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

const int numLeds = 6;
const int ledPins[numLeds] = {2, 3, 4, 5, 6, 7};
const int buttonPins[numLeds] = {8, 9, 10, 11, 12, 13};
const int ultrasonicTrigPin = A0;
const int ultrasonicEchoPin = A1;
const int lcdColumns = 16;
const int lcdRows = 2;

int activeLed = -1;
unsigned long startTime = 0;
unsigned long endTime = 0;
unsigned long reactionTime = 0;
unsigned long totalReactionTime = 0;
int tryCount = 0;
bool handDetected = false;

LiquidCrystal_I2C lcd(0x27, lcdColumns, lcdRows); // Change the address (0x27) if required

void setup() {
  for (int i = 0; i < numLeds; i++) {
    pinMode(ledPins[i], OUTPUT);
    pinMode(buttonPins[i], INPUT_PULLUP);
  }
  pinMode(ultrasonicTrigPin, OUTPUT);
  pinMode(ultrasonicEchoPin, INPUT);
  Serial.begin(9600);
  lcd.begin(lcdColumns, lcdRows);
  lcd.print("Reaction Time:");
  randomSeed(analogRead(0)); // Seed the random number generator with an analog reading.
}

void loop() {
  // Wait for the hand to be detected over the ultrasonic sensor.
  handDetected = detectHand();

  if (handDetected) {
    int ledCount = 0;

    while (ledCount < 5) {
      // Choose a random LED to turn on.
      activeLed = random(numLeds);

      // Turn on the selected LED and record the start time.
      digitalWrite(ledPins[activeLed], HIGH);
      startTime = millis();

      // Wait for the corresponding button to be pressed (reaction).
      while (digitalRead(buttonPins[activeLed]) == HIGH) {
        // You can add other tasks here if needed, but avoid using delay().
      }

      // Record the end time and calculate the reaction time.
      endTime = millis();
      reactionTime = endTime - startTime;

      // Turn off the active LED.
      digitalWrite(ledPins[activeLed], LOW);

      // Display the reaction time on the Serial Monitor.
      Serial.print("LED ");
      Serial.print(activeLed + 1);
      Serial.print(": Reaction Time (ms): ");
      Serial.println(reactionTime);

      // Add the reaction time to the total.
      totalReactionTime += reactionTime;

      // Increment the LED count and try count.
      ledCount++;
      tryCount++;

      // Wait for a brief pause before starting the next test.
      delay(1000);
    }

    // Calculate the average reaction time and display on the LCD.
    unsigned long averageReactionTime = totalReactionTime / 5;
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Avg Reaction:");
    lcd.setCursor(0, 1);
    lcd.print(averageReactionTime);

    // Reset the total reaction time and try count for the next set of 5 tries.
    totalReactionTime = 0;
    tryCount = 0;

    // Wait for a brief pause before starting the next set of 5 tries.
    delay(3000);
  }
}

bool detectHand() {
  // Send a trigger signal to the ultrasonic sensor.
  digitalWrite(ultrasonicTrigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(ultrasonicTrigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(ultrasonicTrigPin, LOW);

  // Measure the time it takes for the ultrasonic signal to bounce back.
  unsigned long duration = pulseIn(ultrasonicEchoPin, HIGH);

  // Calculate the distance (in cm) based on the speed of sound (343 m/s).
  // Divide by 2 because the sound travels to the object and back.
  unsigned int distance = duration * 0.0343 / 2;

  // If the detected distance is less than 10 cm, consider it as a hand detected.
  if (distance < 10) {
    delay(3000); // Wait for at least 3 seconds to confirm the hand presence.
    return true;
  } else {
    return false;
  }
}