mirror of
https://github.com/Garmelon/PFERD.git
synced 2023-12-21 10:23:01 +01:00
453 lines
17 KiB
Python
453 lines
17 KiB
Python
import json
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import re
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from dataclasses import dataclass
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from datetime import date, datetime, timedelta
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from enum import Enum
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# TODO In Python 3.9 and above, AsyncContextManager is deprecated
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from typing import List, Optional, Union
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from urllib.parse import urljoin, urlparse
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from bs4 import BeautifulSoup, Tag
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from PFERD.utils import url_set_query_params
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TargetType = Union[str, int]
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class IliasElementType(Enum):
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EXERCISE = "exercise"
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FILE = "file"
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FOLDER = "folder"
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FORUM = "forum"
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LINK = "link"
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MEETING = "meeting"
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VIDEO = "video"
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VIDEO_PLAYER = "video_player"
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VIDEO_FOLDER = "video_folder"
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VIDEO_FOLDER_MAYBE_PAGINATED = "video_folder_maybe_paginated"
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@dataclass
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class IliasPageElement:
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type: IliasElementType
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url: str
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name: str
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mtime: Optional[datetime] = None
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description: Optional[str] = None
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class IliasPage:
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def __init__(self, soup: BeautifulSoup, _page_url: str, source_element: Optional[IliasPageElement]):
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self._soup = soup
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self._page_url = _page_url
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self._page_type = source_element.type if source_element else None
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self._source_name = source_element.name if source_element else ""
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def get_child_elements(self) -> List[IliasPageElement]:
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"""
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Return all child page elements you can find here.
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"""
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if self._is_video_player():
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return self._player_to_video()
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if self._is_video_listing():
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return self._find_video_entries()
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if self._is_exercise_file():
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return self._find_exercise_entries()
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return self._find_normal_entries()
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def _is_video_player(self) -> bool:
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return "paella_config_file" in str(self._soup)
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def _is_video_listing(self) -> bool:
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# ILIAS fluff around it
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if self._soup.find(id="headerimage"):
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element: Tag = self._soup.find(id="headerimage")
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if "opencast" in element.attrs["src"].lower():
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return True
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# Raw listing without ILIAS fluff
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video_element_table: Tag = self._soup.find(
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name="table", id=re.compile(r"tbl_xoct_.+")
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)
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return video_element_table is not None
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def _is_exercise_file(self) -> bool:
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# we know it from before
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if self._page_type == IliasElementType.EXERCISE:
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return True
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# We have no suitable parent - let's guesss
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if self._soup.find(id="headerimage"):
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element: Tag = self._soup.find(id="headerimage")
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if "exc" in element.attrs["src"].lower():
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return True
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return False
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def _player_to_video(self) -> List[IliasPageElement]:
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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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regex: re.Pattern[str] = re.compile(
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r"({\"streams\"[\s\S]+?),\s*{\"paella_config_file", re.IGNORECASE
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)
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json_match = regex.search(str(self._soup))
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if json_match is None:
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print(f"Could not find json stream info for {self._page_url!r}")
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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 [IliasPageElement(IliasElementType.VIDEO, video_url, self._source_name)]
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def _find_video_entries(self) -> List[IliasPageElement]:
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# ILIAS has three stages for video pages
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# 1. The initial dummy page without any videos. This page contains the link to the listing
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# 2. The video listing which might be paginated
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# 3. An unpaginated video listing (or at least one that includes 800 videos)
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#
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# We need to figure out where we are.
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video_element_table: Tag = self._soup.find(
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name="table", id=re.compile(r"tbl_xoct_.+")
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)
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if video_element_table is None:
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# We are in stage 1
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# The page is actually emtpy but contains the link to stage 2
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content_link: Tag = self._soup.select_one("#tab_series a")
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url: str = self._abs_url_from_link(content_link)
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query_params = {"limit": "800", "cmd": "asyncGetTableGUI", "cmdMode": "asynch"}
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url = url_set_query_params(url, query_params)
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return [IliasPageElement(IliasElementType.VIDEO_FOLDER_MAYBE_PAGINATED, url, "")]
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is_paginated = self._soup.find(id=re.compile(r"tab_page_sel.+")) is not None
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if is_paginated and not self._page_type == IliasElementType.VIDEO_FOLDER:
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# We are in stage 2 - try to break pagination
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return self._find_video_entries_paginated()
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return self._find_video_entries_no_paging()
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def _find_video_entries_paginated(self) -> List[IliasPageElement]:
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table_element: Tag = self._soup.find(name="table", id=re.compile(r"tbl_xoct_.+"))
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if table_element is None:
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# TODO: Properly log this
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print(
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"Could not increase elements per page (table not found)."
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" Some might not be crawled!"
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)
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return self._find_video_entries_no_paging()
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id_match = re.match(r"tbl_xoct_(.+)", table_element.attrs["id"])
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if id_match is None:
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# TODO: Properly log this
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print(
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"Could not increase elements per page (table id not found)."
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" Some might not be crawled!"
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)
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return self._find_video_entries_no_paging()
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table_id = id_match.group(1)
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query_params = {f"tbl_xoct_{table_id}_trows": "800",
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"cmd": "asyncGetTableGUI", "cmdMode": "asynch"}
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url = url_set_query_params(self._page_url, query_params)
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return [IliasPageElement(IliasElementType.VIDEO_FOLDER, url, "")]
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def _find_video_entries_no_paging(self) -> List[IliasPageElement]:
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"""
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Crawls the "second stage" video page. This page contains the actual video urls.
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"""
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# Video start links are marked with an "Abspielen" link
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video_links: List[Tag] = self._soup.findAll(
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name="a", text=re.compile(r"\s*Abspielen\s*")
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)
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results: List[IliasPageElement] = []
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# TODO: Sadly the download button is currently broken, so never do that
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for link in video_links:
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results.append(self._listed_video_to_element(link))
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return results
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def _listed_video_to_element(self, link: Tag) -> IliasPageElement:
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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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modification_time = datetime.strptime(modification_string, "%d.%m.%Y - %H:%M")
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title = link.parent.parent.parent.select_one("td.std:nth-child(3)").getText().strip()
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title += ".mp4"
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video_name: str = _sanitize_path_name(title)
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video_url = self._abs_url_from_link(link)
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return IliasPageElement(IliasElementType.VIDEO_PLAYER, video_url, video_name, modification_time)
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def _find_exercise_entries(self) -> List[IliasPageElement]:
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results: List[IliasPageElement] = []
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# Each assignment is in an accordion container
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assignment_containers: List[Tag] = self._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[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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# 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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file_name = _sanitize_path_name(file_name)
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url = self._abs_url_from_link(file_link)
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results.append(IliasPageElement(
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IliasElementType.FILE,
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url,
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container_name + "/" + file_name,
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None # We do not have any timestamp
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))
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return results
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def _find_normal_entries(self) -> List[IliasPageElement]:
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result: List[IliasPageElement] = []
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# Fetch all links and throw them to the general interpreter
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links: List[Tag] = self._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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element_name = _sanitize_path_name(link.getText())
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element_type = self._find_type_from_link(element_name, link, abs_url)
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description = self._find_link_description(link)
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if not element_type:
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continue
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if element_type == IliasElementType.MEETING:
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element_name = _sanitize_path_name(self._normalize_meeting_name(element_name))
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elif element_type == IliasElementType.FILE:
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result.append(self._file_to_element(element_name, abs_url, link))
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continue
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result.append(IliasPageElement(element_type, abs_url, element_name, description=description))
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return result
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def _find_link_description(self, link: Tag) -> Optional[str]:
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tile: Tag = link.findParent("div", {"class": lambda x: x and "il_ContainerListItem" in x})
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if not tile:
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return None
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description_element: Tag = tile.find("div", {"class": lambda x: x and "il_Description" in x})
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if not description_element:
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return None
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return description_element.getText().strip()
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def _file_to_element(self, name: str, url: str, link_element: Tag) -> IliasPageElement:
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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: 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|Yesterday)|(Heute|Today)|(Morgen|Tomorrow)), \d+:\d+)",
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all_properties_text
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)
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if modification_date_match is None:
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modification_date = None
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# TODO: Properly log this
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print(f"Could not extract start date from {all_properties_text!r}")
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else:
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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 = _sanitize_path_name(link_element.getText())
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full_path = name + "." + file_type
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return IliasPageElement(IliasElementType.FILE, url, full_path, modification_date)
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@staticmethod
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def _find_type_from_link(
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element_name: str,
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link_element: Tag,
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url: str
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) -> Optional[IliasElementType]:
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"""
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Decides which sub crawler to use for a given top level element.
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"""
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parsed_url = urlparse(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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return IliasElementType.FILE
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# Skip forums
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if "cmd=showThreads" in parsed_url.query:
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return IliasElementType.FORUM
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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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return IliasPage._find_type_from_folder_like(link_element, url)
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# TODO: Log this properly
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print(f"Unknown type: The element was at {str(element_name)!r} and it is {link_element!r})")
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return None
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@staticmethod
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def _find_type_from_folder_like(link_element: Tag, url: str) -> Optional[IliasElementType]:
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"""
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Try crawling something that looks like a folder.
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"""
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# pylint: disable=too-many-return-statements
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found_parent: Optional[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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break
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if found_parent is None:
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# TODO: Log this properly
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print(f"Could not find element icon for {url!r}")
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return None
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# Find the small descriptive icon to figure out the type
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img_tag: Optional[Tag] = found_parent.select_one("img.ilListItemIcon")
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if img_tag is None:
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# TODO: Log this properly
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print(f"Could not find image tag for {url!r}")
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return None
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if "opencast" in str(img_tag["alt"]).lower():
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return IliasElementType.VIDEO_FOLDER
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if str(img_tag["src"]).endswith("icon_exc.svg"):
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return IliasElementType.EXERCISE
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if str(img_tag["src"]).endswith("icon_webr.svg"):
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return IliasElementType.LINK
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if str(img_tag["src"]).endswith("frm.svg"):
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return IliasElementType.FORUM
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if str(img_tag["src"]).endswith("sess.svg"):
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return IliasElementType.MEETING
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return IliasElementType.FOLDER
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@staticmethod
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def _normalize_meeting_name(meeting_name: str) -> str:
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"""
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Normalizes meeting names, which have a relative time as their first part,
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to their date in ISO format.
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"""
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date_portion_str = meeting_name.split(" - ")[0]
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date_portion = demangle_date(date_portion_str)
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if not date_portion:
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return meeting_name
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rest_of_name = meeting_name
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if rest_of_name.startswith(date_portion_str):
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rest_of_name = rest_of_name[len(date_portion_str):]
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return datetime.strftime(date_portion, "%Y-%m-%d, %H:%M") + rest_of_name
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def _abs_url_from_link(self, link_tag: Tag) -> str:
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"""
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Create an absolute url from an <a> tag.
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"""
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return urljoin(self._page_url, link_tag.get("href"))
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german_months = ['Jan', 'Feb', 'Mär', 'Apr', 'Mai', 'Jun', 'Jul', 'Aug', 'Sep', 'Okt', 'Nov', 'Dez']
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english_months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
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def demangle_date(date_str: str) -> Optional[datetime]:
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"""
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Demangle a given date in one of the following formats:
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"Gestern, HH:MM"
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"Heute, HH:MM"
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"Morgen, HH:MM"
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"dd. mon yyyy, HH:MM
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"""
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try:
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date_str = re.sub(r"\s+", " ", date_str)
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date_str = re.sub("Gestern|Yesterday", _format_date_english(_yesterday()), date_str, re.I)
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date_str = re.sub("Heute|Today", _format_date_english(date.today()), date_str, re.I)
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date_str = re.sub("Morgen|Tomorrow", _format_date_english(_tomorrow()), date_str, re.I)
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for german, english in zip(german_months, english_months):
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date_str = date_str.replace(german, english)
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# Remove trailing dots for abbreviations, e.g. "20. Apr. 2020" -> "20. Apr 2020"
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date_str = date_str.replace(english + ".", english)
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# We now have a nice english String in the format: "dd. mmm yyyy, hh:mm"
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day_part, time_part = date_str.split(",")
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day_str, month_str, year_str = day_part.split(" ")
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day = int(day_str.strip().replace(".", ""))
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month = english_months.index(month_str.strip()) + 1
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year = int(year_str.strip())
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hour_str, minute_str = time_part.split(":")
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hour = int(hour_str)
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minute = int(minute_str)
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return datetime(year, month, day, hour, minute)
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except Exception:
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# TODO: Properly log this
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print(f"Could not parse date {date_str!r}")
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return None
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def _format_date_english(date_to_format: date) -> str:
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month = english_months[date_to_format.month - 1]
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return f"{date_to_format.day:02d}. {month} {date_to_format.year:04d}"
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def _yesterday() -> date:
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return date.today() - timedelta(days=1)
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def _tomorrow() -> date:
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return date.today() + timedelta(days=1)
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def _sanitize_path_name(name: str) -> str:
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return name.replace("/", "-").replace("\\", "-").strip()
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