from django.conf import settings
from django.core.validators import MinValueValidator
from django.db import models

from items.models import Item


class Cart(models.Model):
    user = models.OneToOneField(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="cart",
        verbose_name="Пользователь",
    )
    created_at = models.DateTimeField(auto_now_add=True, verbose_name="Дата создания")
    updated_at = models.DateTimeField(auto_now=True, verbose_name="Дата обновления")

    class Meta:
        verbose_name = "Корзина"
        verbose_name_plural = "Корзины"

    def __str__(self):
        return f"Корзина пользователя {self.user}"


class CartItem(models.Model):
    cart = models.ForeignKey(
        Cart,
        on_delete=models.CASCADE,
        related_name="items",
        verbose_name="Корзина",
    )
    item = models.ForeignKey(
        Item,
        on_delete=models.CASCADE,
        related_name="cart_entries",
        verbose_name="Товар",
    )
    quantity = models.PositiveIntegerField(
        validators=[MinValueValidator(1)],
        verbose_name="Количество",
    )
    created_at = models.DateTimeField(auto_now_add=True, verbose_name="Дата создания")
    updated_at = models.DateTimeField(auto_now=True, verbose_name="Дата обновления")

    class Meta:
        ordering = ("created_at", "id")
        constraints = [
            models.UniqueConstraint(fields=("cart", "item"), name="unique_cart_item_per_cart"),
        ]
        verbose_name = "Позиция корзины"
        verbose_name_plural = "Позиции корзины"

    def __str__(self):
        return f"{self.item} x {self.quantity}"

    @property
    def subtotal(self):
        return self.item.price * self.quantity


class Order(models.Model):
    class DeliveryMethod(models.TextChoices):
        COURIER = "courier", "Курьерская доставка"
        PICKUP = "pickup", "Самовывоз"

    class PaymentMethod(models.TextChoices):
        CARD = "card", "Банковская карта"
        CREDIT = "credit", "Кредит"
        INSTALLMENT = "installment", "Рассрочка"

    class Status(models.TextChoices):
        PAID = "paid", "Оплачен"

    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="orders",
        verbose_name="Пользователь",
    )
    customer_name = models.CharField(max_length=255, verbose_name="ФИО")
    phone = models.CharField(max_length=32, verbose_name="Телефон")
    email = models.EmailField(verbose_name="E-mail")
    delivery_method = models.CharField(
        max_length=16,
        choices=DeliveryMethod.choices,
        default=DeliveryMethod.COURIER,
        verbose_name="Способ доставки",
    )
    region = models.CharField(max_length=255, blank=True, verbose_name="Регион")
    address = models.CharField(max_length=512, blank=True, verbose_name="Адрес")
    payment_method = models.CharField(
        max_length=16,
        choices=PaymentMethod.choices,
        default=PaymentMethod.CARD,
        verbose_name="Способ оплаты",
    )
    promo_code = models.CharField(max_length=64, blank=True, verbose_name="Промокод")
    products_total = models.DecimalField(max_digits=10, decimal_places=2, verbose_name="Сумма товаров")
    discount_total = models.DecimalField(max_digits=10, decimal_places=2, default=0, verbose_name="Скидка")
    delivery_total = models.DecimalField(max_digits=10, decimal_places=2, default=0, verbose_name="Доставка")
    floor_lift_total = models.DecimalField(max_digits=10, decimal_places=2, default=0, verbose_name="Подъём на этаж")
    total = models.DecimalField(max_digits=10, decimal_places=2, verbose_name="Итого к оплате")
    status = models.CharField(
        max_length=16,
        choices=Status.choices,
        default=Status.PAID,
        verbose_name="Статус",
    )
    created_at = models.DateTimeField(auto_now_add=True, verbose_name="Дата создания")

    class Meta:
        ordering = ("-created_at", "-id")
        verbose_name = "Заказ"
        verbose_name_plural = "Заказы"

    def __str__(self):
        return f"Заказ №{self.pk}"


class OrderItem(models.Model):
    order = models.ForeignKey(
        Order,
        on_delete=models.CASCADE,
        related_name="items",
        verbose_name="Заказ",
    )
    item = models.ForeignKey(
        Item,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="order_entries",
        verbose_name="Товар",
    )
    item_name = models.CharField(max_length=255, verbose_name="Название товара")
    item_slug = models.SlugField(blank=True, verbose_name="URL товара")
    item_price = models.DecimalField(max_digits=10, decimal_places=2, verbose_name="Цена товара")
    quantity = models.PositiveIntegerField(validators=[MinValueValidator(1)], verbose_name="Количество")
    line_total = models.DecimalField(max_digits=10, decimal_places=2, verbose_name="Сумма строки")

    class Meta:
        ordering = ("id",)
        verbose_name = "Позиция заказа"
        verbose_name_plural = "Позиции заказа"

    def __str__(self):
        return f"{self.item_name} x {self.quantity}"