Move video url extraction logic to crawler

PFERD/ilias/crawler.py

@@ -3,6 +3,7 @@ Contains an ILIAS crawler alongside helper functions.
 """
 
 import datetime
+import json
 import logging
 import re
 from enum import Enum
@@ -380,22 +381,44 @@ class IliasCrawler:
 
         video_path: Path = Path(parent_path, title)
 
+        video_url = self._abs_url_from_link(link)
+
         # The video had a direct download button we can use instead
         if direct_download:
             LOGGER.debug("Using direct download for video %r", str(video_path))
-            return [IliasDownloadInfo(
-                video_path,
-                self._abs_url_from_link(link),
-                modification_time
-            )]
+            return [IliasDownloadInfo(video_path, video_url, modification_time)]
 
         return [IliasDownloadInfo(
             video_path,
-            self._abs_url_from_link(link),
-            modification_time,
-            unpack_video=True
+            self._crawl_video_url_from_play_link(video_url),
+            modification_time
         )]
 
+    def _crawl_video_url_from_play_link(self, play_url: str) -> Callable[[], Optional[str]]:
+        def inner() -> Optional[str]:
+            # Fetch the actual video page. This is a small wrapper page initializing a javscript
+            # player. Sadly we can not execute that JS. The actual video stream url is nowhere
+            # on the page, but defined in a JS object inside a script tag, passed to the player
+            # library.
+            # We do the impossible and RegEx the stream JSON object out of the page's HTML source
+            video_page_soup = soupify(self._session.get(play_url))
+            regex: re.Pattern = re.compile(
+                r"({\"streams\"[\s\S]+?),\s*{\"paella_config_file", re.IGNORECASE
+            )
+            json_match = regex.search(str(video_page_soup))
+
+            if json_match is None:
+                PRETTY.warning(f"Could not find json stream info for {play_url!r}")
+                return None
+            json_str = json_match.group(1)
+
+            # parse it
+            json_object = json.loads(json_str)
+            # and fetch the video url!
+            video_url = json_object["streams"][0]["sources"]["mp4"][0]["src"]
+            return video_url
+        return inner
+
     def _crawl_exercises(self, element_path: Path, url: str) -> List[IliasDownloadInfo]:
         """
         Crawl files offered for download in exercises.

PFERD/ilias/downloader.py

@@ -1,12 +1,9 @@
 """Contains a downloader for ILIAS."""
 
 import datetime
-import json
 import logging
-import re
-from dataclasses import dataclass
-from pathlib import Path
-from typing import Callable, List, Optional
+from pathlib import Path, PurePath
+from typing import Callable, List, Optional, Union
 
 import bs4
 import requests
@@ -26,15 +23,24 @@ class ContentTypeException(Exception):
     """Thrown when the content type of the ilias element can not be handled."""
 
 
-@dataclass
 class IliasDownloadInfo(Transformable):
     """
     This class describes a single file to be downloaded.
     """
 
-    url: str
-    modification_date: Optional[datetime.datetime]
-    unpack_video: bool = False
+    def __init__(
+            self,
+            path: PurePath,
+            url: Union[str, Callable[[], Optional[str]]],
+            modifcation_date: Optional[datetime.datetime]
+    ):
+        super().__init__(path)
+        if isinstance(url, str):
+            string_url = url
+            self.url: Callable[[], Optional[str]] = lambda: string_url
+        else:
+            self.url = url
+        self.modification_date = modifcation_date
 
 
 IliasDownloadStrategy = Callable[[Organizer, IliasDownloadInfo], bool]
@@ -109,47 +115,19 @@ class IliasDownloader:
 
         tmp_file = self._tmp_dir.new_path()
 
-        while not self._download_file(info, tmp_file):
+        while not self._try_download(info, tmp_file):
             LOGGER.info("Retrying download: %r", info)
             self._authenticator.authenticate(self._session)
 
         self._organizer.accept_file(tmp_file, info.path)
 
-    def _download_file(self, info: IliasDownloadInfo, target: Path) -> bool:
-        if info.unpack_video:
-            return self._download_unpack_video(info, target)
-
-        return self._try_download(info, target)
-
-    def _download_unpack_video(self, info: IliasDownloadInfo, target: Path) -> bool:
-        # Fetch the actual video page. This is a small wrapper page initializing a javscript
-        # player. Sadly we can not execute that JS. The actual video stream url is nowhere
-        # on the page, but defined in a JS object inside a script tag, passed to the player
-        # library.
-        # We do the impossible and RegEx the stream JSON object out of the page's HTML source
-        video_page_soup = soupify(self._session.get(info.url))
-        regex: re.Pattern = re.compile(
-            r"({\"streams\"[\s\S]+?),\s*{\"paella_config_file", re.IGNORECASE
-        )
-        json_match = regex.search(str(video_page_soup))
-
-        if json_match is None:
-            PRETTY.warning(f"Could not find json stream info for {info.url!r}")
-            return True
-        json_str = json_match.group(1)
-
-        # parse it
-        json_object = json.loads(json_str)
-        # and fetch the video url!
-        video_url = json_object["streams"][0]["sources"]["mp4"][0]["src"]
-
-        return self._try_download(
-            IliasDownloadInfo(info.path, video_url, info.modification_date),
-            target
-        )
-
     def _try_download(self, info: IliasDownloadInfo, target: Path) -> bool:
-        with self._session.get(info.url, stream=True) as response:
+        url = info.url()
+        if url is None:
+            PRETTY.warning(f"Could not download {str(info.path)!r} as I got no URL :/")
+            return True
+
+        with self._session.get(url, stream=True) as response:
             content_type = response.headers["content-type"]
 
             if content_type.startswith("text/html"):