# -*- coding: utf-8 -*-
#
# Copyright 2012-2015 Spotify AB
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
"""
This library is a wrapper of ftplib or pysftp.
It is convenient to move data from/to (S)FTP servers.

There is an example on how to use it (example/ftp_experiment_outputs.py)

You can also find unittest for each class.

Be aware that normal ftp does not provide secure communication.
"""

import datetime
import ftplib
import os
import random
import tempfile
import io

import luigi
import luigi.local_target
import luigi.format
import luigi.target
from luigi.format import FileWrapper

import logging

logger = logging.getLogger('luigi-interface')


class RemoteFileSystem(luigi.target.FileSystem):

    def __init__(self, host, username=None, password=None, port=None,
                 tls=False, timeout=60, sftp=False, pysftp_conn_kwargs=None):
        self.host = host
        self.username = username
        self.password = password
        self.tls = tls
        self.timeout = timeout
        self.sftp = sftp
        self.pysftp_conn_kwargs = pysftp_conn_kwargs or {}

        if port is None:
            if self.sftp:
                self.port = 22
            else:
                self.port = 21
        else:
            self.port = port

    def _connect(self):
        """
        Log in to ftp.
        """
        if self.sftp:
            self._sftp_connect()
        else:
            self._ftp_connect()

    def _sftp_connect(self):
        try:
            import pysftp
        except ImportError:
            logger.warning('Please install pysftp to use SFTP.')

        self.conn = pysftp.Connection(self.host, username=self.username, password=self.password,
                                      port=self.port, **self.pysftp_conn_kwargs)

    def _ftp_connect(self):
        if self.tls:
            self.conn = ftplib.FTP_TLS()
        else:
            self.conn = ftplib.FTP()
        self.conn.connect(self.host, self.port, timeout=self.timeout)
        self.conn.login(self.username, self.password)
        if self.tls:
            self.conn.prot_p()

    def _close(self):
        """
        Close ftp connection.
        """
        if self.sftp:
            self._sftp_close()
        else:
            self._ftp_close()

    def _sftp_close(self):
        self.conn.close()

    def _ftp_close(self):
        self.conn.quit()

    def exists(self, path, mtime=None):
        """
        Return `True` if file or directory at `path` exist, False otherwise.

        Additional check on modified time when mtime is passed in.

        Return False if the file's modified time is older mtime.
        """
        self._connect()

        if self.sftp:
            exists = self._sftp_exists(path, mtime)
        else:
            exists = self._ftp_exists(path, mtime)

        self._close()

        return exists

    def _sftp_exists(self, path, mtime):
        exists = False
        if mtime:
            exists = self.conn.stat(path).st_mtime > mtime
        elif self.conn.exists(path):
            exists = True
        return exists

    def _ftp_exists(self, path, mtime):
        dirname, fn = os.path.split(path)

        files = self.conn.nlst(dirname)

        exists = False
        if path in files or fn in files:
            if mtime:
                mdtm = self.conn.sendcmd('MDTM ' + path)
                modified = datetime.datetime.strptime(mdtm[4:], "%Y%m%d%H%M%S")
                exists = modified > mtime
            else:
                exists = True
        return exists

    def remove(self, path, recursive=True):
        """
        Remove file or directory at location ``path``.

        :param path: a path within the FileSystem to remove.
        :type path: str
        :param recursive: if the path is a directory, recursively remove the directory and
                          all of its descendants. Defaults to ``True``.
        :type recursive: bool
        """
        self._connect()

        if self.sftp:
            self._sftp_remove(path, recursive)
        else:
            self._ftp_remove(path, recursive)

        self._close()

    def _sftp_remove(self, path, recursive):
        if self.conn.isfile(path):
            self.conn.unlink(path)
        else:
            if not recursive:
                raise RuntimeError("Path is not a regular file, and recursive option is not set")
            directories = []
            # walk the tree, and execute call backs when files,
            # directories and unknown types are encountered
            # files must be removed first.  then directories can be removed
            # after the files are gone.
            self.conn.walktree(path, self.conn.unlink, directories.append, self.conn.unlink)
            for directory in reversed(directories):
                self.conn.rmdir(directory)
            self.conn.rmdir(path)

    def _ftp_remove(self, path, recursive):
        if recursive:
            self._rm_recursive(self.conn, path)
        else:
            try:
                # try delete file
                self.conn.delete(path)
            except ftplib.all_errors:
                # it is a folder, delete it
                self.conn.rmd(path)

    def _rm_recursive(self, ftp, path):
        """
        Recursively delete a directory tree on a remote server.

        Source: https://gist.github.com/artlogic/2632647
        """
        wd = ftp.pwd()

        # check if it is a file first, because some FTP servers don't return
        # correctly on ftp.nlst(file)
        try:
            ftp.cwd(path)
        except ftplib.all_errors:
            # this is a file, we will just delete the file
            ftp.delete(path)
            return

        try:
            names = ftp.nlst()
        except ftplib.all_errors:
            # some FTP servers complain when you try and list non-existent paths
            return

        for name in names:
            if os.path.split(name)[1] in ('.', '..'):
                continue

            try:
                ftp.cwd(name)   # if we can cwd to it, it's a folder
                ftp.cwd(wd)   # don't try a nuke a folder we're in
                ftp.cwd(path)  # then go back to where we were
                self._rm_recursive(ftp, name)
            except ftplib.all_errors:
                ftp.delete(name)

        try:
            ftp.cwd(wd)  # do not delete the folder that we are in
            ftp.rmd(path)
        except ftplib.all_errors as e:
            print('_rm_recursive: Could not remove {0}: {1}'.format(path, e))

    def put(self, local_path, path, atomic=True):
        """
        Put file from local filesystem to (s)FTP.
        """
        self._connect()

        if self.sftp:
            self._sftp_put(local_path, path, atomic)
        else:
            self._ftp_put(local_path, path, atomic)

        self._close()

    def _sftp_put(self, local_path, path, atomic):
        normpath = os.path.normpath(path)
        directory = os.path.dirname(normpath)
        self.conn.makedirs(directory)

        if atomic:
            tmp_path = os.path.join(directory, 'luigi-tmp-{:09d}'.format(random.randrange(0, 10_000_000_000)))
        else:
            tmp_path = normpath

        self.conn.put(local_path, tmp_path)

        if atomic:
            self.conn.rename(tmp_path, normpath)

    def _ftp_put(self, local_path, path, atomic):
        normpath = os.path.normpath(path)
        folder = os.path.dirname(normpath)

        # create paths if do not exists
        for subfolder in folder.split(os.sep):
            if subfolder and subfolder not in self.conn.nlst():
                self.conn.mkd(subfolder)

            self.conn.cwd(subfolder)

        # go back to ftp root folder
        self.conn.cwd("/")

        # random file name
        if atomic:
            tmp_path = folder + os.sep + 'luigi-tmp-%09d' % random.randrange(0, 10_000_000_000)
        else:
            tmp_path = normpath

        self.conn.storbinary('STOR %s' % tmp_path, open(local_path, 'rb'))

        if atomic:
            self.conn.rename(tmp_path, normpath)

    def get(self, path, local_path):
        """
        Download file from (s)FTP to local filesystem.
        """
        normpath = os.path.normpath(local_path)
        folder = os.path.dirname(normpath)
        if folder and not os.path.exists(folder):
            os.makedirs(folder)

        tmp_local_path = local_path + '-luigi-tmp-%09d' % random.randrange(0, 10_000_000_000)

        # download file
        self._connect()

        if self.sftp:
            self._sftp_get(path, tmp_local_path)
        else:
            self._ftp_get(path, tmp_local_path)

        self._close()

        os.rename(tmp_local_path, local_path)

    def _sftp_get(self, path, tmp_local_path):
        self.conn.get(path, tmp_local_path)

    def _ftp_get(self, path, tmp_local_path):
        self.conn.retrbinary('RETR %s' % path, open(tmp_local_path, 'wb').write)

    def listdir(self, path='.'):
        """
        Gets an list of the contents of path in (s)FTP
        """
        self._connect()

        if self.sftp:
            contents = self._sftp_listdir(path)
        else:
            contents = self._ftp_listdir(path)

        self._close()

        return contents

    def _sftp_listdir(self, path):
        return self.conn.listdir(remotepath=path)

    def _ftp_listdir(self, path):
        return self.conn.nlst(path)


class AtomicFtpFile(luigi.target.AtomicLocalFile):
    """
    Simple class that writes to a temp file and upload to ftp on close().

    Also cleans up the temp file if close is not invoked.
    """

    def __init__(self, fs, path):
        """
        Initializes an AtomicFtpfile instance.
        :param fs:
        :param path:
        :type path: str
        """
        self._fs = fs
        super(AtomicFtpFile, self).__init__(path)

    def move_to_final_destination(self):
        self._fs.put(self.tmp_path, self.path)

    @property
    def fs(self):
        return self._fs


class RemoteTarget(luigi.target.FileSystemTarget):
    """
    Target used for reading from remote files.

    The target is implemented using intermediate files on the local system.
    On Python2, these files may not be cleaned up.
    """

    def __init__(
        self, path, host, format=None, username=None,
        password=None, port=None, mtime=None, tls=False,
            timeout=60, sftp=False, pysftp_conn_kwargs=None
    ):
        if format is None:
            format = luigi.format.get_default_format()

        self.path = path
        self.mtime = mtime
        self.format = format
        self.tls = tls
        self.timeout = timeout
        self.sftp = sftp
        self._fs = RemoteFileSystem(host, username, password, port, tls, timeout, sftp, pysftp_conn_kwargs)

    @property
    def fs(self):
        return self._fs

    def open(self, mode):
        """
        Open the FileSystem target.

        This method returns a file-like object which can either be read from or written to depending
        on the specified mode.

        :param mode: the mode `r` opens the FileSystemTarget in read-only mode, whereas `w` will
                     open the FileSystemTarget in write mode. Subclasses can implement
                     additional options.
        :type mode: str
        """
        if mode == 'w':
            return self.format.pipe_writer(AtomicFtpFile(self._fs, self.path))

        elif mode == 'r':
            temppath = '{}-luigi-tmp-{:09d}'.format(
                self.path.lstrip('/'), random.randrange(0, 10_000_000_000)
            )
            try:
                # store reference to the TemporaryDirectory because it will be removed on GC
                self.__temp_dir = tempfile.TemporaryDirectory(
                    prefix="luigi-contrib-ftp_"
                )
            except AttributeError:
                # TemporaryDirectory only available in Python3, use old behaviour in Python2
                # this file will not be cleaned up automatically
                self.__tmp_path = os.path.join(
                    tempfile.gettempdir(), 'luigi-contrib-ftp', temppath
                )
            else:
                self.__tmp_path = os.path.join(self.__temp_dir.name, temppath)

            # download file to local
            self._fs.get(self.path, self.__tmp_path)

            return self.format.pipe_reader(
                FileWrapper(io.BufferedReader(io.FileIO(self.__tmp_path, 'r')))
            )
        else:
            raise Exception("mode must be 'r' or 'w' (got: %s)" % mode)

    def exists(self):
        return self.fs.exists(self.path, self.mtime)

    def put(self, local_path, atomic=True):
        self.fs.put(local_path, self.path, atomic)

    def get(self, local_path):
        self.fs.get(self.path, local_path)
