from django.db import models
from django.core.validators import MinValueValidator
from django_softdelete.models import SoftDeleteModel
from rest_framework.exceptions import ValidationError

from authentication.models import ToolshedUser, KnownIdentity
from files.models import File


class Category(SoftDeleteModel):
    name = models.CharField(max_length=255, unique=True)
    description = models.TextField(null=True, blank=True)
    parent = models.ForeignKey('self', on_delete=models.CASCADE, null=True, blank=True, related_name='children')
    origin = models.CharField(max_length=255, null=False, blank=False)

    class Meta:
        verbose_name_plural = 'categories'

    def __str__(self):
        parent = str(self.parent) + "/" if self.parent else ""
        return parent + self.name


class Property(models.Model):
    name = models.CharField(max_length=255)
    description = models.TextField(null=True, blank=True)
    category = models.ForeignKey(Category, on_delete=models.CASCADE, null=True, blank=True, related_name='properties')
    unit_symbol = models.CharField(max_length=16, null=True, blank=True)
    unit_name = models.CharField(max_length=255, null=True, blank=True)
    unit_name_plural = models.CharField(max_length=255, null=True, blank=True)
    base2_prefix = models.BooleanField(default=False)
    dimensions = models.IntegerField(null=False, blank=False, default=1, validators=[MinValueValidator(1)])
    origin = models.CharField(max_length=255, null=False, blank=False)

    class Meta:
        verbose_name_plural = 'properties'

    def __str__(self):
        return self.name


class Tag(models.Model):
    name = models.CharField(max_length=255)
    description = models.TextField(null=True, blank=True)
    category = models.ForeignKey(Category, on_delete=models.CASCADE, null=True, blank=True, related_name='tags')
    origin = models.CharField(max_length=255, null=False, blank=False)

    def __str__(self):
        return self.name


class InventoryItem(SoftDeleteModel):
    published = models.BooleanField(default=False)
    name = models.CharField(max_length=255, null=True, blank=True)
    description = models.TextField(null=True, blank=True)
    category = models.ForeignKey(Category, on_delete=models.CASCADE, null=True, blank=True,
                                 related_name='inventory_items')
    availability_policy = models.CharField(max_length=255, default="private")
    owned_quantity = models.IntegerField(default=1, validators=[MinValueValidator(0)])
    owner = models.ForeignKey(ToolshedUser, on_delete=models.CASCADE, related_name='inventory_items')
    created_at = models.DateTimeField(auto_now_add=True)
    tags = models.ManyToManyField(Tag, through='ItemTag', related_name='inventory_items')
    properties = models.ManyToManyField(Property, through='ItemProperty')
    files = models.ManyToManyField(File, related_name='connected_items')

    def clean(self):
        if (self.name is None or self.name == "") and self.files.count() == 0:
            raise ValidationError("Name or at least one file must be set")


class ItemProperty(models.Model):
    property = models.ForeignKey(Property, on_delete=models.CASCADE)
    inventory_item = models.ForeignKey(InventoryItem, on_delete=models.CASCADE)
    value = models.CharField(max_length=255)


class ItemTag(models.Model):
    tag = models.ForeignKey(Tag, on_delete=models.CASCADE)
    inventory_item = models.ForeignKey(InventoryItem, on_delete=models.CASCADE)