add simple service

src/SimpleService.h

@@ -0,0 +1,85 @@
+#ifndef Service_h
+#define Service_h
+
+#include <ESP8266WiFi.h>
+#include <ESPAsyncTCP.h>
+#include <ESPAsyncWebServer.h>
+#include <AsyncJson.h>
+#include <ArduinoJson.h>
+#include <AsyncJsonRequestWebHandler.h>
+#include <AsyncJsonCallbackResponse.h>
+
+/**
+* At the moment, not expecting services to have to deal with large JSON
+* files this could be made configurable fairly simply, it's exposed on
+* AsyncJsonRequestWebHandler with a setter.
+*/
+#define MAX_SETTINGS_SIZE 1024
+
+/*
+* Abstraction of a service which reads and writes data from an endpoint.
+*
+* Not currently used, but indended for use by features which do not
+* require setting persistance.
+*/
+class SimpleService {
+
+private:
+
+  AsyncJsonRequestWebHandler _updateHandler;
+
+  void fetchConfig(AsyncWebServerRequest *request){
+    AsyncJsonResponse * response = new AsyncJsonResponse();
+    writeToJsonObject(response->getRoot());
+    response->setLength();
+    request->send(response);
+  }
+
+  void updateConfig(AsyncWebServerRequest *request, JsonVariant &json){
+    if (json.is<JsonObject>()){
+      JsonObject& newConfig = json.as<JsonObject>();
+      readFromJsonObject(newConfig);
+
+      // write settings back with a callback to reconfigure the wifi
+      AsyncJsonCallbackResponse * response = new AsyncJsonCallbackResponse([this] () {onConfigUpdated();});
+      writeToJsonObject(response->getRoot());
+      response->setLength();
+      request->send(response);
+    } else{
+      request->send(400);
+    }
+  }
+
+  protected:
+
+    // will serve setting endpoints from here
+    AsyncWebServer* _server;
+
+    // reads the local config from the
+    virtual void readFromJsonObject(JsonObject& root){}
+    virtual void writeToJsonObject(JsonObject& root){}
+
+    // implement to perform action when config has been updated
+    virtual void onConfigUpdated(){}
+
+  public:
+
+    SimpleService(AsyncWebServer* server, char const* servicePath):
+    _server(server) {
+
+      // configure fetch config handler
+      _server->on(servicePath, HTTP_GET, std::bind(&SimpleService::fetchConfig, this, std::placeholders::_1));
+
+      // configure update settings handler
+      _updateHandler.setUri(servicePath);
+      _updateHandler.setMethod(HTTP_POST);
+      _updateHandler.setMaxContentLength(MAX_SETTINGS_SIZE);
+      _updateHandler.onRequest(std::bind(&SimpleService::updateConfig, this, std::placeholders::_1, std::placeholders::_2));
+      _server->addHandler(&_updateHandler);
+    }
+
+    virtual ~SimpleService() {}
+
+};
+
+#endif // end SimpleService