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

LiquidCrystal_I2C lcd(0x27, 16, 2);

// Pins
const int ledPins[3] = {2, 3, 4};
const int buttonPin = 5;

unsigned long startTime;
unsigned long reactionTime;
bool measuring = false;

void setup() {
  for (int i = 0; i < 3; i++) {
    pinMode(ledPins[i], OUTPUT);
    digitalWrite(ledPins[i], LOW);
  }

  pinMode(buttonPin, INPUT_PULLUP);

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Reaktionstest");
  lcd.setCursor(0, 1);
  lcd.print("Bereit...");
  delay(2000);

  randomSeed(analogRead(A0));
}

void loop() {
  // Zufällige Wartezeit (2–5 Sekunden)
  lcd.clear();
  lcd.print("Warte...");
  delay(random(2000, 5000));

  // LEDs einschalten → Start
  for (int i = 0; i < 3; i++) {
    digitalWrite(ledPins[i], HIGH);
  }

  lcd.clear();
  lcd.print("JETZT DRUECKEN");
  startTime = millis();
  measuring = true;

  // Warten auf Tastendruck
  while (measuring) {
    if (digitalRead(buttonPin) == LOW) {
      reactionTime = millis() - startTime;
      measuring = false;
    }
  }

  // LEDs aus
  for (int i = 0; i < 3; i++) {
    digitalWrite(ledPins[i], LOW);
  }

  // Ergebnis anzeigen
  lcd.clear();
  lcd.print("Zeit:");
  lcd.setCursor(0, 1);
  lcd.print(reactionTime);
  lcd.print(" ms");

  delay(4000);
}