from django.db import models

from vbv_lernwelt.core.models import User
from vbv_lernwelt.course.models import CourseSessionUser


class LearningMentor(models.Model):
    mentor_email = models.EmailField(primary_key=True)
    mentor = models.OneToOneField(
        User, on_delete=models.SET_NULL, null=True, blank=True
    )

    students = models.ManyToManyField(CourseSessionUser, related_name="students")

    def __str__(self):
        return self.mentor_email

    @property
    def course_sessions(self):
        return self.students.values_list("course_session", flat=True).distinct()