fix: config: Merge defaults into config at load time

Merge defaults into config at load time to ensure that all config
options show up in the configuration dialog, even if they were added
after the local configuration was last changed.

Also use the merge method to merge the local config with the new config
in set_config, ensuring the config contains all keys even if the
submitted config leaves some out.

Signed-off-by: Matthias Blankertz <matthias@blankertz.org>

software/src/utils/config.py

@@ -30,6 +30,7 @@ class Configuration:
         try:
             with open(self.config_path, 'r') as conf_file:
                 self.config = json.load(conf_file)
+            self._merge_configs(self.DEFAULT_CONFIG, self.config)
         except OSError as ex:
             if ex.errno == ENOENT:
                 self.config = Configuration.DEFAULT_CONFIG
@@ -51,6 +52,16 @@ class Configuration:
                 raise
         os.sync()
 
+    def _merge_configs(self, default, config):
+        for k in default.keys():
+            if k not in config:
+                if isinstance(default[k], dict):
+                    config[k] = default[k].copy()
+                else:
+                    config[k] = default[k]
+            elif isinstance(default[k], dict):
+                self._merge_configs(default[k], config[k])
+
     def _save(self):
         with open(self.config_path + '.new', 'w') as conf_file:
             json.dump(self.config, conf_file)
@@ -59,7 +70,7 @@ class Configuration:
         os.sync()
 
     def _get(self, key):
-        return self.config.get(key, self.DEFAULT_CONFIG[key])
+        return self.config[key]
 
     def get_led_count(self) -> int:
         return self._get('LED_COUNT')
@@ -93,5 +104,6 @@ class Configuration:
         self._validate(self.DEFAULT_CONFIG, config)
         if 'TAGMODE' in config and config['TAGMODE'] not in ['tagremains', 'tagstartstop']:
             raise ValueError("Invalid TAGMODE: Must be 'tagremains' or 'tagstartstop'")
+        self._merge_configs(self.config, config)
         self.config = config
         self._save()