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


#define TRIG_PIN 9
#define ECHO_PIN 10
#define BUTTON1_PIN 8
#define BUTTON2_PIN 11
#define LED1_PIN 12
#define LED2_PIN 13
#define LCD_ADDRESS 0x27
#define LCD_COLS 16
#define LCD_ROWS 2

LiquidCrystal_I2C lcd(LCD_ADDRESS, LCD_COLS, LCD_ROWS);

float distance, length, width, area;
bool button1_pressed, button2_pressed;
float addValue;
unsigned long button2PressTime, button2PressDuration;
bool areaDisplayed, welcomeDisplayed;

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(BUTTON1_PIN, INPUT_PULLUP);
  pinMode(BUTTON2_PIN, INPUT_PULLUP);
  pinMode(LED1_PIN, OUTPUT);
  pinMode(LED2_PIN, OUTPUT);

  lcd.init();
  lcd.backlight();
  lcd.setCursor(1, 0);
  lcd.print("W e l c o m e");

  distance = length = width = area = addValue = 0.0f;
  button1_pressed = button2_pressed = areaDisplayed = false;
  welcomeDisplayed = true;
  button2PressTime = button2PressDuration = 0;

  
  digitalWrite(LED1_PIN, HIGH);
  digitalWrite(LED2_PIN, LOW);
}

void loop() {
  if (welcomeDisplayed) {
    if (digitalRead(BUTTON1_PIN) == LOW) {
      unsigned long startTime = millis();
      while (digitalRead(BUTTON1_PIN) == LOW);
      if ((millis() - startTime) > 100) {
        welcomeDisplayed = false;
        lcd.clear();

        
        digitalWrite(LED1_PIN, LOW);
        digitalWrite(LED2_PIN, HIGH);
      }
    }
    return;
  }
  
  distance = measureDistance() + addValue;

  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  lcd.print(distance);
  lcd.print(" m     ");
  
  button1_pressed = digitalRead(BUTTON1_PIN) == LOW;
  
  if (button1_pressed) {
    length = distance;
    lcd.setCursor(0, 1);
    lcd.print("Length: ");
    lcd.print(length);
    lcd.print(" m     ");
    while (digitalRead(BUTTON1_PIN) == LOW);
    areaDisplayed = false;
  }
  
  if (digitalRead(BUTTON2_PIN) == LOW) {
    if (button2PressTime == 0) {
      button2PressTime = millis();
    } else {
      button2PressDuration = millis() - button2PressTime;
      if (button2PressDuration > 500) {
        width = distance;
        area = length * width;
        areaDisplayed = true;
      }
    }
  } else {
    if (button2PressDuration > 1 && button2PressDuration <= 1000) {
      width = distance;
      lcd.setCursor(0, 1);
      lcd.print("Width: ");
      lcd.print(width);
      lcd.print(" m     ");
    }
    button2PressTime = 0;
    button2PressDuration = 0;
  }

  if (areaDisplayed) {
    lcd.setCursor(0, 1);
    lcd.print("Area: ");
    lcd.print(area);
    lcd.print(" m2     ");
  }
}

float measureDistance() {
  float duration;
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  duration = pulseIn(ECHO_PIN, HIGH);
  return ((duration * 0.034 / 2) / 100) + 0.2; 
}