From 12dc8730d1796bf629004ecc427505829a3d051a Mon Sep 17 00:00:00 2001
From: Artur Glavic <artur.glavic@psi.ch>
Date: Wed, 18 Mar 2026 14:58:42 +0100
Subject: [PATCH] Implement compatibility with older nexus file mappings

---
 eos/compat.py      | 40 ++++++++++++++++++++++++++++++++++++++++
 eos/file_reader.py | 11 ++++++++++-
 2 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100644 eos/compat.py

diff --git a/eos/compat.py b/eos/compat.py
new file mode 100644
index 0000000..b141416
--- /dev/null
+++ b/eos/compat.py
@@ -0,0 +1,40 @@
+"""
+Presever compatibility with previous versions of AMOR datafiles.
+"""
+
+from datetime import datetime
+
+# old hdf parameter mappings, key is last date of validity
+legacy_hdf_paths = {
+        datetime(2026, 3, 18).timestamp():
+        dict(
+        title=('entry1/title', str),
+        proposal_id=('entry1/proposal_id', str),
+        user_name=('entry1/user/name', str),
+        user_email=('entry1/user/email', str),
+        sample_name=('entry1/sample/name', str),
+        source_name=('entry1/Amor/source/name', str),
+        sample_model=('entry1/sample/model', str),
+        start_time=('entry1/start_time', str),
+        start_time_fallback=('entry1/Amor/instrument_control_parameters/start_time', str),
+
+        chopper_separation=('entry1/Amor/chopper/pair_separation', float),
+        detector_distance=('entry1/Amor/detector/transformation/distance', float),
+        chopper_distance=('entry1/Amor/chopper/distance', float),
+        sample_temperature=('entry1/sample/temperature', float),
+        sample_magnetic_field=('entry1/sample/magnetic_field', float),
+
+        mu=('entry1/Amor/instrument_control_parameters/mu', float, 'mu'),
+        nu=('entry1/Amor/instrument_control_parameters/nu', float, 'nu'),
+        kap=('entry1/Amor/instrument_control_parameters/kappa', float, 'kappa'),
+        kad=('entry1/Amor/instrument_control_parameters/kappa_offset', float, 'kappa_offset'),
+        div=('entry1/Amor/instrument_control_parameters/div', float, 'div'),
+        ch1_trigger_phase=('entry1/Amor/chopper/ch1_trigger_phase', float, 'ch1_trigger_phase'),
+        ch2_trigger_phase=('entry1/Amor/chopper/ch2_trigger_phase', float, 'ch2_trigger_phase'),
+        chopper_speed=('entry1/Amor/chopper/rotation_speed', float, 'chopper_phase'),
+        chopper_phase=('entry1/Amor/chopper/phase', float, 'chopper_phase'),
+        polarization_config_label=('entry1/Amor/polarization/configuration', int, 'polarization_config_label', '/*'),
+        )
+    }
+# create a sorted list of validity timestamps for quick comparison
+legacy_cutoffs = list(sorted(legacy_hdf_paths.keys()))
diff --git a/eos/file_reader.py b/eos/file_reader.py
index f20a4c4..5b37fda 100644
--- a/eos/file_reader.py
+++ b/eos/file_reader.py
@@ -14,7 +14,7 @@ from datetime import datetime
 from orsopy import fileio
 from orsopy.fileio.model_language import SampleModel
 
-from . import const
+from . import const, compat
 from .header import Header
 from .event_data_types import AmorGeometry, AmorTiming, AmorEventStream, LOG_TYPE, PACKET_TYPE, EVENT_TYPE, PULSE_TYPE, \
     PC_TYPE
@@ -147,6 +147,15 @@ class AmorHeader:
         else:
             TZ = AMOR_LOCAL_TIMEZONE
         start_date = datetime.fromisoformat(start_time)
+
+        start_timestamp = start_date.timestamp()
+        if start_timestamp<=compat.legacy_cutoffs[-1]:
+            logging.info("      Detected legacy file format, using older mapping")
+            for cutoff in compat.legacy_cutoffs:
+                if start_timestamp<=cutoff:
+                    self.hdf_paths = compat.legacy_hdf_paths[cutoff]
+                    break
+
         self.fileDate = start_date.replace(tzinfo=TZ)
         self._start_time_ns = np.uint64(self.fileDate.timestamp()*1e9)