config: add new Configuration class to simplify handling json config update api

src/Config.cpp

@@ -9,6 +9,50 @@
 #include <LittleFS.h>
 #include <vector>
 
+void
+ConfigTaskMixin::handleEvent(const InputEvent &evt)
+{
+  if (evt.intent == InputEvent::ConfigurationChanged) {
+      const JsonObject& cfg = *evt.as<JsonObject>();
+      handleConfigChange(Configuration(cfg));
+  }
+}
+
+Configuration::Configuration(const JsonObject& data)
+  : m_json(data)
+{
+}
+
+const char*
+Configuration::get(const char* key, const char* defaultVal) const
+{
+    if (m_json.containsKey(key)) {
+      return m_json[key];
+    } else {
+      return defaultVal;
+    }
+}
+
+int
+Configuration::get(const char* key, int defaultVal) const
+{
+    if (m_json.containsKey(key)) {
+      return m_json[key];
+    } else {
+      return defaultVal;
+    }
+}
+
+bool
+Configuration::get(const char* key, bool defaultVal) const
+{
+    if (m_json.containsKey(key)) {
+      return m_json[key];
+    } else {
+      return defaultVal;
+    }
+}
+
 StaticJsonDocument<1024> jsonConfig;
 
 constexpr uint16_t HardwareConfig::MAX_LED_NUM;