from rest_framework import serializers
from apps.certificate.models import Certificate
from apps.course.serializers import CourseDetailSerializer
from django.conf import settings



class CertificateSerializer(serializers.ModelSerializer):
    course = serializers.SerializerMethodField()
    certificate_file = serializers.SerializerMethodField()

    class Meta:
        model = Certificate
        fields = ['id', 'student', 'course', 'status', 'created_at', 'updated_at', 'certificate_file']
        read_only_fields = ['id', 'student', 'status', 'created_at', 'updated_at',]

    def get_course(self, obj):
        return CourseDetailSerializer(obj.course, context=self.context).data

    def get_certificate_file(self, obj):
        if obj.certificate_file:
            request = self.context.get('request')
            if request is not None:
                return request.build_absolute_uri(obj.certificate_file.url)
            return obj.certificate_file.url
        return None




class CertificateRequestSerializer(serializers.ModelSerializer):
    class Meta:
        model = Certificate
        fields = ['id', 'course']
        read_only_fields = ['id']

    def create(self, validated_data):
        user = self.context['request'].user
        course = validated_data['course']

        if Certificate.objects.filter(student=user, course=course, status__in=['pending', 'approved']).exists():
            raise serializers.ValidationError({
                "course": "A certificate request for this course is already pending or approved."
            })
        return Certificate.objects.create(student=user, course=course)