[cleanup] Misc fixes

Cherry-picks from: #3498, #3947
Related: #3949, https://github.com/yt-dlp/yt-dlp/issues/1839#issuecomment-1140313836
Authored by: pukkandan, flashdagger, gamer191

2 files changed, 48 insertions, 50 deletions

diff --git a/yt_dlp/extractor/common.py b/yt_dlp/extractor/common.py
index c1a160e82..2e62660c7 100644
--- a/yt_dlp/extractor/common.py
+++ b/yt_dlp/extractor/common.py
@@ -786,7 +786,8 @@ class InfoExtractor:
                 self.report_warning(errmsg)
                 return False
 
-    def _download_webpage_handle(self, url_or_request, video_id, note=None, errnote=None, fatal=True, encoding=None, data=None, headers={}, query={}, expected_status=None):
+    def _download_webpage_handle(self, url_or_request, video_id, note=None, errnote=None, fatal=True,
+                                 encoding=None, data=None, headers={}, query={}, expected_status=None):
         """
         Return a tuple (page content as string, URL handle).
 
@@ -943,7 +944,7 @@ class InfoExtractor:
                 except ValueError:
                     raise e
         except ValueError as ve:
-            errmsg = '%s: Failed to parse JSON ' % video_id
+            errmsg = f'{video_id}: Failed to parse JSON'
             if fatal:
                 raise ExtractorError(errmsg, cause=ve)
             else:
diff --git a/yt_dlp/extractor/youtube.py b/yt_dlp/extractor/youtube.py
index c9bdd309d..8b2332dc1 100644
--- a/yt_dlp/extractor/youtube.py
+++ b/yt_dlp/extractor/youtube.py
@@ -15,7 +15,7 @@ import time
 import traceback
 
 from .common import InfoExtractor, SearchInfoExtractor
-from ..compat import functools
+from ..compat import functools  # isort: split
 from ..compat import (
     compat_chr,
     compat_HTTPError,
@@ -483,6 +483,11 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
         if data:
             return self._parse_json(data, item_id, fatal=fatal)
 
+    def _extract_yt_initial_variable(self, webpage, regex, video_id, name):
+        return self._parse_json(self._search_regex(
+            (fr'{regex}\s*{self._YT_INITIAL_BOUNDARY_RE}',
+             regex), webpage, name, default='{}'), video_id, fatal=False, lenient=True)
+
     @staticmethod
     def _extract_session_index(*data):
         """
@@ -2733,54 +2738,38 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         chapter_time = lambda chapter: parse_duration(self._get_text(chapter, 'timeDescription'))
         chapter_title = lambda chapter: self._get_text(chapter, 'title')
 
-        return next((
-            filter(None, (
-                self._extract_chapters(
-                    traverse_obj(contents, (..., 'macroMarkersListItemRenderer')),
-                    chapter_time, chapter_title, duration)
-                for contents in content_list
-            ))), [])
+        return next(filter(None, (
+            self._extract_chapters(traverse_obj(contents, (..., 'macroMarkersListItemRenderer')),
+                                   chapter_time, chapter_title, duration)
+            for contents in content_list)), [])
 
-    @staticmethod
-    def _extract_chapters_from_description(description, duration):
-        chapters = [{'start_time': 0}]
-        for timestamp, title in re.findall(
-                r'(?m)^((?:\d+:)?\d{1,2}:\d{2})\b\W*\s(.+?)\s*$', description or ''):
-            start = parse_duration(timestamp)
-            if start and title and chapters[-1]['start_time'] < start < duration:
-                chapters[-1]['end_time'] = start
-                chapters.append({
-                    'start_time': start,
-                    'title': title,
-                })
-        chapters[-1]['end_time'] = duration
-        return chapters[1:]
-
-    def _extract_chapters(self, chapter_list, chapter_time, chapter_title, duration):
-        chapters = []
-        last_chapter = {'start_time': 0}
-        for idx, chapter in enumerate(chapter_list or []):
-            title = chapter_title(chapter)
-            start_time = chapter_time(chapter)
-            if start_time is None:
-                continue
-            last_chapter['end_time'] = start_time
-            if start_time < last_chapter['start_time']:
-                if idx == 1:
-                    chapters.pop()
-                    self.report_warning('Invalid start time for chapter "%s"' % last_chapter['title'])
-                else:
-                    self.report_warning(f'Invalid start time for chapter "{title}"')
-                    continue
-            last_chapter = {'start_time': start_time, 'title': title}
-            chapters.append(last_chapter)
-        last_chapter['end_time'] = duration
-        return chapters
+    def _extract_chapters_from_description(self, description, duration):
+        return self._extract_chapters(
+            re.findall(r'(?m)^((?:\d+:)?\d{1,2}:\d{2})\b\W*\s(.+?)\s*$', description or ''),
+            chapter_time=lambda x: parse_duration(x[0]), chapter_title=lambda x: x[1],
+            duration=duration, strict=False)
 
-    def _extract_yt_initial_variable(self, webpage, regex, video_id, name):
-        return self._parse_json(self._search_regex(
-            (fr'{regex}\s*{self._YT_INITIAL_BOUNDARY_RE}',
-             regex), webpage, name, default='{}'), video_id, fatal=False, lenient=True)
+    def _extract_chapters(self, chapter_list, chapter_time, chapter_title, duration, strict=True):
+        if not duration:
+            return
+        chapter_list = [{
+            'start_time': chapter_time(chapter),
+            'title': chapter_title(chapter),
+        } for chapter in chapter_list or []]
+        if not strict:
+            chapter_list.sort(key=lambda c: c['start_time'] or 0)
+
+        chapters = [{'start_time': 0, 'title': '<Untitled>'}]
+        for idx, chapter in enumerate(chapter_list):
+            if chapter['start_time'] is None or not chapter['title']:
+                self.report_warning(f'Incomplete chapter {idx}')
+            elif chapters[-1]['start_time'] <= chapter['start_time'] <= duration:
+                chapters[-1]['end_time'] = chapter['start_time']
+                chapters.append(chapter)
+            else:
+                self.report_warning(f'Invalid start time for chapter "{chapter["title"]}"')
+        chapters[-1]['end_time'] = duration
+        return chapters if len(chapters) > 1 and chapters[1]['start_time'] else chapters[1:]
 
     def _extract_comment(self, comment_renderer, parent=None):
         comment_id = comment_renderer.get('commentId')
@@ -3663,7 +3652,15 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
 
         # Youtube Music Auto-generated description
         if video_description:
-            mobj = re.search(r'(?s)(?P<track>[^·\n]+)·(?P<artist>[^\n]+)\n+(?P<album>[^\n]+)(?:.+?℗\s*(?P<release_year>\d{4})(?!\d))?(?:.+?Released on\s*:\s*(?P<release_date>\d{4}-\d{2}-\d{2}))?(.+?\nArtist\s*:\s*(?P<clean_artist>[^\n]+))?.+\nAuto-generated by YouTube\.\s*$', video_description)
+            mobj = re.search(
+                r'''(?xs)
+                    (?P<track>[^·\n]+)·(?P<artist>[^\n]+)\n+
+                    (?P<album>[^\n]+)
+                    (?:.+?℗\s*(?P<release_year>\d{4})(?!\d))?
+                    (?:.+?Released on\s*:\s*(?P<release_date>\d{4}-\d{2}-\d{2}))?
+                    (.+?\nArtist\s*:\s*(?P<clean_artist>[^\n]+))?
+                    .+\nAuto-generated\ by\ YouTube\.\s*$
+                ''', video_description)
             if mobj:
                 release_year = mobj.group('release_year')
                 release_date = mobj.group('release_date')