From 172ab5efdfc4a654700dcf9a36d96e29383d6f5e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Krier?= <ced@b2ck.com>
Date: Sun, 11 Oct 2020 16:12:36 +0200
Subject: [PATCH] Keep cost of unused input products

We set the average cost price of the input products as the unit price of the
output of the same product. This way the cost price computation for this
product does not change.

issue9637
review316051002
---
 CHANGELOG                              |  1 +
 production.py                          | 38 +++++++++++++++++++++++---
 tests/scenario_production_set_cost.rst | 25 ++++++++++-------
 3 files changed, 50 insertions(+), 14 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 67d93b272f..a611353c99 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,4 @@
+* Keep cost of unused input products
 * Use the shipment assign wizard for production
 * Rename production state from cancel to cancelled
 
diff --git a/production.py b/production.py
index 76dcc0e951..3beebf3a0f 100644
--- a/production.py
+++ b/production.py
@@ -1,5 +1,6 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
+from collections import defaultdict
 from decimal import Decimal
 from itertools import chain
 
@@ -529,7 +530,36 @@ class Production(ShipmentAssignMixin, Workflow, ModelSQL, ModelView):
         for production in productions:
             sum_ = Decimal(0)
             prices = {}
+            cost = production.cost
+
+            input_quantities = defaultdict(Decimal)
+            input_costs = defaultdict(Decimal)
+            for input_ in production.inputs:
+                if input_.cost_price is not None:
+                    cost_price = input_.cost_price
+                else:
+                    cost_price = input_.product.cost_price
+                input_quantities[input_.product] += (
+                    Decimal(str(input_.internal_quantity)))
+                input_costs[input_.product] += (
+                    Decimal(str(input_.internal_quantity)) * cost_price)
+            outputs = []
             for output in production.outputs:
+                product = output.product
+                if input_quantities.get(output.product):
+                    cost_price = (
+                        input_costs[product] / input_quantities[product])
+                    unit_price = round_price(Uom.compute_price(
+                            product.default_uom, cost_price, output.uom))
+                    if output.unit_price != unit_price:
+                        output.unit_price = unit_price
+                        moves.append(output)
+                    cost -= min(
+                        unit_price * Decimal(str(output.quantity)), cost)
+                else:
+                    outputs.append(output)
+
+            for output in outputs:
                 product = output.product
                 with Transaction().set_context(production._list_price_context):
                     list_price = product.list_price_used
@@ -541,7 +571,7 @@ class Production(ShipmentAssignMixin, Workflow, ModelSQL, ModelView):
 
             if not sum_ and production.product:
                 prices.clear()
-                for output in production.outputs:
+                for output in outputs:
                     if output.product == production.product:
                         quantity = Uom.compute_qty(
                             output.uom, output.quantity,
@@ -550,13 +580,13 @@ class Production(ShipmentAssignMixin, Workflow, ModelSQL, ModelView):
                         prices[output] = quantity
                         sum_ += quantity
 
-            for output in production.outputs:
+            for output in outputs:
                 if sum_:
                     ratio = prices.get(output, 0) / sum_
                 else:
-                    ratio = Decimal(1) / len(production.outputs)
+                    ratio = Decimal(1) / len(outputs)
                 quantity = Decimal(str(output.quantity))
-                unit_price = round_price(production.cost * ratio / quantity)
+                unit_price = round_price(cost * ratio / quantity)
                 if output.unit_price != unit_price:
                     output.unit_price = unit_price
                     moves.append(output)
diff --git a/tests/scenario_production_set_cost.rst b/tests/scenario_production_set_cost.rst
index 1fd245f91e..cc61dcaf4b 100644
--- a/tests/scenario_production_set_cost.rst
+++ b/tests/scenario_production_set_cost.rst
@@ -51,13 +51,13 @@ Create Bill of Material::
     >>> bom = BOM(name='product')
     >>> input = bom.inputs.new()
     >>> input.product = component
-    >>> input.quantity = 2
+    >>> input.quantity = 3
     >>> output = bom.outputs.new()
     >>> output.product = product
     >>> output.quantity = 1
     >>> bom.save()
 
-Make a production::
+Make a production with 2 unused component::
 
     >>> Production = Model.get('production')
     >>> production = Production()
@@ -67,15 +67,20 @@ Make a production::
     >>> production.click('wait')
     >>> production.click('assign_force')
     >>> production.click('run')
+    >>> output = production.outputs.new()
+    >>> output.product = component
+    >>> output.quantity = 2
+    >>> output.unit_price = Decimal(0)
+    >>> output.from_location = production.location
+    >>> output.to_location = production.warehouse.storage_location
     >>> production.click('done')
 
 Check output price::
 
     >>> production.cost
-    Decimal('20.0000')
-    >>> output, = production.outputs
-    >>> output.unit_price
-    Decimal('10.0000')
+    Decimal('30.0000')
+    >>> sorted([o.unit_price for o in production.outputs])
+    [Decimal('5.0000'), Decimal('10.0000')]
 
 
 Change cost of input::
@@ -97,9 +102,9 @@ Launch cron task::
     >>> cron_set_cost.companies.append(Company(company.id))
     >>> cron_set_cost.click('run_once')
 
-    >>> output.reload()
-    >>> output.unit_price
-    Decimal('12.0000')
-    >>> input.reload()
+    >>> production.reload()
+    >>> sorted([o.unit_price for o in production.outputs])
+    [Decimal('6.0000'), Decimal('12.0000')]
+    >>> input, = production.inputs
     >>> bool(input.production_cost_price_updated)
     False