from rest_framework import viewsets
from rest_framework.permissions import IsAuthenticated, AllowAny
from rest_framework.decorators import action
from rest_framework.response import Response
from django_filters.rest_framework import DjangoFilterBackend
from django.db.models import Q
from .models import Profile, Opportunity, IntroductionRequest
from .serializers import ProfileSerializer, OpportunitySerializer, IntroductionRequestSerializer, LeaderRowSerializer
from .services.matching import rank_users_for, rank_opportunities_for
from .services.benefit import build_leaderboard_queryset

class ProfileViewSet(viewsets.ModelViewSet):
    queryset = Profile.objects.all()
    serializer_class = ProfileSerializer
    permission_classes = [IsAuthenticated]
    filter_backends = [DjangoFilterBackend]
    filterset_fields = {
        'user__username': ['exact', 'icontains'],
        'is_verified': ['exact'],
        'industry': ['exact', 'icontains'],
        'interests': ['icontains'],
        'tags__name': ['exact', 'icontains'],
    }

    @action(detail=False, methods=['get'], permission_classes=[IsAuthenticated])
    def match(self, request):
        """Return top user matches for the authenticated user."""
        ranked = rank_users_for(request.user, k=int(request.query_params.get('k', 20)))
        payload = [
            {
                'score': round(item.score, 4),
                'profile': ProfileSerializer(item.profile, context={'request': request}).data,
            }
            for item in ranked
        ]
        return Response(payload)

class OpportunityViewSet(viewsets.ModelViewSet):
    queryset = Opportunity.objects.all()
    serializer_class = OpportunitySerializer
    permission_classes = [IsAuthenticated]
    filter_backends = [DjangoFilterBackend]
    filterset_fields = {
        'title': ['exact', 'icontains'],
        'created_at': ['gte', 'lte'],
    }

    @action(detail=False, methods=['get'], permission_classes=[IsAuthenticated])
    def recommend(self, request):
        """Return top opportunity recommendations for the authenticated user."""
        ranked = rank_opportunities_for(request.user, k=int(request.query_params.get('k', 20)))
        payload = [
            {
                'score': round(item.score, 4),
                'opportunity': OpportunitySerializer(item.opportunity, context={'request': request}).data,
            }
            for item in ranked
        ]
        return Response(payload)

class IntroductionRequestViewSet(viewsets.ModelViewSet):
    queryset = IntroductionRequest.objects.all()
    serializer_class = IntroductionRequestSerializer
    permission_classes = [IsAuthenticated]
    filter_backends = [DjangoFilterBackend]
    filterset_fields = {
        'from_user__username': ['exact', 'icontains'],
        'to_user__username': ['exact', 'icontains'],
        'is_accepted': ['exact'],
        'message': ['icontains'],
    }

    def get_queryset(self):
        return IntroductionRequest.objects.filter(
            Q(from_user=self.request.user) | Q(to_user=self.request.user)
        )

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


class LeaderboardView(viewsets.ViewSet):
    permission_classes = [AllowAny]

    def list(self, request):
        period = request.query_params.get('period', 'weekly')
        try:
            limit = min(int(request.query_params.get('limit', 100)), 500)
        except Exception:
            limit = 100
        try:
            offset = int(request.query_params.get('offset', 0))
        except Exception:
            offset = 0
        qs = build_leaderboard_queryset(period)
        page = qs[offset:offset+limit]
        data = LeaderRowSerializer(page, many=True).data
        return Response({"period": period, "offset": offset, "limit": limit, "results": data})


class LeaderboardMeView(viewsets.ViewSet):
    permission_classes = [IsAuthenticated]

    def list(self, request):
        period = request.query_params.get('period', 'weekly')
        qs = build_leaderboard_queryset(period)
        me = qs.filter(id=request.user.id).first()
        if not me:
            return Response({
                "period": period,
                "result": None,
                "detail": "No rank for current user in this period.",
            })
        return Response({"period": period, "result": LeaderRowSerializer(me).data})