import datetime
import logging
import typing

from django.conf import settings
from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError

from apps.google import constants, utils
from apps.google.types import GoogleCalendarEvent as GoogleCalendarEventType

logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)


class GoogleCalendarEvent:
    def __init__(self, event: GoogleCalendarEventType):
        self.raw_event = event
        self._start_time = utils.datetime_strptime(event["start"]["dateTime"])
        self._end_time = utils.datetime_strptime(event["end"]["dateTime"])

        self.start_time_utc = self._start_time.astimezone(datetime.timezone.utc)
        self.end_time_utc = self._end_time.astimezone(datetime.timezone.utc)


class GoogleCalendarHTTPError(Exception):
    def __init__(self, http_error) -> None:
        self.error = http_error


class GoogleCalendarAPIClient:
    MAX_NUMBER_OF_CALENDAR_EVENTS_TO_FETCH = 250
    """
    By default the value is 250 events. The page size can never be larger than 2500 events
    """

    CALENDAR_ID = "primary"
    """
    for right now we only consider the user's primary calendar. If in the future we
    want to allow the user to specify a different calendar, we'd need to [retrieve all their calendars](https://developers.google.com/calendar/v3/reference/calendarList/list)
    , display this list to them + perist their choice

    See `calendarId` under the "Parameters" section [here](https://developers.google.com/calendar/api/v3/reference/events/list)
    """

    def __init__(self, access_token: str, refresh_token: str):
        """
        https://developers.google.com/calendar/api/quickstart/python
        https://google-auth.readthedocs.io/en/stable/reference/google.oauth2.credentials.html
        """
        credentials = Credentials(
            token=access_token,
            refresh_token=refresh_token,
            token_uri="https://www.googleapis.com/oauth2/v3/token",
            client_id=settings.SOCIAL_AUTH_GOOGLE_OAUTH2_KEY,
            client_secret=settings.SOCIAL_AUTH_GOOGLE_OAUTH2_SECRET,
        )

        self.service = build("calendar", "v3", credentials=credentials)

    def fetch_out_of_office_events(self) -> typing.List[GoogleCalendarEvent]:
        """
        https://developers.google.com/calendar/api/v3/reference/events/list
        """
        logger.info(
            f"GoogleCalendarAPIClient - Getting the upcoming {self.MAX_NUMBER_OF_CALENDAR_EVENTS_TO_FETCH} "
            "out of office events"
        )

        now = datetime.datetime.now(datetime.UTC)
        time_min = utils.datetime_strftime(now)
        time_max = utils.datetime_strftime(
            now + datetime.timedelta(days=constants.DAYS_IN_FUTURE_TO_CONSIDER_OUT_OF_OFFICE_EVENTS)
        )

        try:
            events_result = (
                self.service.events()
                .list(
                    calendarId=self.CALENDAR_ID,
                    timeMin=time_min,
                    timeMax=time_max,
                    maxResults=self.MAX_NUMBER_OF_CALENDAR_EVENTS_TO_FETCH,
                    singleEvents=True,
                    orderBy="startTime",
                    eventTypes="outOfOffice",
                )
                .execute()
            )
        except HttpError as e:
            logger.error(f"GoogleCalendarAPIClient - Error fetching out of office events: {e}")
            raise GoogleCalendarHTTPError(e)

        return [GoogleCalendarEvent(event) for event in events_result.get("items", [])]