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)


class AdminCertificateSerializer(serializers.ModelSerializer):
    student_name = serializers.CharField(source='student.fullname', read_only=True)
    student_email = serializers.CharField(source='student.email', read_only=True)
    course_title = serializers.SerializerMethodField()

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

    def get_course_title(self, obj):
        if not obj.course:
            return None
        request = self.context.get('request')
        lang = getattr(request, 'LANGUAGE_CODE', None) or 'en'
        from apps.course.models.course import get_localized_field
        return get_localized_field(lang, obj.course.title)