// Define pin numbers for components
const int ldrPin = A0; // LDR pin
const int ultrasonicTrigPin = 9; // Ultrasonic sensor trigger pin
const int ultrasonicEchoPin = 10; // Ultrasonic sensor echo pin
const int buzzerPin = 8; // Buzzer pin
const int ledPins[] = {2, 3, 4, 5, 6}; // Array of LED pins

// Define variables
int ldrThreshold = 500; // LDR threshold for night mode
long distance;
int distanceLEDs[5] = {1, 2, 3, 4, 5}; // LEDs corresponding to distance levels

void setup() {
  // Initialize serial communication
  Serial.begin(9600);

  // Initialize ultrasonic sensor pins
  pinMode(ultrasonicTrigPin, OUTPUT);
  pinMode(ultrasonicEchoPin, INPUT);

  // Initialize buzzer pin
  pinMode(buzzerPin, OUTPUT);

  // Initialize LED pins
  for (int i = 0; i < 5; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
}

void loop() {
  // Read LDR value
  int ldrValue = analogRead(ldrPin);

  // Check if it's night mode
  if (ldrValue < ldrThreshold) {
    // Night mode
    // Enable ultrasonic sensor
    digitalWrite(ultrasonicTrigPin, LOW);
    delayMicroseconds(2);
    digitalWrite(ultrasonicTrigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(ultrasonicTrigPin, LOW);

    // Read ultrasonic sensor
    distance = pulseIn(ultrasonicEchoPin, HIGH) * 0.034 / 2; // Convert to cm

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

    // Display corresponding LED pattern based on distance
    if (distance == 50) {
      displayLEDs(0);
    } else if (distance == 75) {
      displayLEDs(1);
    } else if (distance == 100) {
      displayLEDs(2);
    } else if (distance == 125) {
      displayLEDs(3);
    } else if (distance == 150) {
      displayLEDs(4);
    }

    // Check if specific distance values encountered and display on monitor
    if (distance == 50 || distance == 75 || distance == 100 || distance == 125 || distance == 150) {
      Serial.print("Distance of ");
      Serial.print(distance);
      Serial.println(" cm encountered.");
    }
  } else {
    // Day mode
    // Disable ultrasonic sensor
    digitalWrite(ultrasonicTrigPin, LOW);

    // Turn off all LEDs
    for (int i = 0; i < 5; i++) {
      digitalWrite(ledPins[i], LOW);
    }
  }
}

// Function to display LEDs based on distance level
void displayLEDs(int level) {
  for (int i = 0; i < 5; i++) {
    if (i <= level) {
      digitalWrite(ledPins[i], HIGH);
    } else {
      digitalWrite(ledPins[i], LOW);
    }
  }
}