#include <WiFi.h>
#include <ThingSpeak.h> 
const int trig = 2;
const int echo = 4;

long duration;
float distance;
#define SECRET_SSID "Wokwi-GUEST"   
#define SECRET_PASS "" 

#define SECRET_CH_ID  2639620   
#define SECRET_CH_IDr  2639620
#define SECRET_WRITE_APIKEY "DBZ0Z3683OLUDQ0N"   
#define SECRET_READ_APIKEY "GPLMVZ3KXTZRUC27"   

char ssid[] = SECRET_SSID;  
char pass[] = SECRET_PASS;   
int keyIndex = 0;            
WiFiClient  client;
unsigned long myChannelNumber = SECRET_CH_ID;
unsigned long readmyChannelNumber = SECRET_CH_IDr;
const char * myWriteAPIKey = SECRET_WRITE_APIKEY;
const char * myReadAPIKey = SECRET_READ_APIKEY;
unsigned int dataFieldOne = 1; 

float aConst = 2.25E-02;

void setup() {
  Serial.begin(115200);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  pinMode(15, OUTPUT);
  while (!Serial) {
    ; 
  }
    WiFi.mode(WIFI_STA);  
  ThingSpeak.begin(client);  
}

void loop() {
if(WiFi.status() != WL_CONNECTED)
  {
    Serial.print("Attempting to connect to SSID: ");
    Serial.println(SECRET_SSID);
    while(WiFi.status() != WL_CONNECTED)
    {
      WiFi.begin(ssid, pass); // Connect to WPA/WPA2 network. Change this  line if using open or WEP network
      Serial.print(".");
      delay(5000);     
    } 
    Serial.println("\nConnected.");
  }

//Ultrasonic
  digitalWrite(trig,LOW);
delayMicroseconds(2);
digitalWrite(trig, HIGH);
delayMicroseconds(10);
digitalWrite(trig, LOW);

duration = pulseIn(echo, HIGH);
//Serial.println(duration);
distance = duration*0.034/2;
Serial.println(distance);

//Thingspeak
  int statusCode;
  ThingSpeak.setField(3, distance);
  statusCode = ThingSpeak.writeFields(myChannelNumber,SECRET_WRITE_APIKEY);

  aConst = readTSData( readmyChannelNumber, dataFieldOne );
  Serial.println(aConst);
  if(aConst == 1){
    digitalWrite(15, HIGH);
     Serial.println("Relay on");
  }
  else{
    digitalWrite(15,LOW);
     Serial.println("Relay off");
  }

  if(statusCode == 200) { //successful writing code
      Serial.println("Channel update successful.");
  }
  else {
      Serial.println("Problem Writing data. HTTP error code :" + String(statusCode));
  }
  delay(15000); // data to be uploaded every 15secs 
 
  
}

float readTSData( long TSChannel, unsigned int TSField ) {

  float data =  ThingSpeak.readFloatField( TSChannel, TSField, SECRET_READ_APIKEY );
 // Serial.println( " Data read from ThingSpeak: " + String( data, 9 ) );
  return data;

}