Add forum crawling

This downloads all forum posts when needed and saves each thread in its
own html file, named after the thread title.

CHANGELOG.md

@@ -24,6 +24,7 @@ ambiguous situations.
 
 ### Added
 - Download of page descriptions
+- Forum download support
 
 ### Changed
 - Add `cpp` extension to default `link_regex` of IPD crawler

PFERD/cli/command_kit_ilias_web.py

@@ -62,6 +62,11 @@ GROUP.add_argument(
     action=BooleanOptionalAction,
     help="crawl and download videos"
 )
+GROUP.add_argument(
+    "--forums",
+    action=BooleanOptionalAction,
+    help="crawl and download forum posts"
+)
 GROUP.add_argument(
     "--http-timeout", "-t",
     type=float,
@@ -90,6 +95,8 @@ def load(
         section["link_redirect_delay"] = str(args.link_redirect_delay)
     if args.videos is not None:
         section["videos"] = "yes" if args.videos else "no"
+    if args.forums is not None:
+        section["forums"] = "yes" if args.forums else "no"
     if args.http_timeout is not None:
         section["http_timeout"] = str(args.http_timeout)
 

PFERD/crawl/ilias/kit_ilias_html.py

@@ -3,7 +3,7 @@ import re
 from dataclasses import dataclass
 from datetime import date, datetime, timedelta
 from enum import Enum
-from typing import List, Optional, Union
+from typing import Dict, List, Optional, Union
 from urllib.parse import urljoin, urlparse
 
 from bs4 import BeautifulSoup, Tag
@@ -55,6 +55,20 @@ class IliasPageElement:
         return self.url
 
 
+@dataclass
+class IliasDownloadForumData:
+    url: str
+    form_data: Dict[str, Union[str, List[str]]]
+
+
+@dataclass
+class IliasForumThread:
+    title: str
+    title_tag: Tag
+    content_tag: Tag
+    mtime: Optional[datetime]
+
+
 class IliasPage:
 
     def __init__(self, soup: BeautifulSoup, _page_url: str, source_element: Optional[IliasPageElement]):
@@ -110,13 +124,39 @@ class IliasPage:
 
         return BeautifulSoup(raw_html, "html.parser")
 
+    def get_download_forum_data(self) -> Optional[IliasDownloadForumData]:
+        form = self._soup.find("form", attrs={"action": lambda x: x and "fallbackCmd=showThreads" in x})
+        if not form:
+            return None
+        post_url = self._abs_url_from_relative(form["action"])
+
+        form_data: Dict[str, Union[str, List[ſtr]]] = {
+            "thread_ids[]": [f["value"] for f in form.find_all(attrs={"name": "thread_ids[]"})],
+            "selected_cmd2": "html",
+            "select_cmd2": "Ausführen",
+            "selected_cmd": "",
+        }
+
+        return IliasDownloadForumData(post_url, form_data)
+
     def get_next_stage_element(self) -> Optional[IliasPageElement]:
+        if self._is_forum_page():
+            if "trows=800" in self._page_url:
+                return None
+            return self._get_show_max_forum_entries_per_page_url()
         if self._is_ilias_opencast_embedding():
             return self.get_child_elements()[0]
         if self._page_type == IliasElementType.VIDEO_FOLDER_MAYBE_PAGINATED:
             return self._find_video_entries_paginated()[0]
         return None
 
+    def _is_forum_page(self) -> bool:
+        read_more_btn = self._soup.find(
+            "button",
+            attrs={"onclick": lambda x: x and "cmdClass=ilobjforumgui&cmd=markAllRead" in x}
+        )
+        return read_more_btn is not None
+
     def _is_video_player(self) -> bool:
         return "paella_config_file" in str(self._soup)
 
@@ -194,6 +234,19 @@ class IliasPage:
 
         return items
 
+    def _get_show_max_forum_entries_per_page_url(self) -> Optional[IliasPageElement]:
+        correct_link = self._soup.find(
+            "a",
+            attrs={"href": lambda x: x and "trows=800" in x and "cmd=showThreads" in x}
+        )
+
+        if not correct_link:
+            return None
+
+        link = self._abs_url_from_link(correct_link)
+
+        return IliasPageElement(IliasElementType.FORUM, link, "show all forum threads")
+
     def _find_personal_desktop_entries(self) -> List[IliasPageElement]:
         items: List[IliasPageElement] = []
 
@@ -877,3 +930,38 @@ def _tomorrow() -> date:
 
 def _sanitize_path_name(name: str) -> str:
     return name.replace("/", "-").replace("\\", "-").strip()
+
+
+def parse_ilias_forum_export(forum_export: BeautifulSoup) -> List[IliasForumThread]:
+    elements = []
+    for p in forum_export.select("body > p"):
+        title_tag = p
+        content_tag = p.find_next_sibling("ul")
+        title = p.find("b").text
+        if ":" in title:
+            title = title[title.find(":") + 1:]
+        title = title.strip()
+        mtime = _guess_timestamp_from_forum_post_content(content_tag)
+        elements.append(IliasForumThread(title, title_tag, content_tag, mtime))
+
+    return elements
+
+
+def _guess_timestamp_from_forum_post_content(content: Tag) -> Optional[datetime]:
+    posts: Optional[Tag] = content.select(".ilFrmPostHeader > span.small")
+    if not posts:
+        return None
+
+    newest_date: Optional[datetime] = None
+
+    for post in posts:
+        text = post.text.strip()
+        text = text[text.rfind("|") + 1:]
+        date = demangle_date(text, fail_silently=True)
+        if not date:
+            continue
+
+        if not newest_date or newest_date < date:
+            newest_date = date
+
+    return newest_date

PFERD/crawl/ilias/kit_ilias_web_crawler.py

@@ -18,7 +18,8 @@ from ..crawler import AWrapped, CrawlError, CrawlToken, CrawlWarning, DownloadTo
 from ..http_crawler import HttpCrawler, HttpCrawlerSection
 from .file_templates import Links
 from .ilias_html_cleaner import clean, insert_base_markup
-from .kit_ilias_html import IliasElementType, IliasPage, IliasPageElement
+from .kit_ilias_html import (IliasElementType, IliasForumThread, IliasPage, IliasPageElement,
+                             _sanitize_path_name, parse_ilias_forum_export)
 
 TargetType = Union[str, int]
 
@@ -67,6 +68,9 @@ class KitIliasWebCrawlerSection(HttpCrawlerSection):
     def videos(self) -> bool:
         return self.s.getboolean("videos", fallback=False)
 
+    def forums(self) -> bool:
+        return self.s.getboolean("forums", fallback=False)
+
 
 _DIRECTORY_PAGES: Set[IliasElementType] = set([
     IliasElementType.EXERCISE,
@@ -183,6 +187,7 @@ instance's greatest bottleneck.
         self._link_file_redirect_delay = section.link_redirect_delay()
         self._links = section.links()
         self._videos = section.videos()
+        self._forums = section.forums()
         self._visited_urls: Set[str] = set()
 
     async def _run(self) -> None:
@@ -335,22 +340,27 @@ instance's greatest bottleneck.
         element_path = PurePath(parent_path, element.name)
 
         if element.type in _VIDEO_ELEMENTS:
-            log.explain_topic(f"Decision: Crawl video element {fmt_path(element_path)}")
             if not self._videos:
-                log.explain("Video crawling is disabled")
-                log.explain("Answer: no")
+                log.status(
+                    "[bold bright_black]",
+                    "Ignored",
+                    fmt_path(element_path),
+                    "[bright_black](enable with option 'videos')"
+                )
                 return None
-            else:
-                log.explain("Video crawling is enabled")
-                log.explain("Answer: yes")
 
         if element.type == IliasElementType.FILE:
             return await self._handle_file(element, element_path)
         elif element.type == IliasElementType.FORUM:
-            log.explain_topic(f"Decision: Crawl {fmt_path(element_path)}")
-            log.explain("Forums are not supported")
-            log.explain("Answer: No")
+            if not self._forums:
+                log.status(
+                    "[bold bright_black]",
+                    "Ignored",
+                    fmt_path(element_path),
+                    "[bright_black](enable with option 'forums')"
+                )
                 return None
+            return await self._handle_forum(element, element_path)
         elif element.type == IliasElementType.TEST:
             log.explain_topic(f"Decision: Crawl {fmt_path(element_path)}")
             log.explain("Tests contain no relevant files")
@@ -635,6 +645,68 @@ instance's greatest bottleneck.
         if not await try_stream():
             raise CrawlError("File streaming failed after authenticate()")
 
+    async def _handle_forum(
+        self,
+        element: IliasPageElement,
+        element_path: PurePath,
+    ) -> Optional[Coroutine[Any, Any, None]]:
+        maybe_cl = await self.crawl(element_path)
+        if not maybe_cl:
+            return None
+        return self._crawl_forum(element, maybe_cl)
+
+    @_iorepeat(3, "crawling forum")
+    @anoncritical
+    async def _crawl_forum(self, element: IliasPageElement, cl: CrawlToken) -> None:
+        elements = []
+
+        async with cl:
+            next_stage_url = element.url
+            while next_stage_url:
+                log.explain_topic(f"Parsing HTML page for {fmt_path(cl.path)}")
+                log.explain(f"URL: {next_stage_url}")
+
+                soup = await self._get_page(next_stage_url)
+                page = IliasPage(soup, next_stage_url, None)
+
+                if next := page.get_next_stage_element():
+                    next_stage_url = next.url
+                else:
+                    break
+
+            download_data = page.get_download_forum_data()
+            if not download_data:
+                raise CrawlWarning("Failed to extract forum data")
+            html = await self._post_authenticated(download_data.url, download_data.form_data)
+            elements = parse_ilias_forum_export(soupify(html))
+
+        elements.sort(key=lambda elem: elem.title)
+
+        tasks: List[Awaitable[None]] = []
+        for elem in elements:
+            tasks.append(asyncio.create_task(self._download_forum_thread(cl.path, elem)))
+
+        # And execute them
+        await self.gather(tasks)
+
+    @anoncritical
+    @_iorepeat(3, "saving forum thread")
+    async def _download_forum_thread(
+        self,
+        parent_path: PurePath,
+        element: IliasForumThread,
+    ) -> None:
+        path = parent_path / (_sanitize_path_name(element.title) + ".html")
+        maybe_dl = await self.download(path, mtime=element.mtime)
+        if not maybe_dl:
+            return
+
+        async with maybe_dl as (bar, sink):
+            content = element.title_tag.prettify()
+            content += element.content_tag.prettify()
+            sink.file.write(content.encode("utf-8"))
+            sink.done()
+
     async def _get_page(self, url: str) -> BeautifulSoup:
         auth_id = await self._current_auth_id()
         async with self.session.get(url) as request:
@@ -652,6 +724,30 @@ instance's greatest bottleneck.
                 return soup
         raise CrawlError("get_page failed even after authenticating")
 
+    async def _post_authenticated(
+        self,
+        url: str,
+        data: dict[str, Union[str, List[str]]]
+    ) -> BeautifulSoup:
+        auth_id = await self._current_auth_id()
+
+        form_data = aiohttp.FormData()
+        for key, val in data.items():
+            form_data.add_field(key, val)
+
+        async with self.session.post(url, data=form_data(), allow_redirects=False) as request:
+            if request.status == 200:
+                return await request.read()
+
+        # We weren't authenticated, so try to do that
+        await self.authenticate(auth_id)
+
+        # Retry once after authenticating. If this fails, we will die.
+        async with self.session.post(url, data=data, allow_redirects=False) as request:
+            if request.status == 200:
+                return await request.read()
+        raise CrawlError("post_authenticated failed even after authenticating")
+
     # We repeat this as the login method in shibboleth doesn't handle I/O errors.
     # Shibboleth is quite reliable as well, the repeat is likely not critical here.
     @ _iorepeat(3, "Login", failure_is_error=True)

PFERD/logging.py

@@ -197,7 +197,7 @@ directly or as a GitHub issue: https://github.com/Garmelon/PFERD/issues/new
         if self.output_explain:
             self.print(f"  {escape(text)}")
 
-    def status(self, style: str, action: str, text: str) -> None:
+    def status(self, style: str, action: str, text: str, suffix: str = "") -> None:
         """
         Print a status update while crawling. Allows markup in the "style"
         argument which will be applied to the "action" string.
@@ -205,7 +205,7 @@ directly or as a GitHub issue: https://github.com/Garmelon/PFERD/issues/new
 
         if self.output_status:
             action = escape(f"{action:<{self.STATUS_WIDTH}}")
-            self.print(f"{style}{action}[/] {escape(text)}")
+            self.print(f"{style}{action}[/] {escape(text)} {suffix}")
 
     def report(self, text: str) -> None:
         """