[FIX] account: fix usage of include_base_amount taxes in invoices

Suppose 3 taxes, all with include_base_amount checked:
- 21%
- 21% TVAC
- 12%

Suppose an invoice with 3 lines, one per tax, all with quantity = 1:
- price_unit = 100 with 21%
- price_unit = 121 with 21% TVAC
- price_unit = 100 with 12%

- Validate the invoice and take a look to the taxes set on taxes journal entries:
Originator Tax: 12%
Taxes: /

Originator Tax: 21%
Taxes: 12%

Originator Tax: 21% TVAC
Taxes: 21% 12%

... instead of:
Originator Tax: 12%
Taxes: /

Originator Tax: 21%
Taxes: /

Originator Tax: 21% TVAC
Taxes: /

-opw: 1861177

5 files changed, 195 insertions, 23 deletions

diff --git a/addons/account/models/account.py b/addons/account/models/account.py
index 8bc67fcf1e8..431cd15fbce 100644
--- a/addons/account/models/account.py
+++ b/addons/account/models/account.py
@@ -1030,7 +1030,8 @@ class AccountTax(models.Model):
         return str(invoice_tax_val['tax_id']) + '-' + \
                str(invoice_tax_val['account_id']) + '-' + \
                str(invoice_tax_val['account_analytic_id']) + '-' + \
-               str(invoice_tax_val.get('analytic_tag_ids', []))
+               str(invoice_tax_val.get('analytic_tag_ids', [])) + '-' + \
+               str(invoice_tax_val.get('tax_ids') or [])
 
     def _compute_amount(self, base_amount, price_unit, quantity=1.0, product=None, partner=None):
         """ Returns the amount of a single tax. base_amount is the actual amount on which the tax is applied, which is
diff --git a/addons/account/models/account_invoice.py b/addons/account/models/account_invoice.py
index 28e0a4429ac..e11c31ae6a0 100644
--- a/addons/account/models/account_invoice.py
+++ b/addons/account/models/account_invoice.py
@@ -1077,12 +1077,13 @@ class AccountInvoice(models.Model):
         else:
             return self.env.ref('account.invoice_form').id
 
-    def _prepare_tax_line_vals(self, line, tax):
-        """ Prepare values to create an account.invoice.tax line
-
-        The line parameter is an account.invoice.line, and the
-        tax parameter is the output of account.tax.compute_all().
-        """
+    def _prepare_tax_line_vals(self, line, tax, tax_ids):
+        ''' Prepare values to create an account.invoice.tax line.
+        :param line:    An account.invoice.line record.
+        :param tax:     Tax values outputted by compute_all() in account.tax.
+        :param taxes:   A list of account.tax ids affecting the tax base amount.
+        :return:        The account.invoice.tax values to create a new record.
+        '''
         vals = {
             'invoice_id': self.id,
             'name': tax['name'],
@@ -1094,6 +1095,7 @@ class AccountInvoice(models.Model):
             'account_analytic_id': tax['analytic'] and line.account_analytic_id.id or False,
             'account_id': self.type in ('out_invoice', 'in_invoice') and (tax['account_id'] or line.account_id.id) or (tax['refund_account_id'] or line.account_id.id),
             'analytic_tag_ids': tax['analytic'] and line.analytic_tag_ids.ids or False,
+            'tax_ids': tax_ids and [(6, None, tax_ids)] or False,
         }
 
         # If the taxes generate moves on the same financial account as the invoice line,
@@ -1106,6 +1108,11 @@ class AccountInvoice(models.Model):
 
     @api.multi
     def get_taxes_values(self, tax_group_fields=False):
+        def is_tax_affecting_base_amount(tax):
+            return (tax.amount_type not in ('group', 'division') and tax.include_base_amount and tax.price_include)\
+                   or (tax.amount_type == 'division' and tax.include_base_amount and not tax.price_include)
+        # Avoid redundant browsing.
+        tax_map = dict((t.id, t) for t in self.invoice_line_ids.mapped('invoice_line_tax_ids'))
         default_tax_group_fields = set(['amount', 'base'])
         if tax_group_fields:
             default_tax_group_fields |= set(tax_group_fields)
@@ -1114,18 +1121,38 @@ class AccountInvoice(models.Model):
         for line in self.invoice_line_ids:
             if not line.account_id:
                 continue
+
             price_unit = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
             taxes = line.invoice_line_tax_ids.compute_all(price_unit, self.currency_id, line.quantity, line.product_id, self.partner_id)['taxes']
-            for tax in taxes:
-                val = self._prepare_tax_line_vals(line, tax)
-                key = self.env['account.tax'].browse(tax['id']).get_grouping_key(val)
+
+            affecting_base_tax_ids = []
+            for tax_vals in taxes:
+                # Retrieve the tax record (not in tax_vals when dealing with group of taxes).
+                if tax_map.get(tax_vals['id']):
+                    tax = tax_map[tax_vals['id']]
+                else:
+                    tax = tax_map[tax_vals['id']] = self.env['account.tax'].browse(tax_vals['id'])
+
+                val = self._prepare_tax_line_vals(line, tax_vals, affecting_base_tax_ids)
+                key = tax.get_grouping_key({
+                    'tax_id': val['tax_id'],
+                    'account_id': val['account_id'],
+                    'account_analytic_id': val['account_analytic_id'],
+                    'analytic_tag_ids': val['analytic_tag_ids'],
+                    'tax_ids': affecting_base_tax_ids,
+                })
 
                 if key not in tax_grouped:
                     tax_grouped[key] = val
                     tax_grouped[key]['base'] = round_curr(val['base'])
                 else:
                     for field in default_tax_group_fields:
-                        tax_grouped[key][field] += round_curr(val.get(field) or 0)
+                        tax_grouped[key][field] += val.get(field) or 0
+
+                if tax.amount_type == "group":
+                    affecting_base_tax_ids += tax.children_tax_ids.filtered(lambda t: is_tax_affecting_base_amount(t)).ids
+                elif is_tax_affecting_base_amount(tax):
+                    affecting_base_tax_ids.append(tax.id)
         return tax_grouped
 
     @api.multi
@@ -1232,19 +1259,14 @@ class AccountInvoice(models.Model):
             res.append(move_line_dict)
         return res
 
-    @api.model
+    @api.multi
     def tax_line_move_line_get(self):
+        self.ensure_one()
+
         res = []
-        # keep track of taxes already processed
-        done_taxes = []
         # loop the invoice.tax.line in reversal sequence
         for tax_line in sorted(self.tax_line_ids, key=lambda x: -x.sequence):
             if tax_line.amount_total:
-                tax = tax_line.tax_id
-                if tax.amount_type == "group":
-                    for child_tax in tax.children_tax_ids:
-                        done_taxes.append(child_tax.id)
-
                 analytic_tag_ids = [(4, analytic_tag.id, None) for analytic_tag in tax_line.analytic_tag_ids]
                 res.append({
                     'invoice_tax_line_id': tax_line.id,
@@ -1258,9 +1280,8 @@ class AccountInvoice(models.Model):
                     'account_analytic_id': tax_line.account_analytic_id.id,
                     'analytic_tag_ids': analytic_tag_ids,
                     'invoice_id': self.id,
-                    'tax_ids': [(6, 0, list(done_taxes))] if tax_line.tax_id.include_base_amount else []
+                    'tax_ids': [(6, 0, tax_line.tax_ids.ids)],
                 })
-                done_taxes.append(tax.id)
         return res
 
     def inv_line_characteristic_hashcode(self, invoice_line):
@@ -2034,7 +2055,7 @@ class AccountInvoiceLine(models.Model):
 class AccountInvoiceTax(models.Model):
     _name = "account.invoice.tax"
     _description = "Invoice Tax"
-    _order = 'sequence'
+    _order = 'sequence, id desc'
 
     def _prepare_invoice_tax_val(self):
         self.ensure_one()
@@ -2042,7 +2063,9 @@ class AccountInvoiceTax(models.Model):
             'tax_id': self.tax_id.id,
             'account_id': self.account_id.id,
             'account_analytic_id': self.account_analytic_id.id,
-            'analytic_tag_ids': self.analytic_tag_ids.ids or False}
+            'analytic_tag_ids': self.analytic_tag_ids.ids or False,
+            'tax_ids': self.tax_ids and tax.tax_ids.ids,
+        }
 
     @api.depends('invoice_id.invoice_line_ids')
     def _compute_base_amount(self):
@@ -2072,6 +2095,8 @@ class AccountInvoiceTax(models.Model):
     company_id = fields.Many2one('res.company', string='Company', related='account_id.company_id', store=True, readonly=True)
     currency_id = fields.Many2one('res.currency', related='invoice_id.currency_id', store=True, readonly=True)
     base = fields.Monetary(string='Base', compute='_compute_base_amount', store=True)
+    tax_ids = fields.Many2many('account.tax', string='Affecting Base Taxes',
+        help='Taxes affecting the tax base amount applied before this one.')
 
     @api.depends('amount', 'amount_rounding')
     def _compute_amount_total(self):
diff --git a/addons/account/tests/__init__.py b/addons/account/tests/__init__.py
index e87ae79c27a..0eb1d84e613 100644
--- a/addons/account/tests/__init__.py
+++ b/addons/account/tests/__init__.py
@@ -16,6 +16,7 @@ from . import test_product_id_change
 from . import test_reconciliation
 from . import test_search
 from . import test_tax
+from . import test_invoice_taxes
 from . import test_account_move_taxes_edition
 from . import test_templates_consistency
 from . import test_account_fiscal_year
diff --git a/addons/account/tests/test_invoice_taxes.py b/addons/account/tests/test_invoice_taxes.py
new file mode 100644
index 00000000000..bb8dd06b617
--- /dev/null
+++ b/addons/account/tests/test_invoice_taxes.py
@@ -0,0 +1,141 @@
+# -*- coding: utf-8 -*-
+from odoo.addons.account.tests.account_test_classes import AccountingTestCase
+from odoo.tests.common import Form
+from odoo.tests import tagged
+
+
+@tagged('post_install', '-at_install')
+class TestInvoiceTaxes(AccountingTestCase):
+
+    def setUp(self):
+        super(TestInvoiceTaxes, self).setUp()
+
+        self.percent_tax_1 = self.env['account.tax'].create({
+            'name': '21%',
+            'amount_type': 'percent',
+            'amount': 21,
+            'sequence': 10,
+        })
+        self.percent_tax_1_incl = self.env['account.tax'].create({
+            'name': '21% incl',
+            'amount_type': 'percent',
+            'amount': 21,
+            'price_include': True,
+            'include_base_amount': True,
+            'sequence': 20,
+        })
+        self.percent_tax_2 = self.env['account.tax'].create({
+            'name': '12%',
+            'amount_type': 'percent',
+            'amount': 12,
+            'sequence': 30,
+        })
+        self.group_tax = self.env['account.tax'].create({
+            'name': 'group 12% + 21%',
+            'amount_type': 'group',
+            'amount': 21,
+            'children_tax_ids': [
+                (4, self.percent_tax_1_incl.id),
+                (4, self.percent_tax_2.id)
+            ],
+            'sequence': 40,
+        })
+
+    def _create_invoice(self, taxes_per_line):
+        ''' Create an invoice on the fly.
+
+        :param taxes_per_line: A list of tuple (price_unit, account.tax recordset)
+        '''
+        self_ctx = self.env['account.invoice'].with_context(type='out_invoice')
+        journal_id = self_ctx._default_journal().id
+        self_ctx = self_ctx.with_context(journal_id=journal_id)
+
+        with Form(self_ctx, view='account.invoice_form') as invoice_form:
+            invoice_form.partner_id = self.env.ref('base.partner_demo')
+
+            for amount, taxes in taxes_per_line:
+                with invoice_form.invoice_line_ids.new() as invoice_line_form:
+                    invoice_line_form.name = 'xxxx'
+                    invoice_line_form.quantity = 1
+                    invoice_line_form.price_unit = amount
+                    invoice_line_form.invoice_line_tax_ids.clear()
+                    for tax in taxes:
+                        invoice_line_form.invoice_line_tax_ids.add(tax)
+        return invoice_form.save()
+
+    def test_one_tax_per_line(self):
+        ''' Test:
+        price_unit | Taxes
+        ------------------
+        100        | 21%
+        121        | 21% incl
+        100        | 12%
+
+        Expected:
+        Tax         | Taxes     | Base      | Amount
+        --------------------------------------------
+        21%         | /         | 100       | 21
+        21% incl    | /         | 100       | 21
+        12%         | /         | 100       | 12
+        '''
+        invoice = self._create_invoice([
+            (100, self.percent_tax_1),
+            (121, self.percent_tax_1_incl),
+            (100, self.percent_tax_2),
+        ])
+        invoice.action_invoice_open()
+        self.assertRecordValues(invoice.tax_line_ids, [
+            {'name': self.percent_tax_1.name,       'base': 100, 'amount': 21, 'tax_ids': []},
+            {'name': self.percent_tax_1_incl.name,  'base': 100, 'amount': 21, 'tax_ids': []},
+            {'name': self.percent_tax_2.name,       'base': 100, 'amount': 12, 'tax_ids': []},
+        ])
+
+    def test_affecting_base_amount(self):
+        ''' Test:
+        price_unit | Taxes
+        ------------------
+        121        | 21% incl, 12%
+        100        | 12%
+
+        Expected:
+        Tax         | Taxes     | Base      | Amount
+        --------------------------------------------
+        21% incl    | /         | 100       | 21
+        12%         | 21% incl  | 121       | 14.52
+        12%         | /         | 100       | 12
+        '''
+        invoice = self._create_invoice([
+            (121, self.percent_tax_1_incl + self.percent_tax_2),
+            (100, self.percent_tax_2),
+        ])
+        invoice.action_invoice_open()
+        self.assertRecordValues(invoice.tax_line_ids, [
+            {'name': self.percent_tax_1_incl.name,      'base': 100, 'amount': 21,      'tax_ids': []},
+            {'name': self.percent_tax_2.name,           'base': 100, 'amount': 12,      'tax_ids': []},
+            {'name': self.percent_tax_2.name,           'base': 121, 'amount': 14.52,   'tax_ids': [self.percent_tax_1_incl.id]},
+        ])
+
+    def test_group_of_taxes(self):
+        ''' Test:
+        price_unit | Taxes
+        ------------------
+        121        | 21% incl + 12%
+        100        | 12%
+
+        Expected:
+        Tax         | Taxes     | Base      | Amount
+        --------------------------------------------
+        21% incl    | /         | 100       | 21
+        12%         | 21% incl  | 121       | 14.52
+        12%         | /         | 100       | 12
+        '''
+        invoice = self._create_invoice([
+            (121, self.group_tax),
+            (100, self.percent_tax_2),
+        ])
+        invoice.action_invoice_open()
+        self.assertRecordValues(invoice.tax_line_ids, [
+            {'name': self.percent_tax_1_incl.name,      'base': 100, 'amount': 21,      'tax_ids': []},
+            {'name': self.percent_tax_2.name,           'base': 100, 'amount': 12,      'tax_ids': []},
+            {'name': self.percent_tax_2.name,           'base': 121, 'amount': 14.52,   'tax_ids': [self.percent_tax_1_incl.id]},
+        ])
diff --git a/addons/account/views/account_invoice_view.xml b/addons/account/views/account_invoice_view.xml
index e81ca343db5..b8dd9c25e05 100644
--- a/addons/account/views/account_invoice_view.xml
+++ b/addons/account/views/account_invoice_view.xml
@@ -124,6 +124,7 @@
                     <field name="name"/>
                     <field name="account_id" groups="account.group_account_user"/>
                     <field name="base"/>
+                    <field name="tax_ids"/>
                     <field name="amount_total" string="Amount"/>
                     <field name="currency_id" invisible="1"/>
                 </tree>
@@ -143,6 +144,7 @@
                         <field name="manual"/>
                         <field name="amount_total" string="Amount"/>
                         <field name="base"/>
+                        <field name="tax_ids"/>
                         <field name="currency_id" invisible="1"/>
                     </group>
                 </form>
@@ -353,6 +355,7 @@
                                                 <field name="name"/>
                                                 <!--Need invisible fields for on_change to create all necessary info -->
                                                 <field name="tax_id" invisible="1"/>
+                                                <field name="tax_ids" invisible="1"/>
                                                 <field name="sequence" invisible="1"/>
                                                 <field name="manual" invisible="1"/>
                                                 <field name="account_id" groups="account.group_account_user"/>
@@ -618,6 +621,7 @@
                                     <field name="name"/>
                                     <!--Need invisible fields for on_change to create all necessary info -->
                                     <field name="tax_id" invisible="1"/>
+                                    <field name="tax_ids" invisible="1"/>
                                     <field name="sequence" invisible="1"/>
                                     <field name="manual" invisible="1"/>
                                     <field name="account_id" groups="account.group_account_user"/>