import datetime

from django_filters import constants
from django_filters import rest_framework as filters
from django_filters import widgets

from django import forms
from django.db.models import Exists, OuterRef, Q, QuerySet
from django.utils import timezone
from program import models


class StaticFilterHelpTextMixin:
    @classmethod
    def filter_for_field(cls, field, field_name, lookup_expr=None):
        _filter = super().filter_for_field(field, field_name, lookup_expr)
        if "help_text" not in _filter.extra:
            help_texts = getattr(cls.Meta, "help_texts", {})
            _filter.extra["help_text"] = help_texts.get(field_name, "")
        return _filter


class IntegerInFilter(filters.BaseInFilter):
    class QueryArrayWidget(widgets.QueryArrayWidget):
        # see: https://github.com/carltongibson/django-filter/issues/1047
        def value_from_datadict(self, data, files, name):
            new_data = {}
            for key in data.keys():
                if len(data.getlist(key)) == 1 and "," in data[key]:
                    new_data[key] = data[key]
                else:
                    new_data[key] = data.getlist(key)
            return super().value_from_datadict(new_data, files, name)

    field_class = forms.IntegerField

    def __init__(self, *args, **kwargs):
        kwargs.setdefault("widget", self.QueryArrayWidget())
        super().__init__(*args, **kwargs)


class ShowOrderingFilter(filters.OrderingFilter):
    def filter(self, qs: QuerySet, value):
        if value in constants.EMPTY_VALUES:
            return qs
        ordering = [self.get_ordering_value(param) for param in value]
        fields = (field.lstrip("-") for field in ordering)
        if "is_owner" in fields:
            _id = getattr(self.parent.request.user, "id", None)
            qs = qs.annotate(
                is_owner=Exists(
                    models.Show.owners.through.objects.filter(user=_id, show=OuterRef("pk")),
                )
            )
        return qs.order_by(*ordering)


class ShowFilterSet(StaticFilterHelpTextMixin, filters.FilterSet):
    order = ShowOrderingFilter(
        fields=["name", "slug", "id", "is_active", "is_owner", "updated_at", "updated_by"],
        help_text="Order shows by the given field(s).",
    )
    category_ids = IntegerInFilter(
        field_name="category",
        help_text="Return only shows of the given category or categories.",
    )
    category_slug = filters.CharFilter(
        field_name="category__slug",
        help_text="Return only shows of the given category slug.",
    )
    host_ids = IntegerInFilter(
        field_name="hosts",
        help_text="Return only shows assigned to the given host(s).",
    )
    is_active = filters.BooleanFilter(
        field_name="is_active",
        method="filter_active",
        help_text=(
            "Return only currently running shows (with timeslots in the future) if true "
            "or past or upcoming shows if false."
        ),
    )
    is_public = filters.BooleanFilter(
        field_name="is_public",
        help_text="Return only shows that are public/non-public.",
    )
    language_ids = IntegerInFilter(
        field_name="language",
        help_text="Return only shows of the given language(s).",
    )
    music_focus_ids = IntegerInFilter(
        field_name="music_focus",
        help_text="Return only shows with given music focus(es).",
    )
    music_focus_slug = filters.CharFilter(
        field_name="music_focus__slug",
        help_text="Return only shows with the give music focus slug.",
    )
    owner_ids = IntegerInFilter(
        field_name="owners",
        help_text="Return only shows that belong to the given owner(s).",
    )
    topic_ids = IntegerInFilter(
        field_name="topic",
        help_text="Return only shows of the given topic(s).",
    )
    topic_slug = filters.CharFilter(
        field_name="topic__slug",
        help_text="Return only shows of the given topic slug.",
    )
    type_id = IntegerInFilter(
        field_name="type",
        help_text="Return only shows of a given type.",
    )
    type_slug = filters.CharFilter(
        field_name="type__slug",
        help_text="Return only shows of the given type slug.",
    )

    def filter_active(self, queryset: QuerySet, name: str, value: bool):
        # Filter currently running shows
        # Get currently running schedules to filter by first
        # For single dates we test if there'll be one in the future (and ignore the until date)
        # TODO: Really consider first_date? (=currently active, not just upcoming ones)
        # Add limit for future?
        show_ids = (
            models.Schedule.objects.filter(
                # not "once" schedules with first_date in the past and last_date in the future
                Q(
                    rrule__freq__gt=0,
                    first_date__lte=timezone.now(),
                    last_date__gte=timezone.now(),
                )
                # "once" schedules with first_date in the future
                | Q(rrule__freq=0, first_date__gte=timezone.now())
            )
            .distinct()
            .values_list("show_id", flat=True)
        )
        if value:
            # Filter active shows based on timeslots as well as on the is_active flag
            # Even if there are future timeslots but is_active=True the show will be considered as
            # inactive
            return queryset.filter(id__in=show_ids, is_active=True)
        else:
            return queryset.exclude(id__in=show_ids, is_active=True)

    class Meta:
        model = models.Show
        fields = [
            "order",
            "category_ids",
            "category_slug",
            "host_ids",
            "is_active",
            "is_public",
            "language_ids",
            "music_focus_ids",
            "music_focus_slug",
            "owner_ids",
            "topic_ids",
            "topic_slug",
            "type_id",
            "type_slug",
        ]


class ScheduleFilterSet(filters.FilterSet):
    show_ids = IntegerInFilter(
        field_name="show",
        help_text="Return only schedules that belong to the specified show(s).",
    )


class TimeSlotFilterSet(filters.FilterSet):
    order = filters.OrderingFilter(
        fields=[field.name for field in models.TimeSlot._meta.get_fields()]
    )
    surrounding = filters.DateTimeFilter(
        method="filter_surrounding",
        label="Return surrounding timeslots",
        help_text=(
            "Returns the 10 nearest timeslots around the specified datetime. "
            "If specified without a datetime value the current date and time is assumed."
        ),
    )
    # The start/end filters will always be applied even if no query parameter has been set.
    # This is because we enforce a value in the clean_start and clean_end methods
    # of the filterset form.
    start = filters.DateFilter(
        method="filter_start",
        help_text=(
            "Only returns timeslots after that start on or after the specified date. "
            "By default, this is set to the current date."
        ),
    )
    end = filters.DateFilter(
        method="filter_end",
        help_text=(
            "Only returns timeslots that end on or before the specified date. "
            "By default, this is set to value of the start filter + 60 days."
        ),
    )

    schedule_ids = IntegerInFilter(
        field_name="schedule",
        help_text="Return only timeslots that belong to the specified schedule(s).",
    )

    show_ids = IntegerInFilter(
        field_name="schedule__show",
        help_text="Return only timeslots that belong to the specified show(s).",
    )

    def filter_surrounding(self, queryset: QuerySet, name: str, value: datetime.datetime):
        nearest_timeslots_in_future = (
            models.TimeSlot.objects.filter(start__gte=value)
            .order_by("start")
            .values_list("id", flat=True)[:5]
        )
        nearest_timeslots_in_past = (
            models.TimeSlot.objects.filter(start__lt=value)
            .order_by("-start")
            .values_list("id", flat=True)[:5]
        )
        relevant_timeslot_ids = list(nearest_timeslots_in_future) + list(nearest_timeslots_in_past)
        return queryset.filter(id__in=relevant_timeslot_ids)

    def filter_start(self, queryset: QuerySet, name: str, value: datetime.date):
        start = timezone.make_aware(datetime.datetime.combine(value, datetime.time.min))
        return queryset.filter(start__gte=start)

    def filter_end(self, queryset: QuerySet, name: str, value: datetime.date):
        end = timezone.make_aware(datetime.datetime.combine(value, datetime.time.max))
        return queryset.filter(end__lte=end)

    def filter_queryset(self, queryset):
        queryset = super().filter_queryset(queryset)
        # This is for backwards compatibility as the surrounding-filter was formerly implemented
        # by just checking for the existence of the query parameter.
        if self.request.GET.get("surrounding", None) == "":
            queryset = self.filter_surrounding(queryset, "surrounding", timezone.now())
        return queryset

    def get_form_class(self):
        form_cls = super().get_form_class()

        class TimeSlotFilterSetFormWithDefaults(form_cls):
            def clean_start(self):
                start = self.cleaned_data.get("start", None)
                return start or timezone.now().date()

            def clean_end(self):
                end = self.cleaned_data.get("end", None)
                return end or self.cleaned_data["start"] + datetime.timedelta(days=60)

        # We only want defaults to apply in the context of the list action.
        # When accessing individual timeslots we don’t want the queryset to be restricted
        # to the default range of 60 days as get_object would yield a 404 otherwise.
        if self.request.parser_context["view"].action == "list":
            return TimeSlotFilterSetFormWithDefaults
        else:
            return form_cls

    class Meta:
        model = models.TimeSlot
        fields = [
            "order",
            "start",
            "end",
            "surrounding",
            "schedule_ids",
            "show_ids",
        ]


class NoteFilterSet(StaticFilterHelpTextMixin, filters.FilterSet):
    ids = IntegerInFilter(
        field_name="id",
        help_text="Return only notes matching the specified id(s).",
    )
    owner_ids = IntegerInFilter(
        field_name="owner",
        help_text="Return only notes that belong to the specified owner(s).",
    )
    show_ids = IntegerInFilter(
        field_name="timeslot__show",
        help_text="Return only notes that belong to the specified show(s).",
    )
    show_owner_ids = IntegerInFilter(
        field_name="timeslot__show__owners",
        help_text="Return only notes by show the specified owner(s): all notes the user may edit.",
    )
    timeslot_ids = IntegerInFilter(
        field_name="timeslot",
        help_text="Return only notes that belong to the specified timeslot(s).",
    )

    class Meta:
        model = models.Note
        fields = [
            "ids",
            "owner_ids",
            "show_ids",
            "show_owner_ids",
            "timeslot_ids",
        ]


class ActiveFilterSet(StaticFilterHelpTextMixin, filters.FilterSet):
    is_active = filters.BooleanFilter(field_name="is_active")

    class Meta:
        fields = [
            "is_active",
        ]