Initial support for notification settings

Signed-off-by: Travis Ralston <travpc@gmail.com>

src/settings/controllers/SettingController.js

@@ -0,0 +1,49 @@
+/*
+Copyright 2017 Travis Ralston
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/**
+ * Represents a controller for individual settings to alter the reading behaviour
+ * based upon environmental conditions, or to react to changes and therefore update
+ * the working environment.
+ *
+ * This is not intended to replace the functionality of a SettingsHandler, it is only
+ * intended to handle environmental factors for specific settings.
+ */
+export default class SettingController {
+
+    /**
+     * Gets the overridden value for the setting, if any. This must return null if the
+     * value is not to be overridden, otherwise it must return the new value.
+     * @param {string} level The level at which the value was requested at.
+     * @param {String} roomId The room ID, may be null.
+     * @param {*} calculatedValue The value that the handlers think the setting should be,
+     * may be null.
+     * @return {*} The value that should be used, or null if no override is applicable.
+     */
+    getValueOverride(level, roomId, calculatedValue) {
+        return null; // no override
+    }
+
+    /**
+     * Called when the setting value has been changed.
+     * @param {string} level The level at which the setting has been modified.
+     * @param {String} roomId The room ID, may be null.
+     * @param {*} newValue The new value for the setting, may be null.
+     */
+    onChange(level, roomId, newValue) {
+        // do nothing by default
+    }
+}