text: """
  This module implements the core developer interface for pytube.
  
  The problem domain of the :class:`YouTube <YouTube> class focuses almost
  exclusively on the developer interface. Pytube offloads the heavy lifting to
  smaller peripheral modules and functions.
  
  """
  import logging
  from typing import Any, Callable, Dict, List, Optional
  
  import pytube
  import pytube.exceptions as exceptions
  from pytube import extract, request
  from pytube import Stream, StreamQuery
  from pytube.helpers import install_proxy
  from pytube.innertube import InnerTube
  from pytube.metadata import YouTubeMetadata
  from pytube.monostate import Monostate
  
  logger = logging.getLogger(__name__)
  
  
  class YouTube:
      """Core developer interface for pytube."""
  
      def __init__(
          self,
          url: str,
          on_progress_callback: Optional[Callable[[Any, bytes, int], None]] = None,
          on_complete_callback: Optional[Callable[[Any, Optional[str]], None]] = None,
          proxies: Dict[str, str] = None,
          extra_headers: Dict[str, str] = None,
          use_oauth: bool = False,
          allow_oauth_cache: bool = True
      ):
          """Construct a :class:`YouTube <YouTube>`.
  
          :param str url:
              A valid YouTube watch URL.
          :param func on_progress_callback:
              (Optional) User defined callback function for stream download
              progress events.
          :param func on_complete_callback:
              (Optional) User defined callback function for stream download
              complete events.
          :param dict proxies:
              (Optional) A dict mapping protocol to proxy address which will be used by pytube.
          :param bool use_oauth:
              (Optional) Prompt the user to authenticate to YouTube.
              If allow_oauth_cache is set to True, the user should only be prompted once.
          :param bool allow_oauth_cache:
              (Optional) Cache OAuth tokens locally on the machine. Defaults to True.
              These tokens are only generated if use_oauth is set to True as well.
          """
          self.extra_headers = extra_headers
  
          self._js: Optional[str] = None  # js fetched by js_url
          self._js_url: Optional[str] = None  # the url to the js, parsed from watch html
  
          self._vid_info: Optional[Dict] = None  # content fetched from innertube/player
  
          self._watch_html: Optional[str] = None  # the html of /watch?v=<video_id>
          self._embed_html: Optional[str] = None
          self._player_config_args: Optional[Dict] = None  # inline js in the html containing
          self._age_restricted: Optional[bool] = None
  
          self._fmt_streams: Optional[List[Stream]] = None
  
          self._initial_data = None
          self._metadata: Optional[YouTubeMetadata] = None
  
          # video_id part of /watch?v=<video_id>
          self.video_id = extract.video_id(url)
  
          self.watch_url = f"https://youtube.com/watch?v={self.video_id}"
          self.embed_url = f"https://www.youtube.com/embed/{self.video_id}"
  
          # Shared between all instances of `Stream` (Borg pattern).
          self.stream_monostate = Monostate(
              on_progress=on_progress_callback, on_complete=on_complete_callback
          )
  
          if proxies:
              install_proxy(proxies)
  
          self._author = None
          self._title = None
          self._publish_date = None
  
          self.use_oauth = use_oauth
          self.allow_oauth_cache = allow_oauth_cache
  
      def __repr__(self):
          return f'<pytube.__main__.YouTube object: videoId={self.video_id}>'
  
      @property
      def watch_html(self):
          if self._watch_html:
              return self._watch_html
          self._watch_html = request.get(url=self.watch_url)
          return self._watch_html
  
      @property
      def embed_html(self):
          if self._embed_html:
              return self._embed_html
          self._embed_html = request.get(url=self.embed_url)
          return self._embed_html
  
      @property
      def age_restricted(self):
          if self._age_restricted:
              return self._age_restricted
          self._age_restricted = extract.is_age_restricted(self.watch_html)
          return self._age_restricted
  
      @property
      def js_url(self):
          if self._js_url:
              return self._js_url
  
          if self.age_restricted:
              self._js_url = extract.js_url(self.embed_html)
          else:
              self._js_url = extract.js_url(self.watch_html)
  
          return self._js_url
  
      @property
      def js(self):
          if self._js:
              return self._js
  
          # If the js_url doesn't match the cached url, fetch the new js and update
          #  the cache; otherwise, load the cache.
          if pytube.__js_url__ != self.js_url:
              self._js = request.get(self.js_url)
              pytube.__js__ = self._js
              pytube.__js_url__ = self.js_url
          else:
              self._js = pytube.__js__
  
          return self._js
  
      @property
      def initial_data(self):
          if self._initial_data:
              return self._initial_data
          self._initial_data = extract.initial_data(self.watch_html)
          return self._initial_data
  
      @property
      def streaming_data(self):
          """Return streamingData from video info."""
          if 'streamingData' in self.vid_info:
              return self.vid_info['streamingData']
          else:
              self.bypass_age_gate()
              return self.vid_info['streamingData']
  
      @property
      def fmt_streams(self):
          """Returns a list of streams if they have been initialized.
  
          If the streams have not been initialized, finds all relevant
          streams and initializes them.
          """
          self.check_availability()
          if self._fmt_streams:
              return self._fmt_streams
  
          self._fmt_streams = []
  
          stream_manifest = extract.apply_descrambler(self.streaming_data)
  
          # If the cached js doesn't work, try fetching a new js file
          # https://github.com/pytube/pytube/issues/1054
          try:
              extract.apply_signature(stream_manifest, self.vid_info, self.js)
          except exceptions.ExtractError:
              # To force an update to the js file, we clear the cache and retry
              self._js = None
              self._js_url = None
              pytube.__js__ = None
              pytube.__js_url__ = None
              extract.apply_signature(stream_manifest, self.vid_info, self.js)
  
          # build instances of :class:`Stream <Stream>`
          # Initialize stream objects
          for stream in stream_manifest:
              video = Stream(
                  stream=stream,
                  monostate=self.stream_monostate,
              )
              self._fmt_streams.append(video)
  
          self.stream_monostate.title = self.title
          self.stream_monostate.duration = self.length
  
          return self._fmt_streams
  
      def check_availability(self):
          """Check whether the video is available.
  
          Raises different exceptions based on why the video is unavailable,
          otherwise does nothing.
          """
          status, messages = extract.playability_status(self.watch_html)
  
          for reason in messages:
              if status == 'UNPLAYABLE':
                  if reason == (
                      'Join this channel to get access to members-only content '
                      'like this video, and other exclusive perks.'
                  ):
                      raise exceptions.MembersOnly(video_id=self.video_id)
                  elif reason == 'This live stream recording is not available.':
                      raise exceptions.RecordingUnavailable(video_id=self.video_id)
                  else:
                      raise exceptions.VideoUnavailable(video_id=self.video_id)
              elif status == 'LOGIN_REQUIRED':
                  if reason == (
                      'This is a private video. '
                      'Please sign in to verify that you may see it.'
                  ):
                      raise exceptions.VideoPrivate(video_id=self.video_id)
              elif status == 'ERROR':
                  if reason == 'Video unavailable':
                      raise exceptions.VideoUnavailable(video_id=self.video_id)
              elif status == 'LIVE_STREAM':
                  raise exceptions.LiveStreamError(video_id=self.video_id)
  
      @property
      def vid_info(self):
          """Parse the raw vid info and return the parsed result.
  
          :rtype: Dict[Any, Any]
          """
          if self._vid_info:
              return self._vid_info
  
          innertube = InnerTube(use_oauth=self.use_oauth, allow_cache=self.allow_oauth_cache)
  
          innertube_response = innertube.player(self.video_id)
          self._vid_info = innertube_response
          return self._vid_info
  
      def bypass_age_gate(self):
          """Attempt to update the vid_info by bypassing the age gate."""
          innertube = InnerTube(
              client='ANDROID_EMBED',
              use_oauth=self.use_oauth,
              allow_cache=self.allow_oauth_cache
          )
          innertube_response = innertube.player(self.video_id)
  
          playability_status = innertube_response['playabilityStatus'].get('status', None)
  
          # If we still can't access the video, raise an exception
          # (tier 3 age restriction)
          if playability_status == 'UNPLAYABLE':
              raise exceptions.AgeRestrictedError(self.video_id)
  
          self._vid_info = innertube_response
  
      @property
      def caption_tracks(self) -> List[pytube.Caption]:
          """Get a list of :class:`Caption <Caption>`.
  
          :rtype: List[Caption]
          """
          raw_tracks = (
              self.vid_info.get("captions", {})
              .get("playerCaptionsTracklistRenderer", {})
              .get("captionTracks", [])
          )
          return [pytube.Caption(track, self.extra_headers) for track in raw_tracks]
  
      @property
      def captions(self) -> pytube.CaptionQuery:
          """Interface to query caption tracks.
  
          :rtype: :class:`CaptionQuery <CaptionQuery>`.
          """
          return pytube.CaptionQuery(self.caption_tracks)
  
      @property
      def streams(self) -> StreamQuery:
          """Interface to query both adaptive (DASH) and progressive streams.
  
          :rtype: :class:`StreamQuery <StreamQuery>`.
          """
          self.check_availability()
          return StreamQuery(self.fmt_streams)
  
      @property
      def thumbnail_url(self) -> str:
          """Get the thumbnail url image.
  
          :rtype: str
          """
          thumbnail_details = (
              self.vid_info.get("videoDetails", {})
              .get("thumbnail", {})
              .get("thumbnails")
          )
          if thumbnail_details:
              thumbnail_details = thumbnail_details[-1]  # last item has max size
              return thumbnail_details["url"]
  
          return f"https://img.youtube.com/vi/{self.video_id}/maxresdefault.jpg"
  
      @property
      def publish_date(self):
          """Get the publish date.
  
          :rtype: datetime
          """
          if self._publish_date:
              return self._publish_date
          self._publish_date = extract.publish_date(self.watch_html)
          return self._publish_date
  
      @publish_date.setter
      def publish_date(self, value):
          """Sets the publish date."""
          self._publish_date = value
  
      @property
      def title(self) -> str:
          """Get the video title.
  
          :rtype: str
          """
          if self._title:
              return self._title
  
          try:
              self._title = self.vid_info['videoDetails']['title']
          except KeyError:
              # Check_availability will raise the correct exception in most cases
              #  if it doesn't, ask for a report.
              self.check_availability()
              raise exceptions.PytubeError(
                  (
                      f'Exception while accessing title of {self.watch_url}. '
                      'Please file a bug report at https://github.com/pytube/pytube'
                  )
              )
  
          return self._title
  
      @title.setter
      def title(self, value):
          """Sets the title value."""
          self._title = value
  
      @property
      def description(self) -> str:
          """Get the video description.
  
          :rtype: str
          """
          return self.vid_info.get("videoDetails", {}).get("shortDescription")
  
      @property
      def rating(self) -> float:
          """Get the video average rating.
  
          :rtype: float
  
          """
          return self.vid_info.get("videoDetails", {}).get("averageRating")
  
      @property
      def length(self) -> int:
          """Get the video length in seconds.
  
          :rtype: int
          """
          return int(self.vid_info.get('videoDetails', {}).get('lengthSeconds'))
  
      @property
      def views(self) -> int:
          """Get the number of the times the video has been viewed.
  
          :rtype: int
          """
          return int(self.vid_info.get("videoDetails", {}).get("viewCount"))
  
      @property
      def author(self) -> str:
          """Get the video author.
          :rtype: str
          """
          if self._author:
              return self._author
          self._author = self.vid_info.get("videoDetails", {}).get(
              "author", "unknown"
          )
          return self._author
  
      @author.setter
      def author(self, value):
          """Set the video author."""
          self._author = value
  
      @property
      def keywords(self) -> List[str]:
          """Get the video keywords.
  
          :rtype: List[str]
          """
          return self.vid_info.get('videoDetails', {}).get('keywords', [])
  
      @property
      def channel_id(self) -> str:
          """Get the video poster's channel id.
  
          :rtype: str
          """
          return self.vid_info.get('videoDetails', {}).get('channelId', None)
  
      @property
      def channel_url(self) -> str:
          """Construct the channel url for the video's poster from the channel id.
  
          :rtype: str
          """
          return f'https://www.youtube.com/channel/{self.channel_id}'
  
      @property
      def metadata(self) -> Optional[YouTubeMetadata]:
          """Get the metadata for the video.
  
          :rtype: YouTubeMetadata
          """
          if self._metadata:
              return self._metadata
          else:
              self._metadata = extract.metadata(self.initial_data)
              return self._metadata
  
      def register_on_progress_callback(self, func: Callable[[Any, bytes, int], None]):
          """Register a download progress callback function post initialization.
  
          :param callable func:
              A callback function that takes ``stream``, ``chunk``,
               and ``bytes_remaining`` as parameters.
  
          :rtype: None
  
          """
          self.stream_monostate.on_progress = func
  
      def register_on_complete_callback(self, func: Callable[[Any, Optional[str]], None]):
          """Register a download complete callback function post initialization.
  
          :param callable func:
              A callback function that takes ``stream`` and  ``file_path``.
  
          :rtype: None
  
          """
          self.stream_monostate.on_complete = func
  