[teachable] Extract chapter metadata (closes #24421)

youtube_dl/extractor/teachable.py

@@ -7,7 +7,9 @@
 from ..utils import (
     clean_html,
     ExtractorError,
+    int_or_none,
     get_element_by_class,
+    strip_or_none,
     urlencode_postdata,
     urljoin,
 )
@@ -173,11 +175,34 @@ def _real_extract(self, url):
 
         title = self._og_search_title(webpage, default=None)
 
+        chapter = None
+        chapter_number = None
+        section_item = self._search_regex(
+            r'(?s)(?P<li><li[^>]+\bdata-lecture-id=["\']%s[^>]+>.+?</li>)' % video_id,
+            webpage, 'section item', default=None, group='li')
+        if section_item:
+            chapter_number = int_or_none(self._search_regex(
+                r'data-ss-position=["\'](\d+)', section_item, 'section id',
+                default=None))
+            if chapter_number is not None:
+                sections = []
+                for s in re.findall(
+                        r'(?s)<div[^>]+\bclass=["\']section-title[^>]+>(.+?)</div>', webpage):
+                    section = strip_or_none(clean_html(s))
+                    if not section:
+                        sections = []
+                        break
+                    sections.append(section)
+                if chapter_number <= len(sections):
+                    chapter = sections[chapter_number - 1]
+
         entries = [{
             '_type': 'url_transparent',
             'url': wistia_url,
             'ie_key': WistiaIE.ie_key(),
             'title': title,
+            'chapter': chapter,
+            'chapter_number': chapter_number,
         } for wistia_url in wistia_urls]
 
         return self.playlist_result(entries, video_id, title)