#!/usr/bin/python

import httplib2
import os
import random
import sys

from apiclient.discovery import build
from apiclient.errors import HttpError
from oauth2client.client import flow_from_clientsecrets
from oauth2client.file import Storage
from oauth2client.tools import argparser, run_flow


# The CLIENT_SECRETS_FILE variable specifies the name of a file that contains
# the OAuth 2.0 information for this application, including its client_id and
# client_secret. You can acquire an OAuth 2.0 client ID and client secret from
# the Google Developers Console at
# https://console.developers.google.com/.
# Please ensure that you have enabled the YouTube Data API for your project.
# For more information about using OAuth2 to access the YouTube Data API, see:
#   https://developers.google.com/youtube/v3/guides/authentication
# For more information about the client_secrets.json file format, see:
#   https://developers.google.com/api-client-library/python/guide/aaa_client_secrets

CLIENT_SECRETS_FILE = "client_secrets.json"

# This variable defines a message to display if the CLIENT_SECRETS_FILE is
# missing.
MISSING_CLIENT_SECRETS_MESSAGE = """
WARNING: Please configure OAuth 2.0

To make this sample run you will need to populate the client_secrets.json file
found at:

   %s

with information from the Developers Console
https://console.developers.google.com/

For more information about the client_secrets.json file format, please visit:
https://developers.google.com/api-client-library/python/guide/aaa_client_secrets
""" % os.path.abspath(os.path.join(os.path.dirname(__file__),
                                   CLIENT_SECRETS_FILE))

# This OAuth 2.0 access scope allows for full read/write access to the
# authenticated user's account.
YOUTUBE_SCOPE = "https://www.googleapis.com/auth/youtube"
YOUTUBE_API_SERVICE_NAME = "youtube"
YOUTUBE_API_VERSION = "v3"

def get_authenticated_service(args):
  flow = flow_from_clientsecrets(CLIENT_SECRETS_FILE, scope=YOUTUBE_SCOPE,
    message=MISSING_CLIENT_SECRETS_MESSAGE)

  storage = Storage("%s-oauth2.json" % sys.argv[0])
  credentials = storage.get()

  if credentials is None or credentials.invalid:
    credentials = run_flow(flow, storage, args)

  return build(YOUTUBE_API_SERVICE_NAME, YOUTUBE_API_VERSION,
    http=credentials.authorize(httplib2.Http()))

def get_current_channel_sections(youtube):
  channel_sections_list_response = youtube.channelSections().list(
    part="snippet,contentDetails",
    mine=True
  ).execute()

  return channel_sections_list_response["items"]

def shuffle_channel_sections(youtube, channel_sections):
  # This will randomly reorder the items in the channel_sections list.
  random.shuffle(channel_sections)

  for channel_section in channel_sections:
    # Each section in the list of shuffled sections is sequentially
    # set to position 0, i.e. the top.
    channel_section["snippet"]["position"] = 0

    youtube.channelSections().update(
      part="snippet,contentDetails",
      body=channel_section
    ).execute()

if __name__ == '__main__':
  args = argparser.parse_args()

  youtube = get_authenticated_service(args)
  try:
    channel_sections = get_current_channel_sections(youtube)
    shuffle_channel_sections(youtube, channel_sections)
  except HttpError, e:
    print "An HTTP error %d occurred:\n%s" % (e.resp.status, e.content)
  else:
    print "The existing channel sections have been randomly shuffled."