Add parameters verification when Audit is being created

We have to check Audit Type and Audit State to make sure
these parameters are in valid status.

Also, we provide default states for the next attributes:

- 'audit_template' is required and should be either UUID or text field
- 'state' is readonly so it raises an error if submitted in POST
  and is set by default to PENDING
- 'deadline' is optional and should be a datetime
- 'type' is a required text field

Change-Id: I2a7e0deec0ee2040e86400b500bb0efd8eade564
Closes-Bug: #1532843
Closes-Bug: #1533210

watcher/api/controllers/v1/audit.py

@@ -49,6 +49,31 @@ from watcher.decision_engine import rpcapi
 from watcher import objects
 
 
+class AuditPostType(wtypes.Base):
+
+    uuid = wtypes.wsattr(types.uuid, mandatory=False)
+
+    audit_template_uuid = wtypes.wsattr(types.uuid, mandatory=True)
+
+    type = wtypes.wsattr(wtypes.text, mandatory=True)
+
+    deadline = wtypes.wsattr(datetime.datetime, mandatory=False)
+
+    state = wsme.wsattr(wtypes.text, readonly=True,
+                        default=objects.audit.State.PENDING)
+
+    def as_audit(self):
+        audit_type_values = [val.value for val in objects.audit.AuditType]
+        if self.type not in audit_type_values:
+            raise exception.AuditTypeNotFound(audit_type=self.type)
+
+        return Audit(
+            uuid=self.uuid or utils.generate_uuid(),
+            audit_template_id=self.audit_template_uuid,
+            type=self.type,
+            deadline=self.deadline)
+
+
 class AuditPatchType(types.JsonPatchType):
 
     @staticmethod
@@ -325,12 +350,13 @@ class AuditsController(rest.RestController):
                                               audit_uuid)
         return Audit.convert_with_links(rpc_audit)
 
-    @wsme_pecan.wsexpose(Audit, body=Audit, status_code=201)
-    def post(self, audit):
+    @wsme_pecan.wsexpose(Audit, body=AuditPostType, status_code=201)
+    def post(self, audit_p):
         """Create a new audit.
 
-        :param audit: a audit within the request body.
+        :param audit_p: a audit within the request body.
         """
+        audit = audit_p.as_audit()
         if self.from_audits:
             raise exception.OperationNotPermitted