Cloud Home Automation Series Part 2 : Use AWS Device Shadow to Control ESP32 with Arduino Code

/*********
  Gourav Das
  Complete project details at https://hackernoon.com/cloud-home-automation-series-part-2-use-aws-device-shadow-to-control-esp32-with-arduino-code-tq9a37aj
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
*********/
#include <AWS_IOT.h>
#include <WiFi.h>
#include <ArduinoJson.h> //Download latest ArduinoJson 6 Version library only by Benoît Blanchon from Manage Libraries

AWS_IOT shadow;
#define ledPin 2 // LED Pin

char WIFI_SSID[]="Wifi-Name";
char WIFI_PASSWORD[]="Wifi_Password";
char HOST_ADDRESS[]="************-***.iot.us-east-1.amazonaws.com";  //AWS IoT Custom Endpoint Address
char CLIENT_ID[]= "ESP32";
char SHADOW_GET[]= "$aws/things/{Thingname}/shadow/get/accepted";
char SENT_GET[]= "$aws/things/{ThingName}/shadow/get";
char SHADOW_UPDATE[]= "$aws/things/{ThingName}/shadow/update";

int status = WL_IDLE_STATUS;
int msgReceived=0;
char payload[512];
char reportpayload[512];
char rcvdPayload[512];

void mySubCallBackHandler (char *topicName, int payloadLen, char *payLoad)
{
    strncpy(rcvdPayload,payLoad,payloadLen);
    rcvdPayload[payloadLen] = 0;
    msgReceived = 1;
}

void updateShadow (int power)
{ 
  sprintf(reportpayload,"{\"state\": {\"reported\": {\"power\": \"%d\"}}}",power);
  delay(3000);   
    if(shadow.publish(SHADOW_UPDATE,reportpayload) == 0)
      {       
        Serial.print("Publish Message:");
        Serial.println(reportpayload);
      }
    else
      {
        Serial.println("Publish failed");
        Serial.println(reportpayload);   
      }  
} 

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
  delay(2000);  

    while (status != WL_CONNECTED)
    {
        Serial.print("Attempting to connect to SSID: ");
        Serial.println(WIFI_SSID);
        status = WiFi.begin(WIFI_SSID, WIFI_PASSWORD); // Connect to WPA/WPA2 network. Change this line if using open or WEP network:        
        delay(5000);// wait 5 seconds for connection:
    }

    Serial.println("Connected to wifi");

    if(shadow.connect(HOST_ADDRESS,CLIENT_ID)== 0) //Connect to AWS IoT COre
    {
        Serial.println("Connected to AWS");
        delay(1000);

        if(0==shadow.subscribe(SHADOW_GET,mySubCallBackHandler)) //Subscribe to Accepted GET Shadow Service
        {
            Serial.println("Subscribe Successfull");
        }
        else
        {
            Serial.println("Subscribe Failed, Check the Thing Name and Certificates");
            while(1);
        }
    }
    else
    {
        Serial.println("AWS connection failed, Check the HOST Address");
        while(1);
    }
  
  
  delay(3000); /*Sent Empty string to fetch Shadow desired state*/ 
    if(shadow.publish(SENT_GET,"{}") == 0)
      {       
        Serial.print("Empty String Published\n");
      }
    else
      {
        Serial.println("Empty String Publish failed\n");
      }  /*Sent Empty string to fetch Shadow desired state*/   
}    

void loop() {
  
 if(msgReceived == 1)
    
  {
        msgReceived = 0;
        Serial.print("Received Message:");
        Serial.println(rcvdPayload);
        StaticJsonDocument<256> doc;
        deserializeJson(doc, rcvdPayload);
        
    
        if (doc.isNull()) { /* Test if parsing succeeds. */
        Serial.println("parseObject() failed");
        return;
        } /* Test if parsing succeeds. */
    
        int power = doc["state"]["desired"]["power"];
        Serial.println(power);
        if(power == 1)
        digitalWrite(ledPin, HIGH);
        else if(power == 0)
        digitalWrite(ledPin, LOW);
    updateShadow(power);  
    }  
}

{"state": {"desired": {"power": "1"}}}