from django.db import models
from django.db.models.signals import post_save, post_delete
from django.dispatch import receiver
from Accounts.models import Profile
from Boxes.models import MysteryBox
from django.utils.crypto import get_random_string
from django.utils.timezone import now


class Cart(models.Model):
    user = models.OneToOneField(Profile, on_delete=models.CASCADE, related_name="cart")
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return f"Cart of {self.user.user.email}"

    @property
    def total_amount(self):
        return sum(item.subtotal for item in self.items.all())


class CartItem(models.Model):
    cart = models.ForeignKey(Cart, on_delete=models.CASCADE, related_name="items")
    box = models.ForeignKey(MysteryBox, on_delete=models.CASCADE)
    quantity = models.PositiveIntegerField(default=1)

    def __str__(self):
        return f"{self.quantity} × {self.box.title}"

    @property
    def subtotal(self):
        return (self.box.price or 0) * (self.quantity or 0)


class Order(models.Model):
    STATUS_CHOICES = [
        ("pending", "Pending"),
        ("paid", "Paid"),
        ("shipped", "Shipped"),
        ("delivered", "Delivered"),
        ("cancelled", "Cancelled"),
    ]

    user = models.ForeignKey(Profile, on_delete=models.CASCADE, related_name="orders")
    order_number = models.CharField(max_length=50, unique=True, editable=False)
    total_amount = models.DecimalField(max_digits=10, decimal_places=2, default=0.00)
    status = models.CharField(max_length=20, choices=STATUS_CHOICES, default="pending")
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return f"Order {self.order_number} ({self.user.user.email})"

    def save(self, *args, **kwargs):
        # Auto-generate order number if missing
        if not self.order_number:
            self.order_number = f"ORD{now().strftime('%Y%m%d')}{get_random_string(5).upper()}"
        super().save(*args, **kwargs)


class OrderItem(models.Model):
    order = models.ForeignKey(Order, on_delete=models.CASCADE, related_name="items")
    box = models.ForeignKey(MysteryBox, on_delete=models.CASCADE)
    quantity = models.PositiveIntegerField(default=1)
    unit_price = models.DecimalField(max_digits=10, decimal_places=2, default=0.00)

    def __str__(self):
        return f"{self.quantity} × {self.box.title}"

    @property
    def subtotal(self):
        return (self.unit_price or 0) * (self.quantity or 0)


class Payment(models.Model):
    METHOD_CHOICES = [
        ("stripe", "Stripe"),
        ("paypal", "PayPal"),
        ("razorpay", "Razorpay"),
        ("cod", "Cash on Delivery"),
    ]
    STATUS_CHOICES = [
        ("pending", "Pending"),
        ("successful", "Successful"),
        ("failed", "Failed"),
    ]

    order = models.OneToOneField(Order, on_delete=models.CASCADE, related_name="payment")
    payment_method = models.CharField(max_length=20, choices=METHOD_CHOICES, default="cod")
    transaction_id = models.CharField(max_length=150, blank=True, null=True)
    status = models.CharField(max_length=20, choices=STATUS_CHOICES, default="pending")
    paid_at = models.DateTimeField(blank=True, null=True)

    def __str__(self):
        return f"Payment {self.status} - {self.order.order_number}"


# 🔹 Signals to auto-update Order total when OrderItems change
@receiver([post_save, post_delete], sender=OrderItem)
def update_order_total(sender, instance, **kwargs):
    order = instance.order
    order.total_amount = sum(item.subtotal for item in order.items.all())
    order.save(update_fields=["total_amount"])