fix: select a S2 version compatible with TNO RM (#103)

* fix: select a S2 version compatible with TNO RM

Signed-off-by: Victor Garcia Reolid <victor@seita.nl>

* feat: create function get_latest_compatible_version to find te latest compatible version to use in a S2 connection.

Signed-off-by: Victor Garcia Reolid <victor@seita.nl>

* test: fix test where the selected version is the latest compatible version (the one provided by the RM).

Signed-off-by: Victor Garcia Reolid <victor@seita.nl>

---------

Signed-off-by: Victor Garcia Reolid <victor@seita.nl>

src/flexmeasures_client/s2/cem.py

@@ -30,11 +30,15 @@
 from flexmeasures_client.client import FlexMeasuresClient
 from flexmeasures_client.s2 import Handler, register
 from flexmeasures_client.s2.control_types import ControlTypeHandler
-from flexmeasures_client.s2.utils import get_reception_status, get_unique_id
+from flexmeasures_client.s2.utils import (
+    get_latest_compatible_version,
+    get_reception_status,
+    get_unique_id,
+)
 
 
 class CEM(Handler):
-    __version__ = "0.1.0"  # TODO: find the right version that we will use
+    __version__ = "0.2.0-beta"
 
     _resource_manager_details: ResourceManagerDetails
 
@@ -227,8 +231,15 @@ def handle_handshake(self, message: Handshake):
         # `selected_protocol_version` that matches the one of the RM
         # TODO: Return a TBD "CloseConnection" message to close the connection
 
+        latest_compatible_version = get_latest_compatible_version(
+            message.supported_protocol_versions,
+            self.__version__,
+            self._logger,
+        )
+
         return HandshakeResponse(
-            message_id=get_unique_id(), selected_protocol_version=self.__version__
+            message_id=get_unique_id(),
+            selected_protocol_version=str(latest_compatible_version),
         )
 
     @register(ResourceManagerDetails)

src/flexmeasures_client/s2/utils.py

@@ -5,6 +5,7 @@
 from uuid import uuid4
 
 import pydantic
+from packaging.version import Version
 
 try:
     from s2python.common import ReceptionStatus, ReceptionStatusValues
@@ -80,3 +81,42 @@ def get_reception_status(
     return ReceptionStatus(
         subject_message_id=str(subject_message.message_id), status=status
     )
+
+
+def is_version_supported(v1: Version, v2: Version) -> bool:
+    return v1 >= v2
+
+
+def get_latest_compatible_version(supported_versions, current_version, logger):
+    """
+    Determines the latest compatible version based on supported protocol versions.
+
+    :param supported_versions: List of supported protocol versions (strings).
+    :param current_version: Current version of the system (string).
+    :param logger: Optional logger instance.
+    :return: Latest compatible version (Version object) or current_version if none
+     found.
+    """
+
+    # RM didn't provide supported versions
+    if not supported_versions or len(supported_versions) == 0:
+        logger.warning("RM didn't provide any supported version")
+        return Version(current_version)
+
+    # Convert supported versions to Version objects and sort in descending order
+    rm_versions = sorted((Version(v) for v in supported_versions), reverse=True)
+    cem_version = Version(current_version)
+
+    # Find the latest compatible version
+    latest_compatible_version = next(
+        (v for v in rm_versions if is_version_supported(v, cem_version)), None
+    )
+
+    if latest_compatible_version is None:
+        logger.warning(
+            f"There are no compatible S2 versions supported both by the "
+            f"RM ({rm_versions}) and CEM ({cem_version})"
+        )
+        return cem_version
+
+    return latest_compatible_version

tests/s2/test_cem.py

@@ -32,7 +32,7 @@ async def test_handshake(rm_handshake):
         response["message_type"] == "HandshakeResponse"
     ), "response message_type should be HandshakeResponse"
     assert (
-        response["selected_protocol_version"] == "0.1.0"
+        response["selected_protocol_version"] == "1.0.0"
     ), "CEM selected protocol version should be supported by the Resource Manager"
 
 

tests/s2/test_utils.py

@@ -0,0 +1,56 @@
+import logging
+
+import pytest
+from packaging.version import Version
+
+from flexmeasures_client.s2.utils import get_latest_compatible_version
+
+
+@pytest.mark.parametrize(
+    "supported_versions, current_version, expected_version",
+    [
+        ([], "2.3.4", "2.3.4"),  # No supported versions → return current_version
+        (None, "2.3.4", "2.3.4"),  # No supported versions → return current_version
+        (
+            ["1.2.3", "1.2.5", "1.2.9"],
+            "1.2.4",
+            "1.2.9",
+        ),  # Pick highest supported (>= 1.2.4)
+        (["2.3.0", "2.3.5", "2.3.9"], "2.3.1", "2.3.9"),  # Pick latest >= 2.3.1
+        (
+            ["1.4.0", "1.3.0", "1.2.3"],
+            "1.2.4",
+            "1.4.0",
+        ),  # Pick highest overall (>= 1.2.4)
+        (
+            ["1.1.0", "1.2.1"],
+            "2.3.4",
+            "2.3.4",
+        ),  # No compatible version (higher major) → return current_version
+        (
+            ["2.3.9-alpha", "2.3.5", "2.3.9"],
+            "2.3.1",
+            "2.3.9",
+        ),  # Pre-release ignored, pick latest valid
+        (
+            ["2.1.0+build123", "2.1.4"],
+            "2.1.2",
+            "2.1.4",
+        ),  # Build metadata ignored, pick latest valid
+    ],
+)
+def test_get_latest_compatible_version(
+    supported_versions, current_version, expected_version, caplog
+):
+    caplog.set_level(logging.WARNING)  # Capture warnings
+
+    latest_version = get_latest_compatible_version(
+        supported_versions, current_version, logger=logging.getLogger()
+    )
+
+    assert str(latest_version) == expected_version
+
+    if not supported_versions:
+        assert "RM didn't provide any supported version" in caplog.text
+    elif latest_version == Version(current_version):
+        assert "There are no compatible S2 versions" in caplog.text