WeMOS: MQTT Simple Read Write

#include <SPI.h>
#include <PubSubClient.h>
#include <ESP8266WiFi.h>
#include <PubSubClient.h>

/*
 * LightSensorMqttDemo
 *
 */

const char* ssid = "o";
const char* password =  "";
const char* mqttServer = "192.168.88.222";
const int mqttPort = 1883;
const char* mqttUser = "mqtt-spy";
const char* mqttPassword = "123456";

WiFiClient espClient;
PubSubClient client(espClient);
long unsigned int mytime;

// defines and variable for sensor/control mode
#define MODE_OFF    0  // not sensing light, LED off
#define MODE_ON     1  // not sensing light, LED on
#define MODE_SENSE  2  // sensing light, LED controlled by software
int senseMode = 0;
char message_buff[100];
void setup()
{
  // initialize the digital pin as an output.
  pinMode(D2, OUTPUT);     // Initialize the LED_BUILTIN pin as an output
  
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.println("Connecting to WiFi..");
  }
  Serial.println("Connected to the WiFi network");
 
  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);
 
  while (!client.connected()) {
    Serial.println("Connecting to MQTT...");
 
//  if (client.connect("ESP8266Client", mqttUser, mqttPassword )) {
    if (client.connect("ESP8266Client" )) {
      Serial.println("connected");  
      } else {
      Serial.print("failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }
  client.publish("esp/test", "Hello from ESP8266");
  client.subscribe("esp/test");
} 

void loop()
{
  if (!client.connected())
  {
      // clientID, username, MD5 encoded password
      // arduino-mqtt, mqtt-spt, e10adc3949ba59abbe56e057f20f883e (123456)
      // arduino-mqtt (bisa tanpa username & password, sebagai anonymous)
      client.connect("ESP8266Client");
      client.publish("esp/test", "I'm alive!");
      client.subscribe("esp/test");
  }
  
  switch (senseMode) {
    case MODE_OFF:
      // light should be off
      digitalWrite(D2, LOW);
      break;
    case MODE_ON:
      // light should be on
      digitalWrite(D2, HIGH);
      break;
    case MODE_SENSE:
      // light is adaptive to light sensor
       
      // read from light sensor (photocell)
      int lightRead = analogRead(A0);

      // if there is light in the room, turn off LED
      // else, if it is "dark", turn it on
      // scale of light in this circit is roughly 0 - 900
      // 500 is a "magic number" for "dark"
      if (lightRead > 500) {
        digitalWrite(D2, LOW);
      } else {
        digitalWrite(D2, HIGH);
      }
      
      // publish light reading every 5 seconds
      if (millis() > (mytime + 5000)) {
        mytime = millis();
        String pubString = "{\"report\":{\"light\": \"" + String(lightRead) + "\"}}";
        pubString.toCharArray(message_buff, pubString.length()+1);
        //Serial.println(pubString);
       client.publish("esp/test", message_buff);
      }
  }
  
  // MQTT client loop processing
  client.loop();
}  

// handles message arrived on subscribed topic(s)
void callback(char* topic, byte* payload, unsigned int length) {

  int i = 0;    

  // Serial.println("Message arrived:  topic: " + String(topic));
  // Serial.println("Length: " + String(length,DEC));
  
  // create character buffer with ending null terminator (string)
  for(i=0; i<length; i++) {
    message_buff[i] = payload[i];
  }
  message_buff[i] = '\0';
  
  String msgString = String(message_buff);
   
  //Serial.println("Payload: " + msgString);
  
  if (msgString.equals("OFF")) {
    senseMode = MODE_OFF;
  } else if (msgString.equals("ON")) {
    senseMode = MODE_ON;
  } else if (msgString.equals("SENSE")) {
    senseMode = MODE_SENSE;
  }
}

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