"""
PawCare API Views — all 20+ REST endpoints.
"""

import logging
from django.contrib.auth import get_user_model
from django.http import JsonResponse
from django.utils import timezone
from rest_framework import generics, status, viewsets, filters
from rest_framework.decorators import action
from rest_framework.permissions import AllowAny, IsAuthenticated
from rest_framework.response import Response
from rest_framework.views import APIView
from rest_framework_simplejwt.tokens import RefreshToken
from rest_framework_simplejwt.views import TokenObtainPairView
from rest_framework_simplejwt.exceptions import TokenError
from django_filters.rest_framework import DjangoFilterBackend

from api.models import Caregiver, Pet, Service, Booking, Conversation, Message, BookingStatus
from api.permissions import IsAdmin, IsAdminOrReadOnly, IsOwnerOrAdmin, IsParticipantOrAdmin, IsCaregiverOwnerOrAdmin
from api.serializers import (
    CustomTokenObtainPairSerializer, RegisterSerializer, UserProfileSerializer,
    CaregiverListSerializer, CaregiverDetailSerializer, CaregiverWriteSerializer,
    PetSerializer, ServiceSerializer,
    BookingCreateSerializer, BookingSerializer,
    BookingStatusUpdateSerializer, BookingReviewSerializer,
    ConversationSerializer, MessageSerializer,
    ImageUploadSerializer,
)
from storage.hf_storage import hf_storage, HFStorageError

logger = logging.getLogger('api')
User = get_user_model()


# ── Axes lockout handler ───────────────────────────────────────────────────
def lockout(request, credentials, *args, **kwargs):
    return JsonResponse(
        {'detail': 'Too many failed login attempts. Account locked for 30 minutes.'},
        status=429,
    )


# ─────────────────────────────────────────────────────────────────────────────
# Auth Views
# ─────────────────────────────────────────────────────────────────────────────
class LoginView(TokenObtainPairView):
    """POST /api/auth/login/  → access + refresh tokens + user info."""
    serializer_class = CustomTokenObtainPairSerializer
    permission_classes = [AllowAny]


class RegisterView(generics.CreateAPIView):
    """POST /api/auth/register/  → create user account (role=user)."""
    serializer_class = RegisterSerializer
    permission_classes = [AllowAny]

    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        user = serializer.save()
        refresh = RefreshToken.for_user(user)
        return Response({
            'access': str(refresh.access_token),
            'refresh': str(refresh),
            'user': {
                'id': str(user.id),
                'email': user.email,
                'full_name': user.full_name,
                'role': user.role,
            },
        }, status=status.HTTP_201_CREATED)


class LogoutView(APIView):
    """POST /api/auth/logout/  → blacklist refresh token."""
    permission_classes = [IsAuthenticated]

    def post(self, request):
        try:
            token = RefreshToken(request.data.get('refresh'))
            token.blacklist()
            return Response({'detail': 'Logged out successfully.'})
        except TokenError as exc:
            return Response({'detail': str(exc)}, status=status.HTTP_400_BAD_REQUEST)


class MeView(generics.RetrieveUpdateAPIView):
    """GET/PATCH /api/auth/me/  → own profile."""
    serializer_class = UserProfileSerializer
    permission_classes = [IsAuthenticated]

    def get_object(self):
        return self.request.user


class ChangePasswordView(APIView):
    """POST /api/auth/change-password/"""
    permission_classes = [IsAuthenticated]

    def post(self, request):
        user = request.user
        old_pw = request.data.get('old_password', '')
        new_pw = request.data.get('new_password', '')
        if not user.check_password(old_pw):
            return Response({'detail': 'Incorrect current password.'}, status=400)
        if len(new_pw) < 10:
            return Response({'detail': 'Password must be at least 10 characters.'}, status=400)
        user.set_password(new_pw)
        user.save()
        return Response({'detail': 'Password changed successfully.'})


# ─────────────────────────────────────────────────────────────────────────────
# Service Views
# ─────────────────────────────────────────────────────────────────────────────
class ServiceListView(generics.ListAPIView):
    """GET /api/services/"""
    queryset = Service.objects.filter(is_active=True)
    serializer_class = ServiceSerializer
    permission_classes = [AllowAny]


# ─────────────────────────────────────────────────────────────────────────────
# Caregiver Views
# ─────────────────────────────────────────────────────────────────────────────
class CaregiverViewSet(viewsets.ModelViewSet):
    """
    GET    /api/caregivers/          → list (public, filterable)
    GET    /api/caregivers/{id}/     → detail (public)
    POST   /api/caregivers/          → create (admin only)
    PUT    /api/caregivers/{id}/     → update (admin only)
    PATCH  /api/caregivers/{id}/     → partial update (admin or self)
    DELETE /api/caregivers/{id}/     → delete (admin only)
    """
    queryset = Caregiver.objects.select_related('user').prefetch_related('services')
    filter_backends = [DjangoFilterBackend, filters.SearchFilter, filters.OrderingFilter]
    filterset_fields = ['city', 'country', 'is_available', 'is_verified', 'is_featured']
    search_fields = ['user__first_name', 'user__last_name', 'bio', 'city', 'specializations']
    ordering_fields = ['rating', 'total_bookings', 'years_of_experience', 'created_at']
    ordering = ['-rating']

    def get_serializer_class(self):
        if self.action == 'list':
            return CaregiverListSerializer
        if self.action in ('create', 'update', 'partial_update'):
            return CaregiverWriteSerializer
        return CaregiverDetailSerializer

    def get_permissions(self):
        if self.action in ('list', 'retrieve'):
            return [AllowAny()]
        if self.action in ('update', 'partial_update'):
            return [IsAuthenticated(), IsCaregiverOwnerOrAdmin()]
        return [IsAuthenticated(), IsAdmin()]

    @action(detail=True, methods=['post'], permission_classes=[IsAuthenticated, IsAdmin])
    def toggle_featured(self, request, pk=None):
        caregiver = self.get_object()
        caregiver.is_featured = not caregiver.is_featured
        caregiver.save(update_fields=['is_featured'])
        return Response({'is_featured': caregiver.is_featured})

    @action(detail=True, methods=['post'], permission_classes=[IsAuthenticated, IsAdmin])
    def verify(self, request, pk=None):
        caregiver = self.get_object()
        caregiver.is_verified = True
        caregiver.background_check_passed = True
        caregiver.save(update_fields=['is_verified', 'background_check_passed'])
        return Response({'is_verified': True})


# ─────────────────────────────────────────────────────────────────────────────
# Pet Views
# ─────────────────────────────────────────────────────────────────────────────
class PetViewSet(viewsets.ModelViewSet):
    """
    Scoped to the requesting user — users only see their own pets.
    GET    /api/pets/
    POST   /api/pets/
    GET    /api/pets/{id}/
    PUT    /api/pets/{id}/
    DELETE /api/pets/{id}/
    """
    serializer_class = PetSerializer
    permission_classes = [IsAuthenticated, IsOwnerOrAdmin]

    def get_queryset(self):
        if self.request.user.role == 'admin' or self.request.user.is_staff:
            return Pet.objects.all()
        return Pet.objects.filter(owner=self.request.user)

    def perform_create(self, serializer):
        serializer.save(owner=self.request.user)


# ─────────────────────────────────────────────────────────────────────────────
# Booking Views
# ─────────────────────────────────────────────────────────────────────────────
class BookingViewSet(viewsets.ModelViewSet):
    """
    GET    /api/bookings/           → own bookings (or all for admin)
    POST   /api/bookings/           → create booking
    GET    /api/bookings/{id}/      → detail
    PATCH  /api/bookings/{id}/status/    → update status
    POST   /api/bookings/{id}/review/    → leave review
    """
    permission_classes = [IsAuthenticated, IsOwnerOrAdmin]
    filter_backends = [DjangoFilterBackend, filters.OrderingFilter]
    filterset_fields = ['status', 'caregiver', 'pet', 'service']
    ordering_fields = ['scheduled_start', 'created_at']
    ordering = ['-created_at']

    def get_serializer_class(self):
        if self.action == 'create':
            return BookingCreateSerializer
        return BookingSerializer

    def get_queryset(self):
        user = self.request.user
        if user.role == 'admin' or user.is_staff:
            return Booking.objects.select_related('user', 'caregiver__user', 'pet', 'service').all()
        if user.role == 'caregiver':
            return Booking.objects.filter(caregiver__user=user).select_related()
        return Booking.objects.filter(user=user).select_related()

    @action(detail=True, methods=['patch'], url_path='status')
    def update_status(self, request, pk=None):
        booking = self.get_object()
        serializer = BookingStatusUpdateSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        new_status = serializer.validated_data['status']
        reason = serializer.validated_data.get('cancellation_reason', '')

        # Guard transitions
        allowed = {
            BookingStatus.PENDING: [BookingStatus.CONFIRMED, BookingStatus.CANCELLED],
            BookingStatus.CONFIRMED: [BookingStatus.IN_PROGRESS, BookingStatus.CANCELLED],
            BookingStatus.IN_PROGRESS: [BookingStatus.COMPLETED],
        }
        current = booking.status
        if new_status not in allowed.get(current, []):
            return Response(
                {'detail': f'Cannot transition from {current!r} to {new_status!r}.'},
                status=status.HTTP_400_BAD_REQUEST,
            )

        booking.status = new_status
        if new_status == BookingStatus.CANCELLED:
            booking.cancellation_reason = reason
        elif new_status == BookingStatus.IN_PROGRESS:
            booking.actual_start = timezone.now()
        elif new_status == BookingStatus.COMPLETED:
            booking.actual_end = timezone.now()
            booking.caregiver.total_bookings += 1
            booking.caregiver.save(update_fields=['total_bookings'])
        booking.save()
        return Response(BookingSerializer(booking).data)

    @action(detail=True, methods=['post'])
    def review(self, request, pk=None):
        booking = self.get_object()
        if booking.user != request.user:
            return Response({'detail': 'Only the booking owner can leave a review.'}, status=403)
        if booking.status != BookingStatus.COMPLETED:
            return Response({'detail': 'Can only review completed bookings.'}, status=400)
        if booking.reviewed_at:
            return Response({'detail': 'This booking has already been reviewed.'}, status=400)

        serializer = BookingReviewSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        serializer.update(booking, serializer.validated_data)
        return Response({'detail': 'Review submitted successfully.'})


# ─────────────────────────────────────────────────────────────────────────────
# Messaging Views
# ─────────────────────────────────────────────────────────────────────────────
class ConversationViewSet(viewsets.ReadOnlyModelViewSet):
    """GET /api/conversations/  {id}/"""
    serializer_class = ConversationSerializer
    permission_classes = [IsAuthenticated]

    def get_queryset(self):
        return Conversation.objects.filter(
            participants=self.request.user
        ).prefetch_related('participants', 'messages')


class MessageViewSet(viewsets.ModelViewSet):
    """
    GET  /api/conversations/{conv_id}/messages/
    POST /api/conversations/{conv_id}/messages/
    """
    serializer_class = MessageSerializer
    permission_classes = [IsAuthenticated, IsParticipantOrAdmin]
    http_method_names = ['get', 'post', 'head', 'options']

    def get_queryset(self):
        conv_id = self.kwargs.get('conversation_pk')
        return Message.objects.filter(
            conversation_id=conv_id,
            conversation__participants=self.request.user,
        ).select_related('sender')

    def perform_create(self, serializer):
        conv_id = self.kwargs.get('conversation_pk')
        try:
            conversation = Conversation.objects.get(
                id=conv_id, participants=self.request.user
            )
        except Conversation.DoesNotExist:
            from rest_framework.exceptions import PermissionDenied
            raise PermissionDenied('You are not part of this conversation.')

        serializer.save(sender=self.request.user, conversation=conversation)
        # Mark other messages as read
        Message.objects.filter(
            conversation=conversation, is_read=False
        ).exclude(sender=self.request.user).update(
            is_read=True, read_at=timezone.now()
        )
        # Bump conversation updated_at
        conversation.save(update_fields=['updated_at'])


# ─────────────────────────────────────────────────────────────────────────────
# Image Upload View
# ─────────────────────────────────────────────────────────────────────────────
class ImageUploadView(APIView):
    """POST /api/upload-image/  → returns {url: '...'}"""
    permission_classes = [IsAuthenticated]

    def post(self, request):
        serializer = ImageUploadSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        file_obj = serializer.validated_data['image']
        folder = serializer.validated_data.get('folder', 'images')

        try:
            url = hf_storage.upload_image(file_obj, folder=folder)
            return Response({'url': url}, status=status.HTTP_201_CREATED)
        except HFStorageError as exc:
            return Response({'detail': str(exc)}, status=status.HTTP_502_BAD_GATEWAY)
        except ValueError as exc:
            return Response({'detail': str(exc)}, status=status.HTTP_400_BAD_REQUEST)


# ─────────────────────────────────────────────────────────────────────────────
# Dashboard Stats (Admin only)
# ─────────────────────────────────────────────────────────────────────────────
class DashboardStatsView(APIView):
    """GET /api/admin/stats/"""
    permission_classes = [IsAuthenticated, IsAdmin]

    def get(self, request):
        from django.db.models import Count, Avg, Sum
        return Response({
            'users': User.objects.filter(role='user').count(),
            'caregivers': Caregiver.objects.count(),
            'verified_caregivers': Caregiver.objects.filter(is_verified=True).count(),
            'pets': Pet.objects.count(),
            'bookings': {
                'total': Booking.objects.count(),
                'pending': Booking.objects.filter(status='pending').count(),
                'confirmed': Booking.objects.filter(status='confirmed').count(),
                'completed': Booking.objects.filter(status='completed').count(),
                'cancelled': Booking.objects.filter(status='cancelled').count(),
            },
            'revenue': Booking.objects.filter(
                status='completed'
            ).aggregate(total=Sum('price_total'))['total'] or 0,
            'avg_rating': Caregiver.objects.aggregate(
                avg=Avg('rating')
            )['avg'] or 0,
        })