#include <Wire.h> // already pre-installed
#include <LiquidCrystal_I2C.h> 
// LiquidCrystal_I2C by Martin Kubovcik muss installiert werden

LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C Adresse meist 0x27 oder 0x3F

// Verbindung:
// GND -> GND
// VCC -> 5V
// SDA -> A4
// SCL -> A5
// Button	-> Pin 7 bzw. Pin 8 und Button ->	GND
const int buttonPin1 = 7;   // Button input pin P1
const int buttonPin2 = 8;   // Button input pin P2

void setup() {
  pinMode(buttonPin1, INPUT_PULLUP); // internal pull-up resistor
  pinMode(buttonPin2, INPUT_PULLUP); // internal pull-up resistor
  lcd.init();        // initialize I2C display
  lcd.backlight();   // turn on backlight

  lcd.setCursor(0,0);
  lcd.print("Reaction Timer!");
  delay(2000);
  lcd.clear();
}

void loop() {
  while (digitalRead(buttonPin1) == LOW || digitalRead(buttonPin2) == LOW) { }
  lcd.setCursor(0,0);
  lcd.print("Get Ready...");
  delay(random(3000,6000));   // random wait 3-6 s
  lcd.clear();
  lcd.setCursor(0,0);

  while (digitalRead(buttonPin1) == LOW || digitalRead(buttonPin2) == LOW) {
        // wait for button release
   }
  lcd.print("NOW!");
  long startTime = millis();
  long reactionTime= 100000;
  int winner = 0;
  while ((digitalRead(buttonPin1) == HIGH)&&(digitalRead(buttonPin2) == HIGH)) {
  // Wait for first valid press
   while (true) {
    if (digitalRead(buttonPin1) == LOW) {
      winner = 1;
      break;
    }
    if (digitalRead(buttonPin2) == LOW) {
      winner = 2;
      break;
    }
   }
   reactionTime = millis() - startTime;
  }

  lcd.clear();
  lcd.print("P");
  lcd.print(winner);
  lcd.print(" wins!");
  lcd.setCursor(0, 1);
  lcd.print("Time:");
  lcd.print(reactionTime);
  lcd.print(" ms");
  delay(2000);
  lcd.clear();
}