from django.db import models

from apps.core.models import TimeStampedModel, UUIDModel


class Payment(UUIDModel, TimeStampedModel):
    class Status(models.TextChoices):
        PENDING = "pending", "Pending"
        SUCCESS = "success", "Success"
        FAILED = "failed", "Failed"
        CANCELLED = "cancelled", "Cancelled"

    # A payment targets either a reservation (upfront) or a processing order.
    reservation = models.ForeignKey(
        "reservations.Reservation", null=True, blank=True, on_delete=models.PROTECT, related_name="payments"
    )
    order = models.ForeignKey(
        "orders.ProcessingOrder", null=True, blank=True, on_delete=models.PROTECT, related_name="payments"
    )
    amount = models.DecimalField(max_digits=18, decimal_places=2)
    currency = models.CharField(max_length=8, default="IRR")
    gateway = models.CharField(max_length=40)
    transaction_id = models.CharField(max_length=120)
    authority = models.CharField(max_length=120, blank=True)
    status = models.CharField(max_length=12, choices=Status.choices, default=Status.PENDING)
    request_time = models.DateTimeField(null=True, blank=True)
    callback_time = models.DateTimeField(null=True, blank=True)
    verification_time = models.DateTimeField(null=True, blank=True)
    error = models.TextField(blank=True)

    class Meta:
        constraints = [
            models.UniqueConstraint(fields=["gateway", "transaction_id"], name="uniq_gateway_transaction"),
            models.CheckConstraint(
                condition=models.Q(order__isnull=False) | models.Q(reservation__isnull=False),
                name="payment_has_target",
            ),
        ]

    def __str__(self) -> str:
        return f"{self.gateway}:{self.transaction_id}"