# -*- coding: utf-8 -*-
from django.shortcuts import render
from django.views.generic import ListView, CreateView, UpdateView, DeleteView, DetailView
from django.urls import reverse_lazy
from django.contrib.auth.mixins import LoginRequiredMixin
from django.contrib import messages
from ..models import Sale, SaleBatchAllocation
from ..forms import SaleForm


class SaleListView(LoginRequiredMixin, ListView):
    """
    Список всех продаж товара (истории реализации)
    """
    model = Sale
    template_name = 'inventory/sale/sale_list.html'
    context_object_name = 'sales'
    paginate_by = 20

    def get_queryset(self):
        queryset = Sale.objects.select_related('product', 'warehouse', 'order').order_by('-date')

        # Фильтры (если переданы)
        product_id = self.request.GET.get('product')
        warehouse_id = self.request.GET.get('warehouse')
        processed = self.request.GET.get('processed')

        if product_id:
            queryset = queryset.filter(product_id=product_id)
        if warehouse_id:
            queryset = queryset.filter(warehouse_id=warehouse_id)
        if processed:
            queryset = queryset.filter(processed=processed == 'true')

        return queryset


class SaleCreateView(LoginRequiredMixin, CreateView):
    """
    Регистрация новой продажи товара.
    После сохранения автоматически применяется FIFO (через сигнал).
    """
    model = Sale
    form_class = SaleForm
    template_name = 'inventory/sale/sale_form.html'
    success_url = reverse_lazy('inventory:sale-list')

    def form_valid(self, form):
        messages.success(
            self.request,
            f'Продажа товара "{form.instance.product.name}" ({form.instance.quantity} шт) успешно зарегистрирована.'
        )
        return super().form_valid(form)


class SaleDetailView(LoginRequiredMixin, DetailView):
    """
    Просмотр деталей продажи с распределением по партиям.
    Показывает SaleBatchAllocation для данной продажи.
    """
    model = Sale
    template_name = 'inventory/sale/sale_detail.html'
    context_object_name = 'sale'

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        # Получаем все распределения этой продажи по партиям
        context['allocations'] = SaleBatchAllocation.objects.filter(
            sale=self.object
        ).select_related('batch', 'batch__product')
        return context


class SaleUpdateView(LoginRequiredMixin, UpdateView):
    """
    Редактирование продажи (только если ещё не обработана).
    Обработанные продажи редактировать нельзя.
    """
    model = Sale
    form_class = SaleForm
    template_name = 'inventory/sale/sale_form.html'
    success_url = reverse_lazy('inventory:sale-list')

    def form_valid(self, form):
        messages.success(self.request, f'Продажа товара обновлена.')
        return super().form_valid(form)


class SaleDeleteView(LoginRequiredMixin, DeleteView):
    """
    Отмена/удаление продажи товара.
    """
    model = Sale
    template_name = 'inventory/sale/sale_confirm_delete.html'
    success_url = reverse_lazy('inventory:sale-list')

    def form_valid(self, form):
        sale = self.get_object()
        messages.success(
            self.request,
            f'Продажа товара "{sale.product.name}" отменена.'
        )
        return super().form_valid(form)