from django.db import models
from datetime import timedelta, date

class Nomenclature(models.Model):
    name = models.CharField(max_length=255)
    gtin = models.CharField(max_length=14, unique=True)
    unit = models.CharField(max_length=50, default="шт")

    def __str__(self):
        return self.name


class Sticker(models.Model):
    nomenclature = models.ForeignKey("Nomenclature", on_delete=models.CASCADE)
    quantity = models.IntegerField()
    emission_date = models.DateField()
    last_revision_date = models.DateField(null=True, blank=True)
    location = models.CharField(max_length=255)
    status = models.CharField(max_length=255, default="в наличии")

    def is_expired(self):
        """Проверяем, истёк ли срок годности (1 год)"""
        if not self.emission_date:
            return False
        expiration_date = self.emission_date + timedelta(days=365)  # 12 месяцев
        return date.today() > expiration_date

    def save(self, *args, **kwargs):
        """При сохранении автоматически обновляем статус"""
        if self.is_expired():
            self.status = "просрочены"
        elif self.is_expiring_soon():
            self.status = "скоро истекает"
        else:
            self.status = "в наличии"
        super().save(*args, **kwargs)

    def is_expiring_soon(self):
        """Срок годности истекает через 1 месяц"""
        if not self.emission_date:
            return False
        expiration_date = self.emission_date + timedelta(days=365)
        return expiration_date - timedelta(days=30) <= date.today() < expiration_date


class StickerMovement(models.Model):
    sticker = models.ForeignKey(Sticker, on_delete=models.CASCADE)
    date = models.DateTimeField(auto_now_add=True)
    from_location = models.CharField(max_length=50)
    to_location = models.CharField(max_length=50)
    quantity = models.IntegerField()

    def save(self, *args, **kwargs):
        if self.from_location == "склад" and self.to_location == "цех":
            self.sticker.location = "цех"
        elif self.to_location == "склад":
            self.sticker.location = "склад"
        self.sticker.save()
        super().save(*args, **kwargs)