#include <Wire.h>
#include <LiquidCrystal_I2C.h>

const byte trig = 9;
const byte echo = 8;
const byte redPin = 11;
const byte greenPin = 10;
const byte bluePin = 6;
const byte switchPin = 2;
double distance, duration;
double lastDistance = -1; // Track the last measured distance

// Initialize LCD
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
 pinMode(switchPin, INPUT); 
 pinMode(redPin, OUTPUT);
pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
  lcd.begin(A4, A5); 
  lcd.backlight(); 

  Serial.begin(115200);
}

void loop() {
  // Check if the switch is ON
  if (digitalRead(switchPin) == LOW) {
    //ultrasonic sensor
    digitalWrite(trig, LOW);
    delayMicroseconds(2);
    digitalWrite(trig, HIGH);
    delayMicroseconds(10);
    digitalWrite(trig, LOW);
    duration = pulseIn(echo, HIGH);
    distance = (duration * 0.0343) / 2;

    //if the distance is not negative 
    // and different from the last recorded value
    if (distance > 0 && distance != lastDistance) {
      lastDistance = distance;

      //distance on the LCD
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Distance is:");
      lcd.setCursor(0, 1);
      lcd.print(distance);
      lcd.print(" cm");

      // Control RGB LED based on distance
      if (distance < 15) {
        setColor(255, 0, 0);  //red
      } else if (distance < 30) {
        setColor(0, 255, 0);  // green
      } else if (distance < 50) {
        setColor(0, 0, 255);  // blue
      } else {
        setColor(255, 255, 255);  // white
      }
    }
  } else {
    // turn everything off if the switch isoff
    setColor(0, 0, 0);
    lcd.clear();
    lastDistance = -1; // reset lastDistance
  }
}

void setColor(int red, int green, int blue) {
  analogWrite(redPin, red);
  analogWrite(greenPin, green);
  analogWrite(bluePin, blue);
}