[FIX] payment_paypal: Less confusing transaction logs

Before this commit, the log displayed "set as done"
before actually trying to put the transaction in done.
If an error then occurred in the'_set_transaction_done'
function and the transaction could not be processed,
this could lead to a misinterpretation of these logs.

This log is therefore moved after the transaction is
processed and is only displayed if it is actually successful.

This is valid for'done','pending' and'cancel'.

closes odoo/odoo#39364

Signed-off-by: Richard Mathot (rim) <rim@openerp.com>

addons/payment_paypal/models/payment.py

@@ -191,12 +191,12 @@ class TxPaypal(models.Model):
     @api.multi
     def _paypal_form_validate(self, data):
         status = data.get('payment_status')
+        former_tx_state = self.state
         res = {
             'acquirer_reference': data.get('txn_id'),
             'paypal_txn_type': data.get('payment_type'),
         }
         if status in ['Completed', 'Processed']:
-            _logger.info('Validated Paypal payment for tx %s: set as done' % (self.reference))
             try:
                 # dateutil and pytz don't recognize abbreviations PDT/PST
                 tzinfos = {
@@ -208,15 +208,22 @@ class TxPaypal(models.Model):
                 date = fields.Datetime.now()
             res.update(date=date)
             self._set_transaction_done()
-            return self.write(res)
+            if self.state == 'done' and self.state != former_tx_state:
+                _logger.info('Validated Paypal payment for tx %s: set as done' % (self.reference))
+                return self.write(res)
+            return True
         elif status in ['Pending', 'Expired']:
-            _logger.info('Received notification for Paypal payment %s: set as pending' % (self.reference))
             res.update(state_message=data.get('pending_reason', ''))
             self._set_transaction_pending()
-            return self.write(res)
+            if self.state == 'pending' and self.state != former_tx_state:
+                _logger.info('Received notification for Paypal payment %s: set as pending' % (self.reference))
+                return self.write(res)
+            return True
         else:
             error = 'Received unrecognized status for Paypal payment %s: %s, set as error' % (self.reference, status)
-            _logger.info(error)
             res.update(state_message=error)
             self._set_transaction_cancel()
-            return self.write(res)
+            if self.state == 'cancel' and self.state != former_tx_state:
+                _logger.info(error)
+                return self.write(res)
+            return True