youtube/comments.py

import base64
import json

from youtube import proto, util, yt_data_extract
from youtube.util import concat_or_none


# Here's what I know about the secret key (starting with ASJN_i)
# *The secret key definitely contains the following information (or perhaps the information is stored at youtube's servers):
#   -Video id
#   -Offset
#   -Sort
# *If the video id or sort in the ctoken contradicts the ASJN, the response is an error. The offset encoded outside the ASJN is ignored entirely.
# *The ASJN is base64 encoded data, indicated by the fact that the character after "ASJN_i" is one of ("0", "1", "2", "3")
# *The encoded data is not valid protobuf
# *The encoded data (after the 5 or so bytes that are always the same) is indistinguishable from random data according to a battery of randomness tests
# *The ASJN in the ctoken provided by a response changes in regular intervals of about a second or two.
# *Old ASJN's continue to work, and start at the same comment even if new comments have been posted since
# *The ASJN has no relation with any of the data in the response it came from

def make_comment_ctoken(video_id, sort=0, offset=0, lc='', secret_key=''):
    video_id = proto.as_bytes(video_id)
    secret_key = proto.as_bytes(secret_key)


    page_info = proto.string(4,video_id) + proto.uint(6, sort)
    offset_information = proto.nested(4, page_info) + proto.uint(5, offset)
    if secret_key:
        offset_information = proto.string(1, secret_key) + offset_information

    page_params = proto.string(2, video_id)
    if lc:
        page_params += proto.string(6, proto.percent_b64encode(proto.string(15, lc)))

    result = proto.nested(2, page_params) + proto.uint(3,6) + proto.nested(6, offset_information)
    return base64.urlsafe_b64encode(result).decode('ascii')

def comment_replies_ctoken(video_id, comment_id, max_results=500):

    params = proto.string(2, comment_id) + proto.uint(9, max_results)
    params = proto.nested(3, params)

    result = proto.nested(2, proto.string(2, video_id)) + proto.uint(3,6) + proto.nested(6, params)
    return base64.urlsafe_b64encode(result).decode('ascii')



mobile_headers = {
    'User-Agent': 'Mozilla/5.0 (iPhone; CPU iPhone OS 10_3_1 like Mac OS X) AppleWebKit/603.1.30 (KHTML, like Gecko) Version/10.0 Mobile/14E304 Safari/602.1',
    'Accept': '*/*',
    'Accept-Language': 'en-US,en;q=0.5',
    'X-YouTube-Client-Name': '2',
    'X-YouTube-Client-Version': '2.20180823',
}
def request_comments(ctoken, replies=False):
    if replies: # let's make it use different urls for no reason despite all the data being encoded
        base_url = "https://m.youtube.com/watch_comment?action_get_comment_replies=1&ctoken="
    else:
        base_url = "https://m.youtube.com/watch_comment?action_get_comments=1&ctoken="
    url = base_url + ctoken.replace("=", "%3D") + "&pbj=1"

    for i in range(0,8):    # don't retry more than 8 times
        content = util.fetch_url(url, headers=mobile_headers, report_text="Retrieved comments", debug_name='request_comments')
        if content[0:4] == b")]}'":             # random closing characters included at beginning of response for some reason
            content = content[4:]
        elif content[0:10] == b'\n<!DOCTYPE':   # occasionally returns html instead of json for no reason
            content = b''
            print("got <!DOCTYPE>, retrying")
            continue
        break

    polymer_json = json.loads(util.uppercase_escape(content.decode('utf-8')))
    return polymer_json


def single_comment_ctoken(video_id, comment_id):
    page_params = proto.string(2, video_id) + proto.string(6, proto.percent_b64encode(proto.string(15, comment_id)))

    result = proto.nested(2, page_params) + proto.uint(3,6)
    return base64.urlsafe_b64encode(result).decode('ascii')



def post_process_comments_info(comments_info):
    for comment in comments_info['comments']:
        comment['author_url'] = concat_or_none(
            util.URL_ORIGIN, comment['author_url'])
        comment['author_avatar'] = concat_or_none(
            '/', comment['author_avatar'])

        comment['permalink'] = concat_or_none(util.URL_ORIGIN, '/watch?v=',
            comments_info['video_id'], '&lc=', comment['id'])

        reply_count = comment['reply_count']
        if reply_count == 0:
            comment['replies_url'] = concat_or_none(util.URL_ORIGIN,
                '/post_comment?parent_id=', comment['id'],
                '&video_id=', comments_info['video_id'])
        else:
            comment['replies_url'] = concat_or_none(util.URL_ORIGIN,
                '/comments?parent_id=', comment['id'],
                '&video_id=', comments_info['video_id'])

        if reply_count == 0:
            comment['view_replies_text'] = 'Reply'
        elif reply_count == 1:
            comment['view_replies_text'] = '1 reply'
        else:
            comment['view_replies_text'] = str(reply_count) + ' replies'


        if comment['like_count'] == 1:
            comment['likes_text'] = '1 like'
        else:
            comment['likes_text'] = str(comment['like_count']) + ' likes'


    if comments_info['ctoken']:
        comments_info['more_comments_url'] = concat_or_none(util.URL_ORIGIN,
            '/comments?ctoken=', comments_info['ctoken'])

    comments_info['page_number'] = page_number = str(int(comments_info['offset']/20) + 1)

    if not comments_info['is_replies']:
        comments_info['sort_text'] = 'top' if comments_info['sort'] == 0 else 'newest'


    comments_info['video_url'] = concat_or_none(util.URL_ORIGIN,
        '/watch?v=', comments_info['video_id'])
    comments_info['video_thumbnail'] = concat_or_none('/i.ytimg.com/vi/',
        comments_info['video_id'], '/mqdefault.jpg')


def video_comments(video_id, sort=0, offset=0, lc='', secret_key=''):
    comments_info = yt_data_extract.extract_comments_info(request_comments(make_comment_ctoken(video_id, sort, offset, lc, secret_key)))
    post_process_comments_info(comments_info)

    post_comment_url = util.URL_ORIGIN + "/post_comment?video_id=" + video_id
    other_sort_url = util.URL_ORIGIN + '/comments?ctoken=' + make_comment_ctoken(video_id, sort=1 - sort, lc=lc)
    other_sort_text = 'Sort by ' + ('newest' if sort == 0 else 'top')
    comments_info['comment_links'] = [('Post comment', post_comment_url), (other_sort_text, other_sort_url)]

    return comments_info

    return {}