from django.db import models

from mptt.models import MPTTModel, TreeForeignKey


class Category(MPTTModel):
    parent = TreeForeignKey("self", null=True, blank=True, related_name='children',
                            db_index=True, verbose_name='catégorie parente', on_delete=models.CASCADE)
    name = models.CharField(max_length=64)

    class MPTTMeta:
        order_insertion_by = ['name']

    class Meta:
        verbose_name = 'Catégorie'

    def __str__(self):
        return self.name


class Location(models.Model):
    name = models.CharField(max_length=64)

    class Meta:
        verbose_name = 'Emplacement'

    def __str__(self):
        return self.name


class Equipment(models.Model):
    category = TreeForeignKey(Category, verbose_name='catégorie', on_delete=models.CASCADE)
    quantity = models.PositiveIntegerField(default=0, verbose_name='quantité')
    location = models.ForeignKey(Location, verbose_name='emplacement', on_delete=models.CASCADE)

    class Meta:
        verbose_name = 'Équipement'
        unique_together = (
            ('category', 'location',),
        )

    def __str__(self):
        return '%d %s à %s' % (self.quantity, self.category, self.location)