"""
BusinessObject API ViewSet
"""
from rest_framework import viewsets, filters, status
from rest_framework.decorators import action
from rest_framework.response import Response
from rest_framework.pagination import LimitOffsetPagination
from django_filters.rest_framework import DjangoFilterBackend
from django_filters import rest_framework as django_filters
from stateflow import models, services
from stateflow.serializers import (
    BusinessObjectListSerializer,
    BusinessObjectDetailSerializer,
    BusinessObjectCreateUpdateSerializer,
    StateListSerializer,
)


class BusinessObjectFilterSet(django_filters.FilterSet):
    """业务对象过滤器"""
    name = django_filters.CharFilter(lookup_expr='icontains')
    process_name = django_filters.CharFilter(field_name='process__name', lookup_expr='icontains')
    overall_status = django_filters.ChoiceFilter(
        choices=[
            ('not_started', '未开始'),
            ('in_progress', '进行中'),
            ('completed', '已完成')
        ],
        method='filter_overall_status'
    )
    content_type_str = django_filters.CharFilter(method='filter_content_type')
    has_content_object = django_filters.BooleanFilter(method='filter_has_content_object')
    
    def filter_overall_status(self, queryset, name, value):
        """过滤整体状态"""
        business_object_ids = []
        for obj in queryset:
            if services.get_overall_status(obj) == value:
                business_object_ids.append(obj.id)
        return queryset.filter(id__in=business_object_ids)
    
    def filter_content_type(self, queryset, name, value):
        """通过 app_label.model 字符串过滤"""
        try:
            from django.contrib.contenttypes.models import ContentType
            app_label, model = value.split('.')
            content_type = ContentType.objects.get(app_label=app_label, model=model)
            return queryset.filter(content_type=content_type)
        except:
            return queryset.none()
    
    def filter_has_content_object(self, queryset, name, value):
        """过滤是否有关联对象"""
        if value:
            return queryset.exclude(content_type__isnull=True)
        else:
            return queryset.filter(content_type__isnull=True)
    
    class Meta:
        model = models.BusinessObject
        fields = ['name', 'process', 'process_name', 'overall_status', 
                  'content_type_str', 'has_content_object']


class BusinessObjectViewSet(viewsets.ModelViewSet):
    """
    业务对象 CRUD 接口
    
    业务对象是流程的实例，可以选择性地关联到实际的业务模型（如订单、工单等）
    
    list: 获取业务对象列表
    retrieve: 获取业务对象详情（包含时间线和日志）
    create: 创建业务对象
    update: 更新业务对象
    partial_update: 部分更新业务对象
    destroy: 删除业务对象
    
    查询参数:
    - name: 按名称模糊查询
    - process: 按流程ID过滤
    - process_name: 按流程名称模糊查询
    - overall_status: 按整体状态过滤 (not_started/in_progress/completed)
    - content_type_str: 按关联对象类型过滤，格式: app_label.model
    - has_content_object: 是否有关联对象 (true/false)
    - search: 全文搜索（名称和描述）
    - ordering: 排序字段
    """
    queryset = models.BusinessObject.objects.all()
    pagination_class = LimitOffsetPagination
    filter_backends = [DjangoFilterBackend, filters.SearchFilter, filters.OrderingFilter]
    filterset_class = BusinessObjectFilterSet
    search_fields = ['name', 'description']
    ordering_fields = ['id', 'name', 'created_at', 'updated_at']
    ordering = ['-created_at']
    
    def get_serializer_class(self):
        """根据动作选择序列化器"""
        if self.action == 'list':
            return BusinessObjectListSerializer
        elif self.action in ['create', 'update', 'partial_update']:
            return BusinessObjectCreateUpdateSerializer
        else:  # retrieve
            return BusinessObjectDetailSerializer
    
    def get_queryset(self):
        """优化查询"""
        queryset = super().get_queryset()
        if self.action == 'list':
            queryset = queryset.select_related('process', 'content_type')
        elif self.action == 'retrieve':
            queryset = queryset.select_related('process', 'content_type').prefetch_related(
                'state_logs__state',
                'state_logs__completed_by',
                'process__process_nodes__state'
            )
        return queryset
    
    @action(detail=True, methods=['post'])
    def advance(self, request, pk=None):
        """推进到下一个状态"""
        business_object = self.get_object()
        user = request.user
        
        success, message = services.advance_to_next_state(business_object, user)
        
        if success:
            return Response({
                'success': True,
                'message': message,
                'business_object': BusinessObjectDetailSerializer(business_object).data
            })
        else:
            return Response({
                'success': False,
                'message': message
            }, status=status.HTTP_400_BAD_REQUEST)
    
    @action(detail=True, methods=['post'])
    def reset(self, request, pk=None):
        """重置进度"""
        business_object = self.get_object()
        services.reset_business_object_progress(business_object)
        
        return Response({
            'success': True,
            'message': '进度已重置',
            'business_object': BusinessObjectDetailSerializer(business_object).data
        })
    
    @action(detail=True, methods=['get'])
    def timeline(self, request, pk=None):
        """获取状态时间线"""
        business_object = self.get_object()
        timeline = services.get_business_object_state_timeline(business_object)
        
        timeline_data = [
            {
                'state': StateListSerializer(item['state']).data,
                'status': item['status'],
                'order': item['order'],
                'completed_at': item['completed_at'],
                'completed_by': item['completed_by'].username if item['completed_by'] else None,
                'cancelled_at': item['cancelled_at'],
                'is_cancelled': item['is_cancelled'],
            }
            for item in timeline
        ]
        
        return Response(timeline_data)