class Line(PartBaseModel):
    line_id = models.IntegerField()
    radio_towers_number = models.IntegerField(blank=True)
    control_station_numbers = models.IntegerField(blank=True)
    railway_department = models.CharField(max_length=100)
    railway_carto_geo_center = models.CharField(max_length=100)
    status_type = models.SmallIntegerField(choices=[(i.value, i.name) for i in EngineerStatusChoice])
    radio_object_connection_length = models.FloatField()
    control_station_connection_length = models.FloatField()
    project = models.ForeignKey(Project, related_name='lines', on_delete=models.CASCADE)
    workers = models.ManyToManyField(User, through='Role')


class Role(models.Model):
    line = models.ForeignKey(Line, on_delete=models.CASCADE)
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    role = models.SmallIntegerField(choices=[(i.value, i.name) for i in UserRoleChoice])

    class Meta:
        unique_together = ('line', 'user', 'role')