slack-backup/slack_backup/download.py

"""
Module for download files, store them in local filesystem and convert the URLs
to local ones, so that sophisticated writers can make a use of it
"""
import functools
import logging
import os

import requests

from slack_backup import utils


def retry(count):
    """
    Decorator for a case, when there is some network hiccup, or slack servers
    are too busy to respond or on connection timeout. Parameter count says how
    many times it should try to perform request.
    """
    def wrapper(func):
        @functools.wraps(func)
        def inner(obj, *args, **kwargs):
            counter = count

            while counter:
                counter -= 1
                try:
                    return func(obj, *args, **kwargs)
                except requests.exceptions.RequestException as exc:
                    if not counter:
                        logging.error('Request for %s failed. Reported '
                                      'reason: %s', args[0], exc.__doc__)
                        raise
                    logging.warning('Request for %s failed. Reported '
                                    'reason: %s. Retrying.', args[0],
                                    exc.__doc__)
                    # Renew the session before retry
                    obj.authorize()
        return inner
    return wrapper


class NotAuthorizedError(requests.HTTPError):
    pass


class Download(object):
    """Download class for taking care of Slack internally uploaded files"""

    def __init__(self, args, assets_dir):
        self.session = None
        self.team = args.team
        self.user = args.user
        self.password = args.password
        self.assets_dir = assets_dir
        self._files = os.path.join(self.assets_dir, 'files')
        self._images = os.path.join(self.assets_dir, 'images')
        self._authorized = False
        self._hier_created = False
        self.cookies = {}

    def download(self, url, filetype):
        """
        Download asset, return local path to it
        """

        if not self._hier_created:
            self._create_assets_dir()

        fname = self.prepare_filepath(url, filetype)

        self._download(url, fname)
        return fname

    def _create_assets_dir(self):
        for path in (self._files, self._images):
            utils.makedirs(path)

        self._hier_created = True

    def prepare_filepath(self, url, filetype):
        """Prepare directory where to download file into"""

        typemap = {'avatar': self._images,
                   'file': self._files}

        if filetype == 'file' and not self._authorized:
            logging.warning("There was no (valid) credentials passed, "
                            "therefore file `%s' cannot be downloaded", url)
            return

        splitted = url.split('/')

        if len(splitted) == 7 and 'slack.com' in splitted[2]:
            part = url.split('/')[-3]
            fname = url.split('/')[-1]
        else:
            logging.info("URL doesn't seem to be slack internal: %s", url)
            part = ''
            fname = splitted[-1]

        path = typemap[filetype]

        if part:
            utils.makedirs(os.path.join(path, part))
            path = os.path.join(path, part)

        path = os.path.join(path, fname)
        count = 1

        while filetype != 'avatar' and os.path.exists(path):
            if count == 1:
                base, ext = os.path.splitext(path)
            path = base + ".%0.3d" % count + ext
            count += 1

        return path

    @retry(3)
    def _download(self, url, local):
        """Download file"""

        res = self.session.get(url, stream=True)

        with open(local, 'wb') as fobj:
            for chunk in res.iter_content(chunk_size=5120):
                if chunk:
                    fobj.write(chunk)
        logging.debug("Downloaded `%s' to `'%s'", url, local)

    def authorize(self):
        """
        Authenticate and gather session for Slack
        """
        self.session = requests.session()  # new session
        res = self.session.get('https://%s.slack.com/' % self.team)

        if not all((self.team, self.password, self.user)):
            logging.warning('There is neither username, password or team name'
                            ' provided. Downloading will not be performed.')
            return

        crumb = ''
        for line in res.text.split('\n'):
            if 'crumb' in line and 'value' in line:
                crumb = line.split('value=')[1].split('"')[1]
                break
        else:
            logging.error('Cannot access Slack login page')
            return

        res = self.session.post("https://%s.slack.com/" % self.team,
                                {'crumb': crumb,
                                 'email': self.user,
                                 'password': self.password,
                                 'signin': 1})
        self.cookies = requests.utils.dict_from_cookiejar(self.session.cookies)
        if not ('a' in self.cookies and 'b' in self.cookies and
                ('a-' + self.cookies['a']) in self.cookies):
            logging.error('Failed to login into Slack app')
        else:
            self._authorized = True