From 7576bce450030ee162b0332bc277fab84b460b5c Mon Sep 17 00:00:00 2001
From: David Hurta <dhurta@redhat.com>
Date: Thu, 29 Aug 2024 17:19:35 +0200
Subject: [PATCH] Return `400 Bad Request` for responses that contain empty
 graph

Return `400 Bad Request` for responses that contain an empty graph. Such
responses are currently only generated when a specified channel and
architecture result in an empty update graph due to the filtering.

This commit is part of the effort to improve the UX regarding requests
that contain invalid query parameters. In the future, more fine-grained
return messages will be returned.
---
 commons/src/errors.rs      | 6 ++++++
 policy-engine/src/graph.rs | 4 ++++
 2 files changed, 10 insertions(+)

diff --git a/commons/src/errors.rs b/commons/src/errors.rs
index 5eb4ceb3c..2db0f8647 100644
--- a/commons/src/errors.rs
+++ b/commons/src/errors.rs
@@ -85,6 +85,10 @@ pub enum GraphError {
     /// Resource does not exist
     #[error("does not exist: {}", _0)]
     DoesNotExist(String),
+
+    /// No version were found.
+    #[error("no versions found: {}", _0)]
+    NoVersionsFound(String),
 }
 
 impl actix_web::error::ResponseError for GraphError {
@@ -129,6 +133,7 @@ impl GraphError {
             GraphError::ArchVersionError(_) => http::StatusCode::INTERNAL_SERVER_ERROR,
             GraphError::FileOpenError(_) => http::StatusCode::INTERNAL_SERVER_ERROR,
             GraphError::DoesNotExist(_) => http::StatusCode::NOT_FOUND,
+            GraphError::NoVersionsFound(_) => http::StatusCode::BAD_REQUEST,
         }
     }
 
@@ -146,6 +151,7 @@ impl GraphError {
             GraphError::ArchVersionError(_) => "arch_version_error",
             GraphError::FileOpenError(_) => "file_open_err",
             GraphError::DoesNotExist(_) => "does_not_exist",
+            GraphError::NoVersionsFound(_) => "no_versions_found",
         };
         kind.to_string()
     }
diff --git a/policy-engine/src/graph.rs b/policy-engine/src/graph.rs
index f43da7fe9..6d71558d2 100644
--- a/policy-engine/src/graph.rs
+++ b/policy-engine/src/graph.rs
@@ -113,6 +113,10 @@ where
         Err(other_error) => GraphError::FailedPluginExecution(other_error.to_string()),
     })?;
 
+    if internal_io.graph.releases_count() == 0 {
+        return Err(GraphError::NoVersionsFound("the specified architecture and/or channel does not contain any versions".to_string()));
+    }
+
     let versioned_graph = add_version_information(&internal_io);
 
     let graph_json = serde_json::to_string(&versioned_graph)