from decimal import Decimal

from django.conf import settings
from django.core.validators import MaxValueValidator, MinValueValidator
from django.db import models
from django.urls import reverse
from django.utils.text import slugify

from core.models import TimeStampedModel, UUIDPrimaryKeyModel


class Product(UUIDPrimaryKeyModel, TimeStampedModel):
    class Fulfillment(models.TextChoices):
        STOCKED = "stocked", "On-hand stock"
        MADE_TO_ORDER = "made_to_order", "Made to order"

    name = models.CharField(max_length=200)
    slug = models.SlugField(max_length=220, unique=True)
    sku = models.CharField(max_length=64, unique=True)
    description = models.TextField(blank=True)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    currency = models.CharField(max_length=8, default="usd")
    fulfillment = models.CharField(
        max_length=16,
        choices=Fulfillment.choices,
        default=Fulfillment.STOCKED,
    )
    stock_qty = models.IntegerField(default=0)
    print_minutes = models.PositiveIntegerField(
        default=0,
        help_text="Estimated print time per unit (made-to-order).",
    )
    filament_grams = models.PositiveIntegerField(default=0)
    is_published = models.BooleanField(default=False)
    track_inventory = models.BooleanField(default=True)

    class Meta:
        ordering = ["name"]

    def __str__(self) -> str:
        return f"{self.name} ({self.sku})"

    def get_absolute_url(self) -> str:
        return reverse("shop:detail", kwargs={"slug": self.slug})

    @property
    def amount_cents(self) -> int:
        return int((self.price * Decimal("100")).quantize(Decimal("1")))

    def save(self, *args, **kwargs):
        if not self.slug:
            base = slugify(self.name)[:200] or "product"
            slug = base
            n = 2
            while Product.objects.filter(slug=slug).exclude(pk=self.pk).exists():
                slug = f"{base}-{n}"
                n += 1
            self.slug = slug
        if not self.sku:
            self.sku = (self.slug or "sku").upper().replace("-", "")[:64]
        super().save(*args, **kwargs)


class Order(UUIDPrimaryKeyModel, TimeStampedModel):
    class Status(models.TextChoices):
        DRAFT = "draft", "Draft"
        OPEN = "open", "Open"
        PAID = "paid", "Paid"
        FULFILLED = "fulfilled", "Fulfilled"
        CANCELLED = "cancelled", "Cancelled"

    number = models.CharField(max_length=32, unique=True)
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="shop_orders",
    )
    email = models.EmailField()
    customer_name = models.CharField(max_length=200, blank=True)
    status = models.CharField(
        max_length=16, choices=Status.choices, default=Status.DRAFT
    )
    amount = models.DecimalField(max_digits=10, decimal_places=2, default=Decimal("0"))
    currency = models.CharField(max_length=8, default="usd")
    shipping_address = models.JSONField(default=dict, blank=True)
    stripe_checkout_session_id = models.CharField(max_length=255, blank=True)
    hosted_checkout_url = models.URLField(blank=True)
    paid_at = models.DateTimeField(null=True, blank=True)
    notes = models.TextField(blank=True)

    class Meta:
        ordering = ["-created_at"]

    def __str__(self) -> str:
        return f"{self.number} · {self.email} · {self.amount}"

    @property
    def amount_cents(self) -> int:
        return int((self.amount * Decimal("100")).quantize(Decimal("1")))


class OrderItem(UUIDPrimaryKeyModel, TimeStampedModel):
    order = models.ForeignKey(Order, on_delete=models.CASCADE, related_name="items")
    product = models.ForeignKey(
        Product,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="order_items",
    )
    name = models.CharField(max_length=200)
    sku = models.CharField(max_length=64)
    quantity = models.PositiveIntegerField(default=1)
    unit_price = models.DecimalField(max_digits=10, decimal_places=2)
    print_minutes = models.PositiveIntegerField(default=0)

    class Meta:
        ordering = ["created_at"]

    def __str__(self) -> str:
        return f"{self.quantity}× {self.name}"

    @property
    def line_total(self) -> Decimal:
        return self.unit_price * self.quantity


class ProductReview(UUIDPrimaryKeyModel, TimeStampedModel):
    product = models.ForeignKey(
        Product, on_delete=models.CASCADE, related_name="reviews"
    )
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="product_reviews",
    )
    order = models.ForeignKey(
        Order, on_delete=models.CASCADE, related_name="reviews"
    )
    rating = models.PositiveSmallIntegerField(
        validators=[MinValueValidator(1), MaxValueValidator(5)]
    )
    title = models.CharField(max_length=120, blank=True)
    body = models.TextField(blank=True)

    class Meta:
        ordering = ["-created_at"]
        constraints = [
            models.UniqueConstraint(
                fields=["user", "product"],
                name="shop_review_user_product",
            ),
            models.CheckConstraint(
                condition=models.Q(rating__gte=1) & models.Q(rating__lte=5),
                name="shop_review_rating_range",
            ),
        ]

    def __str__(self) -> str:
        return f"{self.rating}★ {self.product.name}"