gistfile1.txt

diff --git a/sale_order_revision/model/sale_order.py b/sale_order_revision/model/sale_order.py
index 16eb121..8270d5e 100644
--- a/sale_order_revision/model/sale_order.py
+++ b/sale_order_revision/model/sale_order.py
@@ -69,21 +69,64 @@ class sale_order(models.Model):
     @api.returns('self', lambda value: value.id)
     @api.multi
     def copy(self, defaults=None):
+
         if not defaults:
             defaults = {}
         if self.env.context.get('new_sale_revision'):
+
+            latest_rev_no = 0
+
+            # Update current record with new revision id (postfix) and insert
+            # new record as (old revision) and set active false and state
+            # cancel
+            # Get current name and store in prev_name so after updating current
+            # record with latest revision number we can insert old revision
             prev_name = self.name
+
+            # Hold the current revision number so it can be used in
+            # revision/history record
             revno = self.revision_number
-            self.write({'revision_number': revno + 1,
+
+            # Get name prefix so we can find the latest revision number
+            name_prefix = prev_name.split('-')[0]
+
+            # Find record contains latest revision number
+            active_record = self.env['sale.order'].search([
+                '&',
+                ('name', 'like', name_prefix + '-'),
+                ('active', '=', True)
+            ], order='revision_number desc', limit=1)
+            inactive_record = self.env['sale.order'].search([
+                '&',
+                ('name', 'like', name_prefix + '-'),
+                ('active', '=', False)
+            ], order='revision_number desc', limit=1)
+
+            latest_record = active_record if (
+                active_record.revision_number > inactive_record.revision_number
+                ) else inactive_record
+
+            # Check if its not the first revision
+            if latest_record:
+                latest_rev_no = int(latest_record.name.split('-')[-1])
+
+            # Update values in current record with latest revision number and
+            # name(unique)
+            self.write({'revision_number': latest_rev_no + 1,
                         'name': '%s-%02d' % (self.unrevisioned_name,
-                                             revno + 1)
+                                             latest_rev_no + 1),
+                        'active': True,
                         })
+
+            # Update default values so it can be insert as new record as a
+            # history/revision of current record
             defaults.update({'name': prev_name,
                              'revision_number': revno,
                              'active': False,
                              'state': 'cancel',
                              'current_revision_id': self.id,
                              })
+
         return super(sale_order, self).copy(defaults)
 
     @api.model