fix: youtube: Polymer UI and JSON endpoints for playlists

We already had a few copies of Polymer-style pagination handling logic
for certain circumstances, but now we're forced into using it for all
playlists since we can no longer disable Polymer. Refactor the logic to
move it to the parent class for all entry lists (including e.g. search
results, feeds, and list of playlists), and generify a bit to cover the
child classes' use cases.

youtube_dlc/extractor/youtube.py

@@ -36,6 +36,7 @@ from ..utils import (
     get_element_by_attribute,
     get_element_by_id,
     int_or_none,
+    js_to_json,
     mimetype2ext,
     orderedSet,
     parse_codecs,
@@ -70,6 +71,8 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
     _LOGIN_REQUIRED = False
 
     _PLAYLIST_ID_RE = r'(?:PL|LL|EC|UU|FL|RD|UL|TL|PU|OLAK5uy_)[0-9A-Za-z-_]{10,}'
+    _INITIAL_DATA_RE = r'(?:window\["ytInitialData"\]|ytInitialData)\W?=\W?({.*?});'
+    _YTCFG_DATA_RE = r"ytcfg.set\(({.*?})\)"
 
     _YOUTUBE_CLIENT_HEADERS = {
         'x-youtube-client-name': '1',
@@ -274,7 +277,6 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
 
     def _download_webpage_handle(self, *args, **kwargs):
         query = kwargs.get('query', {}).copy()
-        query['disable_polymer'] = 'true'
         kwargs['query'] = query
         return super(YoutubeBaseInfoExtractor, self)._download_webpage_handle(
             *args, **compat_kwargs(kwargs))
@@ -297,15 +299,60 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
 
 
 class YoutubeEntryListBaseInfoExtractor(YoutubeBaseInfoExtractor):
-    # Extract entries from page with "Load more" button
+    def _find_entries_in_json(self, extracted):
+        entries = []
+        c = {}
+
+        def _real_find(obj):
+            if obj is None or isinstance(obj, str):
+                return
+
+            if type(obj) is list:
+                for elem in obj:
+                    _real_find(elem)
+
+            if type(obj) is dict:
+                if self._is_entry(obj):
+                    entries.append(obj)
+                    return
+
+                if 'continuationCommand' in obj:
+                    c['continuation'] = obj
+                    return
+
+                for _, o in obj.items():
+                    _real_find(o)
+
+        _real_find(extracted)
+
+        return entries, try_get(c, lambda x: x["continuation"])
+
     def _entries(self, page, playlist_id):
-        more_widget_html = content_html = page
+        seen = []
+
+        yt_conf = {}
+        for m in re.finditer(self._YTCFG_DATA_RE, page):
+            parsed = self._parse_json(m.group(1), playlist_id,
+                                      transform_source=js_to_json, fatal=False)
+            if parsed:
+                yt_conf.update(parsed)
+
+        data_json = self._parse_json(self._search_regex(self._INITIAL_DATA_RE, page, 'ytInitialData'), None)
+
         for page_num in itertools.count(1):
-            for entry in self._process_page(content_html):
+            entries, continuation = self._find_entries_in_json(data_json)
+            processed = self._process_entries(entries, seen)
+
+            if not processed:
+                break
+            for entry in processed:
                 yield entry
 
-            mobj = re.search(r'data-uix-load-more-href="/?(?P<more>[^"]+)"', more_widget_html)
-            if not mobj:
+            if not continuation or not yt_conf:
+                break
+            continuation_token = try_get(continuation, lambda x: x['continuationCommand']['token'])
+            continuation_url = try_get(continuation, lambda x: x['commandMetadata']['webCommandMetadata']['apiUrl'])
+            if not continuation_token or not continuation_url:
                 break
 
             count = 0
@@ -314,12 +361,22 @@ class YoutubeEntryListBaseInfoExtractor(YoutubeBaseInfoExtractor):
                 try:
                     # Downloading page may result in intermittent 5xx HTTP error
                     # that is usually worked around with a retry
-                    more = self._download_json(
-                        'https://www.youtube.com/%s' % mobj.group('more'), playlist_id,
-                        'Downloading page #%s%s'
-                        % (page_num, ' (retry #%d)' % count if count else ''),
+                    data_json = self._download_json(
+                        'https://www.youtube.com%s' % continuation_url,
+                        playlist_id,
+                        'Downloading page #%s%s' % (page_num, ' (retry #%d)' % count if count else ''),
                         transform_source=uppercase_escape,
-                        headers=self._YOUTUBE_CLIENT_HEADERS)
+                        query={
+                            'key': try_get(yt_conf, lambda x: x['INNERTUBE_API_KEY'])
+                        },
+                        data=bytes(json.dumps({
+                            'context': try_get(yt_conf, lambda x: x['INNERTUBE_CONTEXT']),
+                            'continuation': continuation_token
+                        }), encoding='utf-8'),
+                        headers={
+                            'Content-Type': 'application/json'
+                        }
+                    )
                     break
                 except ExtractorError as e:
                     if isinstance(e.cause, compat_HTTPError) and e.cause.code in (500, 503):
@@ -328,31 +385,30 @@ class YoutubeEntryListBaseInfoExtractor(YoutubeBaseInfoExtractor):
                             continue
                     raise
 
-            content_html = more['content_html']
-            if not content_html.strip():
-                # Some webpages show a "Load more" button but they don't
-                # have more videos
-                break
-            more_widget_html = more['load_more_widget_html']
+    def _extract_title(self, renderer):
+        title = try_get(renderer, lambda x: x['title']['runs'][0]['text'], compat_str)
+        if title:
+            return title
+        return try_get(renderer, lambda x: x['title']['simpleText'], compat_str)
 
 
 class YoutubePlaylistBaseInfoExtractor(YoutubeEntryListBaseInfoExtractor):
-    def _process_page(self, content):
-        for video_id, video_title in self.extract_videos_from_page(content):
-            yield self.url_result(video_id, 'Youtube', video_id, video_title)
+    def _is_entry(self, obj):
+        return 'videoId' in obj
+
+    def _process_entries(self, entries, seen):
+        ids_in_page = []
+        titles_in_page = []
+        for renderer in entries:
+            video_id = try_get(renderer, lambda x: x['videoId'])
+            video_title = self._extract_title(renderer)
 
-    def extract_videos_from_page_impl(self, video_re, page, ids_in_page, titles_in_page):
-        for mobj in re.finditer(video_re, page):
-            # The link with index 0 is not the first video of the playlist (not sure if still actual)
-            if 'index' in mobj.groupdict() and mobj.group('id') == '0':
+            if video_id is None or video_title is None:
+                # we do not have a videoRenderer or title extraction broke
                 continue
-            video_id = mobj.group('id')
-            video_title = unescapeHTML(
-                mobj.group('title')) if 'title' in mobj.groupdict() else None
-            if video_title:
-                video_title = video_title.strip()
-            if video_title == '► Play all':
-                video_title = None
+
+            video_title = video_title.strip()
+
             try:
                 idx = ids_in_page.index(video_id)
                 if video_title and not titles_in_page[idx]:
@@ -361,19 +417,16 @@ class YoutubePlaylistBaseInfoExtractor(YoutubeEntryListBaseInfoExtractor):
                 ids_in_page.append(video_id)
                 titles_in_page.append(video_title)
 
-    def extract_videos_from_page(self, page):
-        ids_in_page = []
-        titles_in_page = []
-        self.extract_videos_from_page_impl(
-            self._VIDEO_RE, page, ids_in_page, titles_in_page)
-        return zip(ids_in_page, titles_in_page)
+        for video_id, video_title in zip(ids_in_page, titles_in_page):
+            yield self.url_result(video_id, 'Youtube', video_id, video_title)
 
 
 class YoutubePlaylistsBaseInfoExtractor(YoutubeEntryListBaseInfoExtractor):
-    def _process_page(self, content):
-        for playlist_id in orderedSet(re.findall(
-                r'<h3[^>]+class="[^"]*yt-lockup-title[^"]*"[^>]*><a[^>]+href="/?playlist\?list=([0-9A-Za-z-_]{10,})"',
-                content)):
+    def _is_entry(self, obj):
+        return 'playlistId' in obj
+
+    def _process_entries(self, entries, seen):
+        for playlist_id in orderedSet(try_get(r, lambda x: x['playlistId']) for r in entries):
             yield self.url_result(
                 'https://www.youtube.com/playlist?list=%s' % playlist_id, 'YoutubePlaylist')
 
@@ -3240,11 +3293,7 @@ class YoutubePlaylistsIE(YoutubePlaylistsBaseInfoExtractor):
     }]
 
 
-class YoutubeSearchBaseInfoExtractor(YoutubePlaylistBaseInfoExtractor):
-    _VIDEO_RE = r'href="\s*/watch\?v=(?P<id>[0-9A-Za-z_-]{11})(?:[^"]*"[^>]+\btitle="(?P<title>[^"]+))?'
-
-
-class YoutubeSearchIE(SearchInfoExtractor, YoutubeSearchBaseInfoExtractor):
+class YoutubeSearchIE(SearchInfoExtractor, YoutubePlaylistBaseInfoExtractor):
     IE_DESC = 'YouTube.com searches'
     # there doesn't appear to be a real limit, for example if you search for
     # 'python' you get more than 8.000.000 results
@@ -3341,11 +3390,10 @@ class YoutubeSearchDateIE(YoutubeSearchIE):
     _SEARCH_PARAMS = 'CAI%3D'
 
 
-class YoutubeSearchURLIE(YoutubeSearchBaseInfoExtractor):
+class YoutubeSearchURLIE(YoutubePlaylistBaseInfoExtractor):
     IE_DESC = 'YouTube.com search URLs'
     IE_NAME = 'youtube:search_url'
     _VALID_URL = r'https?://(?:www\.)?youtube\.com/results\?(.*?&)?(?:search_query|q)=(?P<query>[^&]+)(?:[&]|$)'
-    _SEARCH_DATA = r'(?:window\["ytInitialData"\]|ytInitialData)\W?=\W?({.*?});'
     _TESTS = [{
         'url': 'https://www.youtube.com/results?baz=bar&search_query=youtube-dl+test+video&filters=video&lclk=video',
         'playlist_mincount': 5,
@@ -3357,28 +3405,14 @@ class YoutubeSearchURLIE(YoutubeSearchBaseInfoExtractor):
         'only_matching': True,
     }]
 
-    def _find_videos_in_json(self, extracted):
-        videos = []
-
-        def _real_find(obj):
-            if obj is None or isinstance(obj, str):
-                return
-
-            if type(obj) is list:
-                for elem in obj:
-                    _real_find(elem)
-
-            if type(obj) is dict:
-                if "videoId" in obj:
-                    videos.append(obj)
-                    return
-
-                for _, o in obj.items():
-                    _real_find(o)
-
-        _real_find(extracted)
+    def _process_json_dict(self, obj, videos, c):
+        if "videoId" in obj:
+            videos.append(obj)
+            return
 
-        return videos
+        if "nextContinuationData" in obj:
+            c["continuation"] = obj["nextContinuationData"]
+            return
 
     def extract_videos_from_page_impl(self, page, ids_in_page, titles_in_page):
         search_response = self._parse_json(self._search_regex(self._SEARCH_DATA, page, 'ytInitialData'), None)
@@ -3413,7 +3447,8 @@ class YoutubeSearchURLIE(YoutubeSearchBaseInfoExtractor):
         mobj = re.match(self._VALID_URL, url)
         query = compat_urllib_parse_unquote_plus(mobj.group('query'))
         webpage = self._download_webpage(url, query)
-        return self.playlist_result(self._process_page(webpage), playlist_title=query)
+        data_json = self._process_initial_data(webpage)
+        return self.playlist_result(self._process_data(data_json), playlist_title=query)
 
 
 class YoutubeShowIE(YoutubePlaylistsBaseInfoExtractor):
@@ -3435,14 +3470,12 @@ class YoutubeShowIE(YoutubePlaylistsBaseInfoExtractor):
             'https://www.youtube.com/show/%s/playlists' % playlist_id)
 
 
-class YoutubeFeedsInfoExtractor(YoutubeBaseInfoExtractor):
+class YoutubeFeedsInfoExtractor(YoutubePlaylistBaseInfoExtractor):
     """
     Base class for feed extractors
     Subclasses must define the _FEED_NAME and _PLAYLIST_TITLE properties.
     """
     _LOGIN_REQUIRED = True
-    _FEED_DATA = r'(?:window\["ytInitialData"\]|ytInitialData)\W?=\W?({.*?});'
-    _YTCFG_DATA = r"ytcfg.set\(({.*?})\)"
 
     @property
     def IE_NAME(self):
@@ -3451,96 +3484,35 @@ class YoutubeFeedsInfoExtractor(YoutubeBaseInfoExtractor):
     def _real_initialize(self):
         self._login()
 
-    def _find_videos_in_json(self, extracted):
-        videos = []
-        c = {}
-
-        def _real_find(obj):
-            if obj is None or isinstance(obj, str):
-                return
-
-            if type(obj) is list:
-                for elem in obj:
-                    _real_find(elem)
-
-            if type(obj) is dict:
-                if "videoId" in obj:
-                    videos.append(obj)
-                    return
-
-                if "nextContinuationData" in obj:
-                    c["continuation"] = obj["nextContinuationData"]
-                    return
-
-                for _, o in obj.items():
-                    _real_find(o)
-
-        _real_find(extracted)
-
-        return videos, try_get(c, lambda x: x["continuation"])
-
-    def _entries(self, page):
-        info = []
-
-        yt_conf = self._parse_json(self._search_regex(self._YTCFG_DATA, page, 'ytcfg.set', default="null"), None, fatal=False)
-
-        search_response = self._parse_json(self._search_regex(self._FEED_DATA, page, 'ytInitialData'), None)
-
-        for page_num in itertools.count(1):
-            video_info, continuation = self._find_videos_in_json(search_response)
-
-            new_info = []
-
-            for v in video_info:
-                v_id = try_get(v, lambda x: x['videoId'])
-                if not v_id:
-                    continue
-
-                have_video = False
-                for old in info:
-                    if old['videoId'] == v_id:
-                        have_video = True
-                        break
-
-                if not have_video:
-                    new_info.append(v)
-
-            if not new_info:
-                break
+    def _process_entries(self, entries, seen):
+        new_info = []
+        for v in entries:
+            v_id = try_get(v, lambda x: x['videoId'])
+            if not v_id:
+                continue
 
-            info.extend(new_info)
+            have_video = False
+            for old in seen:
+                if old['videoId'] == v_id:
+                    have_video = True
+                    break
 
-            for video in new_info:
-                yield self.url_result(try_get(video, lambda x: x['videoId']), YoutubeIE.ie_key(), video_title=try_get(video, lambda x: x['title']['runs'][0]['text']) or try_get(video, lambda x: x['title']['simpleText']))
+            if not have_video:
+                new_info.append(v)
 
-            if not continuation or not yt_conf:
-                break
+        if not new_info:
+            return
 
-            search_response = self._download_json(
-                'https://www.youtube.com/browse_ajax', self._PLAYLIST_TITLE,
-                'Downloading page #%s' % page_num,
-                transform_source=uppercase_escape,
-                query={
-                    "ctoken": try_get(continuation, lambda x: x["continuation"]),
-                    "continuation": try_get(continuation, lambda x: x["continuation"]),
-                    "itct": try_get(continuation, lambda x: x["clickTrackingParams"])
-                },
-                headers={
-                    "X-YouTube-Client-Name": try_get(yt_conf, lambda x: x["INNERTUBE_CONTEXT_CLIENT_NAME"]),
-                    "X-YouTube-Client-Version": try_get(yt_conf, lambda x: x["INNERTUBE_CONTEXT_CLIENT_VERSION"]),
-                    "X-Youtube-Identity-Token": try_get(yt_conf, lambda x: x["ID_TOKEN"]),
-                    "X-YouTube-Device": try_get(yt_conf, lambda x: x["DEVICE"]),
-                    "X-YouTube-Page-CL": try_get(yt_conf, lambda x: x["PAGE_CL"]),
-                    "X-YouTube-Page-Label": try_get(yt_conf, lambda x: x["PAGE_BUILD_LABEL"]),
-                    "X-YouTube-Variants-Checksum": try_get(yt_conf, lambda x: x["VARIANTS_CHECKSUM"]),
-                })
+        seen.extend(new_info)
+        for video in new_info:
+            yield self.url_result(try_get(video, lambda x: x['videoId']), YoutubeIE.ie_key(), video_title=self._extract_title(video))
 
     def _real_extract(self, url):
         page = self._download_webpage(
             'https://www.youtube.com/feed/%s' % self._FEED_NAME,
             self._PLAYLIST_TITLE)
-        return self.playlist_result(
-            self._entries(page), playlist_title=self._PLAYLIST_TITLE)
+        return self.playlist_result(self._entries(page, self._PLAYLIST_TITLE),
+                                    playlist_title=self._PLAYLIST_TITLE)
 
 
 class YoutubeWatchLaterIE(YoutubePlaylistIE):