Implement settable configuration and fix #36

src/Homie/Boot/BootNormal.cpp

@@ -248,9 +248,16 @@ void BootNormal::_onMqttMessage(char* topic, char* payload, uint8_t qos, size_t
     return;
   }
 
-  /*if (strcmp_P(topic, PSTR("$implementation/config/set")) == 0) {
-
-  }*/
+  if (strcmp_P(topic, PSTR("$implementation/config/set")) == 0) {
+    if (_interface->config->patch(_mqttPayloadBuffer.get())) {
+      _interface->logger->logln(F("✔ Configuration updated"));
+      _flaggedForReboot = true;
+      _interface->logger->logln(F("Flagged for reboot"));
+    } else {
+      _interface->logger->logln(F("✖ Configuration not updated"));
+    }
+    return;
+  }
 
   // Implicit node properties
   topic[strlen(topic) - 4] = '\0';  // Remove /set

src/Homie/Config.cpp

@@ -196,6 +196,67 @@ void Config::write(const char* config) {
   configFile.close();
 }
 
+bool Config::patch(const char* patch) {
+    if (!_spiffsBegin()) { return false; }
+
+    StaticJsonBuffer<MAX_JSON_CONFIG_ARDUINOJSON_BUFFER_SIZE> patchJsonBuffer;
+    JsonObject& patchObject = patchJsonBuffer.parseObject(patch);
+
+    if (!patchObject.success()) {
+      _interface->logger->logln(F("✖ Invalid or too big JSON"));
+      return false;
+    }
+
+    File configFile = SPIFFS.open(CONFIG_FILE_PATH, "r");
+    if (!configFile) {
+      _interface->logger->logln(F("✖ Cannot open config file"));
+      return false;
+    }
+
+    size_t configSize = configFile.size();
+
+    char configJson[MAX_JSON_CONFIG_FILE_SIZE];
+    configFile.readBytes(configJson, configSize);
+    configFile.close();
+
+    StaticJsonBuffer<MAX_JSON_CONFIG_ARDUINOJSON_BUFFER_SIZE> configJsonBuffer;
+    JsonObject& configObject = configJsonBuffer.parseObject(configJson);
+
+    for (JsonObject::iterator it = patchObject.begin(); it != patchObject.end(); ++it) {
+      if (patchObject[it->key].is<JsonObject&>()) {
+        JsonObject& subObject = patchObject[it->key].as<JsonObject&>();
+        for (JsonObject::iterator it2 = subObject.begin(); it2 != subObject.end(); ++it2) {
+          if (!configObject.containsKey(it->key) || !configObject[it->key].is<JsonObject&>()) {
+            String error = "✖ Config does not contain a ";
+            error.concat(it->key);
+            error.concat(" object");
+            _interface->logger->logln(error);
+            return false;
+          }
+          JsonObject& subConfigObject = configObject[it->key].as<JsonObject&>();
+          subConfigObject[it2->key] = it2->value;
+        }
+      } else {
+        configObject[it->key] = it->value;
+      }
+    }
+
+    ConfigValidationResult configValidationResult = Helpers::validateConfig(configObject);
+    if (!configValidationResult.valid) {
+      _interface->logger->log(F("✖ Config file is not valid, reason: "));
+      _interface->logger->logln(configValidationResult.reason);
+      return false;
+    }
+
+    size_t finalBufferLength = configObject.measureLength() + 1;
+    std::unique_ptr<char[]> finalConfigString(new char[finalBufferLength]);
+    configObject.printTo(finalConfigString.get(), finalBufferLength);
+
+    write(finalConfigString.get());
+
+    return true;
+}
+
 BootMode Config::getBootMode() const {
   return _bootMode;
 }

src/Homie/Config.hpp

@@ -21,6 +21,7 @@ class Config {
   char* getSafeConfigFile() const;
   void erase();
   void write(const char* config);
+  bool patch(const char* patch);
   BootMode getBootMode() const;
   void log() const;  // print the current config to log output