from django.db.models import Q
from django.db.models.functions import Lower
from django.db import transaction
from rest_framework import viewsets
from rest_framework.decorators import action
from rest_framework.response import Response
from adventures.models import Collection, Adventure, Transportation, Note
from adventures.permissions import CollectionShared
from adventures.serializers import CollectionSerializer
from users.models import CustomUser as User
from adventures.utils import pagination

class CollectionViewSet(viewsets.ModelViewSet):
    serializer_class = CollectionSerializer
    permission_classes = [CollectionShared]
    pagination_class = pagination.StandardResultsSetPagination

    # def get_queryset(self):
    #     return Collection.objects.filter(Q(user_id=self.request.user.id) & Q(is_archived=False))

    def apply_sorting(self, queryset):
        order_by = self.request.query_params.get('order_by', 'name')
        order_direction = self.request.query_params.get('order_direction', 'asc')

        valid_order_by = ['name', 'upated_at']
        if order_by not in valid_order_by:
            order_by = 'updated_at'

        if order_direction not in ['asc', 'desc']:
            order_direction = 'asc'

        # Apply case-insensitive sorting for the 'name' field
        if order_by == 'name':
            queryset = queryset.annotate(lower_name=Lower('name'))
            ordering = 'lower_name'
            if order_direction == 'desc':
                ordering = f'-{ordering}'
        else:
            order_by == 'updated_at'
            ordering = 'updated_at'
            if order_direction == 'asc':
                ordering = '-updated_at'

        #print(f"Ordering by: {ordering}")  # For debugging

        return queryset.order_by(ordering)
    
    def list(self, request, *args, **kwargs):
        # make sure the user is authenticated
        if not request.user.is_authenticated:
            return Response({"error": "User is not authenticated"}, status=400)
        queryset = Collection.objects.filter(user_id=request.user.id)
        queryset = self.apply_sorting(queryset)
        collections = self.paginate_and_respond(queryset, request)
        return collections
    
    @action(detail=False, methods=['get'])
    def all(self, request):
        if not request.user.is_authenticated:
            return Response({"error": "User is not authenticated"}, status=400)
       
        queryset = Collection.objects.filter(
            Q(user_id=request.user.id)
        )
        
        queryset = self.apply_sorting(queryset)
        serializer = self.get_serializer(queryset, many=True)
       
        return Response(serializer.data)
    
    @action(detail=False, methods=['get'])
    def archived(self, request):
        if not request.user.is_authenticated:
            return Response({"error": "User is not authenticated"}, status=400)
       
        queryset = Collection.objects.filter(
            Q(user_id=request.user.id) & Q(is_archived=True)
        )
        
        queryset = self.apply_sorting(queryset)
        serializer = self.get_serializer(queryset, many=True)
       
        return Response(serializer.data)
    
    # this make the is_public field of the collection cascade to the adventures
    @transaction.atomic
    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)

        if 'collection' in serializer.validated_data:
            new_collection = serializer.validated_data['collection']
            # if the new collection is different from the old one and the user making the request is not the owner of the new collection return an error
            if new_collection != instance.collection and new_collection.user_id != request.user:
                return Response({"error": "User does not own the new collection"}, status=400)

        # Check if the 'is_public' field is present in the update data
        if 'is_public' in serializer.validated_data:
            new_public_status = serializer.validated_data['is_public']
            
            # if is_publuc has changed and the user is not the owner of the collection return an error
            if new_public_status != instance.is_public and instance.user_id != request.user:
                print(f"User {request.user.id} does not own the collection {instance.id} that is owned by {instance.user_id}")
                return Response({"error": "User does not own the collection"}, status=400)

            # Update associated adventures to match the collection's is_public status
            Adventure.objects.filter(collection=instance).update(is_public=new_public_status)

            # do the same for transportations
            Transportation.objects.filter(collection=instance).update(is_public=new_public_status)

            # do the same for notes
            Note.objects.filter(collection=instance).update(is_public=new_public_status)

            # Log the action (optional)
            action = "public" if new_public_status else "private"
            print(f"Collection {instance.id} and its adventures were set to {action}")

        self.perform_update(serializer)

        if getattr(instance, '_prefetched_objects_cache', None):
            # If 'prefetch_related' has been applied to a queryset, we need to
            # forcibly invalidate the prefetch cache on the instance.
            instance._prefetched_objects_cache = {}

        return Response(serializer.data)
    
    # make an action to retreive all adventures that are shared with the user
    @action(detail=False, methods=['get'])
    def shared(self, request):
        if not request.user.is_authenticated:
            return Response({"error": "User is not authenticated"}, status=400)
        queryset = Collection.objects.filter(
            shared_with=request.user
        )
        queryset = self.apply_sorting(queryset)
        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)
    
    # Adds a new user to the shared_with field of an adventure
    @action(detail=True, methods=['post'], url_path='share/(?P<uuid>[^/.]+)')
    def share(self, request, pk=None, uuid=None):
        collection = self.get_object()
        if not uuid:
            return Response({"error": "User UUID is required"}, status=400)
        try:
            user = User.objects.get(uuid=uuid, public_profile=True)
        except User.DoesNotExist:
            return Response({"error": "User not found"}, status=404)
        
        if user == request.user:
            return Response({"error": "Cannot share with yourself"}, status=400)
        
        if collection.shared_with.filter(id=user.id).exists():
            return Response({"error": "Adventure is already shared with this user"}, status=400)
        
        collection.shared_with.add(user)
        collection.save()
        return Response({"success": f"Shared with {user.username}"})
    
    @action(detail=True, methods=['post'], url_path='unshare/(?P<uuid>[^/.]+)')
    def unshare(self, request, pk=None, uuid=None):
        if not request.user.is_authenticated:
            return Response({"error": "User is not authenticated"}, status=400)
        collection = self.get_object()
        if not uuid:
            return Response({"error": "User UUID is required"}, status=400)
        try:
            user = User.objects.get(uuid=uuid, public_profile=True)
        except User.DoesNotExist:
            return Response({"error": "User not found"}, status=404)
        
        if user == request.user:
            return Response({"error": "Cannot unshare with yourself"}, status=400)
        
        if not collection.shared_with.filter(id=user.id).exists():
            return Response({"error": "Collection is not shared with this user"}, status=400)
        
        collection.shared_with.remove(user)
        collection.save()
        return Response({"success": f"Unshared with {user.username}"})

    def get_queryset(self):
        if self.action == 'destroy':
            return Collection.objects.filter(user_id=self.request.user.id)
        
        if self.action in ['update', 'partial_update']:
            return Collection.objects.filter(
                Q(user_id=self.request.user.id) | Q(shared_with=self.request.user)
            ).distinct()
        
        if self.action == 'retrieve':
            if not self.request.user.is_authenticated:
                return Collection.objects.filter(is_public=True)
            return Collection.objects.filter(
                Q(is_public=True) | Q(user_id=self.request.user.id) | Q(shared_with=self.request.user)
            ).distinct()
        
        # For list action, include collections owned by the user or shared with the user, that are not archived
        return Collection.objects.filter(
            (Q(user_id=self.request.user.id) | Q(shared_with=self.request.user)) & Q(is_archived=False)
        ).distinct()


    def perform_create(self, serializer):
        # This is ok because you cannot share a collection when creating it
        serializer.save(user_id=self.request.user)
    
    def paginate_and_respond(self, queryset, request):
        paginator = self.pagination_class()
        page = paginator.paginate_queryset(queryset, request)
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            return paginator.get_paginated_response(serializer.data)
        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)
