const int sensorPin = 13;
const int ledPin = 23;
int lightInit;  // initial value
int lightVal;   // light reading

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(ledPin, OUTPUT);
  lightInit = analogRead(sensorPin);
}

void loop() {
  lightVal = analogRead(sensorPin); // read the current light levels
  //if lightVal is less than our initial reading withing a threshold then it is dark.
  if(lightVal - lightInit <  50)
  {
      digitalWrite (ledPin, HIGH); // turn on light
  }
  //otherwise, it is bright
  else
  {
    digitalWrite (ledPin, LOW); // turn off light
  }
}