from decimal import Decimal

from django.db import models
from django.urls import reverse
from django.utils.text import slugify

from core.models import StoredFile, 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)
    image = models.ForeignKey(
        StoredFile,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="shop_products",
        help_text="Listing photo; synced from the first gallery image.",
    )
    stl = models.ForeignKey(
        StoredFile,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="shop_product_stls",
        help_text="Print mesh stored as a database blob (not filesystem media).",
    )
    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 image_url(self) -> str:
        if not self.image_id:
            return ""
        return reverse("core:stored_file", kwargs={"pk": self.image_id})

    @property
    def stl_url(self) -> str:
        if not self.stl_id:
            return ""
        return reverse("core:stored_file", kwargs={"pk": self.stl_id})

    @property
    def catalog_images(self) -> list["ProductImage"]:
        return [item for item in self.images.all() if item.color_id is None]

    @property
    def display_stock_qty(self) -> int:
        colors = list(self.colors.all())
        if colors:
            return sum(item.stock_qty for item in colors)
        return self.stock_qty

    def photos_for(self, color: "ProductColor | None" = None) -> list["ProductImage"]:
        images = list(self.images.all())
        if color is not None:
            colored = [item for item in images if item.color_id == color.pk]
            if colored:
                return colored
        return [item for item in images if item.color_id is None]

    def photo_urls_for(self, color: "ProductColor | None" = None) -> list[str]:
        photos = self.photos_for(color)
        if photos:
            return [item.url for item in photos]
        if self.image_id:
            return [self.image_url]
        return []

    def gallery_items(self, color: "ProductColor | None" = None) -> list[dict]:
        photos = self.photo_urls_for(color)
        items: list[dict] = []
        if photos:
            items.append({"kind": "photo", "url": photos[0]})
            if self.stl_id:
                items.append({"kind": "model", "url": self.stl_url})
            items.extend({"kind": "photo", "url": url} for url in photos[1:])
        elif self.stl_id:
            items.append({"kind": "model", "url": self.stl_url})
        return items

    @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 ProductColor(UUIDPrimaryKeyModel, TimeStampedModel):
    product = models.ForeignKey(
        Product, on_delete=models.CASCADE, related_name="colors"
    )
    name = models.CharField(max_length=64)
    hex = models.CharField(max_length=7, default="#808080")
    stock_qty = models.IntegerField(default=0)
    sort_order = models.PositiveIntegerField(default=0)

    class Meta:
        ordering = ["sort_order", "name"]

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

    @property
    def image_url(self) -> str:
        photos = list(self.images.all())
        if photos:
            return photos[0].url
        return ""


class ProductImage(UUIDPrimaryKeyModel, TimeStampedModel):
    product = models.ForeignKey(
        Product, on_delete=models.CASCADE, related_name="images"
    )
    color = models.ForeignKey(
        ProductColor,
        null=True,
        blank=True,
        on_delete=models.CASCADE,
        related_name="images",
    )
    file = models.ForeignKey(
        StoredFile,
        on_delete=models.CASCADE,
        related_name="shop_gallery_images",
    )
    sort_order = models.PositiveIntegerField(default=0)

    class Meta:
        ordering = ["sort_order", "created_at"]

    def __str__(self) -> str:
        return self.file.filename or str(self.pk)

    @property
    def url(self) -> str:
        return reverse("core:stored_file", kwargs={"pk": self.file_id})


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",
    )
    color = models.ForeignKey(
        ProductColor,
        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)
    color_name = models.CharField(max_length=64, blank=True)
    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