from django.contrib.gis.geos import Point, Polygon
from django.contrib.gis.measure import D
from rest_framework import generics, status
from rest_framework.response import Response
from rest_framework.views import APIView

from apps.common.permissions import IsCreator
from apps.utils.fcm import send_notification
from .models import Challenge, ChallengeParticipant
from .serializers import (
    ChallengeCreateSerializer,
    ChallengeUpdateSerializer,
    ChallengeDetailSerializer,
    ChallengeMapSerializer,
    ChallengeParticipantSerializer,
)


def _parse_bbox(bbox_str):
    try:
        min_lon, min_lat, max_lon, max_lat = [float(x) for x in bbox_str.split(",")]
        poly = Polygon.from_bbox((min_lon, min_lat, max_lon, max_lat))
        poly.srid = 4326
        return poly, None
    except Exception:
        return None, "bbox must be four comma-separated floats: minLon,minLat,maxLon,maxLat"


class ChallengeListCreateView(APIView):
    def get(self, request):
        qs = Challenge.objects.select_related("creator")

        # ?mine=true — return the authenticated user's own challenges, all statuses
        if request.query_params.get("mine") == "true":
            qs = qs.filter(creator=request.user)
            return Response(
                ChallengeDetailSerializer(qs, many=True, context={"request": request}).data
            )

        status_filter = request.query_params.get("status", "active")
        qs = qs.filter(status=status_filter)

        bbox_str = request.query_params.get("bbox")
        if bbox_str:
            bbox, error = _parse_bbox(bbox_str)
            if error:
                return Response({"error": "invalid_bbox", "detail": error}, status=status.HTTP_400_BAD_REQUEST)
            qs = qs.filter(region_centroid__within=bbox)

        near_str = request.query_params.get("near")
        if near_str:
            try:
                lat, lon, radius_m = [float(x) for x in near_str.split(",")]
            except Exception:
                return Response(
                    {"error": "invalid_near", "detail": "near must be lat,lon,radius_m"},
                    status=status.HTTP_400_BAD_REQUEST,
                )
            center = Point(lon, lat, srid=4326)
            qs = qs.filter(region_centroid__distance_lte=(center, D(m=radius_m)))

        return Response(ChallengeMapSerializer(qs, many=True).data)

    def post(self, request):
        serializer = ChallengeCreateSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        challenge = serializer.save(creator=request.user)

        return Response(
            ChallengeDetailSerializer(challenge, context={"request": request}).data,
            status=status.HTTP_201_CREATED,
        )


class ChallengeDetailView(APIView):
    def _get_challenge(self, pk):
        try:
            return Challenge.objects.select_related("creator").prefetch_related("participants").get(pk=pk)
        except Challenge.DoesNotExist:
            return None

    def get(self, request, pk):
        challenge = self._get_challenge(pk)
        if not challenge:
            return Response(status=status.HTTP_404_NOT_FOUND)
        return Response(ChallengeDetailSerializer(challenge, context={"request": request}).data)

    def patch(self, request, pk):
        challenge = self._get_challenge(pk)
        if not challenge:
            return Response(status=status.HTTP_404_NOT_FOUND)

        permission = IsCreator()
        if not permission.has_object_permission(request, self, challenge):
            return Response(status=status.HTTP_403_FORBIDDEN)

        serializer = ChallengeUpdateSerializer(challenge, data=request.data, partial=True)
        serializer.is_valid(raise_exception=True)
        serializer.save()

        return Response(ChallengeDetailSerializer(challenge, context={"request": request}).data)

    def delete(self, request, pk):
        challenge = self._get_challenge(pk)
        if not challenge:
            return Response(status=status.HTTP_404_NOT_FOUND)

        permission = IsCreator()
        if not permission.has_object_permission(request, self, challenge):
            return Response(status=status.HTTP_403_FORBIDDEN)

        challenge.status = Challenge.Status.CLOSED
        challenge.save(update_fields=["status", "updated_at"])

        return Response(status=status.HTTP_204_NO_CONTENT)


class ChallengeParticipateView(APIView):
    def post(self, request, pk):
        try:
            challenge = Challenge.objects.select_related("creator").get(pk=pk)
        except Challenge.DoesNotExist:
            return Response(status=status.HTTP_404_NOT_FOUND)

        if challenge.status != Challenge.Status.ACTIVE:
            return Response(
                {"error": "challenge_closed", "detail": "This challenge is no longer active."},
                status=status.HTTP_403_FORBIDDEN,
            )

        participant, created = ChallengeParticipant.objects.get_or_create(
            challenge=challenge,
            user=request.user,
        )

        if created:
            # Notify the challenge creator
            send_notification(
                challenge.creator.fcm_token,
                title="Someone accepted your challenge!",
                body=f'A user is heading out for "{challenge.title}".',
                data={"challenge_id": str(challenge.id), "type": "challenge_accepted"},
            )

        response_status = status.HTTP_201_CREATED if created else status.HTTP_200_OK
        return Response(ChallengeParticipantSerializer(participant).data, status=response_status)

    def delete(self, request, pk):
        try:
            participant = ChallengeParticipant.objects.get(
                challenge_id=pk,
                user=request.user,
            )
        except ChallengeParticipant.DoesNotExist:
            return Response(status=status.HTTP_404_NOT_FOUND)

        if participant.submitted_splat_id:
            return Response(
                {"error": "cannot_leave", "detail": "You cannot remove yourself after submitting a splat."},
                status=status.HTTP_403_FORBIDDEN,
            )

        participant.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)


class ChallengeSplatsView(generics.ListAPIView):
    from apps.splats.serializers import SplatMapSerializer
    serializer_class = SplatMapSerializer

    def get_queryset(self):
        from apps.splats.models import Splat
        return Splat.objects.filter(
            challenge_id=self.kwargs["pk"],
            is_published=True,
        ).order_by("-created_at")