From 76dbd757e32f06a0a335bfe7effa9b1c798047ca Mon Sep 17 00:00:00 2001
From: Andreas Suter <andreas.suter@psi.ch>
Date: Mon, 2 Feb 2026 19:08:12 +0100
Subject: [PATCH] dump_header can now handle HDF4/HDF5 NeXus files, without the
 NeXus library.

---
 src/dump_header.cpp | 44 +++++++++++++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 11 deletions(-)

diff --git a/src/dump_header.cpp b/src/dump_header.cpp
index 4ed86769..c1a49934 100644
--- a/src/dump_header.cpp
+++ b/src/dump_header.cpp
@@ -37,6 +37,7 @@
 #include <cstring>
 #include <ctime>
 #include <cassert>
+#include <cstddef>
 
 #include <iostream>
 #include <fstream>
@@ -365,19 +366,40 @@ int dump_header_root(const std::string fileName, const bool summary, const bool
 int dump_header_nexus(const std::string fileName, const bool counts) {
 
 #ifdef PNEXUS_ENABLED
-  std::cout << std::endl << "new NeXus handling not yet implemented ..." << std::endl << std::endl;
-/* //as35
-  std::unique_ptr<PNeXus> nxs_file = std::make_unique<PNeXus>(fileName.c_str());
+  nxs::HDFType type = nxs::checkHDFType(fileName);
 
-  if (nxs_file->IsValid(false)) {
-    nxs_file->Dump(counts);
-  } else {
-    std::cerr << std::endl;
-    std::cerr << "**ERROR** found invalid NeXus file." << std::endl;
-    std::cerr << std::endl;
-    return 1;
+  // check for type errors, missing enabled HDF4
+  switch (type) {
+    case nxs::HDFType::HDF4:
+      std::cout << std::endl << ">> PRunDataHandler::ReadNexusFile(): HDF4 file." << std::endl;
+#ifndef HAVE_HDF4
+      std::cerr << std::endl << ">> PRunDataHandler::ReadNexusFile(): **ERROR**, HDF4 is not enabled." << std::endl;
+      return 1;
+#endif
+      break;
+    case nxs::HDFType::HDF5:
+      std::cout << std::endl << ">> PRunDataHandler::ReadNexusFile(): HDF5 file." << std::endl;
+      break;
+    case nxs::HDFType::Unknown:
+      std::cerr << std::endl << ">> PRunDataHandler::ReadNexusFile(): Not a valid NeXus file." << std::endl;
+      return 1;
+  }
+
+  if (type == nxs::HDFType::HDF4) {
+#ifdef HAVE_HDF4
+    std::unique_ptr<nxH4::PNeXus> nxs_file = std::make_unique<nxH4::PNeXus>(fileName);
+    if (nxs_file == nullptr) {
+      std::cerr << std::endl << "**ERROR** allocation of nxH4::PNeXus object faild." << std::endl;
+    }
+    nxs_file->Dump();
+#endif
+  } else { // HDF5
+    std::unique_ptr<nxH5::PNeXus> nxs_file = std::make_unique<nxH5::PNeXus>(fileName);
+    if (nxs_file == nullptr) {
+      std::cerr << std::endl << "**ERROR** allocation of nxH5::PNeXus object faild." << std::endl;
+    }
+    nxs_file->Dump();
   }
-*/ //as35
 #else
   std::cout << std::endl << "NeXus not enabled, hence the header information cannot be dumped." << std::endl << std::endl;
 #endif