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ilias crawler: Add some unhelpful documentation
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I-Al-Istannen
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a051e3bcca
@ -48,6 +48,9 @@ class IliasCrawler:
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@staticmethod
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def _url_set_query_param(url: str, param: str, value: str) -> str:
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"""
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Set a query parameter in an url, overwriting existing ones with the same name.
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"""
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scheme, netloc, path, query, fragment = urlsplit(url)
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query_parameters = parse_qs(query)
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query_parameters[param] = [value]
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@ -59,10 +62,13 @@ class IliasCrawler:
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"""
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Starts the crawl process, yielding a list of elements to (potentially) download.
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"""
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# Start crawling at the given course
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root_url = self._url_set_query_param(
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self._base_url + "/goto.php", "target", f"crs_{self._course_id}"
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)
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# And treat it as a folder
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return self._crawl_folder(Path(""), root_url)
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def _switch_on_crawled_type(
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@ -77,6 +83,7 @@ class IliasCrawler:
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parsed_url = urlparse(url)
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LOGGER.debug("Parsed url: %r", parsed_url)
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# file URLs contain "target=file"
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if "target=file_" in parsed_url.query:
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LOGGER.debug("Interpreted as file.")
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return self._crawl_file(path, link_element, url)
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@ -86,6 +93,8 @@ class IliasCrawler:
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LOGGER.debug("Skipping forum %r", url)
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return []
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# Everything with a ref_id can *probably* be opened to reveal nested things
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# video groups, directories, exercises, etc
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if "ref_id=" in parsed_url.query:
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LOGGER.debug("Processing folder-like...")
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return self._switch_on_folder_like(path, link_element, url)
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@ -99,11 +108,17 @@ class IliasCrawler:
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"""
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Crawls a file.
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"""
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# Files have a list of properties (type, modification date, size, etc.)
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# In a series of divs.
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# Find the parent containing all those divs, so we can filter our what we need
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properties_parent: bs4.Tag = link_element.findParent(
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"div", {"class": lambda x: "il_ContainerListItem" in x}
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).select_one(".il_ItemProperties")
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# The first one is always the filetype
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file_type = properties_parent.select_one("span.il_ItemProperty").getText().strip()
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# The rest does not have a stable order. Grab the whole text and reg-ex the date
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# out of it
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all_properties_text = properties_parent.getText().strip()
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modification_date_match = re.search(
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r"(((\d+\. \w+ \d+)|(Gestern)|(Heute)), \d+:\d+)",
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@ -116,15 +131,10 @@ class IliasCrawler:
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modification_date_str = modification_date_match.group(1)
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modification_date = demangle_date(modification_date_str)
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# Grab the name from the link text
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name = link_element.getText()
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full_path = Path(path, name + "." + file_type)
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match_result = re.match(r".+target=file_(\d+).+", url)
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if match_result is None:
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LOGGER.warning("Could not download file %r", url)
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return []
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return [IliasDownloadInfo(full_path, url, modification_date)]
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def _switch_on_folder_like(
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@ -133,8 +143,13 @@ class IliasCrawler:
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link_element: bs4.Tag,
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url: str
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) -> List[IliasDownloadInfo]:
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"""
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Try crawling something that looks like a folder.
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"""
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found_parent: Optional[bs4.Tag] = None
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# We look for the outer div of our inner link, to find information around it
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# (mostly the icon)
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for parent in link_element.parents:
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if "ilContainerListItemOuter" in parent["class"]:
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found_parent = parent
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@ -144,22 +159,26 @@ class IliasCrawler:
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LOGGER.warning("Could not find element icon for %r", url)
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return []
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# Find the small descriptive icon to figure out the type
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img_tag: Optional[bs4.Tag] = found_parent.select_one("img.ilListItemIcon")
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if img_tag is None:
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LOGGER.warning("Could not find image tag for %r", url)
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return []
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# A forum
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if str(img_tag["src"]).endswith("frm.svg"):
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LOGGER.debug("Skipping forum at %r", url)
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return []
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element_path = Path(path, link_element.getText().strip())
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# An exercise
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if str(img_tag["src"]).endswith("icon_exc.svg"):
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LOGGER.debug("Crawling exercises at %r", url)
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return self._crawl_exercises(element_path, url)
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# Match the opencast video plugin
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if "opencast" in str(img_tag["alt"]).lower():
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LOGGER.debug("Found video site: %r", url)
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return self._crawl_video_directory(element_path, url)
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@ -168,13 +187,22 @@ class IliasCrawler:
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return self._crawl_folder(element_path, self._abs_url_from_link(link_element))
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def _crawl_video_directory(self, path: Path, url: str) -> List[IliasDownloadInfo]:
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"""
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Crawl the video overview site.
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"""
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initial_soup = self._get_page(url, {})
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# The page is actually emtpy but contains a much needed token in the link below.
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# That token can be used to fetch the *actual* video listing
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content_link: bs4.Tag = initial_soup.select_one("#tab_series a")
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# Fetch the actual video listing. The given parameters return all videos (max 800)
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# in a standalone html page
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video_list_soup = self._get_page(
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self._abs_url_from_link(content_link),
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{"limit": 800, "cmd": "asyncGetTableGUI", "cmdMode": "asynch"}
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)
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# Video start links are marked with an "Abspielen" link
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video_links: List[bs4.Tag] = video_list_soup.findAll(
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name="a", text=re.compile(r"\s*Abspielen\s*")
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)
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@ -187,8 +215,13 @@ class IliasCrawler:
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return results
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def _crawl_single_video(self, path: Path, link: bs4.Tag) -> List[IliasDownloadInfo]:
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"""
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Crawl a single video based on its "Abspielen" link from the video listing.
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"""
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video_page_url = self._abs_url_from_link(link)
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# The link is part of a table with multiple columns, describing metadata.
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# 6th child (1 indexed) is the modification time string
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modification_string = link.parent.parent.parent.select_one(
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"td.std:nth-child(6)"
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).getText().strip()
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@ -199,6 +232,11 @@ class IliasCrawler:
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).getText().strip()
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title += ".mp4"
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# Fetch the actual video page. This is a small wrapper page initializing a javscript
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# player. Sadly we can not execute that JS. The actual video stream url is nowhere
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# on the page, but defined in a JS object inside a script tag, passed to the player
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# library.
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# We do the impossible and RegEx the stream JSON object out of the page's HTML source
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video_page_soup = self._get_page(video_page_url, {})
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regex: re.Pattern = re.compile(
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r"({\"streams\"[\s\S]+?),\s*{\"paella_config_file", re.IGNORECASE
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@ -210,35 +248,49 @@ class IliasCrawler:
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return []
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json_str = json_match.group(1)
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# parse it
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json_object = json.loads(json_str)
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# and fetch the video url!
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video_url = json_object["streams"][0]["sources"]["mp4"][0]["src"]
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return [IliasDownloadInfo(Path(path, title), video_url, modification_time)]
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def _crawl_exercises(self, element_path: Path, url: str) -> List[IliasDownloadInfo]:
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"""
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Crawl files offered for download in exercises.
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"""
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soup = self._get_page(url, {})
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results: List[IliasDownloadInfo] = []
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# Each assignment is in an accordion container
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assignment_containers: List[bs4.Tag] = soup.select(".il_VAccordionInnerContainer")
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for container in assignment_containers:
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# Fetch the container name out of the header to use it in the path
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container_name = container.select_one(".ilAssignmentHeader").getText().strip()
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# Find all download links in the container (this will contain all the files)
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files: List[bs4.Tag] = container.findAll(
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name="a",
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# download links contain the given command class
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attrs={"href": lambda x: x and "cmdClass=ilexsubmissiongui" in x},
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text="Download"
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)
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LOGGER.debug("Found exercise container %r", container_name)
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# Parse the end date to use as modification date
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# TODO: Return None?
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end_date: datetime.datetime = datetime.datetime.now()
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end_date_header: bs4.Tag = container.find(name="div", text="Abgabetermin")
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if end_date_header is not None:
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end_date_text = end_date_header.findNext("div").getText().strip()
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end_date = demangle_date(end_date_text)
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# Grab each file as you now have the link
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for file_link in files:
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# Two divs, side by side. Left is the name, right is the link ==> get left
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# sibling
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file_name = file_link.parent.findPrevious(name="div").getText().strip()
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url = self._abs_url_from_link(file_link)
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@ -253,10 +305,14 @@ class IliasCrawler:
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return results
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def _crawl_folder(self, path: Path, url: str) -> List[IliasDownloadInfo]:
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"""
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Crawl all files in a folder-like element.
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"""
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soup = self._get_page(url, {})
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result: List[IliasDownloadInfo] = []
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# Fetch all links and throw them to the general interpreter
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links: List[bs4.Tag] = soup.select("a.il_ContainerItemTitle")
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for link in links:
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abs_url = self._abs_url_from_link(link)
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@ -292,10 +348,13 @@ class IliasCrawler:
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@staticmethod
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def _is_logged_in(soup: bs4.BeautifulSoup) -> bool:
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# Normal ILIAS pages
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userlog = soup.find("li", {"id": "userlog"})
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if userlog is not None:
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LOGGER.debug("Auth: Found #userlog")
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return True
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# Video listing embeds do not have complete ILIAS html. Try to match them by
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# their video listing table
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video_table = soup.find(
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recursive=True,
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name="table",
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@ -304,6 +363,8 @@ class IliasCrawler:
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if video_table is not None:
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LOGGER.debug("Auth: Found #tbl_xoct.+")
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return True
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# The individual video player wrapper page has nothing of the above.
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# Match it by its playerContainer.
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if soup.select_one("#playerContainer") is not None:
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LOGGER.debug("Auth: Found #playerContainer")
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return True
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