From 810194464ac86d7b2a9e16cc2aefee2438b2280b Mon Sep 17 00:00:00 2001
From: tmadlener <thomas.madlener@desy.de>
Date: Thu, 11 Apr 2024 21:05:45 +0200
Subject: [PATCH] Add helper function to get all meta info in one go

---
 test/utils/test_PIDHandler.cpp                |  7 +++++++
 utils/include/edm4hep/utils/ParticleIDUtils.h |  3 +++
 utils/src/ParticleIDUtils.cc                  | 18 ++++++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/test/utils/test_PIDHandler.cpp b/test/utils/test_PIDHandler.cpp
index 9fdfde85e..412bcedb0 100644
--- a/test/utils/test_PIDHandler.cpp
+++ b/test/utils/test_PIDHandler.cpp
@@ -152,6 +152,13 @@ TEST_CASE("PIDHandler from Frame w/ metadata", "[pid_utils]") {
   REQUIRE_FALSE(handler.getParamIndex(pidAlgo1, "non-existant-param").has_value());
   // Invalid algorithm, the parameter name is not even checked in this case
   REQUIRE_FALSE(handler.getParamIndex(-1, "doesnot matter").has_value());
+
+  const auto pidInfo = utils::PIDHandler::getAlgoInfo(metadata, "particleIds_1").value();
+  REQUIRE(pidInfo.algoName == "pidAlgo_1");
+  REQUIRE(pidInfo.algoType == 42);
+  REQUIRE(pidInfo.paramNames.size() == 2);
+  REQUIRE(pidInfo.paramNames[0] == "first_param");
+  REQUIRE(pidInfo.paramNames[1] == "second_param");
 }
 
 TEST_CASE("PIDHandler from Frame w/o metadata", "[pid_utils]") {
diff --git a/utils/include/edm4hep/utils/ParticleIDUtils.h b/utils/include/edm4hep/utils/ParticleIDUtils.h
index 56ea1f2c6..a1ceabb19 100644
--- a/utils/include/edm4hep/utils/ParticleIDUtils.h
+++ b/utils/include/edm4hep/utils/ParticleIDUtils.h
@@ -77,6 +77,9 @@ class PIDHandler {
 
   static void setAlgoInfo(podio::Frame& metadata, const std::string& collname,
                           const edm4hep::utils::ParticleIDMeta& pidMetaInfo);
+
+  static std::optional<edm4hep::utils::ParticleIDMeta> getAlgoInfo(const podio::Frame& metadata,
+                                                                   const std::string& collName);
 };
 } // namespace edm4hep::utils
 
diff --git a/utils/src/ParticleIDUtils.cc b/utils/src/ParticleIDUtils.cc
index 3d36f7863..70d14b947 100644
--- a/utils/src/ParticleIDUtils.cc
+++ b/utils/src/ParticleIDUtils.cc
@@ -108,4 +108,22 @@ void PIDHandler::setAlgoInfo(podio::Frame& metadata, const std::string& collName
   metadata.putParameter(podio::collMetadataParamName(collName, edm4hep::pidParameterNames), pidMetaInfo.paramNames);
 }
 
+std::optional<edm4hep::utils::ParticleIDMeta> PIDHandler::getAlgoInfo(const podio::Frame& metadata,
+                                                                      const std::string& collName) {
+  ParticleIDMeta pidInfo{};
+
+  pidInfo.algoName = metadata.getParameter<std::string>(podio::collMetadataParamName(collName, edm4hep::pidAlgoName));
+  // Use the algoName as proxy to see whether we could actually get the
+  // information from the metadata
+  if (pidInfo.algoName.empty()) {
+    return std::nullopt;
+  }
+
+  pidInfo.algoType = metadata.getParameter<int>(podio::collMetadataParamName(collName, edm4hep::pidAlgoType));
+  pidInfo.paramNames = metadata.getParameter<std::vector<std::string>>(
+      podio::collMetadataParamName(collName, edm4hep::pidParameterNames));
+
+  return pidInfo;
+}
+
 } // namespace edm4hep::utils