const int trigPin = 9;       // Trigger pin of the ultrasonic sensor
const int echoPin = 10;      // Echo pin of the ultrasonic sensor
const int ldrPin = A0;        // LDR pin
const int ledPin = 11;        // LED pin for the street light

int threshold = 500;          // Adjust this threshold based on your LDR sensitivity
int dimIntensity = 100;       // Adjust this value for the initial dim intensity
int brightIntensity = 255;    // Adjust this value for the maximum brightness

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ldrPin, INPUT);
  pinMode(ledPin, OUTPUT);

  // Turn off the street light initially
  analogWrite(ledPin, 0);
}

void loop() {
  // Read LDR value to determine day or night
  int ldrValue = analogRead(ldrPin);

  // If it's night, check for motion using the ultrasonic sensor
  if (ldrValue < threshold) {
    detectMotion();
  } else {
    // It's day, turn off the street light
    analogWrite(ledPin, 0);
  }

  delay(500);  // Adjust the delay time based on your requirements
}

void detectMotion() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2;

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Check if someone or something is passing by
  if (distance < 100) {  // Adjust this distance threshold based on your needs
    // Motion detected, increase brightness
    analogWrite(ledPin, brightIntensity);
    delay(1000);  // Keep the light on for 1 second (adjust as needed)
    // After detecting motion, return to dim intensity
  }
  analogWrite(ledPin, dimIntensity);
}