import datetime import math from calendar import Calendar from collections import defaultdict from django.core.exceptions import ImproperlyConfigured from django.db.models import Q from django.utils.translation import gettext_lazy as _ from django.views.generic.dates import ( DateMixin, MonthMixin, YearMixin, _date_from_string, ) from django.views.generic.list import BaseListView, MultipleObjectTemplateResponseMixin DAYS = ( _("Monday"), _("Tuesday"), _("Wednesday"), _("Thursday"), _("Friday"), _("Saturday"), _("Sunday"), ) def daterange(start_date, end_date): """ Returns an iterator of dates between two provided ones """ for n in range(int((end_date - start_date).days + 1)): yield start_date + datetime.timedelta(n) class BaseCalendarMonthView(DateMixin, YearMixin, MonthMixin, BaseListView): """ A base view for displaying a calendar month """ first_of_week = 0 # 0 = Monday, 6 = Sunday paginate_by = None # We don't want to use this part of MultipleObjectMixin date_field = None end_date_field = None # For supporting events with duration def get_paginate_by(self, queryset): if self.paginate_by is not None: raise ImproperlyConfigured( "'%s' cannot be paginated, it is a calendar view" % self.__class__.__name__ ) return None def get_allow_future(self): return True def get_end_date_field(self): """ Returns the model field to use for end dates """ return self.end_date_field def get_start_date(self, obj): """ Returns the start date for a model instance """ obj_date = getattr(obj, self.get_date_field()) try: obj_date = obj_date.date() except AttributeError: # It's a date rather than datetime, so we use it as is pass return obj_date def get_end_date(self, obj): """ Returns the end date for a model instance """ obj_date = getattr(obj, self.get_end_date_field()) try: obj_date = obj_date.date() except AttributeError: # It's a date rather than datetime, so we use it as is pass return obj_date def get_first_of_week(self): """ Returns an integer representing the first day of the week. 0 represents Monday, 6 represents Sunday. """ if self.first_of_week is None: raise ImproperlyConfigured( "%s.first_of_week is required." % self.__class__.__name__ ) if self.first_of_week not in range(7): raise ImproperlyConfigured( "%s.first_of_week must be an integer between 0 and 6." % self.__class__.__name__ ) return self.first_of_week def get_queryset(self): """ Returns a queryset of models for the month requested """ qs = super().get_queryset() year = self.get_year() month = self.get_month() date_field = self.get_date_field() end_date_field = self.get_end_date_field() date = _date_from_string( year, self.get_year_format(), month, self.get_month_format() ) since = date until = self.get_next_month(date) # Adjust our start and end dates to allow for next and previous # month edges if since.weekday() != self.get_first_of_week(): diff = math.fabs(since.weekday() - self.get_first_of_week()) since = since - datetime.timedelta(days=diff) if until.weekday() != ((self.get_first_of_week() + 6) % 7): diff = math.fabs(((self.get_first_of_week() + 6) % 7) - until.weekday()) until = until + datetime.timedelta(days=diff) if end_date_field: # 5 possible conditions for showing an event: # 1) Single day event, starts after 'since' # 2) Multi-day event, starts after 'since' and ends before 'until' # 3) Starts before 'since' and ends after 'since' and before 'until' # 4) Starts after 'since' but before 'until' and ends after 'until' # 5) Starts before 'since' and ends after 'until' predicate1 = Q(**{"%s__gte" % date_field: since, end_date_field: None}) predicate2 = Q( **{"%s__gte" % date_field: since, "%s__lt" % end_date_field: until} ) predicate3 = Q( **{ "%s__lt" % date_field: since, "%s__gte" % end_date_field: since, "%s__lt" % end_date_field: until, } ) predicate4 = Q( **{ "%s__gte" % date_field: since, "%s__lt" % date_field: until, "%s__gte" % end_date_field: until, } ) predicate5 = Q( **{"%s__lt" % date_field: since, "%s__gte" % end_date_field: until} ) return qs.filter( predicate1 | predicate2 | predicate3 | predicate4 | predicate5 ) return qs.filter(**{"%s__gte" % date_field: since}) def get_context_data(self, **kwargs): """ Injects variables necessary for rendering the calendar into the context. Variables added are: `calendar`, `weekdays`, `month`, `next_month` and `previous_month`. """ data = super().get_context_data(**kwargs) year = self.get_year() month = self.get_month() date = _date_from_string( year, self.get_year_format(), month, self.get_month_format() ) cal = Calendar(self.get_first_of_week()) month_calendar = [] now = datetime.datetime.utcnow() date_lists = defaultdict(list) multidate_objs = [] for obj in data["object_list"]: obj_date = self.get_start_date(obj) end_date_field = self.get_end_date_field() if end_date_field: end_date = self.get_end_date(obj) if end_date and end_date != obj_date: multidate_objs.append( { "obj": obj, "range": [x for x in daterange(obj_date, end_date)], } ) continue # We don't put multi-day events in date_lists date_lists[obj_date].append(obj) for week in cal.monthdatescalendar(date.year, date.month): week_range = set(daterange(week[0], week[6])) week_events = [] for val in multidate_objs: intersect_length = len(week_range.intersection(val["range"])) if intersect_length: # Event happens during this week slot = 1 width = ( intersect_length ) # How many days is the event during this week? nowrap_previous = ( True ) # Does the event continue from the previous week? nowrap_next = True # Does the event continue to the next week? if val["range"][0] >= week[0]: slot = 1 + (val["range"][0] - week[0]).days else: nowrap_previous = False if val["range"][-1] > week[6]: nowrap_next = False week_events.append( { "event": val["obj"], "slot": slot, "width": width, "nowrap_previous": nowrap_previous, "nowrap_next": nowrap_next, } ) week_calendar = {"events": week_events, "date_list": []} for day in week: week_calendar["date_list"].append( { "day": day, "events": date_lists[day], "today": day == now.date(), "is_current_month": day.month == date.month, } ) month_calendar.append(week_calendar) data["calendar"] = month_calendar data["weekdays"] = [DAYS[x] for x in cal.iterweekdays()] data["month"] = date data["next_month"] = self.get_next_month(date) data["previous_month"] = self.get_previous_month(date) return data class CalendarMonthView(MultipleObjectTemplateResponseMixin, BaseCalendarMonthView): """ A view for displaying a calendar month, and rendering a template response """ template_name_suffix = "_calendar_month"