#include <LiquidCrystal.h>

// Set up the LCD: (RS, E, D4, D5, D6, D7)
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

const int buttonPin = 7;       // Button input pin
const int backlightPin = 9;    // LCD backlight control pin (PWM)

void setup() {
  pinMode(buttonPin, INPUT_PULLUP); // Use internal pull-up resistor
  pinMode(backlightPin, OUTPUT);    // Backlight pin as output
  analogWrite(backlightPin, 255);   // Full brightness

  lcd.begin(16, 2);           // Initialize LCD size
  lcd.print("Reaction Timer!");  // Welcome message
  delay(2000);                // Show it for 2 seconds
  lcd.clear();                // Clear screen
}
 
void loop() {
  // Wait until the button is released
  while (digitalRead(buttonPin) == LOW) {
    // Wait for release (button held down)
  }

  lcd.print("Get Ready...");

  // Wait a random time before showing "NOW!"
  unsigned long waitTime = random(3000, 6000); // 3-6 seconds
  unsigned long startWait = millis();

  while (millis() - startWait < waitTime) {
    if (digitalRead(buttonPin) == LOW) {
      // Player pressed too early!
      lcd.clear();
      lcd.print("Too early!");
      delay(2000);
      lcd.clear();
      return; // Restart the loop
    }
  }

  lcd.clear();
  lcd.print("NOW!");

  // Record the time when signal was shown
  unsigned long startTime = millis();

  // Wait for the button to be pressed
  while (digitalRead(buttonPin) == HIGH) {
    // Waiting for button press
  }

  // Measure reaction time
  unsigned long reactionTime = millis() - startTime;

  // Show result
  lcd.clear();
  lcd.print("Reaction time:");
  lcd.setCursor(0, 1);
  lcd.print(reactionTime);
  lcd.print(" ms");

  // Wait until button is released before restarting
  while (digitalRead(buttonPin) == LOW) {
    // Waiting for button release
  }

  delay(1000);
  lcd.clear(); // Clear before next round
}