from enum import IntEnum
import datetime
import re

from dateutil import rrule

from .calendar_api import calendar_api
from .utils import to_dateTime, from_dateTime


class weekdays(IntEnum):
    SUN = 6
    MON = 0
    TUE = 1
    WED = 2
    THU = 3
    FRI = 4
    SAT = 5


class Calendar:
    """Model for representing a Google calendar"""

    pass


class Event:
    """Model for a calendar event that can be uploaded"""

    def __init__(
        self,
        start,
        end,
        name,
        description=None,
        recurrence=None,
        reminders=None,
        attendees=None,
        location=None,
        id=None,
    ):
        self.start = start
        self.attendees = attendees
        self.end = end
        self.name = name
        self.description = description
        self.location = location
        self.recurrence = recurrence
        self.id = id
        if reminders is None:
            self.reminders = {"useDefault": True}
        else:
            self.reminders = reminders

    def add_reminder(self, until, method="popup"):
        """Add a reminder minutes before an event.
        Use either a notification (popup) or email"""
        assert method in ("email", "popup")
        self.reminders["useDefault"] = False
        if isinstance(until, datetime.timedelta):
            minutes_until = until.days * 24 * 60
            minutes_until += until.seconds // 60
        else:
            minutes_until = until
            self.reminders.setdefault("overrides", []).append(
                {"method": method, "minutes": minutes_until}
            )

    def add_weekly_recurrence(self, until: datetime.datetime, *days):
        if not until.tzinfo:
            until = until.astimezone()
        ret = rrule.rrule(
            freq=rrule.WEEKLY,
            dtstart=self.start,
            wkst=weekdays.SUN,
            until=until,
            byweekday=days,
        )
        ret_str = str(ret).split("\n")[-1]
        ret_str = re.sub(r"(UNTIL=[^;]+)", r"\1Z", ret_str)
        if self.recurrence is None:
            self.recurrence = []
        self.recurrence.append(ret_str)

    def to_json(self):
        keys = ("attendees", "description", "location", "recurrence", "reminders")
        ret = {
            "summary": self.name,
            "start": to_dateTime(self.start),
            "end": to_dateTime(self.end),
        }
        for key in keys:
            try:
                value = self.__getattribute__(key)
                if value:
                    ret[key] = value
            except AttributeError:
                pass
        return ret

    def add_attendees(self):
        pass

    @classmethod
    def from_json(cls, body):
        args = {}
        args["name"] = body.get("summary", "unnamed")
        args["start"] = from_dateTime(body["start"])
        args["end"] = from_dateTime(body["end"])
        keys = ("attendees", "description", "location", "recurrence", "reminders", "id")
        for key in keys:
            try:
                args[key] = body[key]
            except KeyError:
                pass
        instance = cls(**args)
        return instance

    @classmethod
    def from_id(cls, api: calendar_api, calendar_id, event_id):
        """creates an event model from specified calendar and event_id"""
        event = api.get_event_by_id(calendar_id, event_id)
        return cls.from_json(event)

    def upload(self, api: calendar_api, calendar_id):
        """Upload an event to calendar.
        Either modifies an event in place or creates a new event."""
        if self.id is not None:
            event_id = api.update_event(calendar_id, self.id, self.to_json())
        else:
            event_id = api.create_event(calendar_id, self.to_json())
        self.id = event_id
        return event_id

    def delete(self, api: calendar_api):
        pass