from calendar import monthrange
from datetime import date, timedelta

from django.contrib.auth.decorators import login_required
from django.contrib.auth.mixins import LoginRequiredMixin
from django.db.models import Avg, Max, Min, Sum
from django.http import HttpResponse
from django.shortcuts import render
from django.urls import reverse_lazy
from django.utils import timezone
from django.views.generic import CreateView, ListView

from .forms import FuelPurchaseForm
from .models import FuelPurchase


class FuelPurchaseMonthlyListView(ListView):
    model = FuelPurchase
    template_name = "fuelpurchase_list.html"
    context_object_name = "purchases"

    def get_queryset(self):
        year = int(self.kwargs.get("year", timezone.now().year))
        month = int(self.kwargs.get("month", timezone.now().month))
        self.current_year = year
        self.current_month = month

        start_date = date(year, month, 1)
        end_date = date(year, month, monthrange(year, month)[1])

        return FuelPurchase.objects.filter(
            purchase_date__range=(start_date, end_date)
        ).order_by("-purchase_date")

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

        qs = self.object_list
        summary = qs.aggregate(
            total_cost_sum=Sum("total_cost"),
            total_litres_sum=Sum("amount_litres"),
            avg_price=Avg("price_per_litre"),
            min_price=Min("price_per_litre"),
            max_price=Max("price_per_litre"),
        )

        context["summary"] = summary
        context["current_year"] = self.current_year
        context["current_month"] = self.current_month

        # Kuukausinavigointi
        current_date = date(self.current_year, self.current_month, 1)
        prev_month = current_date - timedelta(days=1)
        next_month = (current_date.replace(day=28) + timedelta(days=4)).replace(day=1)

        context["prev_year"] = prev_month.year
        context["prev_month"] = prev_month.month
        context["next_year"] = next_month.year
        context["next_month"] = next_month.month

        # Kaikki kuukaudet alasvetovalikkoon
        all_dates = FuelPurchase.objects.dates("purchase_date", "month", order="DESC")
        context["available_months"] = all_dates

        return context


class FuelPurchaseCreateView(LoginRequiredMixin, CreateView):
    model = FuelPurchase
    form_class = FuelPurchaseForm
    template_name = "main/fuelpurchase_add.html"
    success_url = "/"