from rest_framework import viewsets, generics, permissions, status
from rest_framework.response import Response
from rest_framework.decorators import action
from rest_framework.views import APIView
from rest_framework_simplejwt.views import TokenObtainPairView
from rest_framework_simplejwt.serializers import TokenObtainPairSerializer
from rest_framework_simplejwt.tokens import RefreshToken
from django.contrib.auth import get_user_model
from django.core.cache import cache
import random
from .serializers import (
    UserSerializer, RegisterSerializer, EnterpriseSerializer, EnterpriseRegisterSerializer,
    EnterpriseMemberSerializer, RoleSerializer, PermissionSerializer, EnterpriseLoginSerializer,
    EnterpriseMemberAddSerializer, AdminUserCreateSerializer, ChangePasswordSerializer,
    PasswordResetRequestSerializer, PasswordResetConfirmSerializer
)
from .models import Enterprise, EnterpriseMember, Role, Permission
from .permissions import HasAPIPermission
from rest_framework import permissions as drf_permissions

class EnterpriseLoginView(APIView):
    """
    @author: xujl
    Api说明: 企业管理员专属登录通道接口。校验企业身份并返回携带对应权限的JWT Token。
    """
    permission_classes = [permissions.AllowAny]

    def post(self, request, *args, **kwargs):
        serializer = EnterpriseLoginSerializer(data=request.data)
        if serializer.is_valid():
            user = serializer.validated_data['user']
            refresh = RefreshToken.for_user(user)
            return Response({
                'refresh': str(refresh),
                'access': str(refresh.access_token),
                'user': UserSerializer(user).data
            })
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

class MyTokenObtainPairSerializer(TokenObtainPairSerializer):
    def validate(self, attrs):
        username = attrs.get(self.username_field)
        password = attrs.get('password')
        
        from django.contrib.auth import get_user_model
        from django.db.models import Q
        from rest_framework.exceptions import AuthenticationFailed
        from rest_framework_simplejwt.tokens import RefreshToken
        from django.contrib.auth.models import update_last_login
        
        User = get_user_model()
        user = User.objects.filter(Q(username=username) | Q(phone=username) | Q(email=username)).first()
        
        if not user:
            raise AuthenticationFailed('账号未注册', code='not_registered')
            
        if not user.is_active or user.is_deleted:
            raise AuthenticationFailed('您的账号已被禁用，可能因为违规操作或安全风险。如有疑问请联系平台管理员。', code='account_disabled')

        if not user.check_password(password):
            raise AuthenticationFailed('密码错误，请检查后再试', code='wrong_password')

        refresh = RefreshToken.for_user(user)
        update_last_login(None, user)
        
        return {
            'refresh': str(refresh),
            'access': str(refresh.access_token),
            'user': UserSerializer(user).data
        }

class MyTokenObtainPairView(TokenObtainPairView):
    """
    @author: xujl
    Api说明: 标准用户认证授权(JWT)接口视图。验证普通用户账号密码并下发访问凭证。
    """
    serializer_class = MyTokenObtainPairSerializer

User = get_user_model()

class UserViewSet(viewsets.ModelViewSet):
    """
    @author: xujl
    Api说明: 平台用户中心接口视图。用于用户的增删改查、信息完善、封禁及状态管理，以及管理员的全局管控。
    """
    serializer_class = UserSerializer
    permission_classes = [drf_permissions.IsAuthenticated]
    
    # Custom attributes for HasAPIPermission check
    required_permissions = {
        'GET': 'api:users:read',
        'POST': 'api:users:write',
        'PUT': 'api:users:write',
        'PATCH': 'api:users:write',
        'DELETE': 'api:users:delete'
    }

    def get_queryset(self):
        from django.db.models import Q
        from tasks.models import Task, TaskApplication, TaskStatus, ApplyStatus
        queryset = User.objects.filter(is_deleted=False)
        
        # Non-admins can only see OPC users
        if not (self.request.user.is_staff or self.request.user.is_superuser):
            queryset = queryset.filter(user_roles__role__code='OPC_USER')
        
        role = self.request.query_params.get('role')
        username = self.request.query_params.get('username')
        nickname = self.request.query_params.get('nickname')
        real_name = self.request.query_params.get('real_name')
        phone = self.request.query_params.get('phone')
        email = self.request.query_params.get('email')
        status_filter = self.request.query_params.get('status')
        idle = self.request.query_params.get('idle')
        
        if role:
            queryset = queryset.filter(user_roles__role__code=role)
        if username:
            queryset = queryset.filter(username__icontains=username)
        if nickname:
            queryset = queryset.filter(nickname__icontains=nickname)
        if real_name:
            queryset = queryset.filter(opc_certifications__real_name__icontains=real_name)
        if phone:
            queryset = queryset.filter(phone__icontains=phone)
        if email:
            queryset = queryset.filter(email__icontains=email)
            
        if status_filter == 'active':
            queryset = queryset.filter(is_active=True)
        elif status_filter == 'disabled':
            queryset = queryset.filter(is_active=False)
            
        if idle == 'true':
            active_app_users = TaskApplication.objects.filter(
                status__in=[ApplyStatus.PENDING, ApplyStatus.APPROVED, ApplyStatus.DELIVERED]
            ).values_list('applicant_id', flat=True)
            
            active_task_publishers = Task.objects.filter(
                status__in=[TaskStatus.OPEN, TaskStatus.IN_PROGRESS]
            ).values_list('publisher_id', flat=True)
            
            queryset = queryset.exclude(id__in=active_app_users).exclude(id__in=active_task_publishers)
            
        return queryset.order_by('-is_recommended', '-recommend_priority', '-created_at').distinct()

    def get_permissions(self):
        if self.action in ['me', 'update_profile', 'avatar', 'change_password', 'list', 'retrieve']:
            return [drf_permissions.IsAuthenticated()]
        if self.action in ['admin_create', 'toggle_status', 'reset_password', 'create', 'update', 'partial_update', 'destroy', 'update_opc_stats']:
            return [HasAPIPermission()]
        if self.action in ['request_password_reset', 'confirm_password_reset']:
            return [drf_permissions.AllowAny()]
        return super().get_permissions()

    @action(detail=False, methods=['post'], permission_classes=[permissions.IsAdminUser])
    def admin_create(self, request):
        serializer = AdminUserCreateSerializer(data=request.data)
        if serializer.is_valid():
            user = serializer.save()
            user.set_password(serializer.validated_data['password'])
            user.save()
            return Response(UserSerializer(user).data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    def update(self, request, *args, **kwargs):
        partial = kwargs.pop('partial', False)
        instance = self.get_object()
        serializer = self.get_serializer(instance, data=request.data, partial=partial)
        serializer.is_valid(raise_exception=True)
        self.perform_update(serializer)
        
        # Handle explicitly read-only fields for Admin
        if request.user.is_staff or request.user.is_superuser:
            needs_save = False
            for field in ['is_active', 'status', 'avatar_url', 'bio', 'location', 'face_url']:
                if field in request.data:
                    setattr(instance, field, request.data[field])
                    needs_save = True
            if needs_save:
                instance.save()

            # Handle Role Assignments inside the big form
            if 'roles' in request.data:
                role_codes = request.data['roles']
                from .models import Role, UserRole
                UserRole.objects.filter(user=instance).delete()
                for code in role_codes:
                    role = Role.objects.filter(code=code).first()
                    if role:
                        UserRole.objects.create(user=instance, role=role, granted_by=request.user)

        # Handle enterprise_info updates
        enterprise_info = request.data.get('enterprise_info')
        if enterprise_info and 'ENTERPRISE' in instance.roles:
            from .models import Enterprise
            ent, created = Enterprise.objects.get_or_create(user=instance, defaults={'status': 'VERIFIED'})
            ent.company_name = enterprise_info.get('company_name', ent.company_name)
            ent.credit_code = enterprise_info.get('credit_code', ent.credit_code)
            ent.business_license = enterprise_info.get('business_license', ent.business_license)
            ent.logo_url = enterprise_info.get('logo_url', ent.logo_url)
            ent.contact_name = enterprise_info.get('contact_name', ent.contact_name)
            ent.contact_phone = enterprise_info.get('contact_phone', ent.contact_phone)
            ent.contact_email = enterprise_info.get('contact_email', ent.contact_email)
            ent.address = enterprise_info.get('address', ent.address)
            ent.description = enterprise_info.get('description', ent.description)
            ent.save()

        # Handle opc_certification updates
        opc_certification = request.data.get('opc_certification')
        if opc_certification and 'OPC_USER' in instance.roles:
            from opc_cert.models import OpcCertification
            cert, created = OpcCertification.objects.get_or_create(user=instance, defaults={'status': 'APPROVED'})
            cert.real_name = opc_certification.get('real_name', cert.real_name)
            cert.id_card = opc_certification.get('id_card', cert.id_card)
            cert.experience = opc_certification.get('experience', cert.experience)
            cert.resume_url = opc_certification.get('resume_url', cert.resume_url)
            cert.attachments = opc_certification.get('attachments', cert.attachments)
            cert.skills = opc_certification.get('skills', cert.skills)
            cert.status = opc_certification.get('status', cert.status)
            if 'rating' in opc_certification:
                cert.rating = opc_certification.get('rating')
            cert.save()

            if 'rating' in opc_certification:
                instance.rating = opc_certification.get('rating')
                instance.save()

        if getattr(instance, '_prefetched_objects_cache', None):
            instance._prefetched_objects_cache = {}

        return Response(self.get_serializer(instance).data)

    @action(detail=False, methods=['post'])
    def change_password(self, request):
        serializer = ChangePasswordSerializer(data=request.data)
        if serializer.is_valid():
            user = request.user
            if not user.check_password(serializer.validated_data['old_password']):
                return Response({'old_password': ['原密码错误']}, status=status.HTTP_400_BAD_REQUEST)
            user.set_password(serializer.validated_data['new_password'])
            user.save()
            return Response({'status': '密码修改成功'})
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=False, methods=['post'], permission_classes=[drf_permissions.AllowAny])
    def request_password_reset(self, request):
        serializer = PasswordResetRequestSerializer(data=request.data)
        if serializer.is_valid():
            email = serializer.validated_data['email']
            user = User.objects.filter(email=email).first()
            if user:
                # Mock sending code: Generate 6-digit code and store in cache
                code = ''.join(random.choices('0123456789', k=6))
                cache.set(f'pwd_reset_{email}', code, timeout=300) # 5 minutes
                # In production, send via Email/SMS. Here we return it or print it.
                print(f"--- MOCK EMAIL --- Password reset code for {email}: {code}")
                return Response({'status': '验证码已发送 (开发环境请查看控制台输出)'})
            else:
                # To prevent email enumeration, still return success
                return Response({'status': '验证码已发送 (开发环境请查看控制台输出)'})
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=False, methods=['post'], permission_classes=[drf_permissions.AllowAny])
    def confirm_password_reset(self, request):
        serializer = PasswordResetConfirmSerializer(data=request.data)
        if serializer.is_valid():
            email = serializer.validated_data['email']
            code = serializer.validated_data['verification_code']
            cached_code = cache.get(f'pwd_reset_{email}')
            
            if not cached_code or cached_code != code:
                return Response({'verification_code': ['验证码无效或已过期']}, status=status.HTTP_400_BAD_REQUEST)
                
            user = User.objects.filter(email=email).first()
            if user:
                user.set_password(serializer.validated_data['new_password'])
                user.save()
                cache.delete(f'pwd_reset_{email}')
                return Response({'status': '密码重置成功'})
            return Response({'detail': '用户不存在'}, status=status.HTTP_404_NOT_FOUND)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=True, methods=['post'])
    def reset_password(self, request, pk=None):
        user = self.get_object()
        new_password = request.data.get('password', '123456')
        user.set_password(new_password)
        user.save()
        return Response({'status': '密码已重置'})

    @action(detail=False, methods=['get'])
    def me(self, request):
        serializer = self.get_serializer(request.user)
        return Response(serializer.data)

    def perform_destroy(self, instance):
        from tasks.models import Task, TaskApplication, TaskStatus, ApplyStatus
        from django.utils import timezone
        
        force = self.request.query_params.get('force', '').lower() == 'true'
        
        # Check active expert applications
        active_apps = TaskApplication.objects.filter(
            applicant=instance, 
            status__in=[ApplyStatus.PENDING, ApplyStatus.APPROVED, ApplyStatus.DELIVERED]
        )
        
        # Check active enterprise tasks
        active_tasks = Task.objects.filter(
            publisher=instance,
            status__in=[TaskStatus.OPEN, TaskStatus.IN_PROGRESS]
        )
        
        has_blockers = active_apps.exists() or active_tasks.exists()
        
        if has_blockers and not force:
            from rest_framework.exceptions import ValidationError
            blocker_details = []
            if active_apps.exists():
                blocker_details.append(f'专家接单 {active_apps.count()} 项')
            if active_tasks.exists():
                blocker_details.append(f'发布任务 {active_tasks.count()} 项')
            raise ValidationError(
                f'用户 {instance.username} 有正在进行中的任务（{"、".join(blocker_details)}），无法直接删除。请先取消相关任务或强制删除。'
            )
        
        if has_blockers and force:
            # Lock tasks instead of cancelling — mark as anomalous
            # For tasks where this user is the ONLY active participant, set CANCELLED
            # Otherwise keep IN_PROGRESS but lock the user's application
            for app in active_apps:
                app.status = ApplyStatus.REJECTED
                app.reject_reason = f'用户 {instance.nickname or instance.username} 账户已被管理员删除/锁定'
                app.save()
                
                # Check if task still has other active participants
                other_apps = app.task.applications.filter(
                    status__in=[ApplyStatus.APPROVED, ApplyStatus.DELIVERED]
                ).exclude(applicant=instance)
                if not other_apps.exists() and app.task.status == TaskStatus.IN_PROGRESS:
                    app.task.status = TaskStatus.CANCELLED
                    app.task.cancel_reason = f'唯一执行专家 {instance.nickname or instance.username} 已被系统锁定，任务异常中止'
                    app.task.cancelled_at = timezone.now()
                    app.task.save()
            
            active_tasks.update(
                status=TaskStatus.CANCELLED,
                cancelled_at=timezone.now(),
                cancel_reason=f'管理员强制删除用户 {instance.username}，系统自动取消关联任务'
            )
        
        # Check and cascade close enterprise
        enterprise = Enterprise.objects.filter(user=instance, is_deleted=False).first()
        if enterprise:
            # Close enterprise: soft delete + remove all members
            enterprise.is_deleted = True
            enterprise.status = 'REJECTED'
            enterprise.save()
            EnterpriseMember.objects.filter(enterprise=enterprise).delete()
            # Cancel enterprise's published tasks
            Task.objects.filter(
                enterprise=enterprise,
                status__in=[TaskStatus.OPEN, TaskStatus.IN_PROGRESS]
            ).update(
                status=TaskStatus.CANCELLED,
                cancelled_at=timezone.now(),
                cancel_reason=f'企业 {enterprise.company_name} 已被清退，关联任务自动取消'
            )
            
        instance.is_deleted = True
        instance.is_active = False
        # Free up unique fields for re-registration while preserving for audit
        deleted_suffix = f'__deleted_{instance.id}'
        if instance.phone:
            instance.phone = instance.phone + deleted_suffix
        if instance.email:
            instance.email = instance.email + deleted_suffix
        instance.username = instance.username + deleted_suffix
        instance.save()

    @action(detail=False, methods=['post'], permission_classes=[permissions.IsAdminUser])
    def batch_delete(self, request):
        user_ids = request.data.get('user_ids', [])
        force = request.data.get('force', False)
        if not user_ids:
            return Response({'detail': '缺少 user_ids'}, status=status.HTTP_400_BAD_REQUEST)
            
        users = User.objects.filter(id__in=user_ids)
        from tasks.models import Task, TaskApplication, TaskStatus, ApplyStatus
        from django.utils import timezone
        
        blocked_users = []
        for user in users:
            active_apps = TaskApplication.objects.filter(
                applicant=user, 
                status__in=[ApplyStatus.PENDING, ApplyStatus.APPROVED, ApplyStatus.DELIVERED]
            )
            active_tasks = Task.objects.filter(
                publisher=user,
                status__in=[TaskStatus.OPEN, TaskStatus.IN_PROGRESS]
            )
            if active_apps.exists() or active_tasks.exists():
                blocked_users.append({
                    'id': str(user.id),
                    'username': user.username,
                    'nickname': user.nickname or user.username,
                    'app_count': active_apps.count(),
                    'task_count': active_tasks.count(),
                })
        
        if blocked_users and not force:
            return Response({
                'detail': f'共 {len(blocked_users)} 个用户有正在进行中的任务，无法直接批量删除。',
                'blocked_users': blocked_users,
                'has_blockers': True,
            }, status=status.HTTP_400_BAD_REQUEST)
        
        if blocked_users and force:
            for user in users:
                TaskApplication.objects.filter(
                    applicant=user,
                    status__in=[ApplyStatus.PENDING, ApplyStatus.APPROVED, ApplyStatus.DELIVERED]
                ).update(status=ApplyStatus.WITHDRAWN)
                Task.objects.filter(
                    publisher=user,
                    status__in=[TaskStatus.OPEN, TaskStatus.IN_PROGRESS]
                ).update(
                    status=TaskStatus.CANCELLED,
                    cancelled_at=timezone.now(),
                    cancel_reason=f'管理员批量强制删除，系统自动取消关联任务'
                )
                
        for user in users:
            user.is_deleted = True
            user.is_active = False
            deleted_suffix = f'__deleted_{user.id}'
            if user.phone:
                user.phone = user.phone + deleted_suffix
            if user.email:
                user.email = user.email + deleted_suffix
            user.username = user.username + deleted_suffix
            user.save()
        return Response({'status': '批量删除成功'})

    @action(detail=True, methods=['post'], permission_classes=[permissions.IsAdminUser])
    def assign_roles(self, request, pk=None):
        user = self.get_object()
        role_codes = request.data.get('roles', [])
        from .models import Role, UserRole
        # 清除旧角色
        UserRole.objects.filter(user=user).delete()
        # 重新分配
        for code in role_codes:
            role = Role.objects.filter(code=code).first()
            if role:
                UserRole.objects.create(user=user, role=role, granted_by=request.user)
        return Response({'status': '角色分配成功'})

    @action(detail=True, methods=['post'], permission_classes=[permissions.IsAdminUser])
    def update_rating(self, request, pk=None):
        user = self.get_object()
        rating = request.data.get('rating')
        if rating is not None:
            user.rating = rating
            user.save()
            return Response({'status': '评分已更新'})
        return Response({'detail': '缺少评分参数'}, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=True, methods=['get'], permission_classes=[permissions.IsAdminUser])
    def active_tasks(self, request, pk=None):
        user = self.get_object()
        from tasks.models import Task, TaskApplication, TaskStatus, ApplyStatus
        
        results = []
        
        # Expert tasks
        expert_apps = TaskApplication.objects.filter(
            applicant=user, 
            status__in=[ApplyStatus.PENDING, ApplyStatus.APPROVED, ApplyStatus.DELIVERED]
        )
        for app in expert_apps:
            results.append({
                'id': app.task.id,
                'title': app.task.title,
                'role': '专家接单',
                'status': app.status,
                'task_status': app.task.status,
                'type': 'application'
            })
            
        # Publisher tasks
        pub_tasks = Task.objects.filter(
            publisher=user, 
            status__in=[TaskStatus.OPEN, TaskStatus.IN_PROGRESS]
        )
        for t in pub_tasks:
            results.append({
                'id': t.id,
                'title': t.title,
                'role': '任务发布方',
                'status': t.status,
                'task_status': t.status,
                'type': 'task'
            })
            
        return Response(results)

    @action(detail=False, methods=['put'])
    def update_profile(self, request):
        user = request.user
        serializer = UserSerializer(user, data=request.data, partial=True)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=True, methods=['post'], permission_classes=[permissions.IsAdminUser])
    def toggle_status(self, request, pk=None):
        user = self.get_object()
        user.is_active = not user.is_active
        user.save()
        return Response({'status': '状态已更新', 'is_active': user.is_active})

    @action(detail=True, methods=['put'], permission_classes=[permissions.IsAdminUser])
    def update_opc_stats(self, request, pk=None):
        user = self.get_object()
        
        rating = request.data.get('rating')
        completed_tasks = request.data.get('completed_tasks')
        
        if rating is not None:
            user.rating = rating
        if completed_tasks is not None:
            user.completed_tasks = completed_tasks
            
        user.save()
        return Response(UserSerializer(user).data)

    @action(detail=True, methods=['post'], permission_classes=[permissions.IsAdminUser])
    def toggle_recommend(self, request, pk=None):
        user = self.get_object()
        user.is_recommended = request.data.get('is_recommended', not user.is_recommended)
        user.recommend_priority = request.data.get('recommend_priority', user.recommend_priority)
        user.save(update_fields=['is_recommended', 'recommend_priority'])
        return Response({'is_recommended': user.is_recommended, 'recommend_priority': user.recommend_priority})

    @action(detail=False, methods=['get'], permission_classes=[permissions.IsAdminUser])
    def deleted_users(self, request):
        """List soft-deleted users for admin review/recovery."""
        deleted = User.objects.filter(is_deleted=True).order_by('-updated_at')
        page = self.paginate_queryset(deleted)
        if page is not None:
            serializer = UserSerializer(page, many=True)
            return self.get_paginated_response(serializer.data)
        serializer = UserSerializer(deleted, many=True)
        return Response(serializer.data)

    @action(detail=True, methods=['post'], permission_classes=[permissions.IsAdminUser])
    def restore(self, request, pk=None):
        """Restore a soft-deleted user by clearing the deletion suffix."""
        try:
            user = User.objects.get(id=pk, is_deleted=True)
        except User.DoesNotExist:
            return Response({'detail': '未找到已删除的用户'}, status=status.HTTP_404_NOT_FOUND)
        
        deleted_suffix = f'__deleted_{user.id}'
        
        # Restore unique fields
        if user.username.endswith(deleted_suffix):
            original_username = user.username[:-len(deleted_suffix)]
            if User.objects.filter(username=original_username, is_deleted=False).exists():
                return Response({'detail': f'用户名 {original_username} 已被新用户占用，无法恢复'}, status=status.HTTP_400_BAD_REQUEST)
            user.username = original_username
            
        if user.phone and user.phone.endswith(deleted_suffix):
            original_phone = user.phone[:-len(deleted_suffix)]
            if User.objects.filter(phone=original_phone, is_deleted=False).exists():
                return Response({'detail': f'手机号 {original_phone} 已被新用户占用，无法恢复'}, status=status.HTTP_400_BAD_REQUEST)
            user.phone = original_phone
            
        if user.email and user.email.endswith(deleted_suffix):
            original_email = user.email[:-len(deleted_suffix)]
            if User.objects.filter(email=original_email, is_deleted=False).exists():
                return Response({'detail': f'邮箱 {original_email} 已被新用户占用，无法恢复'}, status=status.HTTP_400_BAD_REQUEST)
            user.email = original_email
        
        user.is_deleted = False
        user.is_active = True
        user.save()
        return Response({'status': f'用户 {user.username} 已成功恢复'})

    @action(detail=False, methods=['post'])
    def avatar(self, request):
        # In a real app, handle file upload to MinIO
        # For now, we expect a URL or just mock it
        user = request.user
        avatar_url = request.data.get('avatar_url')
        if avatar_url:
            user.avatar_url = avatar_url
            user.save()
            return Response({'status': '头像已更新', 'avatar_url': avatar_url})
        return Response({'detail': '缺少 avatar_url'}, status=status.HTTP_400_BAD_REQUEST)


class RegisterView(generics.CreateAPIView):
    """
    @author: xujl
    Api说明: 平台普通用户注册接口视图。提供基础的账号密码/手机/邮箱注册流程。
    """
    queryset = User.objects.all()
    permission_classes = [permissions.AllowAny]
    serializer_class = RegisterSerializer

class EnterpriseViewSet(viewsets.ModelViewSet):
    """
    @author: xujl
    Api说明: 企业资质及账号管理接口视图。企业用户提交工商资料认证、基本信息更新，管理员对企业入驻进行审核。
    """
    queryset = Enterprise.objects.filter(is_deleted=False).order_by('-created_at')
    permission_classes = [permissions.IsAuthenticated]
    
    def get_serializer_class(self):
        if self.action == 'create' and (self.request.user.is_staff or self.request.user.is_superuser):
            from .serializers import AdminEnterpriseCreateSerializer
            return AdminEnterpriseCreateSerializer
        from .serializers import EnterpriseSerializer
        return EnterpriseSerializer
    
    required_permissions = {
        'GET': 'api:enterprises:read',
        'POST': 'api:enterprises:write',
        'PUT': 'api:enterprises:write',
        'PATCH': 'api:enterprises:write',
        'DELETE': 'api:enterprises:delete'
    }

    def get_permissions(self):
        if self.action in ['me', 'create', 'update', 'partial_update']:
            return [drf_permissions.IsAuthenticated()]
        if self.action in ['list', 'retrieve', 'verify_status']:
            return [HasAPIPermission()]
        return super().get_permissions()
    
    @action(detail=False, methods=['get'])
    def me(self, request):
        try:
            # First check if user is the enterprise owner
            enterprise = Enterprise.objects.filter(user=request.user).first()
            role = 'ADMIN'
            
            if not enterprise:
                # If not owner, check if user is a member
                member = EnterpriseMember.objects.filter(user=request.user).first()
                if member:
                    enterprise = member.enterprise
                    role = member.role
                else:
                    return Response({'detail': '未找到企业信息'}, status=status.HTTP_404_NOT_FOUND)
            
            serializer = self.get_serializer(enterprise)
            data = serializer.data
            data['my_role'] = role
            return Response(data)
        except Exception as e:
            return Response({'detail': str(e)}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)

    def perform_create(self, serializer):
        if self.request.user.is_staff or self.request.user.is_superuser:
            serializer.save()
        else:
            enterprise = serializer.save(user=self.request.user)
            # Auto assign ENTERPRISE role
            from .models import Role, UserRole
            role, created = Role.objects.get_or_create(code='ENTERPRISE', defaults={'name': '企业用户'})
            UserRole.objects.get_or_create(user=self.request.user, role=role)

    def _check_admin_permission(self, request, enterprise):
        if request.user.is_superuser or request.user.is_staff:
            return True
        if request.user == enterprise.user:
            return True
        member = EnterpriseMember.objects.filter(enterprise=enterprise, user=request.user).first()
        return member and member.role == 'ADMIN'

    def update(self, request, *args, **kwargs):
        enterprise = self.get_object()
        if not self._check_admin_permission(request, enterprise):
            return Response({'detail': '只有企业管理员可以编辑企业数据'}, status=status.HTTP_403_FORBIDDEN)
        return super().update(request, *args, **kwargs)

    def partial_update(self, request, *args, **kwargs):
        enterprise = self.get_object()
        if not self._check_admin_permission(request, enterprise):
            return Response({'detail': '只有企业管理员可以编辑企业数据'}, status=status.HTTP_403_FORBIDDEN)
        return super().partial_update(request, *args, **kwargs)

    def perform_destroy(self, instance):
        """Cascade enterprise deletion: soft-delete, remove members, cancel active tasks, free email."""
        from tasks.models import Task, TaskStatus
        from django.utils import timezone
        
        # Cancel all active tasks for this enterprise
        Task.objects.filter(
            enterprise=instance,
            status__in=[TaskStatus.OPEN, TaskStatus.IN_PROGRESS]
        ).update(
            status=TaskStatus.CANCELLED,
            cancelled_at=timezone.now(),
            cancel_reason=f'企业 {instance.company_name} 已被清退，项目中止'
        )
        
        # Remove all team members
        EnterpriseMember.objects.filter(enterprise=instance).delete()
        
        # Free up the enterprise user's email for re-use (suffix pattern)
        owner = instance.user
        suffix = f'__deleted_{str(instance.id)[:8]}'
        if owner.email and '__deleted_' not in owner.email:
            owner.email = owner.email + suffix
            owner.save(update_fields=['email'])
        
        # Free up credit_code
        if instance.credit_code and '__deleted_' not in instance.credit_code:
            instance.credit_code = instance.credit_code + suffix
        
        # Soft delete enterprise
        instance.is_deleted = True
        instance.status = 'REJECTED'
        instance.save()

    @action(detail=False, methods=['get'])
    def deleted_enterprises(self, request):
        """List soft-deleted enterprises for the recycle bin."""
        deleted = Enterprise.objects.filter(is_deleted=True).order_by('-updated_at')
        serializer = self.get_serializer(deleted, many=True)
        return Response(serializer.data)

    @action(detail=True, methods=['post'])
    def restore(self, request, pk=None):
        """Restore a soft-deleted enterprise."""
        enterprise = Enterprise.objects.filter(pk=pk, is_deleted=True).first()
        if not enterprise:
            return Response({'detail': '未找到已删除的企业'}, status=status.HTTP_404_NOT_FOUND)
        
        # Restore credit_code
        if enterprise.credit_code and '__deleted_' in enterprise.credit_code:
            original_code = enterprise.credit_code.split('__deleted_')[0]
            if Enterprise.objects.filter(credit_code=original_code, is_deleted=False).exists():
                return Response({'detail': f'统一社会信用代码 {original_code} 已被其他企业占用'}, status=status.HTTP_409_CONFLICT)
            enterprise.credit_code = original_code
        
        # Restore owner email
        owner = enterprise.user
        if owner.email and '__deleted_' in owner.email:
            original_email = owner.email.split('__deleted_')[0]
            if User.objects.filter(email=original_email, is_deleted=False).exclude(pk=owner.pk).exists():
                return Response({'detail': f'邮箱 {original_email} 已被其他用户占用，无法恢复'}, status=status.HTTP_409_CONFLICT)
            owner.email = original_email
            owner.save(update_fields=['email'])
        
        enterprise.is_deleted = False
        enterprise.status = 'VERIFIED'
        enterprise.save()
        return Response({'detail': '企业已恢复'})

    @action(detail=True, methods=['post'])
    def verify_status(self, request, pk=None):
        enterprise = self.get_object()
        status_val = request.data.get('status')
        if status_val not in [choice[0] for choice in Enterprise.EnterpriseStatus.choices]:
            return Response({'detail': '无效的状态'}, status=status.HTTP_400_BAD_REQUEST)
        
        enterprise.status = status_val
        enterprise.save()
        return Response({'status': '企业审核状态已更新', 'enterprise_status': enterprise.status})

class EnterpriseRegisterView(generics.CreateAPIView):
    """
    @author: xujl
    Api说明: 企业级账号入驻/注册接口视图。提交企业信用代码和法人代表等认证资料。
    """
    serializer_class = EnterpriseRegisterSerializer
    permission_classes = [permissions.AllowAny]

    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response({'status': '企业注册成功'}, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

class EnterpriseMemberViewSet(viewsets.ModelViewSet):
    """
    @author: xujl
    Api说明: 企业内部成员管理接口视图。用于给企业内部关联多个员工账号并分配角色（管理员、普通成员）。
    """
    serializer_class = EnterpriseMemberSerializer
    permission_classes = [permissions.IsAuthenticated]

    def get_queryset(self):
        if self.request.user.is_staff or self.request.user.is_superuser:
            enterprise_id = self.request.query_params.get('enterprise')
            if enterprise_id:
                return EnterpriseMember.objects.filter(enterprise_id=enterprise_id).order_by('-joined_at')
            return EnterpriseMember.objects.all().order_by('-joined_at')
            
        try:
            enterprise = Enterprise.objects.get(user=self.request.user)
            return EnterpriseMember.objects.filter(enterprise=enterprise).order_by('-joined_at')
        except Enterprise.DoesNotExist:
            return EnterpriseMember.objects.none()

    def perform_create(self, serializer):
        enterprise = Enterprise.objects.get(user=self.request.user)
        serializer.save(enterprise=enterprise)

    @action(detail=False, methods=['post'], permission_classes=[permissions.IsAuthenticated])
    def add_member(self, request):
        serializer = EnterpriseMemberAddSerializer(data=request.data, context={'request': request})
        if serializer.is_valid():
            member = serializer.save()
            return Response(EnterpriseMemberSerializer(member).data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    @action(detail=False, methods=['post'], permission_classes=[permissions.IsAdminUser])
    def batch_delete(self, request):
        member_ids = request.data.get('member_ids', [])
        if not member_ids:
            return Response({'detail': '缺少 member_ids'}, status=status.HTTP_400_BAD_REQUEST)
        
        EnterpriseMember.objects.filter(id__in=member_ids).delete()
        return Response({'status': '批量删除成功'})

    @action(detail=False, methods=['post'])
    def invite(self, request):
        email = request.data.get('email')
        role = request.data.get('role', 'MEMBER')
        
        try:
            enterprise = Enterprise.objects.get(user=request.user)
            user = User.objects.get(email=email)
            
            if EnterpriseMember.objects.filter(enterprise=enterprise, user=user).exists():
                return Response({'detail': '该用户已在团队中'}, status=status.HTTP_400_BAD_REQUEST)
                
            member = EnterpriseMember.objects.create(
                enterprise=enterprise,
                user=user,
                role=role
            )
            return Response(EnterpriseMemberSerializer(member).data, status=status.HTTP_201_CREATED)
        except Enterprise.DoesNotExist:
            return Response({'detail': '未找到企业信息'}, status=status.HTTP_404_NOT_FOUND)
        except User.DoesNotExist:
            return Response({'detail': '该用户尚未注册平台，请先引导其注册'}, status=status.HTTP_404_NOT_FOUND)

class RoleViewSet(viewsets.ModelViewSet):
    """
    @author: xujl
    Api说明: RBAC 角色管理接口视图。用于定义平台角色类别，以及为用户进行角色的授予和回收。
    """
    queryset = Role.objects.all().order_by('sort_order', 'created_at')
    serializer_class = RoleSerializer
    pagination_class = None  # Return all roles without pagination
    permission_classes = [HasAPIPermission]
    required_permissions = {
        'GET': 'menu:account:roles',
        'POST': 'menu:account:roles',
        'PUT': 'menu:account:roles',
        'DELETE': 'menu:account:roles'
    }

    @action(detail=True, methods=['post'])
    def assign_permissions(self, request, pk=None):
        role = self.get_object()
        permission_ids = request.data.get('permissions', [])
        from .models import Permission, RolePermission
        RolePermission.objects.filter(role=role).delete()
        for pid in permission_ids:
            perm = Permission.objects.filter(id=pid).first()
            if perm:
                RolePermission.objects.create(role=role, permission=perm)
        return Response({'status': '权限分配成功'})

class PermissionViewSet(viewsets.ModelViewSet):
    """
    @author: xujl
    Api说明: RBAC 权限节点管理接口视图。用于查询系统的路由、菜单及按钮级别的权限树结构。
    """
    queryset = Permission.objects.all().order_by('sort_order', 'created_at')
    serializer_class = PermissionSerializer
    pagination_class = None  # Return all permissions without pagination
    permission_classes = [HasAPIPermission]
    required_permissions = {
        'GET': 'menu:account:permissions',
        'POST': 'menu:account:permissions',
        'PUT': 'menu:account:permissions',
        'DELETE': 'menu:account:permissions'
    }