"""消息通知与预警 ViewSets：
1. NotificationViewSet: 查询、标记已读、全部已读
2. AlertRuleViewSet: 预警规则维护、触发全量检测
"""

from rest_framework import status
from rest_framework.decorators import action
from rest_framework.response import Response
from rest_framework.exceptions import ValidationError
from django.db.models import Q
from django.utils import timezone
from asgiref.sync import sync_to_async

from apps.core.viewset import BaseTenantViewSet
from .models import Notification, AlertRule
from .serializers import NotificationSerializer, AlertRuleSerializer
from . import services as notify_services


class NotificationViewSet(BaseTenantViewSet):
    model = Notification
    serializer_class = NotificationSerializer
    search_fields = ["title", "content"]

    async def get_queryset(self):
        qs = await super().get_queryset()
        # 仅查全员广播或当前用户的通知
        user = self.request.user
        if user.is_authenticated:
            qs = qs.filter(Q(recipient__isnull=True) | Q(recipient=user))
        else:
            # Keep the queryset safe even if this view is reused without the
            # default IsAuthenticated permission.
            qs = qs.none()
        return qs

    @action(detail=True, methods=["post"], url_path="mark-read")
    async def mark_read(self, request, pk=None):
        """标为已读。"""
        # Use the same tenant and recipient scope as list/retrieve.  This
        # makes another user's notification indistinguishable from a missing
        # notification instead of allowing its state to be changed.
        queryset = await self.get_queryset()
        try:
            notification = await sync_to_async(queryset.get)(pk=pk)
        except self.model.DoesNotExist:
            return Response({"detail": "通知不存在"}, status=status.HTTP_404_NOT_FOUND)

        notification.is_read = True
        notification.read_at = timezone.now()
        await sync_to_async(notification.save)(update_fields=["is_read", "read_at"])
        return Response({"ok": True, "id": notification.id, "is_read": True})

    @action(detail=False, methods=["post"], url_path="mark-all-read")
    async def mark_all_read(self, request):
        """全部标为已读。"""
        tenant = await self.get_tenant()
        if not tenant:
            raise ValidationError({"tenant": "无法识别租户"})

        user = request.user
        if not user.is_authenticated:
            return Response({"ok": True, "updated_count": 0})
        updated = await sync_to_async(
            self.model.objects.filter(tenant=tenant, is_read=False)
            .filter(Q(recipient__isnull=True) | Q(recipient=user))
            .update
        )(is_read=True, read_at=timezone.now())
        return Response({"ok": True, "updated_count": updated})


class AlertRuleViewSet(BaseTenantViewSet):
    model = AlertRule
    serializer_class = AlertRuleSerializer
    search_fields = ["code", "name"]

    @action(detail=False, methods=["post"], url_path="init-default")
    async def init_default(self, request):
        """初始化默认预警规则。"""
        tenant = await self.get_tenant()
        if not tenant:
            raise ValidationError({"tenant": "无法识别租户"})
        n = await sync_to_async(notify_services.init_default_alert_rules)(tenant)
        return Response({"ok": True, "created_count": n})

    @action(detail=False, methods=["post"], url_path="run-checks")
    async def run_checks(self, request):
        """主动触发全量业务智能预警扫描（库存低限、应收逾期）。"""
        tenant = await self.get_tenant()
        if not tenant:
            raise ValidationError({"tenant": "无法识别租户"})
        result = await sync_to_async(notify_services.run_all_alert_checks)(tenant)
        return Response({"ok": True, "result": result})