from django.db import models

from apps.core.models import TimeStampedModel, UUIDModel


class PricingRule(UUIDModel, TimeStampedModel):
    class RuleType(models.TextChoices):
        FIXED = "fixed", "Fixed"
        PER_KG = "per_kg", "Per kilogram"
        PER_UNIT = "per_unit", "Per unit"
        PERCENTAGE = "percentage", "Percentage"
        TIERED = "tiered", "Tiered"
        DISCOUNT = "discount", "Discount"
        TAX = "tax", "Tax"
        FEE = "fee", "Additional fee"

    step = models.ForeignKey(
        "workflows.WorkflowStep", on_delete=models.CASCADE, related_name="pricing_rules"
    )
    name = models.CharField(max_length=200)
    rule_type = models.CharField(max_length=16, choices=RuleType.choices)
    # Base amount. Meaning depends on rule_type:
    #   fixed/per_kg/per_unit -> money; percentage/discount/tax -> percent.
    amount = models.DecimalField(max_digits=18, decimal_places=2, default=0)
    config = models.JSONField(default=dict, blank=True)
    active = models.BooleanField(default=True)
    priority = models.IntegerField(default=0)

    class Meta:
        ordering = ["priority"]

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