"""
This module is responsible for doing all the authentication.
Adapted from the Google API Documentation.
"""

from __future__ import print_function
import os
import httplib2

import apiclient
import oauth2client

try:
    import argparse
    flags = argparse.ArgumentParser(
        parents=[oauth2client.tools.argparser]).parse_args()
except ImportError:
    flags = None

SCOPES = 'https://www.googleapis.com/auth/drive'
CLIENT_SECRET_FILE = 'client_secret.json'

# Enter your project name here!!
APPLICATION_NAME = 'API Project'


def get_credentials():
    """Gets valid user credentials from storage.

    If nothing has been stored, or if the stored credentials are invalid,
    the OAuth2 flow is completed to obtain the new credentials.

    Returns:
        Credentials, the obtained credential.
    """
    home_dir = os.path.expanduser('~')
    credential_dir = os.path.join(home_dir, '.gdrive-credentials-cache')
    if not os.path.exists(credential_dir):
        os.makedirs(credential_dir)
    credential_path = os.path.join(credential_dir,
                                   'gdrive-credentials.json')

    store = oauth2client.file.Storage(credential_path)
    credentials = store.get()
    if not credentials or credentials.invalid:
        flow = oauth2client.client.flow_from_clientsecrets(
            CLIENT_SECRET_FILE, SCOPES)
        flow.user_agent = APPLICATION_NAME
        if flags:
            credentials = oauth2client.tools.run_flow(flow, store, flags)
        else:  # Needed only for compatibility with Python 2.6
            credentials = oauth2client.tools.run(flow, store)
        print('Storing credentials to ' + credential_path)
    return credentials


credentials = get_credentials()
http = credentials.authorize(httplib2.Http())
file_service = apiclient.discovery.build('drive', 'v3', http=http).files()