from django.contrib import messages
from django.contrib.auth.mixins import LoginRequiredMixin
from django.db.models import Sum
from django.shortcuts import get_object_or_404, redirect
from django.urls import reverse_lazy
from django.views import View
from django.views.generic import FormView, TemplateView

from apps.billing.models import PointsLedger, RechargeOrder
from apps.billing.services import get_balance_snapshot
from apps.users.models import ApiKey

from .forms import ApiKeyCreateForm


NEW_API_KEY_SESSION_KEY = "portal_new_api_key"
RECORDS_PAGE_SIZE = 50


def _sum_or_zero(queryset, field_name: str):
    return queryset.aggregate(total=Sum(field_name))["total"] or 0


def get_portal_account_summary(user) -> dict:
    paid_orders = RechargeOrder.objects.filter(
        user=user,
        status=RechargeOrder.Status.PAID,
    )
    consume_entries = PointsLedger.objects.filter(
        user=user,
        change_type=PointsLedger.ChangeType.CONSUME,
    )
    refund_entries = PointsLedger.objects.filter(
        user=user,
        change_type=PointsLedger.ChangeType.REFUND,
    )
    recharge_entries = PointsLedger.objects.filter(
        user=user,
        change_type=PointsLedger.ChangeType.RECHARGE,
    )
    consumed_points = abs(int(_sum_or_zero(consume_entries, "points_delta")))
    refunded_points = int(_sum_or_zero(refund_entries, "points_delta"))
    return {
        "recharge_total_amount": _sum_or_zero(paid_orders, "amount_money"),
        "recharge_points_total": int(_sum_or_zero(recharge_entries, "points_delta")),
        "consumed_points_total": consumed_points,
        "refunded_points_total": refunded_points,
        "net_used_points": consumed_points - refunded_points,
        "paid_recharge_count": paid_orders.count(),
    }


def get_recharge_orders_for_user(user):
    return RechargeOrder.objects.filter(user=user).order_by("-created_at", "-id")


def get_usage_ledger_entries_for_user(user):
    return (
        PointsLedger.objects.filter(
            user=user,
            change_type__in=(
                PointsLedger.ChangeType.CONSUME,
                PointsLedger.ChangeType.REFUND,
            ),
        )
        .select_related("ref_call", "ref_call__api_key")
        .order_by("-created_at", "-id")
    )


class DashboardView(LoginRequiredMixin, TemplateView):
    template_name = "portal/dashboard.html"

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context["balance"] = get_balance_snapshot(self.request.user)
        context.update(get_portal_account_summary(self.request.user))
        context["recent_recharge_orders"] = get_recharge_orders_for_user(
            self.request.user
        )[:5]
        context["recent_usage_entries"] = get_usage_ledger_entries_for_user(
            self.request.user
        )[:5]
        return context


class ApiKeyListCreateView(LoginRequiredMixin, FormView):
    template_name = "portal/apikeys.html"
    form_class = ApiKeyCreateForm
    success_url = reverse_lazy("portal-apikeys")

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context["api_keys"] = ApiKey.objects.filter(user=self.request.user).order_by(
            "-created_at",
            "-id",
        )
        context["new_api_key"] = self.request.session.pop(NEW_API_KEY_SESSION_KEY, None)
        return context

    def form_valid(self, form):
        name = form.cleaned_data["name"].strip()
        api_key, raw_key = ApiKey.create_for_user(self.request.user, name=name)
        self.request.session[NEW_API_KEY_SESSION_KEY] = {
            "name": api_key.name,
            "key_prefix": api_key.key_prefix,
            "raw_key": raw_key,
        }
        messages.success(self.request, "API Key 已生成")
        return super().form_valid(form)


class ApiKeyDeleteView(LoginRequiredMixin, View):
    def post(self, request, pk):
        api_key = get_object_or_404(ApiKey, pk=pk, user=request.user)
        if api_key.status != ApiKey.Status.REVOKED:
            api_key.status = ApiKey.Status.REVOKED
            api_key.save(update_fields=("status", "updated_at"))
            messages.success(request, "API Key 已删除")
        return redirect("portal-apikeys")


class RechargeRecordListView(LoginRequiredMixin, TemplateView):
    template_name = "portal/recharge_records.html"

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        orders = get_recharge_orders_for_user(self.request.user)
        context.update(get_portal_account_summary(self.request.user))
        context["recharge_orders"] = orders[:RECORDS_PAGE_SIZE]
        return context


class UsageRecordListView(LoginRequiredMixin, TemplateView):
    template_name = "portal/usage_records.html"

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        entries = get_usage_ledger_entries_for_user(self.request.user)
        context.update(get_portal_account_summary(self.request.user))
        context["usage_entries"] = entries[:RECORDS_PAGE_SIZE]
        return context