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

// Pin definitions
#define INCREMENT_BUTTON 2
#define DECREMENT_BUTTON 3
#define START_RESET_BUTTON 4
#define BUZZER_PIN 5

// LCD setup
LiquidCrystal_I2C lcd(0x27, 16, 2); // Set the LCD address to 0x27 for a 16x2 display

// Variables
int setTime = 1; // Default time in minutes
int remainingTime = 0; // Remaining time in seconds
bool countdownActive = false;
bool buzzerActive = false;
bool inSetTimeScreen = false; // Track if we are in the set time screen
unsigned long previousMillis = 0;
const long interval = 1000; // 1 second interval

// EEPROM address for storing the set time
const int eepromAddress = 0;

void setup() {
  // Initialize LCD
  lcd.begin(16, 2); // Initialize the LCD with 16 columns and 2 rows
  lcd.backlight();

  // Show initial screen message
  showInitialScreen();

  // Initialize buttons
  pinMode(INCREMENT_BUTTON, INPUT_PULLUP);
  pinMode(DECREMENT_BUTTON, INPUT_PULLUP);
  pinMode(START_RESET_BUTTON, INPUT_PULLUP);

  // Initialize buzzer
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);

  // Load saved time from EEPROM
  setTime = EEPROM.read(eepromAddress);
  if (setTime < 1 || setTime > 60) {
    setTime = 18; // Default to 1 minute if EEPROM value is invalid
  }
}

void loop() {
  // Handle button presses
  if (!countdownActive) {
    if (!inSetTimeScreen) {
      // Initial screen: Wait for user to press Enter to go to set time screen
      if (digitalRead(START_RESET_BUTTON) == LOW) {
        delay(200); // Debounce
        inSetTimeScreen = true; // Transition to set time screen
        lcd.clear();
        lcd.print("Set Time: ");
        lcd.setCursor(0, 1);
        lcd.print(setTime);
        lcd.print(" min");
        while (digitalRead(START_RESET_BUTTON) == LOW); // Wait for button release
      }
    } else {
      // Set time screen: Allow user to set time and start countdown
      if (digitalRead(INCREMENT_BUTTON) == LOW) {
        delay(200); // Debounce
        if (setTime < 60) {
          setTime++;
          updateDisplay();
        }
        while (digitalRead(INCREMENT_BUTTON) == LOW); // Wait for button release
      }

      if (digitalRead(DECREMENT_BUTTON) == LOW) {
        delay(200); // Debounce
        if (setTime > 1) {
          setTime--;
          updateDisplay();
        }
        while (digitalRead(DECREMENT_BUTTON) == LOW); // Wait for button release
      }

      if (digitalRead(START_RESET_BUTTON) == LOW) {
        delay(200); // Debounce
        startCountdown();
        while (digitalRead(START_RESET_BUTTON) == LOW); // Wait for button release
      }
    }
  } else {
    // Countdown logic
    unsigned long currentMillis = millis();
    if (currentMillis - previousMillis >= interval) {
      previousMillis = currentMillis;
      remainingTime--;
      updateDisplay();

      // Check if countdown is complete
      if (remainingTime <= 0) {
        countdownActive = false;
        buzzerActive = true;
        lcd.clear();
        lcd.print("Time's up!");
        digitalWrite(BUZZER_PIN, HIGH); // Continuous buzzer

        // Wait for 2 seconds before resetting to the initial screen
        delay(2000);
        resetSystem();
      } else if (remainingTime <= 10) {
        // Beep for the last 10 seconds
        digitalWrite(BUZZER_PIN, HIGH);
        delay(100);
        digitalWrite(BUZZER_PIN, LOW);
      }
    }

    // Reset on start button press
    if (digitalRead(START_RESET_BUTTON) == LOW) {
      delay(200); // Debounce
      resetSystem();
      beep();
    }
  }
}

void showInitialScreen() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(" ALARM V 1.0 ");
  lcd.setCursor(0, 1);
  lcd.print("Press Enter Start");
}

void updateDisplay() {
  lcd.setCursor(10, 0);
  lcd.print("    "); // Clear previous time
  lcd.setCursor(10, 0);
  lcd.print(setTime);
  lcd.print(" min");

  if (countdownActive) {
    lcd.setCursor(0, 1);
    lcd.print("Remaining: ");
    lcd.print(remainingTime / 60);
    lcd.print(":");
    if (remainingTime % 60 < 10) lcd.print("0");
    lcd.print(remainingTime % 60);
  }
}

void startCountdown() {
  // Save the set time to EEPROM
  EEPROM.write(eepromAddress, setTime);

  // Initialize countdown
  remainingTime = setTime * 60;
  countdownActive = true;
  buzzerActive = false;
  lcd.clear();
  lcd.print("Countdown:");
  updateDisplay();
}

void resetSystem() {
  countdownActive = false;
  buzzerActive = false;
  inSetTimeScreen = false;
  digitalWrite(BUZZER_PIN, LOW);
  showInitialScreen();
}

void beep() {
  tone(BUZZER_PIN, 1000); // 1kHz beep
  delay(100);
  noTone(BUZZER_PIN);
}