from requests_futures.sessions import FuturesSession


class Twitch(object):
    def __init__(self, client_id):
        self.client_id = client_id

    def fetch_videos(self, channel_id):
        if not channel_id:
            return []
        session = FuturesSession()
        def get_videos(offset, limit):
            url = 'https://api.twitch.tv/v5/channels/{0}/videos'.format(channel_id)
            params = dict(
                client_id=self.client_id,
                offset=offset,
                limit=limit)
            return session.get(url, params=params)
        request = get_videos(0, 1)
        total = request.result().json().get('_total')
        if not total:
            return []
        requests = []
        limit = 100
        for offset in range(0, total, limit):
            requests.append(get_videos(offset, limit))
        result = []
        for request in requests:
            result.extend(request.result().json().get('videos', []))
        return result

    def fetch_comments(self, videos):
        if not videos:
            return []
        session = FuturesSession(max_workers=len(videos))
        def get_comments(video_id, cursor):
            url = 'https://api.twitch.tv/v5/videos/{0}/comments'.format(video_id)
            params = dict(
                client_id=self.client_id,
                cursor=cursor)
            return session.get(url, params=params)
        pairs = [(video_id, '') for video_id in videos]
        result = []
        while pairs:
            requests = []
            for video_id, cursor in pairs:
                requests.append(get_comments(video_id, cursor))
            videos, _ = zip(*pairs)
            pairs = []
            for video_id, request in zip(videos, requests):
                data = request.result().json()
                result.extend(data.get('comments', []))
                cursor = data.get('_next')
                if cursor:
                    pairs.append((video_id, cursor))
        return result