import datetime
import os.path
from base64 import b32hexencode

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

# If modifying these scopes, delete the file token.json.
SCOPES = ['https://www.googleapis.com/auth/calendar.readonly',
          'https://www.googleapis.com/auth/calendar.events']

CALENDAR_ID = '40e4v6t1s2spr9f1d9d45br3ik@group.calendar.google.com'


def authenticate_google() -> Credentials:
    creds = None
    # The file token.json stores the user's access and refresh tokens, and is
    # created automatically when the authorization flow completes for the first
    # time.
    if os.path.exists('token.json'):
        creds = Credentials.from_authorized_user_file('token.json', SCOPES)
    # If there are no (valid) credentials available, let the user log in.
    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=0)
        # Save the credentials for the next run
        with open('token.json', 'w') as token:
            token.write(creds.to_json())

    return creds


def insert_or_update_event(service, id, title, start, end):
    event_id = b32hexencode(id.encode('ascii')).decode('ascii').lower()
    event = {
        "id": event_id,
        "summary": title,
        "start": {
            "dateTime": start.isoformat() + 'Z',  # 'Z' indicates UTC time
        },
        "end": {
            "dateTime": end.isoformat() + 'Z',  # 'Z' indicates UTC time
        },
    }

    print(f"Adding/updating event: {title}, start: {start}, end: {end}")

    try:
        service \
            .events() \
            .update(calendarId=CALENDAR_ID, eventId=event_id, body=event) \
            .execute()

    except HttpError as error:
        # Create event if it doesn't exist
        if error.status_code == 409:
            service \
                .events() \
                .insert(calendarId=CALENDAR_ID, body=event) \
                .execute()

        else:
            raise error


def main():
    creds = authenticate_google()
    service = build('calendar', 'v3', credentials=creds)

    insert_or_update_event(service,
                           "octoprint_test_event",
                           "Test!",
                           datetime.datetime.utcnow(),
                           datetime.datetime.utcnow() + datetime.timedelta(hours=1))


if __name__ == '__main__':
    main()