#define NodeID 0

typedef struct {
  String Source;
  String Target;
  String Data;
} json_t;

boolean requestFlag = false;

void setup() {
  Serial.begin(9600);
  while (!Serial) ;; // wait for serial port to connect. Needed for native USB port only

  Serial.println("Starting Node" + String(NodeID));
  delay(1000);
  sendJson("Node1", 0);
}

void loop() {
  if(requestFlag) {
    sendJson("Node1", 5000);
    requestFlag = false;
  }
  decJson("Node1","Node0");
}

String encJson(json_t doc_json) {
  String json_str = "{";
  json_str += "\"Source\":\"" + doc_json.Source + "\",";
  json_str += "\"Target\":\"" + doc_json.Target + "\",";
  json_str += "\"Data\":\"" + doc_json.Data + "\"}";
  return json_str;
}

void sendJson(String target, uint32_t interval) {
  // Put values to struct
  json_t doc_json;
  doc_json.Source = "Node" + String(NodeID);
  doc_json.Target = target;
  doc_json.Data = String(millis());

  unsigned long currentMillis = millis();
  static unsigned long previousMillis = 0;
  if (currentMillis - previousMillis >= interval) {
    // pinMode(RS_DI, OUTPUT);
    String json_str = encJson(doc_json);
    Serial.println("JSON sent: " + json_str);
    // pinMode(RS_DI, INPUT);
    previousMillis = currentMillis;
  }
}

void decJson(String source, String target) {
  json_t doc_json;

  if (Serial.available() > 0) {
    String json_str = Serial.readStringUntil('\n');
    Serial.println("JSON received: " + json_str);

    json_str.trim(); // Remove blank spaces at start & end of string

    // Find start & end field
    int start = json_str.indexOf("\"Source\":") + 9;
    int end = json_str.indexOf(",", start);
    doc_json.Source = json_str.substring(start, end);

    start = json_str.indexOf("\"Target\":") + 9;
    end = json_str.indexOf(",", start);
    doc_json.Target = json_str.substring(start, end);

    start = json_str.indexOf("\"Data\":") + 7;
    end = json_str.indexOf("}", start);
    doc_json.Data = json_str.substring(start, end);

    // Print json data
    if((doc_json.Source == "\""+source+"\"") \
    && (doc_json.Target == "\""+target+"\"")) {
      Serial.println("Source: " + doc_json.Source);
      Serial.println("Target: " + doc_json.Target);
      Serial.println("Data: " + doc_json.Data);
      requestFlag = true;
    }
  }
}