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


// Define the LCD
LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16x2 display


// Define pins for the LEDs and light sensor
const int greenLedPin = 10;
const int redLedPin = 9;
const int lightSensorPin = 2; // Connected to D0 of LM393 module


// Variables to track the state and time
bool isLightOn = false;
unsigned long lightOnStartTime = 0;


void setup() {
  // Initialize the LCD
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Light Off");


  // Set up the LED pins
  pinMode(greenLedPin, OUTPUT);
  pinMode(redLedPin, OUTPUT);
 
  // Set up the light sensor pin
  pinMode(lightSensorPin, INPUT_PULLUP);


  // Start with LEDs off
  digitalWrite(greenLedPin, LOW);
  digitalWrite(redLedPin, HIGH); // Red LED is initially ON
 
  // Initialize the serial communication for debugging
  Serial.begin(9600);
}


void loop() {
  // Read the light sensor value
  int lightLevel = digitalRead(lightSensorPin); // Assumes HIGH when above 300 LUX


  // Check if the light level is below 300 LUX (LM393 output is LOW)
  if (lightLevel == HIGH) {
    if (isLightOn) {
      // Light is off now
      isLightOn = false;
      digitalWrite(greenLedPin, LOW);
      digitalWrite(redLedPin, HIGH);
      lcd.setCursor(0, 0);
      lcd.print("Battery Life:     ");
    }
  } else {
    if (!isLightOn) {
      // Light is on now
      isLightOn = true;
      lightOnStartTime = millis();
      digitalWrite(greenLedPin, HIGH);
      digitalWrite(redLedPin, LOW);
      lcd.setCursor(0, 0);
      lcd.print("Light On:    ");
    }
   
    // Calculate the duration the light has been on
    unsigned long lightOnDuration = millis() - lightOnStartTime;


    // Convert and update the duration on the LCD in HH:MM:SS format
    lcd.setCursor(5, 1);
    printDurationOnLCD(lightOnDuration);
  }
}


void printDurationOnLCD(unsigned long duration) {
  unsigned long seconds = duration / 1000;
  unsigned long minutes = seconds / 60;
  unsigned long hours = minutes / 60;
 
  // Calculate remaining minutes and seconds after hours
  seconds %= 60;
  minutes %= 60;


  // Print the duration on the LCD in HH:MM:SS format with both digits for seconds
  if (hours < 10) {
    lcd.print("0"); // Add leading zero for single-digit minutes
  }
  lcd.print(hours);
  lcd.print("h"); // Add 'h' for hours
  lcd.print(":");
  if (minutes < 10) {
    lcd.print("0"); // Add leading zero for single-digit minutes
  }
  lcd.print(minutes);
  lcd.print("m"); // Add 'm' for minutes
  lcd.print(":");
  if (seconds < 10) {
    lcd.print("0"); // Add leading zero for single-digit seconds
  }
  lcd.print(seconds);
  lcd.print("s"); // Add 's' for seconds
}