pferd/PFERD/ilias/downloader.py
2020-04-20 18:49:01 +02:00

67 lines
2.1 KiB
Python

"""Contains a downloader for ILIAS."""
from pathlib import Path
from typing import Any, Dict
import bs4
import requests
from ..new_organizer import Organizer
from ..tmp_dir import TmpDir
from ..utils import soupify, stream_to_path
from .authenticators import IliasAuthenticator
class ContentTypeException(Exception):
"""Thrown when the content type of the ilias element can not be handled."""
def __init__(self, message: str):
"""Create a new exception."""
super().__init__(message)
class IliasDownloader():
"""A downloader for ILIAS."""
def __init__(self, tmp_dir: TmpDir, organizer: Organizer, authenticator: IliasAuthenticator):
"""Create a new IliasDownloader."""
self._authenticator = authenticator
self._session = requests.Session()
self._tmp_dir = tmp_dir
self._organizer = organizer
def download(self, url: str, target_path: Path, params: Dict[str, Any]) -> None:
"""Download a file from ILIAS.
Retries authentication until eternity, if it could not fetch the file.
"""
tmp_file = self._tmp_dir.new_file()
while not self._try_download(url, tmp_file, params):
self._authenticator.authenticate(self._session)
self._organizer.accept_file(tmp_file, target_path)
def _try_download(self, url: str, target_path: Path, params: Dict[str, Any]) -> bool:
with self._session.get(url, params=params, stream=True) as r:
content_type = r.headers["content-type"]
if content_type.startswith("text/html"):
# Dangit, we're probably not logged in.
soup = soupify(r)
if self._is_logged_in(soup):
raise ContentTypeException(
"Attempting to download a web page, not a file"
)
return False
else:
# Yay, we got the file :)
stream_to_path(r, target_path)
return True
def _is_logged_in(self, soup: Any) -> bool:
userlog = soup.find("li", {"id": "userlog"})
return userlog is not None