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

LiquidCrystal_I2C lcd(0x27, 16, 2);
Servo motor;

const int btnUp = 2;
const int btnGo = 3;
const int btnDown = 4;
const int servoPin = 9;
const int buzzerPin = 8;  // Buzzer connected here

int minutes = 0;
const int maxMinutes = 90;
int timeLeft = 0;  // Minutes remaining in countdown
bool running = false;

unsigned long previousMillis = 0;
const unsigned long interval = 1000;  // 1 second update interval

int elapsedSeconds = 0;  // Seconds elapsed since countdown start

// Previous button states for detecting press event
bool prevBtnUpState = LOW;
bool prevBtnDownState = LOW;
bool prevBtnGoState = LOW;

void setup() {
  pinMode(btnUp, INPUT);
  pinMode(btnGo, INPUT);
  pinMode(btnDown, INPUT);
  pinMode(buzzerPin, OUTPUT);
  digitalWrite(buzzerPin, LOW);

  lcd.init();
  lcd.backlight();

  motor.attach(servoPin);
  motor.write(90);  // Start at 90°

  updateDisplay();
}

void loop() {
  // Read current button states
  bool currentBtnUpState = digitalRead(btnUp);
  bool currentBtnDownState = digitalRead(btnDown);
  bool currentBtnGoState = digitalRead(btnGo);

  if (!running) {
    // Detect rising edge (not pressed -> pressed) for Up button
    if (currentBtnUpState == HIGH && prevBtnUpState == LOW) {
      if (minutes < maxMinutes) {
        minutes++;
        updateDisplay();
      }
    }
    // Detect rising edge for Down button
    if (currentBtnDownState == HIGH && prevBtnDownState == LOW) {
      if (minutes > 0) {
        minutes--;
        updateDisplay();
      }
    }
    // Detect rising edge for Go button
    if (currentBtnGoState == HIGH && prevBtnGoState == LOW) {
      if (minutes > 0) {
        timeLeft = minutes;
        elapsedSeconds = 0;
        running = true;
        previousMillis = millis();
        motor.write(90);  // Reset servo position
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Starting...");
        delay(1000);
        drawProgressBar(timeLeft);
      }
    }
  } else {
    // During countdown, detect down button press to reduce timeLeft by 1 minute
    if (currentBtnDownState == HIGH && prevBtnDownState == LOW) {
      if (timeLeft > 0) {
        timeLeft--;
        if (timeLeft < 0) timeLeft = 0;
        drawProgressBar(timeLeft);
      }
    }

    unsigned long currentMillis = millis();

    if (currentMillis - previousMillis >= interval) {
      previousMillis = currentMillis;
      elapsedSeconds++;

      int totalSeconds = minutes * 60;
      int secondsLeft = totalSeconds - elapsedSeconds;
      if (secondsLeft < 0) secondsLeft = 0;

      if (secondsLeft == 0) {
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Done!");
        lcd.setCursor(0, 1);
        lcd.print("                ");
        motor.write(0);
        running = false;
        buzzDone();  // Sound buzzer for 2 seconds
        delay(3000);
        updateDisplay();
      } else {
        // Calculate current angle for servo (90° to 0°)
        int angle = map(secondsLeft, 0, totalSeconds, 0, 90);
        if (angle > 90) angle = 90;
        if (angle < 0) angle = 0;
        motor.write(angle);

        // Update timeLeft in minutes left (rounded up)
        timeLeft = (secondsLeft + 59) / 60;
        drawProgressBar(timeLeft);

        // Display countdown MM:SS
        displayCountdown(secondsLeft);
      }
    }
  }

  // Save current button states for next loop iteration
  prevBtnUpState = currentBtnUpState;
  prevBtnDownState = currentBtnDownState;
  prevBtnGoState = currentBtnGoState;
}

void updateDisplay() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Set Time:");
  lcd.setCursor(0, 1);
  lcd.print(minutes);
  lcd.print(" min  ");
  drawProgressBar(minutes);
}

void drawProgressBar(int timeVal) {
  int barLength = 16;
  int filled = map(timeVal, 0, maxMinutes, 0, barLength);
  if (filled > barLength) filled = barLength;
  if (filled < 0) filled = 0;

  lcd.setCursor(0, 1);
  for (int i = 0; i < barLength; i++) {
    if (i < filled) {
      lcd.write(byte(255));  // Full block
    } else {
      lcd.print("");
    }
  }
}

void displayCountdown(int secondsLeft) {
  int dispMinutes = secondsLeft / 60;
  int dispSeconds = secondsLeft % 60;

  lcd.setCursor(0, 0);
  lcd.print("Time Left: ");
  if (dispMinutes < 10) lcd.print('0');
  lcd.print(dispMinutes);
  lcd.print(':');
  if (dispSeconds < 10) lcd.print('0');
  lcd.print(dispSeconds);
  lcd.print("     ");
}

void buzzDone() {
  tone(buzzerPin, 1500);   // Play 1000 Hz tone
  delay(2500);             // for 2 seconds
  noTone(buzzerPin);       // Stop tone
}