void setup() {
  Serial.begin(9600);
  pinMode(2, INPUT);  // carry out LED
  pinMode(3, INPUT);  // sum1 LED
  pinMode(4, INPUT);  // sum0 LED
  pinMode(5, INPUT);  // button 1 (option A)
  pinMode(6, INPUT);  // button 2 (option B)
  pinMode(7, INPUT);  // touch sensor
  pinMode(8, OUTPUT); // buzzer
}

bool gameMode = false;
bool lastTouch = false;
int currentQuestion = 0;
int score1 = 0;
int score2 = 0;
int currentPlayer = 1;
bool waitingForAnswer = false;

struct Question {
  String q;
  String optA;
  String optB;
  int correct; // 1 = A, 2 = B
};

Question questions[] = {
  {"Does an AND gate output 1 when both inputs are 1?", "A) Yes", "B) No", 1},
  {"What is 1 + 1 in binary?", "A) 10", "B) 11", 1},
  {"Does an OR gate output 1 when only one input is 1?", "A) No", "B) Yes", 2},
  {"What is the output of AND gate with inputs 1 and 0?", "A) 1", "B) 0", 2},
  {"What is 01 + 01 in binary?", "A) 10", "B) 11", 1},
  {"Does a XOR gate output 1 when both inputs are the same?", "A) Yes", "B) No", 2},
  {"What is 10 + 01 in binary?", "A) 10", "B) 11", 2},
  {"Does a NOT gate flip the input?", "A) Yes", "B) No", 1},
  {"What is the output of OR gate with inputs 0 and 0?", "A) 0", "B) 1", 1},
  {"What is 11 + 01 in binary?", "A) 100", "B) 010", 1}
};

int totalQuestions = 10;

void pointSound() {
  tone(8, 1000, 150);
  delay(200);
  tone(8, 1300, 150);
  delay(200);
  noTone(8);
}

void wrongSound() {
  tone(8, 300, 400);
  delay(450);
  tone(8, 250, 400);
  delay(450);
  noTone(8);
}

void winnerSound() {
  tone(8, 1000, 150); delay(180);
  tone(8, 1200, 150); delay(180);
  tone(8, 1400, 150); delay(180);
  tone(8, 1600, 150); delay(180);
  tone(8, 2000, 400); delay(450);
  noTone(8);
}

void askQuestion() {
  Serial.println("------------------------------");
  Serial.print("PLAYER ");
  Serial.print(currentPlayer);
  Serial.println("'S TURN");
  Serial.println(questions[currentQuestion].q);
  Serial.println(questions[currentQuestion].optA);
  Serial.println(questions[currentQuestion].optB);
  Serial.println("Press Button 1 for A, Button 2 for B");
  waitingForAnswer = true;
}

void checkAnswer(int buttonPressed) {
  bool correct = (buttonPressed == questions[currentQuestion].correct);

  if (correct) {
    Serial.println("CORRECT!");
    pointSound();
    if (currentPlayer == 1) score1++;
    else score2++;
  } else {
    Serial.println("WRONG!");
    wrongSound();
  }

  Serial.print("Score -> Player 1: ");
  Serial.print(score1);
  Serial.print("  Player 2: ");
  Serial.println(score2);

  if (score1 >= 3) {
    Serial.println("*** PLAYER 1 WINS THE GAME! ***");
    winnerSound();
    score1 = 0;
    score2 = 0;
    currentQuestion = 0;
    currentPlayer = 1;
    waitingForAnswer = false;
    gameMode = false;
    Serial.println("--- BACK TO ADDER MODE ---");
    return;
  }

  if (score2 >= 3) {
    Serial.println("*** PLAYER 2 WINS THE GAME! ***");
    winnerSound();
    score1 = 0;
    score2 = 0;
    currentQuestion = 0;
    currentPlayer = 1;
    waitingForAnswer = false;
    gameMode = false;
    Serial.println("--- BACK TO ADDER MODE ---");
    return;
  }

  currentQuestion = (currentQuestion + 1) % totalQuestions;
  currentPlayer = (currentPlayer == 1) ? 2 : 1;
  waitingForAnswer = false;
  delay(1000);
  askQuestion();
}

void loop() {
  bool touched = digitalRead(7);

  if (touched && !lastTouch) {
    gameMode = !gameMode;
    delay(300);
    if (gameMode) {
      Serial.println("=== GAME MODE STARTED ===");
      Serial.println("First to 3 points wins!");
      score1 = 0;
      score2 = 0;
      currentQuestion = 0;
      currentPlayer = 1;
      askQuestion();
    } else {
      Serial.println("--- ADDER MODE ---");
      waitingForAnswer = false;
    }
  }
  lastTouch = touched;

  if (!gameMode) {
    int carry = digitalRead(2);
    int sum1 = digitalRead(3);
    int sum0 = digitalRead(4);
    Serial.print("Result: ");
    Serial.print(carry);
    Serial.print(sum1);
    Serial.println(sum0);
    delay(500);
  } else {
    if (waitingForAnswer) {
      if (digitalRead(5) == HIGH) {
        delay(200);
        checkAnswer(1);
      }
      if (digitalRead(6) == HIGH) {
        delay(200);
        checkAnswer(2);
      }
    }
  }
}