import logging

from django.conf import settings
from rest_framework import authentication, mixins, serializers
from rest_framework.authentication import get_authorization_header
from rest_framework.exceptions import AuthenticationFailed
from rest_framework.generics import GenericAPIView
from rest_framework.permissions import IsAuthenticated

from basic_info import models as basic_models
from flower.viewsets import LimitedLimitOffsetPagination
from shipment.models import Shipment

logger = logging.getLogger(__name__)


class AgentAccessPrincipal:
    id = None
    username = "agent"
    is_staff = False
    is_superuser = False
    is_anonymous = False
    is_authenticated = True


class AgentAccessKeyAuthentication(authentication.BaseAuthentication):
    """
    使用固定 AGENT_ACCESS_KEY 的轻量认证。

    约定：
    - 通过 Authorization 头直接传入密钥
    - 不使用 Bearer 前缀
    """

    def authenticate(self, request):
        configured_key = str(getattr(settings, "AGENT_ACCESS_KEY", "") or "").strip()
        if not configured_key:
            logger.warning("Agent API authentication failed: AGENT_ACCESS_KEY is not configured")
            raise AuthenticationFailed("AGENT_ACCESS_KEY 未配置")

        provided_key = get_authorization_header(request).decode("utf-8").strip()
        if not provided_key:
            raise AuthenticationFailed("缺少 Authorization 请求头")

        if provided_key != configured_key:
            raise AuthenticationFailed("AGENT_ACCESS_KEY 无效")

        return AgentAccessPrincipal(), None

    def authenticate_header(self, request):
        return "AgentAccessKey"


class AgentUnshippedShipmentQuerySerializer(serializers.Serializer):
    merchant_id = serializers.IntegerField(min_value=1)
    area = serializers.CharField(allow_blank=False, max_length=30)
    limit = serializers.IntegerField(required=False, min_value=1)
    offset = serializers.IntegerField(required=False, min_value=0)

    def validate(self, attrs):
        area = attrs["area"].strip()
        if not area:
            raise serializers.ValidationError({"area": "地区不能为空"})

        merchant = basic_models.Merchant.objects.filter(id=attrs["merchant_id"]).first()
        if merchant is None:
            raise serializers.ValidationError({"merchant_id": "商户不存在"})

        attrs["area"] = area
        attrs["merchant"] = merchant
        return attrs


class AgentShipmentListSerializer(serializers.ModelSerializer):
    customer_name = serializers.CharField(source="customer.name", read_only=True)
    status_display = serializers.CharField(source="get_status_display", read_only=True)

    class Meta:
        model = Shipment
        fields = [
            "id",
            "merchant_id",
            "customer",
            "customer_name",
            "shipment_date",
            "address",
            "contact_name",
            "contact_phone",
            "area",
            "remark",
            "status",
            "status_display",
            "external_id",
            "delivery",
            "created_at",
            "updated_at",
        ]


class AgentUnshippedShipmentListView(mixins.ListModelMixin, GenericAPIView):
    """
    Agent 专用：查询尚未进入送货单的出货单列表。

    GET /api/v2/ai/shipments/unshipped/?merchant_id=<id>&area=<地区>&limit=<n>&offset=<n>
    """

    authentication_classes = [AgentAccessKeyAuthentication]
    permission_classes = [IsAuthenticated]
    serializer_class = AgentShipmentListSerializer
    pagination_class = LimitedLimitOffsetPagination

    def get(self, request):
        query_serializer = AgentUnshippedShipmentQuerySerializer(data=request.query_params)
        query_serializer.is_valid(raise_exception=True)
        self.validated_query = query_serializer.validated_data
        return self.list(request)

    def get_queryset(self):
        validated_query = getattr(self, "validated_query", None)
        if validated_query is None:
            query_serializer = AgentUnshippedShipmentQuerySerializer(data=self.request.query_params)
            query_serializer.is_valid(raise_exception=True)
            validated_query = query_serializer.validated_data

        merchant = validated_query["merchant"]
        area = validated_query["area"]

        return (
            Shipment.objects.filter(
                merchant=merchant,
                area=area,
                delivery__isnull=True,
            )
            .select_related("customer", "merchant")
            .order_by("-created_at", "-id")
        )