import requests

from ._transcripts import TranscriptListFetcher


class YouTubeTranscriptApi():
    @classmethod
    def get_transcripts(cls, video_ids, languages=('en',), continue_after_error=False, proxies=None):
        """
        Retrieves the transcripts for a list of videos.

        :param video_ids: a list of youtube video ids
        :type video_ids: [str]
        :param languages: A list of language codes in a descending priority. For example, if this is set to ['de', 'en']
        it will first try to fetch the german transcript (de) and then fetch the english transcript (en) if it fails to
        do so.
        :type languages: [str]
        :param continue_after_error: if this is set the execution won't be stopped, if an error occurs while retrieving
        one of the video transcripts
        :type continue_after_error: bool
        :param proxies: a dictionary mapping of http and https proxies to be used for the network requests
        :type proxies: {'http': str, 'https': str} - http://docs.python-requests.org/en/master/user/advanced/#proxies
        :return: a tuple containing a dictionary mapping video ids onto their corresponding transcripts, and a list of
        video ids, which could not be retrieved
        :rtype: ({str: [{'text': str, 'start': float, 'end': float}]}, [str]})
        """
        data = {}
        unretrievable_videos = []

        for video_id in video_ids:
            try:
                data[video_id] = cls.get_transcript(video_id, languages, proxies)
            except Exception as exception:
                if not continue_after_error:
                    raise exception

                unretrievable_videos.append(video_id)

        return data, unretrievable_videos

    @classmethod
    def get_transcript(cls, video_id, languages=('en',), proxies=None):
        """
        Retrieves the transcript for a single video.

        :param video_id: the youtube video id
        :type video_id: str
        :param languages: A list of language codes in a descending priority. For example, if this is set to ['de', 'en']
        it will first try to fetch the german transcript (de) and then fetch the english transcript (en) if it fails to
        do so.
        :type languages: [str]
        :param proxies: a dictionary mapping of http and https proxies to be used for the network requests
        :type proxies: {'http': str, 'https': str} - http://docs.python-requests.org/en/master/user/advanced/#proxies
        :return: a list of dictionaries containing the 'text', 'start' and 'duration' keys
        :rtype: [{'text': str, 'start': float, 'end': float}]
        """
        with requests.Session() as http_client:
            http_client.proxies = proxies if proxies else {}
            return TranscriptListFetcher(http_client).fetch(video_id).find_transcript(languages).fetch()