#
# Copyright 2023 © AE UTBM
# ae@utbm.fr / ae.info@utbm.fr
#
# This file is part of the website of the UTBM Student Association (AE UTBM),
# https://ae.utbm.fr.
#
# You can find the source code of the website at https://github.com/ae-utbm/sith
#
# LICENSED UNDER THE GNU GENERAL PUBLIC LICENSE VERSION 3 (GPLv3)
# SEE : https://raw.githubusercontent.com/ae-utbm/sith/master/LICENSE
# OR WITHIN THE LOCAL FILE "LICENSE"
#
#
import random
from collections import defaultdict
from typing import TYPE_CHECKING

from django.contrib import messages
from django.core.exceptions import PermissionDenied
from django.db import transaction
from django.db.models import Q
from django.http import Http404
from django.shortcuts import get_object_or_404, redirect, resolve_url
from django.urls import reverse
from django.utils.translation import gettext as _
from django.views.generic import CreateView, FormView
from django.views.generic.detail import SingleObjectMixin

from core.auth.mixins import CanViewMixin
from core.views.mixins import FragmentMixin, UseFragmentsMixin
from counter.forms import BasketForm, RefillForm
from counter.models import (
    Counter,
    Customer,
    ProductFormula,
    Refilling,
    ReturnableProduct,
    Selling,
)
from counter.utils import is_logged_in_counter
from counter.views.mixins import CounterTabsMixin
from counter.views.student_card import StudentCardFormFragment

if TYPE_CHECKING:
    from django.utils.safestring import SafeString
    from ninja.main import HttpRequest

    from core.models import User


def get_operator(request: HttpRequest, counter: Counter, customer: Customer) -> User:
    if counter.type != "BAR":
        return request.user
    if counter.customer_is_barman(customer):
        return customer.user
    return random.choice(list(request.barmen))


class CounterClick(
    CounterTabsMixin, UseFragmentsMixin, CanViewMixin, SingleObjectMixin, FormView
):
    """The click view
    This is a detail view not to have to worry about loading the counter
    Everything is made by hand in the post method.
    """

    model = Counter
    queryset = (
        Counter.objects.exclude(type="EBOUTIC")
        .annotate_is_open()
        .select_related("club")
    )
    form_class = BasketForm
    template_name = "counter/counter_click.jinja"
    pk_url_kwarg = "counter_id"
    current_tab = "counter"

    def get_form_kwargs(self):
        return super().get_form_kwargs() | {
            "customer": self.customer,
            "counter": self.object,
            "form_kwargs": {
                "allowed_prices": {price.id: price for price in self.prices}
            },
        }

    def dispatch(self, request, *args, **kwargs):
        self.customer = get_object_or_404(Customer, user_id=self.kwargs["user_id"])
        obj: Counter = self.get_object()

        if not self.customer.can_buy or self.customer.user.is_banned_counter:
            return redirect(obj)  # Redirect to counter

        if obj.type == "OFFICE" and (
            request.user.is_anonymous
            or not (
                obj.sellers.contains(request.user)
                or obj.club.has_rights_in_club(request.user)
            )
        ):
            # To be able to click on an office counter,
            # a user must either be in the board of the club that own the counter
            # or a seller of this counter.
            raise PermissionDenied

        if obj.type == "BAR" and not (
            request.barmen and request.barmen.issubset(set(obj.barmen_list))
        ):
            messages.error(request, _("You cannot click users on this counter"))
            return redirect(obj)  # Redirect to counter

        self.prices = list(obj.get_prices_for(self.customer))

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

    def form_valid(self, formset):
        ret = super().form_valid(formset)

        if len(formset) == 0:
            return ret

        operator = get_operator(self.request, self.object, self.customer)
        with transaction.atomic():
            self.request.session["last_basket"] = []

            # We sort items from cheap to expensive
            # This is important because some items have a negative price
            # Negative priced items gives money to the customer and should
            # be processed first so that we don't throw a not enough money error
            for form in sorted(formset, key=lambda form: form.price.amount):
                self.request.session["last_basket"].append(
                    f"{form.cleaned_data['quantity']} x {form.price.full_label}"
                )

                common_kwargs = {
                    "product": form.price.product,
                    "club_id": form.price.product.club_id,
                    "counter": self.object,
                    "seller": operator,
                    "customer": self.customer,
                }
                Selling(
                    **common_kwargs,
                    label=form.price.full_label,
                    unit_price=form.price.amount,
                    quantity=form.cleaned_data["quantity"]
                    - form.cleaned_data["bonus_quantity"],
                ).save()
                if form.cleaned_data["bonus_quantity"] > 0:
                    Selling(
                        **common_kwargs,
                        label=f"{form.price.full_label} (Plateau)",
                        unit_price=0,
                        quantity=form.cleaned_data["bonus_quantity"],
                    ).save()

            self.customer.update_returnable_balance()

        # Add some info for the main counter view to display
        self.request.session["last_customer"] = self.customer.user.get_display_name()
        self.request.session["last_total"] = f"{formset.total_price:0.2f}"
        self.request.session["new_customer_amount"] = str(self.customer.amount)

        return ret

    def _update_returnable_balance(self, formset):
        ids = [form.cleaned_data["id"] for form in formset]
        returnables = list(
            ReturnableProduct.objects.filter(
                Q(product_id__in=ids) | Q(returned_product_id__in=ids)
            ).annotate_balance_for(self.customer)
        )
        for returnable in returnables:
            cons_quantity = next(
                (
                    form.cleaned_data["quantity"]
                    for form in formset
                    if form.cleaned_data["id"] == returnable.product_id
                ),
                0,
            )
            dcons_quantity = next(
                (
                    form.cleaned_data["quantity"]
                    for form in formset
                    if form.cleaned_data["id"] == returnable.returned_product_id
                ),
                0,
            )
            self.customer.return_balances.update_or_create(
                returnable=returnable,
                defaults={
                    "balance": returnable.balance + cons_quantity - dcons_quantity
                },
            )

    def get_success_url(self):
        return resolve_url(self.object)

    def get_fragment_context_data(self) -> dict[str, SafeString]:
        res = super().get_fragment_context_data()
        if self.object.type == "BAR":
            res["student_card_fragment"] = StudentCardFormFragment.as_fragment()(
                self.request, customer=self.customer
            )
        if self.object.can_refill():
            res["refilling_fragment"] = RefillingCreateView.as_fragment()(
                self.request, customer=self.customer, counter=self.object
            )
        return res

    def get_context_data(self, **kwargs):
        """Add customer to the context."""
        kwargs = super().get_context_data(**kwargs)
        kwargs["prices"] = self.prices
        kwargs["formulas"] = ProductFormula.objects.filter(
            result__in=[p.product_id for p in self.prices]
        ).prefetch_related("products")
        kwargs["categories"] = defaultdict(list)
        for price in self.prices:
            kwargs["categories"][price.product.product_type].append(price)
        kwargs["customer"] = self.customer
        kwargs["cancel_url"] = self.get_success_url()

        # To get all forms errors to the javascript, we create a list of error list
        kwargs["form_errors"] = [
            list(field_error.values()) for field_error in kwargs["form"].errors
        ]
        return kwargs


class RefillingCreateView(FragmentMixin, CreateView):
    """This is a fragment only view which integrates with counter_click.jinja"""

    model = Refilling
    form_class = RefillForm
    template_name = "counter/fragments/create_refill.jinja"

    def dispatch(self, request, *args, **kwargs):
        self.customer: Customer = get_object_or_404(Customer, pk=kwargs["customer_id"])
        if not self.customer.can_buy:
            raise Http404

        if not is_logged_in_counter(request):
            raise PermissionDenied

        self.counter: Counter = get_object_or_404(Counter, id=self.kwargs["counter_id"])

        if not (
            request.barmen
            and request.barmen.issubset(self.counter.barmen_list)
            and self.counter.can_refill()
        ):
            raise PermissionDenied

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

    def render_fragment(self, request, **kwargs) -> SafeString:
        self.customer = kwargs.pop("customer")
        self.counter = kwargs.pop("counter")
        self.object = None
        return super().render_fragment(request, **kwargs)

    def get_form_kwargs(self):
        return super().get_form_kwargs() | {
            "counter": self.counter,
            "operator": get_operator(self.request, self.counter, self.customer),
            "customer": self.customer,
        }

    def get_context_data(self, **kwargs):
        kwargs = super().get_context_data(**kwargs)
        kwargs["action"] = reverse(
            "counter:refilling_create",
            kwargs={"customer_id": self.customer.pk, "counter_id": self.counter.pk},
        )
        return kwargs

    def get_success_url(self, **kwargs):
        return self.request.path