add discount models

hub/services/models.py

@@ -508,6 +508,68 @@ class VSHNAppCatBaseFee(models.Model):
         return f"{self.vshn_appcat_price_config.service.name} Base Fee - {self.amount} {self.currency}"
 
 
+class ProgressiveDiscountModel(models.Model):
+    name = models.CharField(max_length=100)
+    description = models.TextField(blank=True)
+    active = models.BooleanField(default=True)
+
+    def __str__(self):
+        return self.name
+
+    def calculate_discount(self, base_rate, units):
+        """Calculate price using progressive percentage discounts."""
+        final_price = 0
+        remaining_units = units
+        processed_units = 0
+
+        # Get all tiers sorted by threshold
+        discount_tiers = self.tiers.all().order_by("threshold")
+
+        for i, tier in enumerate(discount_tiers):
+            # Calculate how many units fall into this tier
+            if i < discount_tiers.count() - 1:
+                next_threshold = discount_tiers[i + 1].threshold
+                tier_units = min(remaining_units, next_threshold - processed_units)
+            else:
+                # Last tier handles all remaining units
+                tier_units = remaining_units
+
+            # Calculate discounted rate for this tier
+            discounted_rate = base_rate * (1 - tier.discount_percent / 100)
+
+            # Add the price for units in this tier
+            final_price += discounted_rate * tier_units
+
+            # Update tracking variables
+            remaining_units -= tier_units
+            processed_units += tier_units
+
+            # Exit if all units have been processed
+            if remaining_units <= 0:
+                break
+
+        return final_price
+
+
+class DiscountTier(models.Model):
+    discount_model = models.ForeignKey(
+        ProgressiveDiscountModel, on_delete=models.CASCADE, related_name="tiers"
+    )
+    threshold = models.PositiveIntegerField(
+        help_text="Starting unit count for this tier"
+    )
+    discount_percent = models.DecimalField(
+        max_digits=5, decimal_places=2, help_text="Percentage discount applied (0-100)"
+    )
+
+    class Meta:
+        ordering = ["threshold"]
+        unique_together = ["discount_model", "threshold"]
+
+    def __str__(self):
+        return f"{self.discount_model.name}: {self.threshold}+ units → {self.discount_percent}% discount"
+
+
 class VSHNAppCatPrice(models.Model):
     class VariableUnit(models.TextChoices):
         RAM = "RAM", "Memory (RAM)"
@@ -538,6 +600,17 @@ class VSHNAppCatPrice(models.Model):
         choices=Term.choices,
     )
 
+    valid_from = models.DateTimeField(blank=True, null=True)
+    valid_to = models.DateTimeField(blank=True, null=True)
+
+    discount_model = models.ForeignKey(
+        ProgressiveDiscountModel,
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name="price_configs",
+    )
+
     def __str__(self):
         return f"{self.service.name} - {self.get_variable_unit_display()} based pricing"
 
@@ -567,7 +640,15 @@ class VSHNAppCatPrice(models.Model):
         if number_of_units < 0:
             raise ValueError("Number of units cannot be negative")
 
-        total_price = base_fee + (unit_rate * number_of_units)
+        # Apply discount model if available
+        if self.discount_model and self.discount_model.active:
+            discounted_price = self.discount_model.calculate_discount(
+                unit_rate, number_of_units
+            )
+            total_price = base_fee + discounted_price
+        else:
+            total_price = base_fee + (unit_rate * number_of_units)
+
         return total_price