from django.views import View
from django.utils.decorators import method_decorator
from django.views.decorators.csrf import csrf_exempt
from django.http import JsonResponse
from django.core.paginator import Paginator

from events.models import Event, EventLike, EventImages
from mobile_api.utils import validate_token_and_get_user
from eventify_logger.services import log


def _serialize_liked_event(event):
    """Serialize an Event for the liked-events list."""
    primary_img = EventImages.objects.filter(
        event=event, is_primary=True
    ).first()
    if not primary_img:
        primary_img = EventImages.objects.filter(event=event).first()

    return {
        'id': event.id,
        'title': event.title or event.name,
        'image': primary_img.event_image.url if primary_img else '',
        'date': str(event.start_date) if event.start_date else None,
        'location': event.place or '',
        'venue': event.venue_name or '',
        'event_type': event.event_type.event_type if event.event_type else '',
        'event_status': event.event_status,
    }


@method_decorator(csrf_exempt, name='dispatch')
class ToggleLikeView(View):
    """POST /api/events/like/ — toggle like on/off for an event."""

    def post(self, request):
        try:
            user, token, data, error_response = validate_token_and_get_user(request)
            if error_response:
                return error_response

            event_id = data.get('event_id')
            if not event_id:
                return JsonResponse(
                    {'status': 'error', 'message': 'event_id is required'},
                    status=400
                )

            try:
                event = Event.objects.get(pk=event_id)
            except Event.DoesNotExist:
                return JsonResponse(
                    {'status': 'error', 'message': 'Event not found'},
                    status=404
                )

            like, created = EventLike.objects.get_or_create(user=user, event=event)
            if not created:
                like.delete()
                return JsonResponse({'status': 'success', 'liked': False})

            return JsonResponse({'status': 'success', 'liked': True})

        except Exception as e:
            log("error", "ToggleLikeView exception", request=request,
                logger_data={"error": str(e)})
            return JsonResponse(
                {'status': 'error', 'message': 'An unexpected server error occurred.'},
                status=500
            )


@method_decorator(csrf_exempt, name='dispatch')
class MyLikedIdsView(View):
    """POST /api/events/my-likes/ — return all liked event IDs for the user."""

    def post(self, request):
        try:
            user, token, data, error_response = validate_token_and_get_user(request)
            if error_response:
                return error_response

            liked_ids = list(
                EventLike.objects.filter(user=user)
                .values_list('event_id', flat=True)
            )
            return JsonResponse({'status': 'success', 'liked_event_ids': liked_ids})

        except Exception as e:
            log("error", "MyLikedIdsView exception", request=request,
                logger_data={"error": str(e)})
            return JsonResponse(
                {'status': 'error', 'message': 'An unexpected server error occurred.'},
                status=500
            )


@method_decorator(csrf_exempt, name='dispatch')
class MyLikedEventsView(View):
    """POST /api/events/my-liked-events/ — paginated liked events with full data."""

    def post(self, request):
        try:
            user, token, data, error_response = validate_token_and_get_user(request)
            if error_response:
                return error_response

            page = int(data.get('page', 1))
            page_size = min(int(data.get('page_size', 20)), 50)

            # Event IDs liked by this user, newest first
            liked_event_ids = list(
                EventLike.objects.filter(user=user)
                .order_by('-created_at')
                .values_list('event_id', flat=True)
            )

            # Preserve ordering from liked_event_ids
            from django.db.models import Case, When, IntegerField
            ordering = Case(
                *[When(pk=pk, then=pos) for pos, pk in enumerate(liked_event_ids)],
                output_field=IntegerField()
            )
            events_qs = Event.objects.filter(id__in=liked_event_ids).order_by(ordering)

            paginator = Paginator(events_qs, page_size)
            page_obj = paginator.get_page(page)

            events_data = [_serialize_liked_event(e) for e in page_obj]

            return JsonResponse({
                'status': 'success',
                'events': events_data,
                'total': paginator.count,
                'page': page,
                'page_size': page_size,
                'has_next': page_obj.has_next(),
            })

        except Exception as e:
            log("error", "MyLikedEventsView exception", request=request,
                logger_data={"error": str(e)})
            return JsonResponse(
                {'status': 'error', 'message': 'An unexpected server error occurred.'},
                status=500
            )