config: remove derived fields from config file when Solaar version changes

* renamed variables

* Restructured configuration loading and ignore config generated by other versions

This fixes an issue where newer solaar versions may have better support for a
device which are not utilised because it is reading a configuration file
generated by an earlier version before support was added.

* fixed formatting

* discard only absent and battery

* discard name property as well

* do not discard name

lib/solaar/configuration.py

@@ -35,8 +35,8 @@ _log = getLogger(__name__)
 del getLogger
 
 _XDG_CONFIG_HOME = _os.environ.get('XDG_CONFIG_HOME') or _path.expanduser(_path.join('~', '.config'))
-_file_path = _path.join(_XDG_CONFIG_HOME, 'solaar', 'config.json')
 _yaml_file_path = _path.join(_XDG_CONFIG_HOME, 'solaar', 'config.yaml')
+_json_file_path = _path.join(_XDG_CONFIG_HOME, 'solaar', 'config.json')
 
 _KEY_VERSION = '_version'
 _KEY_NAME = '_NAME'
@@ -50,24 +50,71 @@ _config = []
 
 
 def _load():
-    global _config
     loaded_config = []
     if _path.isfile(_yaml_file_path):
+        path = _yaml_file_path
         try:
             with open(_yaml_file_path) as config_file:
                 loaded_config = _yaml.safe_load(config_file)
         except Exception as e:
             _log.error('failed to load from %s: %s', _yaml_file_path, e)
-    elif _path.isfile(_file_path):
+    elif _path.isfile(_json_file_path):
+        path = _json_file_path
         try:
-            with open(_file_path) as config_file:
+            with open(_json_file_path) as config_file:
                 loaded_config = _json.load(config_file)
         except Exception as e:
-            _log.error('failed to load from %s: %s', _file_path, e)
+            _log.error('failed to load from %s: %s', _json_file_path, e)
         loaded_config = _convert_json(loaded_config)
+    else:
+        path = None
     if _log.isEnabledFor(_DEBUG):
         _log.debug('load => %s', loaded_config)
-    _config = _cleanup_load(loaded_config)
+    global _config
+    _config = _parse_config(loaded_config, path)
+
+
+def _parse_config(loaded_config, config_path):
+    current_version = __version__
+    parsed_config = [current_version]
+    try:
+        if not loaded_config:
+            return parsed_config
+
+        loaded_version = loaded_config[0]
+        discard_derived_properties = loaded_version != current_version
+        if discard_derived_properties:
+            _log.warning(
+                'config file \'%s\' was generated by another version of solaar '
+                '(config: %s, current: %s). refreshing detected device capabilities', config_path, loaded_version,
+                current_version
+            )
+
+        for device in loaded_config[1:]:
+            assert isinstance(device, dict)
+            parsed_config.append(_device_entry_from_config_dict(device, discard_derived_properties))
+    except Exception as e:
+        _log.warning('Exception processing config file \'%s\', ignoring contents: %s', config_path, e)
+    return parsed_config
+
+
+def _device_entry_from_config_dict(data, discard_derived_properties):
+    divert = data.get('divert-keys')
+    if divert:
+        sliding = data.get('dpi-sliding')
+        if sliding:  # convert old-style dpi-sliding setting to divert-keys entry
+            divert[int(sliding)] = 3
+        data.pop('dpi-sliding', None)
+        gestures = data.get('mouse-gestures')
+        if gestures:  # convert old-style mouse-gestures setting to divert-keys entry
+            divert[int(gestures)] = 2
+        data.pop('mouse-gestures', None)
+        # remove any string entries (from bad conversions)
+        data['divert-keys'] = {k: v for k, v in divert.items() if isinstance(k, int)}
+    if discard_derived_properties:
+        data.pop('_absent')
+        data.pop('_battery')
+    return _DeviceEntry(**data)
 
 
 save_timer = None
@@ -133,31 +180,6 @@ def _convert_json(json_dict):
     return config
 
 
-def _cleanup_load(c):
-    _config = [__version__]
-    try:
-        for element in c:
-            if isinstance(element, dict):
-                divert = element.get('divert-keys')
-                if divert:
-                    sliding = element.get('dpi-sliding')
-                    if sliding:  # convert old-style dpi-sliding setting to divert-keys entry
-                        divert[int(sliding)] = 3
-                    element.pop('dpi-sliding', None)
-                    gestures = element.get('mouse-gestures')
-                    if gestures:  # convert old-style mouse-gestures setting to divert-keys entry
-                        divert[int(gestures)] = 2
-                    element.pop('mouse-gestures', None)
-                    # remove any string entries (from bad conversions)
-                    element['divert-keys'] = {k: v for k, v in divert.items() if isinstance(k, int)}
-                # convert to device entries
-                element = _DeviceEntry(**element)
-                _config.append(element)
-    except Exception as e:
-        _log.warn('Exception processing config.yaml file, ignoring contents: %s', e)
-    return _config
-
-
 class _DeviceEntry(dict):
 
     def __init__(self, **kwargs):