import calendar
import datetime
from datetime import date

from django.db.models import Q
from django.shortcuts import render
from django.urls import reverse
from django.views.generic import ListView, TemplateView
from django.views.generic.detail import DetailView
from django.views.generic.edit import CreateView

from .forms import RentalCreateForm
from .models import Rental, RentalItem


def _calc_days_from_current_month(month: date) -> list:
    last_day_of_month = month.replace(day=calendar.monthrange(month.year, month.month)[1])

    return [month + datetime.timedelta(days=i) for i in range((last_day_of_month - month).days + 1)]


def _calc_days_from_prev_month(month: date) -> list:
    days_of_prev_period = []

    if month.weekday() != calendar.MONDAY:
        for i in range(1, 7):
            day = month + datetime.timedelta(days=-i)
            days_of_prev_period.append(day)
            if day.weekday() == calendar.MONDAY:
                break

    return sorted(days_of_prev_period)


def _calc_days_from_next_month(month: date) -> list:
    last_day_of_month = month.replace(day=calendar.monthrange(month.year, month.month)[1])
    days_of_next_period = []

    if last_day_of_month.weekday() != calendar.SUNDAY:
        for i in range(1, 7):
            day = last_day_of_month + datetime.timedelta(days=i)
            days_of_next_period.append(day)
            if day.weekday() == calendar.SUNDAY:
                break

    return days_of_next_period


def _get_display_period(view_type: str, period: str) -> date:
    display_date: date = None

    # Handle week view
    if view_type == "week":
        try:
            # Parse the requested calendar week
            display_date = (
                datetime.datetime.strptime(f"{period}-1", "%G-KW%V-%u")
                .replace(tzinfo=datetime.UTC)
                .date()
            )
        except Exception:
            # Get first day of the current week
            today = datetime.datetime.now(tz=datetime.UTC).date()
            display_date = today - datetime.timedelta(days=today.weekday())

    # Handle month view
    else:
        try:
            # Parse the requested month
            display_date = (
                datetime.datetime.strptime(period, "%Y-%m").replace(tzinfo=datetime.UTC).date()
            )
        except Exception:
            # Get the first day of the current month
            display_date = datetime.datetime.now(tz=datetime.UTC).date().replace(day=1)

    return display_date


class RentalListView(ListView):
    model = Rental
    template_name = "rental/calendar.html"

    def __init__(self):
        super().__init__()
        # Current display period and view settings
        self.display_period = None
        self.view_type = "month"  # Default view
        self.rentalitem_filters = []

    def get(self, request, *args, **kwargs):
        # Get view parameters from request
        _view_type = request.GET.get("view_type", "week")
        _period = request.GET.get("period_value", "")
        _prev_period = request.GET.get("prev_period", "")
        _next_period = request.GET.get("next_period", "")

        if _prev_period:
            _period = _prev_period
        elif _next_period:
            _period = _next_period

        self.view_type = _view_type
        self.display_period = _get_display_period(_view_type, _period)

        self.rentalitem_filters = request.GET.getlist("rentalitems", [])
        if not self.rentalitem_filters:
            items = RentalItem.objects.all()
            self.rentalitem_filters = [item.name for item in items]

        # Update request.GET
        _request_get_list = request.GET.copy()
        _request_get_list.pop("prev_period", None)
        _request_get_list.pop("next_period", None)
        _request_get_list["period_value"] = _period
        request.GET = _request_get_list

        return super().get(request, *args, **kwargs)

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)

        if self.view_type != "week":
            # Add the displayed, previous and next month
            context["view_period"] = self.display_period
            context["prev_period"] = self.display_period + datetime.timedelta(days=-1)
            context["next_period"] = self.display_period + datetime.timedelta(
                days=calendar.monthrange(self.display_period.year, self.display_period.month)[1] + 1
            )

            # Add the days of the displayed, previous and next month
            days_of_view_period = _calc_days_from_current_month(self.display_period)
            context["days_of_view_period"] = days_of_view_period
            context["days_of_prev_period"] = _calc_days_from_prev_month(self.display_period)
            context["days_of_next_period"] = _calc_days_from_next_month(self.display_period)

            context["view_type"] = "month"

            context["week_num"] = None

        else:
            # Current week
            year, week_num, _ = self.display_period.isocalendar()
            context["view_period"] = f"{year}-KW{week_num:02d}"  # formats as "2025-KW02"

            # Calculate previous week
            prev_week = self.display_period - datetime.timedelta(days=7)
            prev_year, prev_week_num, _ = prev_week.isocalendar()
            context["prev_period"] = f"{prev_year}-KW{prev_week_num:02d}"

            # Calculate next week
            next_week = self.display_period + datetime.timedelta(days=7)
            next_year, next_week_num, _ = next_week.isocalendar()
            context["next_period"] = f"{next_year}-KW{next_week_num:02d}"

            # Add days of week (7 days starting from first_day_of_week)
            days_of_view_period = [
                self.display_period + datetime.timedelta(days=i) for i in range(7)
            ]
            context["days_of_view_period"] = days_of_view_period
            context["days_of_prev_period"] = []
            context["days_of_next_period"] = []

            context["view_type"] = "week"

            context["week_num"] = week_num

        # Get the current date for the calendar
        context["today"] = datetime.datetime.now(tz=datetime.UTC).date()

        # Add rental items to the context for the filter
        context["rentalitems"] = RentalItem.objects.all()

        # Add the selected rental items to the context for the filter
        context["rentalitem_filters"] = {"rentalitems": self.rentalitem_filters}

        # Create a dictionary with the rental items for each day
        rental_dict = {}
        for rental in self.get_queryset():
            for day in days_of_view_period:
                if rental["date_start"] <= day and rental["date_end"] >= day:
                    if day not in rental_dict:
                        rental_dict[day] = []

                    if rental["rentalitems__name"] not in rental_dict[day]:
                        rental_dict[day].append(rental["rentalitems__name"])

        context["rental_dict"] = rental_dict

        return context

    def get_queryset(self):
        qs = (
            super()
            .get_queryset()
            .filter(
                Q(status=Rental.Status.APPROVED)
                | Q(status=Rental.Status.ISSUED)
                | Q(status=Rental.Status.RETURNED)
            )
        )

        if self.view_type == "week":
            qs_date_end = self.display_period + datetime.timedelta(days=6)
        else:
            qs_date_end = self.display_period.replace(
                day=calendar.monthrange(self.display_period.year, self.display_period.month)[1]
            )

        # Filter by date
        if self.display_period and qs_date_end:
            qs_new = qs.filter(date_start__gte=self.display_period, date_start__lte=qs_date_end)
            qs_new |= qs.filter(date_end__gte=self.display_period, date_end__lte=qs_date_end)

        # Filter by rental items
        qs = qs.filter(rentalitems__name__in=self.rentalitem_filters).distinct()

        return qs.values("id", "date_start", "date_end", "rentalitems__name").distinct()


class RentalCreateView(CreateView):
    form_class = RentalCreateForm
    model = Rental
    template_name = "rental/create.html"

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)

        context["rentalitems_addinfo"] = RentalItem.objects.all()

        return context

    def get_success_url(self):
        return reverse("rental:rental_create_done", kwargs={"pk": self.object.pk})


class RentalCreateDoneView(TemplateView):
    template_name = "rental/create_done.html"

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)

        obj = Rental.objects.get(pk=self.kwargs["pk"])

        total_deposit = 0
        for elem in obj.rentalitems.all():
            total_deposit += elem.deposit

        context["object"] = obj
        context["total_deposit"] = total_deposit

        return context


class RentalItemDetailView(DetailView):
    model = RentalItem
    template_name = "rental/rentalitem_detail.html"


def rental_calendar(request):
    """
    ICS-calendar for Outlook, Google Calendar, etc.
    """
    rentals = Rental.objects.all()

    context = {
        "rentals": rentals,
    }

    response = render(request, "rental/rental_calendar.ics", context, content_type="text/calendar")

    # End of line (EOL) must be CRLF, to be compliant with RFC5545. Django/Python set the EOL to LF.
    response.content = response.content.replace(b"\n", b"\r\n")

    return response