from decimal import Decimal

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)
    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