from __future__ import print_function

import os
import json

from google.auth.transport.requests import Request
from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import InstalledAppFlow
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError
from pprint import pprint

SCOPES = ["https://www.googleapis.com/auth/youtube"]

def authorize():
    creds = None

    if os.path.exists('token.json'):
        creds = Credentials.from_authorized_user_file('token.json', SCOPES)

    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            creds.refresh(Request())
        else:
            flow = InstalledAppFlow.from_client_secrets_file('credentials.json', SCOPES)
            creds = flow.run_local_server(port=7384)

        with open('token.json', 'w') as token:
            token.write(creds.to_json())

    return creds

def construct_youtube_service(creds):
    return build('youtube', 'v3', credentials=creds)

def list_all_video_categories(youtube_service):
    category_list = youtube_service.videoCategories().list(
        part="snippet",
        regionCode="US"
    ).execute()

    return [
        {
            "name": element["snippet"]["title"],
            "id": element["id"]
        }
        for element in category_list["items"] if element["snippet"]["assignable"]
    ]


def main():
    creds = authorize()

    youtube_service = construct_youtube_service(creds)

    category_data = list_all_video_categories(youtube_service)

    print(json.dumps(category_data, indent=4))

if __name__ == '__main__':
    main()