from rest_framework import generics, status
from rest_framework.decorators import api_view, permission_classes
from rest_framework.response import Response
from rest_framework.permissions import IsAuthenticated, AllowAny, IsAdminUser
from django.utils import timezone
from datetime import datetime, timedelta
from .models import AdminWeeklyAvailability, AppointmentRequest, get_admin_availability, set_admin_availability, get_available_slots_for_week, check_date_availability
from .serializers import (
    AdminWeeklyAvailabilitySerializer,
    AdminWeeklyAvailabilityUpdateSerializer,
    AppointmentRequestSerializer,
    AppointmentRequestCreateSerializer,
    AppointmentScheduleSerializer,
    AppointmentRejectSerializer,
    AvailabilityCheckSerializer,
    AvailabilityResponseSerializer,
    WeeklyAvailabilitySerializer,
    AdminAvailabilityConfigSerializer
)
from .email_service import EmailService
from users.models import CustomUser
from django.db.models import Count, Q


class AdminAvailabilityView(generics.RetrieveUpdateAPIView):
    permission_classes = [IsAuthenticated, IsAdminUser]
    
    def get_serializer_class(self):
        if self.request.method == 'GET':
            return AdminWeeklyAvailabilitySerializer
        return AdminWeeklyAvailabilityUpdateSerializer
    
    def get_object(self):
        return get_admin_availability()
    
    def update(self, request, *args, **kwargs):
        response = super().update(request, *args, **kwargs)
        availability = self.get_object()
        full_serializer = AdminWeeklyAvailabilitySerializer(availability)
        return Response(full_serializer.data)


class AdminAvailabilityConfigView(generics.GenericAPIView):
    permission_classes = [AllowAny]
    
    def get(self, request):
        """Get availability configuration"""
        config = AdminAvailabilityConfigSerializer.get_default_config()
        return Response(config.data)


class AppointmentRequestListView(generics.ListAPIView):
    serializer_class = AppointmentRequestSerializer
    permission_classes = [IsAuthenticated]
    
    def get_queryset(self):
        queryset = AppointmentRequest.objects.all()
        
        if self.request.user.is_staff:
            return queryset
            
        return queryset.filter(email=self.request.user.email)


class AppointmentRequestCreateView(generics.CreateAPIView):
    permission_classes = [IsAuthenticated]
    queryset = AppointmentRequest.objects.all()
    serializer_class = AppointmentRequestCreateSerializer
    
    def perform_create(self, serializer):
        appointment = serializer.save()
        
        if appointment.are_preferences_available():
            EmailService.send_admin_notification(appointment)
        else:
            EmailService.send_admin_notification(appointment, availability_mismatch=True)


class AppointmentRequestDetailView(generics.RetrieveAPIView):
    permission_classes = [IsAuthenticated]
    queryset = AppointmentRequest.objects.all()
    serializer_class = AppointmentRequestSerializer
    lookup_field = 'pk'


class ScheduleAppointmentView(generics.GenericAPIView):
    permission_classes = [IsAuthenticated, IsAdminUser]
    serializer_class = AppointmentScheduleSerializer
    queryset = AppointmentRequest.objects.all()
    lookup_field = 'pk'
    
    def post(self, request, pk):
        appointment = self.get_object()
        
        if appointment.status != 'pending_review':
            return Response(
                {'error': 'Only pending review appointments can be scheduled.'},
                status=status.HTTP_400_BAD_REQUEST
            )
        
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        
        appointment.schedule_appointment(
            datetime_obj=serializer.validated_data['scheduled_datetime'],
            duration=serializer.validated_data['scheduled_duration']
        )
        
        EmailService.send_appointment_scheduled(appointment)
        
        response_serializer = AppointmentRequestSerializer(appointment)
        return Response({
            **response_serializer.data,
            'message': 'Appointment scheduled successfully. Jitsi meeting created.',
            'jitsi_meeting_created': appointment.has_jitsi_meeting
        })


class RejectAppointmentView(generics.GenericAPIView):
    permission_classes = [IsAuthenticated]
    serializer_class = AppointmentRejectSerializer
    queryset = AppointmentRequest.objects.all()
    lookup_field = 'pk'
    
    def post(self, request, pk):
        appointment = self.get_object()
        
        if appointment.status != 'pending_review':
            return Response(
                {'error': 'Only pending appointments can be rejected'}, 
                status=status.HTTP_400_BAD_REQUEST
            )
        
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        
        appointment.reject_appointment(
            serializer.validated_data.get('rejection_reason', '')
        )
        EmailService.send_appointment_rejected(appointment)
        
        response_serializer = AppointmentRequestSerializer(appointment)
        return Response(response_serializer.data)


class AvailableDatesView(generics.GenericAPIView):
    permission_classes = [AllowAny]
    
    def get(self, request):
        availability = get_admin_availability()
        if not availability or not availability.availability_schedule:
            return Response([])
        
        today = timezone.now().date()
        available_dates = []
        
        for i in range(1, 31): 
            date = today + timedelta(days=i)
            day_of_week = date.weekday()
            
            available_slots = availability.get_availability_for_day(day_of_week)
            if available_slots:
                available_dates.append({
                    'date': date.strftime('%Y-%m-%d'),
                    'day_name': date.strftime('%A'),
                    'available_slots': available_slots,
                    'available_slots_display': [
                        dict(AdminWeeklyAvailability.TIME_SLOT_CHOICES).get(slot, slot)
                        for slot in available_slots
                    ]
                })
        
        return Response(available_dates)


class CheckDateAvailabilityView(generics.GenericAPIView):
    permission_classes = [AllowAny]
    serializer_class = AvailabilityCheckSerializer
    
    def post(self, request):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        
        date_str = serializer.validated_data['date']
        available_slots = check_date_availability(date_str)
        
        try:
            date_obj = datetime.strptime(date_str, '%Y-%m-%d').date()
            day_name = date_obj.strftime('%A')
            
            response_data = {
                'date': date_str,
                'day_name': day_name,
                'available_slots': available_slots,
                'available_slots_display': [
                    dict(AdminWeeklyAvailability.TIME_SLOT_CHOICES).get(slot, slot)
                    for slot in available_slots
                ],
                'is_available': len(available_slots) > 0
            }
            
            return Response(response_data)
            
        except ValueError:
            return Response(
                {'error': 'Invalid date format'},
                status=status.HTTP_400_BAD_REQUEST
            )


class WeeklyAvailabilityView(generics.GenericAPIView):
    permission_classes = [AllowAny]
    
    def get(self, request):
        availability = get_admin_availability()
        if not availability:
            return Response([])
        
        weekly_availability = []
        for day_num, day_name in AdminWeeklyAvailability.DAYS_OF_WEEK:
            available_slots = availability.get_availability_for_day(day_num)
            weekly_availability.append({
                'day_number': day_num,
                'day_name': day_name,
                'available_slots': available_slots,
                'available_slots_display': [
                    dict(AdminWeeklyAvailability.TIME_SLOT_CHOICES).get(slot, slot)
                    for slot in available_slots
                ],
                'is_available': len(available_slots) > 0
            })
        
        return Response(weekly_availability)

class UserAppointmentsView(generics.ListAPIView):
    permission_classes = [IsAuthenticated]
    serializer_class = AppointmentRequestSerializer
    
    def get_queryset(self):
        return AppointmentRequest.objects.filter(
            email=self.request.user.email
        ).order_by('-created_at')
    
    def post(self, request, *args, **kwargs):
        email = request.data.get('email')
        
        if not email:
            return Response(
                {"error": "Email is required"}, 
                status=status.HTTP_400_BAD_REQUEST
            )
        
        if email != request.user.email:
            return Response(
                {"error": "You can only view your own appointments"},
                status=status.HTTP_403_FORBID_REQUEST
            )
        
        appointments = AppointmentRequest.objects.filter(email__iexact=email).order_by('-created_at')
        
        serializer = self.get_serializer(appointments, many=True)
        return Response(serializer.data)


class AppointmentStatsView(generics.GenericAPIView):
    permission_classes = [IsAuthenticated, IsAdminUser]
    
    def get(self, request):
        total = AppointmentRequest.objects.count()
        users = CustomUser.objects.filter(is_staff=False).count()
        pending = AppointmentRequest.objects.filter(status='pending_review').count()
        scheduled = AppointmentRequest.objects.filter(status='scheduled').count()
        rejected = AppointmentRequest.objects.filter(status='rejected').count()
        completed = AppointmentRequest.objects.filter(status='completed').count()
        
        availability = get_admin_availability()
        availability_coverage = 0
        if availability and availability.availability_schedule:
            days_with_availability = len(availability.availability_schedule)
            availability_coverage = round((days_with_availability / 7) * 100, 2)
        
        return Response({
            'total_requests': total,
            'pending_review': pending,
            'scheduled': scheduled,
            'rejected': rejected,
            'completed': completed,
            'users': users,
            'completion_rate': round((scheduled / total * 100), 2) if total > 0 else 0,
            'availability_coverage': availability_coverage,
            'available_days_count': days_with_availability if availability else 0
        })


class UserAppointmentStatsView(generics.GenericAPIView):
    permission_classes = [IsAuthenticated]
    
    def post(self, request):
        email = request.data.get('email', self.request.user.email)
        
        if not self.request.user.is_staff and email != self.request.user.email:
            return Response(
                {'error': 'You can only view your own statistics'},
                status=status.HTTP_403_FORBIDDEN
            )
        
        appointments = AppointmentRequest.objects.filter(email__iexact=email)
        stats = {
            'total': appointments.count(),
            'pending': appointments.filter(status='pending_review').count(),
            'scheduled': appointments.filter(status='scheduled').count(),
            'rejected': appointments.filter(status='rejected').count(),
            'completed': appointments.filter(status='completed').count(),
        }
        
        total = stats['total']
        scheduled = stats['scheduled']
        completion_rate = round((scheduled / total * 100), 2) if total > 0 else 0
        
        return Response({
            'total_requests': total,
            'pending_review': stats['pending'],
            'scheduled': scheduled,
            'rejected': stats['rejected'],
            'completed': stats['completed'],
            'completion_rate': completion_rate,
            'email': email
        })

class MatchingAvailabilityView(generics.GenericAPIView):
    permission_classes = [IsAuthenticated]
    
    def get(self, request, pk):
        try:
            appointment = AppointmentRequest.objects.get(pk=pk)
            
            if not request.user.is_staff and appointment.email != request.user.email:
                return Response(
                    {'error': 'You can only view your own appointments'},
                    status=status.HTTP_403_FORBIDDEN
                )
            
            matching_slots = appointment.get_matching_availability()
            return Response({
                'appointment_id': str(appointment.id),
                'preferences_match_availability': appointment.are_preferences_available(),
                'matching_slots': matching_slots,
                'total_matching_slots': len(matching_slots)
            })
            
        except AppointmentRequest.DoesNotExist:
            return Response(
                {'error': 'Appointment not found'},
                status=status.HTTP_404_NOT_FOUND
            )


@api_view(['GET'])
@permission_classes([AllowAny])
def availability_overview(request):
    availability = get_admin_availability()
    if not availability:
        return Response({
            'available': False,
            'message': 'No availability set'
        })
    
    all_slots = availability.get_all_available_slots()
    
    return Response({
        'available': len(all_slots) > 0,
        'total_available_slots': len(all_slots),
        'available_days': list(set(slot['day_name'] for slot in all_slots)),
        'next_available_dates': get_next_available_dates(7)
    })


def get_next_available_dates(days_count=7):
    availability = get_admin_availability()
    if not availability:
        return []
    
    today = timezone.now().date()
    next_dates = []
    
    for i in range(1, days_count + 1):
        date = today + timedelta(days=i)
        day_of_week = date.weekday()
        available_slots = availability.get_availability_for_day(day_of_week)
        
        if available_slots:
            next_dates.append({
                'date': date.strftime('%Y-%m-%d'),
                'day_name': date.strftime('%A'),
                'available_slots': available_slots
            })
    
    return next_dates