Inventory: add lowest_value_test for getInventoryAssetPrice

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/Resource_zGetAssetPrice.sql

@@ -9,7 +9,7 @@ during each period.
 Then perform a weighted average over all periods.
 */
 
-set @total_asset_price=0, @total_quantity=0
+set @total_asset_price=0.0, @total_quantity=0.0
 <dtml-var sql_delimiter>
 select
     byperiod.*,
@@ -45,19 +45,28 @@ order by d_year<dtml-if "'Monthly' in valuation_method">, d_month</dtml-if>
 Very similar to (Monthly)WeightedAverage except that we do not have to
 split the timeframe / fold movements and simply perform a weighted average
 on all single movements.
+
+Parameter lowest_value_test compares latest price and Moving average price and takes the
+smallest one.
 */
 
-set @total_asset_price=0, @total_quantity=0
+SET @total_asset_price=0, @total_quantity=0, @latest_price=null, @running_total_asset_price=0
 <dtml-var sql_delimiter>
 select
     (@incoming_total_price:=IF(quantity>0, total_price, 0)) as incoming_total_price,
+    @latest_price:=IF(quantity>0, total_price/quantity, @latest_price) as latest_price,
 
     @unit_price:=((@total_asset_price+@incoming_total_price)/(@total_quantity+GREATEST(0, quantity))) as unit_price,
-    (@total_asset_price:=
-        @total_asset_price +
+    (@running_total_asset_price:=
+        @running_total_asset_price +
         @incoming_total_price +
-        LEAST(0, quantity) * @unit_price) as total_asset_price,
-    (@total_quantity:=@total_quantity+quantity) as dummy
+        LEAST(0, quantity) * @unit_price) as running_total_asset_price,
+    (@total_quantity:=@total_quantity+quantity) as dummy,
+    <dtml-if "lowest_value_test">
+     (@total_asset_price:=LEAST(@running_total_asset_price, @total_quantity*@latest_price)) as total_asset_price
+    <dtml-else>
+     (@total_asset_price:= @running_total_asset_price) as total_asset_price
+    </dtml-if>
 from
    stock, catalog
 where
@@ -93,6 +102,9 @@ Thus, each movement has a value of:
 if @unbalanced_output is initialized to @total_output_quantity and reduced by
 quantity at each step:
   unbalanced_output=max(0, unbalanced_output-quantity)
+
+Parameter lowest_value_test compares latest price and FIFO price and takes the
+smallest one.
 */
 SET
  @unbalanced_output:=
@@ -105,15 +117,26 @@ SET
     AND
       <dtml-var where_expression>
     ),0),
- @total_asset_price=0
+ @total_asset_price=0.0,
+ @running_total_asset_price=0.0,
+ @running_quantity=0.0
 <dtml-var sql_delimiter>
 
 SELECT
 
- (@total_asset_price:=@total_asset_price + 
+ (@running_quantity:=@running_quantity +
+   GREATEST(0, quantity-@unbalanced_output)
+ ) AS running_quantity,
+ (@running_total_asset_price:=@running_total_asset_price +
    GREATEST(0, (quantity-@unbalanced_output) * total_price/quantity)
- ) AS total_asset_price,
- (@unbalanced_output:=GREATEST(0, @unbalanced_output-quantity)) as dummy
+ ) AS running_total_asset_price,
+ (@unbalanced_output:=GREATEST(0, @unbalanced_output-quantity)) as dummy,
+ <dtml-if "lowest_value_test">
+  (@total_asset_price:=LEAST(@running_total_asset_price,
+                             @running_quantity * total_price/quantity)) as total_asset_price
+ <dtml-else>
+  (@total_asset_price:= @running_total_asset_price) as total_asset_price
+ </dtml-if>
 
 FROM
  stock, catalog
@@ -148,15 +171,26 @@ until we reach an incoming movement. Then:
    movement got out of inventory between t=current and T=END. These items are not
    present in the final inventory and can be discarded.
    @unbalanced_inventory=@unbalanced_inventory - quantity
+
+Parameter lowest_value_test compares latest price and FILO price and takes the
+smallest one.
+
 */
 
-SET @unbalanced_output=0, @total_asset_price=0
+SET @unbalanced_output=0.0, @total_asset_price=0.0, @running_total_asset_price=0.0, @latest_price=null, @running_quantity=0.0
 <dtml-var sql_delimiter>
 SELECT
-  (@total_asset_price:=@total_asset_price +
+  (IF(quantity <= 0, @latest_price, @latest_price:=IFNULL(@latest_price, total_price/quantity))) as dummy_latest_price,
+  (@running_total_asset_price:=@running_total_asset_price +
     IF(quantity <= 0, 0,
-    total_price/quantity * GREATEST(0, quantity-@unbalanced_output))) as total_asset_price,
-  (@unbalanced_output:=GREATEST(0, @unbalanced_output-quantity)) as dummy
+    total_price/quantity * GREATEST(0, quantity-@unbalanced_output))) as running_total_asset_price,
+  (@unbalanced_output:=GREATEST(0, @unbalanced_output-quantity)) as dummy,
+  (@running_quantity:=@running_quantity + quantity) as running_quantity,
+  <dtml-if "lowest_value_test">
+   (@total_asset_price:=LEAST(@running_total_asset_price, @running_quantity*@latest_price)) as total_asset_price
+  <dtml-else>
+   (@total_asset_price:= @running_total_asset_price) as total_asset_price
+  </dtml-if>
 FROM
  stock, catalog
 WHERE

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/Resource_zGetAssetPrice.xml

@@ -9,7 +9,9 @@
         <item>
             <key> <string>arguments_src</string> </key>
             <value> <string>where_expression\n
-valuation_method</string> </value>
+valuation_method\n
+lowest_value_test\n
+</string> </value>
         </item>
         <item>
             <key> <string>connection_id</string> </key>

product/ERP5/bootstrap/erp5_core/ToolComponentTemplateItem/portal_components/tool.erp5.SimulationTool.py

@@ -1821,6 +1821,7 @@ class SimulationTool(BaseTool):
   def getInventoryAssetPrice(self, src__=0,
                              simulation_period='',
                              valuation_method=None,
+                             lowest_value_test=False,
                              **kw):
     """
     Same thing as getInventory but returns an asset
@@ -1836,6 +1837,10 @@ class SimulationTool(BaseTool):
       MovingAverage
     When using a specific valuation method, a resource_uid is expected
     as well as one of (section_uid or node_uid).
+
+    Parameter lowest_value_price compares latest price with price
+    calculated with valuation_method and takes the smallest one. This
+    is useful for accountants to avoid overestimating the price of a stock.
     """
     if valuation_method is None:
       method = getattr(self,'get%sInventoryList' % simulation_period)
@@ -1857,6 +1862,9 @@ class SimulationTool(BaseTool):
     if valuation_method not in ('Fifo', 'Filo', 'WeightedAverage',
       'MonthlyWeightedAverage', 'MovingAverage'):
       raise ValueError("Invalid valuation method: %s" % valuation_method)
+    if lowest_value_test and valuation_method not in ('Fifo', 'Filo',
+       'MovingAverage'):
+      raise NotImplementedError('lowest_value_test not implemented')
 
     assert 'node_uid' in kw or 'section_uid' in kw
     sql_kw = self._generateSQLKeywordDict(**kw)
@@ -1868,6 +1876,7 @@ class SimulationTool(BaseTool):
 
     result = self.Resource_zGetAssetPrice(
         valuation_method=valuation_method,
+        lowest_value_test=lowest_value_test,
         src__=src__,
         **sql_kw)
 
@@ -1875,7 +1884,10 @@ class SimulationTool(BaseTool):
       return result
 
     if len(result) > 0:
-      return result[-1].total_asset_price
+      asset_price = result[-1].total_asset_price
+      if asset_price:
+        asset_price = float(asset_price)
+      return asset_price
 
   security.declareProtected(Permissions.AccessContentsInformation,
                             'getCurrentInventoryAssetPrice')

product/ERP5/tests/testInventoryAPI.py

@@ -1516,18 +1516,20 @@ class TestInventoryList(InventoryAPITestCase):
 
   def test_inventory_asset_price(self):
     # examples from http://accountinginfo.com/study/inventory/inventory-120.htm
+    #                                               # total quantity
     movement_list = [
-        (1,  "Beginning Inventory", -700, 10),
-        (3,  "Purchase",            -100, 12),
-        (8,  "Sale",                 500, None),
-        (15, "Purchase",            -600, 14),
-        (19, "Purchase",            -200, 15),
-        (25, "Sale",                 400, None),
-        (27, "Sale",                 100, None),
+        (1,  "Beginning Inventory", -700, 10),      # 700
+        (3,  "Purchase",            -100, 12),      # 800
+        (8,  "Sale",                 500, None),    # 300
+        (15, "Purchase",            -600, 14),      # 900
+        (19, "Purchase",            -200, 15),      # 1100
+        (25, "Sale",                 400, None),    # 700
+        (27, "Sale",                 100, None),    # 600
     ]
     resource = self.getProductModule().newContent(
                                   title='My resource',
                                   portal_type='Product')
+    def makeMovementList(movement_list):
       for m in movement_list:
         self._makeMovement(resource_value=resource,
                          source_value=self.node,
@@ -1537,19 +1539,51 @@ class TestInventoryList(InventoryAPITestCase):
                          quantity=m[2],
                          price=m[3],
                          )
+    makeMovementList(movement_list)
 
     simulation_tool = self.getSimulationTool()
-    def valuate(method):
+    def valuate(method, lowest_value_test=False):
+      self.portal.person_module.log(simulation_tool.getInventoryAssetPrice(
+            src__=1,
+            valuation_method=method,
+            resource_uid=resource.getUid(),
+            node_uid=self.node.getUid(),
+            lowest_value_test=lowest_value_test))
       r = simulation_tool.getInventoryAssetPrice(
             valuation_method=method,
             resource_uid=resource.getUid(),
-            node_uid=self.node.getUid())
+            node_uid=self.node.getUid(),
+            lowest_value_test=lowest_value_test)
       return round(r)
 
 
     self.assertEqual(7895, valuate("MovingAverage"))
     self.assertEqual(7200, valuate("Filo"))
     self.assertEqual(8600, valuate("Fifo"))
+    # latest purchase price is 15, total quantity is 600
+    # average price of 13.15, thus lowest value test change nothing
+    self.assertEqual(7895, valuate("MovingAverage", lowest_value_test=True))
+    # average price of 12.15, thus lowest value test change nothing
+    self.assertEqual(7200, valuate("Filo", lowest_value_test=True))
+    # average price of 14.33, thus lowest value test change nothing
+    self.assertEqual(8600, valuate("Fifo", lowest_value_test=True))
+    movement_list = [
+        (28,  "Purchase",            -100, 11),      # 700
+        (29,  "Sale",                 100, None),    # 600
+    ]
+    makeMovementList(movement_list)
+    self.assertEqual(7710, valuate("MovingAverage"))
+    self.assertEqual(7200, valuate("Filo"))
+    self.assertEqual(8300, valuate("Fifo"))
+    self.assertEqual(7710, valuate("MovingAverage"))
+    self.assertEqual(7200, valuate("Filo"))
+    # latest purchase price is 11, total quantity is 600
+    # average price of 12.85, thus lowest value test change value
+    self.assertEqual(6600, valuate("MovingAverage", lowest_value_test=True))
+    # average price of 12, thus lowest value test change value
+    self.assertEqual(6600, valuate("Filo", lowest_value_test=True))
+    # average price of 13.83, thus lowest value test change value
+    self.assertEqual(6600, valuate("Fifo", lowest_value_test=True))
 
   def test_weighted_average_asset_price(self):
     def h(quantity, total_price):