[FIX] account, account_cancel: cancel payment

Commit b17e4a0f6b prevents gaps in payment numbering by keeping tack
of the account move name used. It also prevents the unlinking of a
payment which already generated an account move.

However, no 'Cancelled' state has been introduced for the payments. It
means that the cancellation of a payment will set it to a draft state,
and it won't be possible to delete or flag it as 'Cancelled' later on.
It will therefore be a misleading entry for the users.

opw-694351

addons/account/models/account_payment.py

@@ -192,7 +192,7 @@ class account_payment(models.Model):
     company_id = fields.Many2one(store=True)
 
     name = fields.Char(readonly=True, copy=False, default="Draft Payment") # The name is attributed upon post()
-    state = fields.Selection([('draft', 'Draft'), ('posted', 'Posted'), ('sent', 'Sent'), ('reconciled', 'Reconciled')], readonly=True, default='draft', copy=False, string="Status")
+    state = fields.Selection([('draft', 'Draft'), ('posted', 'Posted'), ('sent', 'Sent'), ('reconciled', 'Reconciled'), ('cancel', 'Cancelled')], readonly=True, default='draft', copy=False, string="Status")
 
     payment_type = fields.Selection(selection_add=[('transfer', 'Internal Transfer')])
     payment_reference = fields.Char(copy=False, readonly=True, help="Reference of the document used to issue this payment. Eg. check number, file name, etc.")
@@ -315,7 +315,7 @@ class account_payment(models.Model):
                     move.line_ids.remove_move_reconcile()
                 move.button_cancel()
                 move.unlink()
-            rec.state = 'draft'
+            rec.state = 'cancel'
 
     @api.multi
     def unlink(self):
@@ -370,6 +370,10 @@ class account_payment(models.Model):
 
             rec.write({'state': 'posted', 'move_name': move.name})
 
+    @api.multi
+    def action_draft(self):
+        return self.write({'state': 'draft'})
+
     def _create_payment_entry(self, amount):
         """ Create a journal entry corresponding to a payment, if the payment references invoice(s) they are reconciled.
             Return the journal entry.

addons/account/views/account_payment_view.xml

@@ -6,7 +6,7 @@
             <field name="name">account.payment.tree</field>
             <field name="model">account.payment</field>
             <field name="arch" type="xml">
-                <tree decoration-info="state=='draft'" decoration-muted="state=='reconciled'" edit="false">
+                <tree decoration-info="state == 'draft'" decoration-muted="state in ['reconciled', 'cancel']" edit="false">
                     <field name="payment_date"/>
                     <field name="name"/>
                     <field name="journal_id"/>
@@ -25,7 +25,7 @@
             <field name="name">account.supplier.payment.tree</field>
             <field name="model">account.payment</field>
             <field name="arch" type="xml">
-                <tree decoration-info="state=='draft'" decoration-muted="state=='reconciled'" edit="false">
+                <tree decoration-info="state == 'draft'" decoration-muted="state in ['reconciled', 'cancel']" edit="false">
                     <field name="payment_date"/>
                     <field name="name"/>
                     <field name="journal_id"/>
@@ -76,6 +76,7 @@
                 <form string="Register Payment" version="7">
                     <header>
                         <button name="post" class="oe_highlight" states="draft" string="Confirm" type="object"/>
+                        <button name="action_draft" states="cancel" string="Set to Draft" type="object"/>
                         <field name="state" widget="statusbar" statusbar_visible="posted,reconciled"/>
                     </header>
                     <sheet>

addons/account_cancel/views/account_views.xml

@@ -65,7 +65,7 @@
             <field name="inherit_id" ref="account.view_account_payment_form"/>
             <field name="arch" type="xml">
                 <xpath expr="//header/field[@name='state']" position="before">
-                    <button name="cancel" attrs="{'invisible': [('state', '=', 'draft')]}" string="Cancel" type="object"/>
+                    <button name="cancel" states="posted,sent,reconciled" string="Cancel" type="object"/>
                 </xpath>
             </field>
         </record>