from django.db.models import Q
from django.shortcuts import get_object_or_404
from rest_framework import generics, status, permissions
from rest_framework.response import Response
from drf_spectacular.utils import extend_schema, extend_schema_view, OpenApiParameter, OpenApiTypes

from apps.meetings.models import MeetingRequest, MeetingStatus
from apps.meetings.serializers import (
    MeetingListSerializer,
    MeetingDetailSerializer,
    MeetingCreateSerializer,
    MeetingUpdateSerializer,
)
from apps.meetings.permissions import IsMeetingParticipantOrStaff, CanManageMeeting
from apps.profiles.models import InstitutionMember


@extend_schema_view(
    get=extend_schema(
        tags=['Meetings'],
        summary="List scheduled & pending meetings",
        description="List bilateral video meetings involving the authenticated user's affiliated institutions.",
        parameters=[
            OpenApiParameter('status', OpenApiTypes.STR, description="Meeting status (pending, scheduled, completed, cancelled, declined)"),
            OpenApiParameter('institution_id', OpenApiTypes.INT, description="Filter meetings by participating institution ID"),
            OpenApiParameter('start_date', OpenApiTypes.DATE, description="Filter meetings from date (YYYY-MM-DD)"),
            OpenApiParameter('end_date', OpenApiTypes.DATE, description="Filter meetings to date (YYYY-MM-DD)"),
            OpenApiParameter('search', OpenApiTypes.STR, description="Search in title or agenda"),
        ]
    ),
    post=extend_schema(
        tags=['Meetings'],
        summary="Propose a new video meeting",
        description="Schedule/propose a bilateral meeting between institutions (requires institution admin/editor role).",
        request=MeetingCreateSerializer,
        responses={201: MeetingDetailSerializer}
    )
)
class MeetingListCreateView(generics.ListCreateAPIView):
    permission_classes = [permissions.IsAuthenticated]

    def get_serializer_class(self):
        if self.request.method == 'POST':
            return MeetingCreateSerializer
        return MeetingListSerializer

    def get_queryset(self):
        user = self.request.user
        if not user.is_authenticated:
            return MeetingRequest.objects.none()

        if user.is_superuser or getattr(user, 'user_type', None) in ['super_admin', 'regional_admin']:
            qs = MeetingRequest.objects.select_related('requester_institution', 'recipient_institution', 'created_by').all()
        else:
            user_inst_ids = InstitutionMember.objects.filter(user=user).values_list('institution_id', flat=True)
            qs = MeetingRequest.objects.select_related('requester_institution', 'recipient_institution', 'created_by').filter(
                Q(requester_institution_id__in=user_inst_ids) |
                Q(recipient_institution_id__in=user_inst_ids) |
                Q(created_by=user)
            )

        params = self.request.query_params
        status_param = params.get('status')
        if status_param:
            qs = qs.filter(status=status_param)

        institution_id = params.get('institution_id')
        if institution_id and str(institution_id).isdigit():
            inst_id = int(institution_id)
            qs = qs.filter(Q(requester_institution_id=inst_id) | Q(recipient_institution_id=inst_id))

        start_date = params.get('start_date')
        if start_date:
            qs = qs.filter(meeting_date__gte=start_date)

        end_date = params.get('end_date')
        if end_date:
            qs = qs.filter(meeting_date__lte=end_date)

        search = params.get('search')
        if search:
            qs = qs.filter(Q(title__icontains=search) | Q(agenda__icontains=search))

        return qs.distinct()

    def perform_create(self, serializer):
        return serializer.save()

    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data, context={'request': request})
        serializer.is_valid(raise_exception=True)
        meeting = self.perform_create(serializer)
        out_serializer = MeetingDetailSerializer(meeting, context={'request': request})
        return Response(out_serializer.data, status=status.HTTP_201_CREATED)


@extend_schema_view(
    get=extend_schema(
        tags=['Meetings'],
        summary="Retrieve meeting details",
        description="Get full meeting details including video link, agenda, and participants."
    ),
    patch=extend_schema(
        tags=['Meetings'],
        summary="Update or respond to meeting request",
        description="Accept, reschedule, decline (requires rejection_reason or admin_notes explanation), complete, or update meeting room URL and agenda notes.",
        request=MeetingUpdateSerializer,
        responses={200: MeetingDetailSerializer}
    ),
    delete=extend_schema(
        tags=['Meetings'],
        summary="Cancel / delete meeting",
        description="Cancel or delete a meeting request."
    )
)
class MeetingDetailView(generics.RetrieveUpdateDestroyAPIView):
    permission_classes = [IsMeetingParticipantOrStaff]
    lookup_field = 'pk'

    def get_queryset(self):
        return MeetingRequest.objects.select_related('requester_institution', 'recipient_institution', 'created_by').all()

    def get_serializer_class(self):
        if self.request.method in ['PUT', 'PATCH']:
            return MeetingUpdateSerializer
        return MeetingDetailSerializer

    def update(self, request, *args, **kwargs):
        partial = kwargs.pop('partial', True)
        instance = self.get_object()
        
        # Check manage permissions
        checker = CanManageMeeting()
        if not checker.has_object_permission(request, self, instance):
            self.permission_denied(request, message="You do not have permission to manage this meeting.")

        serializer = MeetingUpdateSerializer(instance, data=request.data, partial=partial, context={'request': request})
        serializer.is_valid(raise_exception=True)
        self.perform_update(serializer)
        out_serializer = MeetingDetailSerializer(instance, context={'request': request})
        return Response(out_serializer.data)

    def destroy(self, request, *args, **kwargs):
        instance = self.get_object()
        checker = CanManageMeeting()
        if not checker.has_object_permission(request, self, instance):
            self.permission_denied(request, message="You do not have permission to cancel this meeting.")
        return super().destroy(request, *args, **kwargs)