ResourceNotFound(path)
            else:
                if info.is_dir:
                    raise errors.FileExpected(path)
            if _mode.exclusive:
                raise errors.FileExists(path)
            ftp_file = FTPFile(self, _path, mode)
        return ftp_file  # type: ignore

    def remove(self, path):
        # type: (Text) -> None
        self.check()
        _path = self.validatepath(path)
        with self._lock:
            if self.isdir(path):
                raise errors.FileExpected(path=path)
            with ftp_errors(self, path):
                self.ftp.delete(_encode(_path, self.ftp.encoding))

    def removedir(self, path):
        # type: (Text) -> None
        _path = self.validatepath(path)
        if _path == '/':
            raise errors.RemoveRootError()

        with ftp_errors(self, path):
            try:
                self.ftp.rmd(_encode(_path, self.ftp.encoding))
            except error_perm as error:
                code, _ = _parse_ftp_error(error)
                if code == '550':
                    if self.isfile(path):
                        raise errors.DirectoryExpected(path)
                    if not self.isempty(path):
                        raise errors.DirectoryNotEmpty(path)
                raise  # pragma: no cover

    def _scandir(self,
                 path,            # type: Text
                 namespaces=None  # type: Optional[Container[Text]]
                 ):
        # type: (...) -> Iterator[Info]
        _path = self.validatepath(path)
        with self._lock:
            if self.supports_mlst:
                lines = []
                with ftp_errors(self, path=path):
                    try:
                        self.ftp.retrlines(
                            str("MLSD ") + _encode(_path, self.ftp.encoding),
                            lambda l: lines.append(_decode(l, self.ftp.encoding))
                        )
                    except error_perm:
                        if not self.getinfo(path).is_dir:
                            raise errors.DirectoryExpected(path)
                        raise # pragma: no cover
                if lines:
                    for raw_info in self._parse_mlsx(lines):
                        yield Info(raw_info)
                    return
            with self._lock:
                for info in self._read_dir(_path).values():
                    yield info

    def scandir(self,
                path,               # type: Text
                namespaces=None,    # type: Optional[Container[Text]]
                page=None           # type: Optional[Tuple[int, int]]
                ):
        # type: (...) -> Iterator[Info]
        if not self.supports_mlst and not self.getinfo(path).is_dir:
            raise errors.DirectoryExpected(path)
        iter_info = self._scandir(path, namespaces=namespaces)
        if page is not None:
            start, end = page
            iter_info = itertools.islice(iter_info, start, end)
        return iter_info

    def setbinfile(self, path, file):
        # type: (Text, BinaryIO) -> None
        _path = self.validatepath(path)
        with self._lock:
            with self._manage_ftp() as ftp:
                with ftp_errors(self, path):
                    ftp.storbinary(
                        str("STOR ") + _encode(_path, self.ftp.encoding),
                        file
                    )

    def setbytes(self, path, contents):
        # type: (Text, ByteString) -> None
        if not isinstance(contents, bytes):
            raise TypeError('contents must be bytes')
        self.setbinfile(path, io.BytesIO(contents))

    def setinfo(self, path, info):
        # type: (Text, RawInfo) -> None
        if not self.exists(path):
            raise errors.ResourceNotFound(path)

    def getbytes(self, path):
        # type: (Text) -> bytes
        _path = self.validatepath(path)
        data = io.BytesIO()
        with ftp_errors(self, path):
            with self._manage_ftp() as ftp:
                try:
                    ftp.retrbinary(
                        str("RETR ") + _encode(_path, self.ftp.encoding),
                        data.write
                    )
                except error_perm as error:
                    code, _ = _parse_ftp_error(error)
                    if code == '550':
                        if self.isdir(path):
                            raise errors.FileExpected(path)
                    raise

        data_bytes = data.getvalue()
        return data_bytes

    def close(self):
        # type: () -> None
        if not self.isclosed():
            try:
                self.ftp.quit()
            except Exception:  # pragma: no cover
                pass
            self._ftp = None
        super(FTPFS, self).close()
