# -*- coding: utf-8 -*-
# chrono - agendas system
# Copyright (C) 2016  Entr'ouvert
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import datetime
import fractions
import requests
import vobject

from django.conf import settings
from django.contrib.auth.models import Group
from django.core.exceptions import ValidationError
from django.core.urlresolvers import reverse
from django.db import models, transaction
from django.db.models import Q
from django.utils.dates import WEEKDAYS
from django.utils.encoding import force_text, python_2_unicode_compatible
from django.utils.formats import date_format
from django.utils.text import slugify
from django.utils.timezone import localtime, now, make_aware, make_naive, is_aware
from django.utils.translation import ugettext_lazy as _

from jsonfield import JSONField

from ..interval import Intervals


AGENDA_KINDS = (
    ('events', _('Events')),
    ('meetings', _('Meetings')),
)


def is_midnight(dtime):
    dtime = localtime(dtime)
    return dtime.hour == 0 and dtime.minute == 0


class ICSError(Exception):
    pass


class AgendaImportError(Exception):
    pass


class Agenda(models.Model):
    label = models.CharField(_('Label'), max_length=150)
    slug = models.SlugField(_('Identifier'), max_length=160)
    kind = models.CharField(_('Kind'), max_length=20, choices=AGENDA_KINDS, default='events')
    minimal_booking_delay = models.PositiveIntegerField(
            _('Minimal booking delay (in days)'), default=1)
    maximal_booking_delay = models.PositiveIntegerField(
            _('Maximal booking delay (in days)'), default=56) # eight weeks
    edit_role = models.ForeignKey(Group, blank=True, null=True, default=None,
            related_name='+', verbose_name=_('Edit Role'),
            on_delete=models.SET_NULL)
    view_role = models.ForeignKey(Group, blank=True, null=True, default=None,
            related_name='+', verbose_name=_('View Role'),
            on_delete=models.SET_NULL)

    class Meta:
        ordering = ['label']

    def save(self, *args, **kwargs):
        if not self.slug:
            base_slug = slugify(self.label)
            slug = base_slug
            i = 1
            while True:
                try:
                    Agenda.objects.get(slug=slug)
                except self.DoesNotExist:
                    break
                slug = '%s-%s' % (base_slug, i)
                i += 1
            self.slug = slug
        super(Agenda, self).save(*args, **kwargs)

    def get_absolute_url(self):
        return reverse('chrono-manager-agenda-view', kwargs={'pk': self.id})

    def can_be_managed(self, user):
        if user.is_staff:
            return True
        group_ids = [x.id for x in user.groups.all()]
        return bool(self.edit_role_id in group_ids)

    def can_be_viewed(self, user):
        if self.can_be_managed(user):
            return True
        group_ids = [x.id for x in user.groups.all()]
        return bool(self.view_role_id in group_ids)

    def get_base_meeting_duration(self):
        durations = [x.duration for x in MeetingType.objects.filter(agenda=self)]
        if not durations:
            raise ValueError()
        gcd = durations[0]
        for duration in durations[1:]:
            gcd = fractions.gcd(duration, gcd)
        return gcd

    def export_json(self):
        agenda = {
            'label': self.label,
            'slug': self.slug,
            'kind': self.kind,
            'minimal_booking_delay': self.minimal_booking_delay,
            'maximal_booking_delay': self.maximal_booking_delay,
            'permissions': {
                'view': self.view_role.name if self.view_role else None,
                'edit': self.edit_role.name if self.edit_role else None,
            }
        }
        if self.kind == 'events':
            agenda['events'] = [x.export_json() for x in self.event_set.all()]
        elif self.kind == 'meetings':
            agenda['meetingtypes'] = [x.export_json() for x in self.meetingtype_set.all()]
            agenda['desks'] = [desk.export_json() for desk in self.desk_set.all()]
        return agenda

    @classmethod
    def import_json(cls, data, overwrite=False):
        data = data.copy()
        permissions = data.pop('permissions') or {}
        if data['kind'] == 'events':
            events = data.pop('events')
        elif data['kind'] == 'meetings':
            meetingtypes = data.pop('meetingtypes')
            desks = data.pop('desks')
        for permission in ('view', 'edit'):
            if permissions.get(permission):
                try:
                    data[permission + '_role'] = Group.objects.get(name=permissions[permission])
                except Group.DoesNotExist:
                    raise AgendaImportError(_('Missing "%s" role') % permissions[permission])
        agenda, created = cls.objects.get_or_create(slug=data['slug'], defaults=data)
        if data['kind'] == 'events':
            if overwrite:
                Event.objects.filter(agenda=agenda).delete()
            for event_data in events:
                event_data['agenda'] = agenda
                Event.import_json(event_data).save()
        elif data['kind'] == 'meetings':
            if overwrite:
                MeetingType.objects.filter(agenda=agenda).delete()
                Desk.objects.filter(agenda=agenda).delete()
            for type_data in meetingtypes:
                type_data['agenda'] = agenda
                MeetingType.import_json(type_data).save()
            for desk in desks:
                desk['agenda'] = agenda
                Desk.import_json(desk).save()
        return created

WEEKDAYS_LIST = sorted(WEEKDAYS.items(), key=lambda x: x[0])


@python_2_unicode_compatible
class TimeSlot(object):
    def __init__(self, start_datetime, meeting_type, desk):
        self.start_datetime = start_datetime
        self.end_datetime = start_datetime + datetime.timedelta(minutes=meeting_type.duration)
        self.meeting_type = meeting_type
        self.id = '%s:%s' % (self.meeting_type.id, start_datetime.strftime('%Y-%m-%d-%H%M'))
        self.desk = desk

    def __str__(self):
        return date_format(self.start_datetime, format='DATETIME_FORMAT')


@python_2_unicode_compatible
class TimePeriod(models.Model):
    weekday = models.IntegerField(_('Week day'), choices=WEEKDAYS_LIST)
    start_time = models.TimeField(_('Start'))
    end_time = models.TimeField(_('End'))
    desk = models.ForeignKey('Desk', on_delete=models.CASCADE)

    class Meta:
        ordering = ['weekday', 'start_time']

    def __str__(self):
        return u'%s / %s → %s' % (
                force_text(WEEKDAYS[self.weekday]),
                date_format(self.start_time, 'TIME_FORMAT'),
                date_format(self.end_time, 'TIME_FORMAT'))

    @property
    def weekday_str(self):
        return WEEKDAYS[self.weekday]

    @classmethod
    def import_json(cls, data):
        return cls(**data)

    def export_json(self):
        return {
           'weekday': self.weekday,
           'start_time': self.start_time.strftime('%H:%M'),
           'end_time': self.end_time.strftime('%H:%M'),
        }

    def get_time_slots(self, min_datetime, max_datetime, meeting_type):
        meeting_duration = datetime.timedelta(minutes=meeting_type.duration)
        duration = datetime.timedelta(minutes=self.desk.agenda.get_base_meeting_duration())
        min_datetime = make_naive(min_datetime)
        max_datetime = make_naive(max_datetime)

        real_min_datetime = min_datetime + datetime.timedelta(
                days=self.weekday - min_datetime.weekday())
        if real_min_datetime < min_datetime:
            real_min_datetime += datetime.timedelta(days=7)

        event_datetime = real_min_datetime.replace(hour=self.start_time.hour,
                minute=self.start_time.minute, second=0, microsecond=0)
        while event_datetime < max_datetime:
            end_time = event_datetime + meeting_duration
            next_time = event_datetime + duration
            if end_time.time() > self.end_time or event_datetime.date() != next_time.date():
                # back to morning
                event_datetime = event_datetime.replace(hour=self.start_time.hour, minute=self.start_time.minute)
                # but next week
                event_datetime += datetime.timedelta(days=7)
                next_time = event_datetime + duration

            if event_datetime > max_datetime:
                break

            yield TimeSlot(start_datetime=make_aware(event_datetime), meeting_type=meeting_type, desk=self.desk)
            event_datetime = next_time


class MeetingType(models.Model):
    agenda = models.ForeignKey(Agenda, on_delete=models.CASCADE)
    label = models.CharField(_('Label'), max_length=150)
    slug = models.SlugField(_('Identifier'), max_length=160)
    duration = models.IntegerField(_('Duration (in minutes)'), default=30)

    class Meta:
        ordering = ['duration', 'label']

    def save(self, *args, **kwargs):
        if not self.slug:
            base_slug = slugify(self.label)
            slug = base_slug
            i = 1
            while True:
                try:
                    MeetingType.objects.get(slug=slug, agenda=self.agenda)
                except self.DoesNotExist:
                    break
                slug = '%s-%s' % (base_slug, i)
                i += 1
            self.slug = slug
        super(MeetingType, self).save(*args, **kwargs)

    @classmethod
    def import_json(cls, data):
        return cls(**data)

    def export_json(self):
        return {
           'label': self.label,
           'slug': self.slug,
           'duration': self.duration,
        }


@python_2_unicode_compatible
class Event(models.Model):
    agenda = models.ForeignKey(Agenda, on_delete=models.CASCADE)
    start_datetime = models.DateTimeField(_('Date/time'))
    places = models.PositiveIntegerField(_('Places'))
    waiting_list_places = models.PositiveIntegerField(
            _('Places in waiting list'), default=0)
    label = models.CharField(_('Label'), max_length=150, null=True, blank=True,
            help_text=_('Optional label to identify this date.'))
    description = models.TextField(_('Description'), null=True, blank=True,
            help_text=_('Optional event description.'))
    full = models.BooleanField(default=False)
    meeting_type = models.ForeignKey(MeetingType, null=True, on_delete=models.CASCADE)
    desk = models.ForeignKey('Desk', null=True, on_delete=models.CASCADE)

    class Meta:
        ordering = ['agenda', 'start_datetime', 'label']

    def __str__(self):
        if self.label:
            return self.label
        return date_format(localtime(self.start_datetime), format='DATETIME_FORMAT')

    def save(self, *args, **kwargs):
        self.check_full()
        return super(Event, self).save(*args, **kwargs)

    def check_full(self):
        self.full = bool(
            (self.booked_places >= self.places and self.waiting_list_places == 0) or
            (self.waiting_list_places and self.waiting_list >= self.waiting_list_places))

    def in_bookable_period(self):
        if localtime(now()).date() > localtime(self.start_datetime - datetime.timedelta(days=self.agenda.minimal_booking_delay)).date():
            return False
        if self.agenda.maximal_booking_delay and (
                localtime(now()).date() <= localtime(self.start_datetime - datetime.timedelta(days=self.agenda.maximal_booking_delay)).date()):
            return False
        if self.start_datetime < now():
            # past the event date, we may want in the future to allow for some
            # extra late booking but it's forbidden for now.
            return False
        return True

    @property
    def booked_places(self):
        return self.booking_set.filter(cancellation_datetime__isnull=True,
                in_waiting_list=False).count()

    @property
    def waiting_list(self):
        return self.booking_set.filter(cancellation_datetime__isnull=True,
                in_waiting_list=True).count()

    @property
    def end_datetime(self):
        return self.start_datetime + datetime.timedelta(minutes=self.meeting_type.duration)

    def get_absolute_url(self):
        return reverse('chrono-manager-event-edit', kwargs={'pk': self.id})

    @classmethod
    def import_json(cls, data):
        data['start_datetime'] = make_aware(datetime.datetime.strptime(
            data['start_datetime'], '%Y-%m-%d %H:%M:%S'))
        return cls(**data)

    def export_json(self):
        return {
            'start_datetime': make_naive(self.start_datetime).strftime('%Y-%m-%d %H:%M:%S'),
            'places': self.places,
            'waiting_list_places': self.waiting_list_places,
            'label': self.label,
            'description': self.description,
        }


class Booking(models.Model):
    event = models.ForeignKey(Event, on_delete=models.CASCADE)
    extra_data = JSONField(null=True)
    cancellation_datetime = models.DateTimeField(null=True)
    in_waiting_list = models.BooleanField(default=False)
    creation_datetime = models.DateTimeField(auto_now_add=True)
    # primary booking is used to group multiple bookings together
    primary_booking = models.ForeignKey('self', null=True,
            on_delete=models.CASCADE, related_name='secondary_booking_set')

    label = models.CharField(max_length=250, blank=True)
    user_display_label = models.CharField(verbose_name=_('Label displayed to user'), max_length=250, blank=True)
    user_name = models.CharField(max_length=250, blank=True)
    backoffice_url = models.URLField(blank=True)

    def save(self, *args, **kwargs):
        with transaction.atomic():
            super(Booking, self).save(*args, **kwargs)
            initial_value = self.event.full
            self.event.check_full()
            if self.event.full != initial_value:
                self.event.save()

    def cancel(self):
        timestamp = now()
        with transaction.atomic():
            self.secondary_booking_set.update(cancellation_datetime=timestamp)
            self.cancellation_datetime = timestamp
            self.save()

    def accept(self):
        self.in_waiting_list = False
        with transaction.atomic():
            self.secondary_booking_set.update(in_waiting_list=False)
            self.save()

    def get_ics(self, request=None):
        ics = vobject.iCalendar()
        ics.add('prodid').value = '-//Entr\'ouvert//NON SGML Publik'
        vevent = vobject.newFromBehavior('vevent')
        vevent.add('uid').value = '%s-%s-%s' % (self.event.start_datetime.isoformat(), self.event.agenda.pk, self.pk)

        vevent.add('summary').value = self.user_display_label or self.label
        vevent.add('dtstart').value = self.event.start_datetime
        if self.user_name:
            vevent.add('attendee').value = self.user_name
        if self.event.meeting_type:
            vevent.add('dtend').value = self.event.start_datetime + datetime.timedelta(minutes=self.event.meeting_type.duration)

        for field in ('description', 'location', 'comment', 'url'):
            field_value = request and request.GET.get(field) or self.extra_data.get(field)
            if field_value:
                vevent.add(field).value = field_value
        ics.add(vevent)
        return ics.serialize()



@python_2_unicode_compatible
class Desk(models.Model):
    agenda = models.ForeignKey(Agenda, on_delete=models.CASCADE)
    label = models.CharField(_('Label'), max_length=150)
    slug = models.SlugField(_('Identifier'), max_length=160)
    timeperiod_exceptions_remote_url = models.URLField(
            _('URL to fetch time period exceptions from'),
            blank=True, max_length=500)

    def __str__(self):
        return self.label

    class Meta:
        ordering = ['label']

    def save(self, *args, **kwargs):
        if not self.slug:
            base_slug = slugify(self.label)
            slug = base_slug
            i = 1
            while True:
                try:
                    Desk.objects.get(slug=slug, agenda=self.agenda)
                except self.DoesNotExist:
                    break
                slug = '%s-%s' % (base_slug, i)
                i += 1
            self.slug = slug
        super(Desk, self).save(*args, **kwargs)

    @classmethod
    def import_json(cls, data):
        timeperiods = data.pop('timeperiods')
        exceptions = data.pop('exceptions')
        instance, created = cls.objects.get_or_create(**data)
        for timeperiod in timeperiods:
            timeperiod['desk'] = instance
            TimePeriod.import_json(timeperiod).save()
        for exception in exceptions:
            exception['desk'] = instance
            TimePeriodException.import_json(exception).save()
        return instance

    def export_json(self):
        return {'label': self.label,
                'slug': self.slug,
                'timeperiods': [time_period.export_json() for time_period in self.timeperiod_set.all()],
                'exceptions': [exception.export_json() for exception in self.timeperiodexception_set.all()]
                }

    def get_exceptions_within_two_weeks(self):
        in_two_weeks = make_aware(datetime.datetime.today() + datetime.timedelta(days=14))
        exceptions = self.timeperiodexception_set.filter(end_datetime__gte=now()).filter(
                Q(end_datetime__lte=in_two_weeks) | Q(start_datetime__lt=now()))
        if exceptions.exists():
            return exceptions
        # if none found within the 2 coming weeks, return the next one
        next_exception = self.timeperiodexception_set.filter(
            start_datetime__gte=now()).order_by('start_datetime').first()
        if next_exception:
            return [next_exception]
        return []

    def are_all_exceptions_displayed(self):
        in_two_weeks = self.get_exceptions_within_two_weeks()
        return self.timeperiodexception_set.count() == len(in_two_weeks)

    def create_timeperiod_exceptions_from_remote_ics(self, url):
        try:
            response = requests.get(url, proxies=settings.REQUESTS_PROXIES)
            response.raise_for_status()
        except requests.HTTPError as e:
            raise ICSError(
                _('Failed to retrieve remote calendar (%(url)s, HTTP error %(status_code)s).') %
                {'url': url, 'status_code': e.response.status_code})
        except requests.RequestException as e:
            raise ICSError(
                _('Failed to retrieve remote calendar (%(url)s, %(exception)s).') %
                {'url': url, 'exception': e})

        return self.create_timeperiod_exceptions_from_ics(response.text, keep_synced_by_uid=True)

    def remove_timeperiod_exceptions_from_remote_ics(self):
        TimePeriodException.objects.filter(desk=self).exclude(external_id='').delete()

    def create_timeperiod_exceptions_from_ics(self, data, keep_synced_by_uid=False, recurring_days=600):
        try:
            parsed = vobject.readOne(data)
        except vobject.base.ParseError:
            raise ICSError(_('File format is invalid.'))

        total_created = 0

        if not parsed.contents.get('vevent') and not keep_synced_by_uid:
            raise ICSError(_('The file doesn\'t contain any events.'))

        with transaction.atomic():
            update_datetime = now()
            for vevent in parsed.contents.get('vevent', []):
                if 'summary' in vevent.contents:
                    summary = force_text(vevent.contents['summary'][0].value)
                else:
                    summary = _('Exception')
                try:
                    start_dt = vevent.dtstart.value
                    if not isinstance(start_dt, datetime.datetime):
                        start_dt = datetime.datetime.combine(start_dt, datetime.datetime.min.time())
                    if not is_aware(start_dt):
                        start_dt = make_aware(start_dt)
                except AttributeError:
                    raise ICSError(_('Event "%s" has no start date.') % summary)
                try:
                    end_dt = vevent.dtend.value
                    if not isinstance(end_dt, datetime.datetime):
                        end_dt = datetime.datetime.combine(end_dt, datetime.datetime.min.time())
                    if not is_aware(end_dt):
                        end_dt = make_aware(end_dt)
                    duration = end_dt - start_dt
                except AttributeError:
                    try:
                        duration = vevent.duration.value
                        end_dt = start_dt + duration
                    except AttributeError:
                        # events without end date are considered as ending the same day
                        end_dt = make_aware(datetime.datetime.combine(start_dt, datetime.datetime.max.time()))
                        duration = end_dt - start_dt

                event = {}
                event['start_datetime'] = start_dt
                event['end_datetime'] = end_dt
                event['label'] = summary

                kwargs = {}
                kwargs['desk'] = self
                kwargs['recurrence_id'] = 0
                if keep_synced_by_uid:
                    kwargs['external_id'] = vevent.contents['uid'][0].value
                else:
                    kwargs['label'] = summary

                if not vevent.rruleset:
                    # classical event
                    obj, created = TimePeriodException.objects.update_or_create(defaults=event, **kwargs)
                    if created:
                        total_created += 1
                elif vevent.rruleset.count():
                    # recurring event until recurring_days in the future
                    from_dt = start_dt
                    until_dt = update_datetime + datetime.timedelta(days=recurring_days)
                    if not is_aware(vevent.rruleset[0]):
                        from_dt = make_naive(from_dt)
                        until_dt = make_naive(until_dt)
                    i = -1
                    for i, start_dt in enumerate(vevent.rruleset.between(from_dt, until_dt, inc=True)):
                        # recompute start_dt and end_dt from occurrences and duration
                        if not is_aware(start_dt):
                            start_dt = make_aware(start_dt)
                        end_dt = start_dt + duration
                        kwargs['recurrence_id'] = i
                        event['start_datetime'] = start_dt
                        event['end_datetime'] = end_dt
                        if end_dt < update_datetime:
                            TimePeriodException.objects.filter(**kwargs).update(**event)
                        else:
                            obj, created = TimePeriodException.objects.update_or_create(defaults=event, **kwargs)
                            if created:
                                total_created += 1
                    # delete unseen occurrences
                    kwargs.pop('recurrence_id', None)
                    TimePeriodException.objects.filter(recurrence_id__gt=i, **kwargs).delete()

            if keep_synced_by_uid:
                # delete all outdated exceptions from remote calendar
                TimePeriodException.objects.filter(update_datetime__lt=update_datetime,
                                    desk=self).exclude(external_id='').delete()

        return total_created

    def get_opening_hours(self, date):
        openslots = Intervals()
        for timeperiod in self.timeperiod_set.filter(weekday=date.weekday()):
            start_datetime = make_aware(datetime.datetime.combine(date, timeperiod.start_time))
            end_datetime = make_aware(datetime.datetime.combine(date, timeperiod.end_time))
            openslots.add(start_datetime, end_datetime)

        aware_date = make_aware(datetime.datetime(date.year, date.month, date.day))
        aware_next_date = aware_date + datetime.timedelta(days=1)
        for exception in self.timeperiodexception_set.filter(
                start_datetime__lt=aware_next_date,
                end_datetime__gt=aware_date):
            openslots.remove(exception.start_datetime, exception.end_datetime)

        return openslots.search(aware_date, aware_next_date)


@python_2_unicode_compatible
class TimePeriodException(models.Model):
    desk = models.ForeignKey(Desk, on_delete=models.CASCADE)
    external_id = models.CharField(_('External ID'), max_length=256, blank=True)
    label = models.CharField(_('Optional Label'), max_length=150, blank=True, null=True)
    start_datetime = models.DateTimeField(_('Exception start time'))
    end_datetime = models.DateTimeField(_('Exception end time'))
    update_datetime = models.DateTimeField(auto_now=True)
    recurrence_id = models.PositiveIntegerField(_('Recurrence ID'), default=0)

    class Meta:
        ordering = ['start_datetime']

    def __str__(self):
        if is_midnight(self.start_datetime) and is_midnight(self.end_datetime):
            # if both dates are at midnight don't include the time part
            if self.end_datetime == self.start_datetime + datetime.timedelta(days=1):
                # a single day
                exc_repr = u'%s' % date_format(localtime(self.start_datetime), 'SHORT_DATE_FORMAT')
            else:
                exc_repr = u'%s → %s' % (
                        date_format(localtime(self.start_datetime), 'SHORT_DATE_FORMAT'),
                        date_format(localtime(self.end_datetime), 'SHORT_DATE_FORMAT'))
        else:
            if localtime(self.start_datetime).date() == localtime(self.end_datetime).date():
                # same day
                exc_repr = u'%s → %s' % (
                        date_format(localtime(self.start_datetime), 'SHORT_DATETIME_FORMAT'),
                        date_format(localtime(self.end_datetime), 'TIME_FORMAT'))
            else:
                exc_repr = u'%s → %s' % (
                        date_format(localtime(self.start_datetime), 'SHORT_DATETIME_FORMAT'),
                        date_format(localtime(self.end_datetime), 'SHORT_DATETIME_FORMAT'))

        if self.label:
            exc_repr = u'%s (%s)' % (self.label, exc_repr)

        return exc_repr

    def clean(self):
        super(TimePeriodException, self).clean()
        if self.has_booking_within_time_slot():
            raise ValidationError(_('One or several bookings exists within this time slot.'))

    def has_booking_within_time_slot(self):
        if not (self.start_datetime and self.end_datetime):
            # incomplete time period, can't tell
            return False
        for event in Event.objects.filter(
                desk=self.desk,
                booking__isnull=False,
                booking__cancellation_datetime__isnull=True):
            if self.start_datetime <= event.start_datetime < self.end_datetime:
                return True
        return False

    @classmethod
    def import_json(cls, data):
        def import_datetime(s):
            '''Import datetime as a naive ISO8601 serialization'''
            return make_aware(datetime.datetime.strptime(s, '%Y-%m-%d %H:%M:%S'))

        for k, v in data.items():
            if k.endswith('_datetime'):
                data[k] = import_datetime(v)
        return cls(**data)

    def export_json(self):
        def export_datetime(dt):
            '''Export datetime as a naive ISO8601 serialization'''
            return make_naive(dt).strftime('%Y-%m-%d %H:%M:%S')

        return {
            'label': self.label,
            'start_datetime': export_datetime(self.start_datetime),
            'end_datetime': export_datetime(self.end_datetime),
            'external_id': self.external_id,
            'recurrence_id': self.recurrence_id,
            'update_datetime': export_datetime(self.update_datetime),
        }