Merge branch 'master' into spaces!

InvenTree/common/models.py

@@ -7,6 +7,8 @@ These models are 'generic' and do not fit a particular business logic object.
 from __future__ import unicode_literals
 
 import os
+import decimal
+import math
 
 from django.db import models, transaction
 from django.db.utils import IntegrityError, OperationalError
@@ -730,6 +732,72 @@ class PriceBreak(models.Model):
         return converted.amount
 
 
+def get_price(instance, quantity, moq=True, multiples=True, currency=None):
+    """ Calculate the price based on quantity price breaks.
+
+    - Don't forget to add in flat-fee cost (base_cost field)
+    - If MOQ (minimum order quantity) is required, bump quantity
+    - If order multiples are to be observed, then we need to calculate based on that, too
+    """
+
+    price_breaks = instance.price_breaks.all()
+
+    # No price break information available?
+    if len(price_breaks) == 0:
+        return None
+
+    # Check if quantity is fraction and disable multiples
+    multiples = (quantity % 1 == 0)
+
+    # Order multiples
+    if multiples:
+        quantity = int(math.ceil(quantity / instance.multiple) * instance.multiple)
+
+    pb_found = False
+    pb_quantity = -1
+    pb_cost = 0.0
+
+    if currency is None:
+        # Default currency selection
+        currency = InvenTreeSetting.get_setting('INVENTREE_DEFAULT_CURRENCY')
+
+    pb_min = None
+    for pb in instance.price_breaks.all():
+        # Store smallest price break
+        if not pb_min:
+            pb_min = pb
+
+        # Ignore this pricebreak (quantity is too high)
+        if pb.quantity > quantity:
+            continue
+
+        pb_found = True
+
+        # If this price-break quantity is the largest so far, use it!
+        if pb.quantity > pb_quantity:
+            pb_quantity = pb.quantity
+
+            # Convert everything to the selected currency
+            pb_cost = pb.convert_to(currency)
+
+    # Use smallest price break
+    if not pb_found and pb_min:
+        # Update price break information
+        pb_quantity = pb_min.quantity
+        pb_cost = pb_min.convert_to(currency)
+        # Trigger cost calculation using smallest price break
+        pb_found = True
+
+    # Convert quantity to decimal.Decimal format
+    quantity = decimal.Decimal(f'{quantity}')
+
+    if pb_found:
+        cost = pb_cost * quantity
+        return InvenTree.helpers.normalize(cost + instance.base_cost)
+    else:
+        return None
+
+
 class ColorTheme(models.Model):
     """ Color Theme Setting """