from django.db import models


class BoxType(models.Model):
    """A type of storage box with specific dimensions."""

    name = models.CharField(max_length=255)
    width = models.PositiveIntegerField(help_text='Width in millimeters')
    height = models.PositiveIntegerField(help_text='Height in millimeters')
    length = models.PositiveIntegerField(help_text='Length in millimeters')

    class Meta:
        ordering = ['name']

    def __str__(self):
        return self.name


class Box(models.Model):
    """A storage box in the lab."""

    id = models.CharField(
        max_length=10,
        primary_key=True,
        help_text='Alphanumeric identifier (max 10 characters)'
    )
    box_type = models.ForeignKey(
        BoxType,
        on_delete=models.PROTECT,
        related_name='boxes'
    )

    class Meta:
        verbose_name_plural = 'boxes'

    def __str__(self):
        return self.id