import tempfile
import datetime
import os.path

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

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


class Google():

    def __init__(self, calendar_id, *, credentials, token_file):
        _, credentials_file = tempfile.mkstemp()
        with open(credentials_file, 'w') as fp:
            json.dump(credentials, fp)

        self.calendar_id = calendar_id
        self.credentials_file = credentials_file
        self.token_file = token_file
        self.credentials = None

    def login(self):
        if os.path.exists(self.token_file):
            self.credentials = Credentials.from_authorized_user_file(self.token_file, SCOPES)
        if self.credentials is None or not self.credentials.valid:
            if self.credentials is not None \
                    and self.credentials.expired \
                    and  self.credentials.refresh_token:
                self.credentials.refresh(Request())
            else:
                flow = InstalledAppFlow.from_client_secrets_file(
                    self.credentials_file,
                    SCOPES,
                )
                self.credentials = flow.run_local_server(port=0)
            with open(self.token_file, 'w') as token:
                token.write(self.credentials.to_json())

    def get_events(self, start: datetime.datetime | None=None, until: datetime.timedelta | None=None, limit=None):
        until = until if until else datetime.timedelta(days=365)
        now = start if start else datetime.datetime.utcnow().astimezone()
        now_365 = now + until

        try:
            service = build('calendar', 'v3', credentials=self.credentials)
            events = service.events().list(
                calendarId=self.calendar_id,
                timeMin=now.isoformat(),
                timeMax=now_365.isoformat(),
                maxResults=limit,
            ).execute()
        except HttpError:
            print('an error occured')
            raise
        events = events.get('items', [])
        return events