from rest_framework import generics, permissions
from rest_framework.viewsets import ModelViewSet
from rest_framework.authentication import TokenAuthentication
from drf_yasg.utils import swagger_auto_schema
from drf_yasg import openapi
from django.db.models import Q

from apps.certificate.models import Certificate
from apps.certificate.serializers import AdminCertificateSerializer, CertificateRequestSerializer, CertificateSerializer
from apps.account.permissions import IsSuperAdmin
from apps.course.models import Course
from apps.course.models.course import extract_text_from_json
from utils.pagination import StandardResultsSetPagination


def find_matching_course_ids(search_term: str):
    normalized = (search_term or "").strip().lower()
    if not normalized:
        return []

    matching_ids = list(
        Course.objects.filter(
            Q(title__icontains=search_term) | Q(slug__icontains=search_term)
        ).values_list("id", flat=True)
    )

    if matching_ids:
        return matching_ids

    for course in Course.objects.all().only("id", "title", "slug"):
        title_text = extract_text_from_json(course.title).lower()
        slug_text = extract_text_from_json(course.slug).lower()
        if normalized in title_text or normalized in slug_text:
            matching_ids.append(course.id)

    return matching_ids



class CertificateRequestView(generics.CreateAPIView):
    queryset = Certificate.objects.all()
    serializer_class = CertificateRequestSerializer
    permission_classes = [permissions.IsAuthenticated]
    authentication_classes = [TokenAuthentication]

    @swagger_auto_schema(
        operation_description="Request a certificate for completed course",
        tags=["Imam-Javad - Certificate"],
        responses={
            201: openapi.Response(
                description="Certificate request created successfully"
            )
        }
    )
    def post(self, request, *args, **kwargs):
        return super().post(request, *args, **kwargs)

    def perform_create(self, serializer):
        serializer.save(student=self.request.user)
        
        
class UserCertificatesListView(generics.ListAPIView):
    serializer_class = CertificateSerializer
    permission_classes = [permissions.IsAuthenticated]
    authentication_classes = [TokenAuthentication]
    pagination_class = StandardResultsSetPagination

    @swagger_auto_schema(
        operation_description="Get list of user's certificates",
        tags=["Imam-Javad - Certificate"],
        responses={
            200: openapi.Response(
                description="List of user certificates",
                schema=CertificateSerializer(many=True)
            )
        }
    )
    def get(self, request, *args, **kwargs):
        return super().get(request, *args, **kwargs)

    def get_queryset(self):
        return Certificate.objects.filter(student=self.request.user).order_by('-created_at')


def is_professor(request):
    return getattr(request.user, 'user_type', None) == 'professor'


class AdminCertificateViewSet(ModelViewSet):
    queryset = Certificate.objects.all()
    serializer_class = AdminCertificateSerializer
    permission_classes = [permissions.IsAuthenticated, IsSuperAdmin]
    authentication_classes = [TokenAuthentication]
    pagination_class = StandardResultsSetPagination

    def get_queryset(self):
        queryset = Certificate.objects.all().select_related('student', 'course')

        # Professors can only see certificates for students in their courses
        if is_professor(self.request):
            queryset = queryset.filter(course__professor_id=self.request.user.id)
        
        # Search query
        search_query = self.request.query_params.get('search', None)
        has_search = False
        if search_query:
            has_search = True
            matching_course_ids = find_matching_course_ids(search_query)
            from django.db.models import Case, When, Value, IntegerField
            queryset = queryset.filter(
                Q(student__fullname__icontains=search_query) |
                Q(student__email__icontains=search_query) |
                Q(course_id__in=matching_course_ids)
            ).annotate(
                search_relevance=Case(
                    When(student__fullname__icontains=search_query, then=Value(3)),
                    When(student__email__icontains=search_query, then=Value(2)),
                    When(course_id__in=matching_course_ids, then=Value(1)),
                    default=Value(0),
                    output_field=IntegerField()
                )
            )

        # Filters
        status_param = self.request.query_params.get('status', None)
        if status_param:
            queryset = queryset.filter(status=status_param)

        course_id = self.request.query_params.get('course', None)
        if course_id:
            queryset = queryset.filter(course_id=course_id)

        student_id = self.request.query_params.get('student', None)
        if student_id:
            queryset = queryset.filter(student_id=student_id)

        issued_date = self.request.query_params.get('issued_date', None)
        if issued_date:
            queryset = queryset.filter(created_at__date=issued_date)

        issued_after = self.request.query_params.get('issued_after', None)
        if issued_after:
            queryset = queryset.filter(created_at__date__gte=issued_after)

        issued_before = self.request.query_params.get('issued_before', None)
        if issued_before:
            queryset = queryset.filter(created_at__date__lte=issued_before)

        if has_search:
            return queryset.order_by('-search_relevance', '-created_at')
        return queryset.order_by('-created_at')