[12.0][FIX] account_invoice_triple_discount: subtotal computation

account_invoice_triple_discount/models/__init__.py

@@ -1,3 +1,4 @@
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
+from . import line_triple_discount
 from . import account_invoice

account_invoice_triple_discount/models/account_invoice.py

@@ -2,60 +2,28 @@
 # Copyright 2017 Tecnativa - Pedro M. Baeza
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
-from odoo import api, fields, models
-from odoo.addons import decimal_precision as dp
+from odoo import api, models
 
 
 class AccountInvoice(models.Model):
     _inherit = "account.invoice"
 
     def get_taxes_values(self):
-        vals = {}
-        for line in self.invoice_line_ids:
-            vals[line] = {
-                'price_unit': line.price_unit,
-                'discount': line.discount,
-            }
-            price_unit = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
-            price_unit *= (1 - (line.discount2 or 0.0) / 100.0)
-            price_unit *= (1 - (line.discount3 or 0.0) / 100.0)
-            line.update({
-                'price_unit': price_unit,
-                'discount': 0.0,
-            })
-        tax_grouped = super(AccountInvoice, self).get_taxes_values()
-        for line in self.invoice_line_ids:
-            line.update(vals[line])
+        lines = self.invoice_line_ids
+        prev_values = lines.triple_discount_preprocess()
+        tax_grouped = super().get_taxes_values()
+        lines.triple_discount_postprocess(prev_values)
         return tax_grouped
 
 
 class AccountInvoiceLine(models.Model):
-    _inherit = "account.invoice.line"
-
-    discount2 = fields.Float(
-        'Discount 2 (%)',
-        digits=dp.get_precision('Discount'),
-    )
-    discount3 = fields.Float(
-        'Discount 3 (%)',
-        digits=dp.get_precision('Discount'),
-    )
+    _name = "account.invoice.line"
+    _inherit = ["line.triple_discount.mixin", "account.invoice.line"]
 
     @api.multi
-    @api.depends('discount2', 'discount3')
+    @api.depends('discount2', 'discount3', 'discounting_type')
     def _compute_price(self):
         for line in self:
-            prev_price_unit = line.price_unit
-            prev_discount = line.discount
-            price_unit = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
-            price_unit *= (1 - (line.discount2 or 0.0) / 100.0)
-            price_unit *= (1 - (line.discount3 or 0.0) / 100.0)
-            line.update({
-                'price_unit': price_unit,
-                'discount': 0.0,
-            })
+            prev_values = line.triple_discount_preprocess()
             super(AccountInvoiceLine, line)._compute_price()
-            line.update({
-                'price_unit': prev_price_unit,
-                'discount': prev_discount,
-            })
+            line.triple_discount_postprocess(prev_values)

account_invoice_triple_discount/models/line_triple_discount.py

@@ -0,0 +1,100 @@
+# Copyright 2017 Tecnativa - David Vidal
+# Copyright 2017 Tecnativa - Pedro M. Baeza
+# Copyright 2021 Simone Rubino - Agile Business Group
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import api, fields, models
+from odoo.addons import decimal_precision as dp
+
+
+class LineTripleDiscount (models.AbstractModel):
+    _name = "line.triple_discount.mixin"
+    _description = "Add triple discount fields and logic"
+
+    discount = fields.Float()
+    discount2 = fields.Float(
+        'Discount 2 (%)',
+        digits=dp.get_precision('Discount'),
+    )
+    discount3 = fields.Float(
+        'Discount 3 (%)',
+        digits=dp.get_precision('Discount'),
+    )
+    discounting_type = fields.Selection(
+        string="Discounting type",
+        selection=[
+            ('additive', 'Additive'),
+            ('multiplicative', 'Multiplicative'),
+        ],
+        default="multiplicative",
+        required=True,
+        help="Specifies whether discounts should be additive "
+        "or multiplicative.\nAdditive discounts are summed first and "
+        "then applied.\nMultiplicative discounts are applied sequentially.\n"
+        "Multiplicative discounts are default",
+    )
+
+    _sql_constraints = [
+        ('discount2_limit', 'CHECK (discount2 <= 100.0)',
+         'Discount 2 must be lower than 100%.'),
+        ('discount3_limit', 'CHECK (discount3 <= 100.0)',
+         'Discount 3 must be lower than 100%.'),
+    ]
+
+    def _get_final_discount(self):
+        self.ensure_one()
+        if self.discounting_type == "additive":
+            return self._additive_discount()
+        elif self.discounting_type == "multiplicative":
+            return self._multiplicative_discount()
+
+    def _additive_discount(self):
+        self.ensure_one()
+        discount = sum(
+            [getattr(self, x) or 0.0 for x in self._discount_fields()]
+        )
+        if discount <= 0:
+            return 0
+        elif discount >= 100:
+            return 100
+        return discount
+
+    def _multiplicative_discount(self):
+        self.ensure_one()
+        discounts = [1 - (self[x] or 0.0) / 100
+                     for x in self._discount_fields()]
+        final_discount = 1
+        for discount in discounts:
+            final_discount *= discount
+        return 100 - final_discount * 100
+
+    def _discount_fields(self):
+        return ['discount', 'discount2', 'discount3']
+
+    @api.multi
+    def triple_discount_preprocess(self):
+        """Save the values of the discounts in a dictionary,
+        to be restored in postprocess.
+        Resetting discount2 and discount3 to 0.0 avoids issues if
+        this method is called multiple times.
+        Updating the cache provides consistency through recomputations."""
+        prev_values = dict()
+        for line in self:
+            prev_values[line] = dict(
+                discount=line.discount,
+                discount2=line.discount2,
+                discount3=line.discount3,
+            )
+            line.update({
+                'discount': line._get_final_discount(),
+                'discount2': 0.0,
+                'discount3': 0.0
+            })
+        return prev_values
+
+    @api.model
+    def triple_discount_postprocess(self, prev_values):
+        """Restore the discounts of the lines in the dictionary prev_values.
+        Updating the cache provides consistency through recomputations."""
+        for line, prev_vals_dict in list(prev_values.items()):
+            line.update(prev_vals_dict)

account_invoice_triple_discount/tests/test_invoice_triple_discount.py

@@ -83,3 +83,23 @@ def test_02_discounts_multiple_lines(self):
         self.invoice_line1.discount = 50.0
         self.invoice._onchange_invoice_line_ids()
         self.assertEqual(self.invoice.amount_total, 365.0)
+
+    def test_03_discounts(self):
+        """ Tests discounts in edge case """
+        invoice = self.env['account.invoice'].create({
+            'name': "Test Customer Invoice",
+            'journal_id': self.env['account.journal'].search(
+                [('type', '=', 'sale')])[0].id,
+            'partner_id': self.partner.id,
+            'account_id': self.account.id,
+            'invoice_line_ids': [(0, 0, {
+                'name': 'Line 1',
+                'price_unit': 25.0,
+                'account_id': self.account.id,
+                'quantity': 65,
+                'discount': 50,
+                'discount2': 13,
+                'discount3': 0,
+            })],
+        })
+        self.assertEqual(invoice.invoice_line_ids.price_subtotal, 706.88)

account_invoice_triple_discount/views/account_invoice_view.xml

@@ -10,6 +10,7 @@
                    position="after">
                 <field name="discount2" groups="base.group_no_one"/>
                 <field name="discount3" groups="base.group_no_one"/>
+                <field name="discounting_type" groups="base.group_no_one"/>
             </xpath>
         </field>
     </record>
@@ -24,6 +25,7 @@
                    position="after">
                 <field name="discount2" groups="base.group_no_one"/>
                 <field name="discount3" groups="base.group_no_one"/>
+                <field name="discounting_type" groups="base.group_no_one"/>
             </xpath>
         </field>
     </record>