--- /dev/null
+from __future__ import division, unicode_literals
+
+import re
+import json
+
+from .fragment import FragmentFD
+
+
+class YoutubeLiveChatReplayFD(FragmentFD):
+ """ Downloads YouTube live chat replays fragment by fragment """
+
+ FD_NAME = 'youtube_live_chat_replay'
+
+ def real_download(self, filename, info_dict):
+ video_id = info_dict['video_id']
+ self.to_screen('[%s] Downloading live chat' % self.FD_NAME)
+
+ test = self.params.get('test', False)
+
+ ctx = {
+ 'filename': filename,
+ 'live': True,
+ 'total_frags': None,
+ }
+
+ def dl_fragment(url):
+ headers = info_dict.get('http_headers', {})
+ return self._download_fragment(ctx, url, info_dict, headers)
+
+ def parse_yt_initial_data(data):
+ raw_json = re.search(b'window\["ytInitialData"\]\s*=\s*(.*);', data).group(1)
+ return json.loads(raw_json)
+
+ self._prepare_and_start_frag_download(ctx)
+
+ success, raw_fragment = dl_fragment(
+ 'https://www.youtube.com/watch?v={}'.format(video_id))
+ if not success:
+ return False
+ data = parse_yt_initial_data(raw_fragment)
+ continuation_id = data['contents']['twoColumnWatchNextResults']['conversationBar']['liveChatRenderer']['continuations'][0]['reloadContinuationData']['continuation']
+ # no data yet but required to call _append_fragment
+ self._append_fragment(ctx, b'')
+
+ first = True
+ offset = None
+ while continuation_id is not None:
+ data = None
+ if first:
+ url = 'https://www.youtube.com/live_chat_replay?continuation={}'.format(continuation_id)
+ success, raw_fragment = dl_fragment(url)
+ if not success:
+ return False
+ data = parse_yt_initial_data(raw_fragment)
+ else:
+ url = ('https://www.youtube.com/live_chat_replay/get_live_chat_replay'
+ + '?continuation={}'.format(continuation_id)
+ + '&playerOffsetMs={}'.format(offset - 5000)
+ + '&hidden=false'
+ + '&pbj=1')
+ success, raw_fragment = dl_fragment(url)
+ if not success:
+ return False
+ data = json.loads(raw_fragment)['response']
+
+ first = False
+ continuation_id = None
+
+ live_chat_continuation = data['continuationContents']['liveChatContinuation']
+ offset = None
+ processed_fragment = bytearray()
+ if 'actions' in live_chat_continuation:
+ for action in live_chat_continuation['actions']:
+ if 'replayChatItemAction' in action:
+ replay_chat_item_action = action['replayChatItemAction']
+ offset = int(replay_chat_item_action['videoOffsetTimeMsec'])
+ processed_fragment.extend(
+ json.dumps(action, ensure_ascii=False).encode('utf-8') + b'\n')
+ continuation_id = live_chat_continuation['continuations'][0]['liveChatReplayContinuationData']['continuation']
+
+ self._append_fragment(ctx, processed_fragment)
+
+ if test or offset is None:
+ break
+
+ self._finish_frag_download(ctx)
+
+ return True