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

int Play = 0;
int Set_Dist = 0;
int Button = 2;
int Switch_Button = 3;
int Buzz = 5;
int Led_Red = 7;
int Led_Green = 6;
int trigPin = 9;
int echoPin = 8;
int Distance;
float duration_us, distance;

LiquidCrystal_I2C lcd(0x27,16,2);

void setup() {
  Serial.begin(9600);
  pinMode(Button, INPUT);
  pinMode(Switch_Button, INPUT);
  pinMode(Led_Red, OUTPUT);
  pinMode(Led_Green, OUTPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  lcd.init();
  lcd.backlight();
  lcd.clear();
}

void loop() {
  if (digitalRead(Button) == HIGH && Play == 0) {
    Play = 1;
    Set_On();
    delay(500);
  } else if (digitalRead(Button) == HIGH && Play == 1) {
    Play = 0;
    Set_Off();
    delay(500);
  }

  if (digitalRead(Switch_Button) == HIGH && Play == 1) {
    tone(Buzz, 400, 200);
    lcd.clear();
    Set_Dist = Set_Dist + 1;
    delay(200);
    tone(Buzz, 600, 100);
  }

  if (Play == 1) {
    Led(1);
    switch(Set_Dist) {
      case 0: GetDistance(1, "cm"); break;
      case 1: GetDistance(10, "mm"); break;
      case 2: GetDistance(0.1, "dm"); break;
      case 3: GetDistance(0.01, "m"); break;
      case 4: Set_Dist = 0; break;
      default:break;
    }
  } else {
    Led(0);
    lcd.clear();
  }
}

void GetDistance(float Dist, String Dist_val) {
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration_us = pulseIn(echoPin, HIGH);

  distance = 0.017 * duration_us;
  Distance = distance * Dist;

  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  lcd.print(Distance);
  lcd.print(Dist_val);
  lcd.print(" ");
  delay(500);
}

void Led(int value) {
  if (value == 1) {
    digitalWrite(Led_Green, HIGH);
    digitalWrite(Led_Red, LOW);
  } else {
    digitalWrite(Led_Green, LOW);
    digitalWrite(Led_Red, HIGH);
  }
}

void Set_On() {
  tone(Buzz, 300, 200);
  delay(200);
  tone(Buzz, 400, 200);
  delay(200);
  tone(Buzz, 600, 400);
}

void Set_Off() {
  tone(Buzz, 500, 200);
  delay(200);
  tone(Buzz, 400, 200);
  delay(200);
  tone(Buzz, 200, 400);
}