Prevent to delete lines and origins of statements not cancelled or in draft

Closes #12678

modules/account_statement/message.xml

@@ -36,6 +36,13 @@ this repository contains the full copyright notices and license terms. -->
         <record model="ir.message" id="msg_statement_post_pending_amount">
             <field name="text">To post statement "%(statement)s" you must create lines for pending %(amount)s of origin "%(origin)s".</field>
         </record>
+        <record model="ir.message" id="msg_statement_line_delete_cancel_draft">
+            <field name="text">To delete line "%(line)s" you must cancel or reset to draft statement "%(statement)s".</field>
+        </record>
+        <record model="ir.message" id="msg_statement_origin_delete_cancel_draft">
+            <field name="text">To delete origin "%(origin)s" you must cancel or reset to draft statement "%(statement)s".</field>
+        </record>
+
         <record model="ir.message" id="msg_post_statement_move">
             <field name="text">To post the move "%(move)s" you must post the statement "%(statement)s".</field>
         </record>

modules/account_statement/statement.py

@@ -744,8 +744,9 @@ class Line(origin_mixin(_states), sequence_ordered(), ModelSQL, ModelView):
             },
         states=_states,
         context={'with_payment': False})
-    origin = fields.Many2One('account.statement.origin', 'Origin',
-        readonly=True,
+    origin = fields.Many2One(
+        'account.statement.origin', 'Origin', readonly=True,
+        ondelete='RESTRICT',
         states={
             'invisible': ~Bool(Eval('origin')),
             },
@@ -930,6 +931,18 @@ class Line(origin_mixin(_states), sequence_ordered(), ModelSQL, ModelView):
     def search_rec_name(cls, name, clause):
         return [('statement.rec_name',) + tuple(clause[1:])]
 
+    @classmethod
+    def delete(cls, lines):
+        for line in lines:
+            if line.statement_state not in {'cancelled', 'draft'}:
+                raise AccessError(
+                    gettext(
+                        'account_statement.'
+                        'msg_statement_line_delete_cancel_draft',
+                        line=line.rec_name,
+                        sale=line.statement.rec_name))
+        super().delete(lines)
+
     @classmethod
     def copy(cls, lines, default=None):
         if default is None:
@@ -1173,6 +1186,18 @@ class Origin(origin_mixin(_states), ModelSQL, ModelView):
                 group_by=table.id))
         return [('id', 'in', query)]
 
+    @classmethod
+    def delete(cls, origins):
+        for origin in origins:
+            if origin.statement_state not in {'cancelled', 'draft'}:
+                raise AccessError(
+                    gettext(
+                        'account_statement.'
+                        'msg_statement_origin_delete_cancel_draft',
+                        origin=origin.rec_name,
+                        sale=origin.statement.rec_name))
+        super().delete(origins)
+
     @classmethod
     def copy(cls, origins, default=None):
         default = default.copy() if default is not None else {}