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

#define LCD_ADDR 0x27
LiquidCrystal_I2C lcd(LCD_ADDR, 20, 4);

const int buttonPins[4] = {15, 2, 4, 16}; // Buttons for options A-D
const int buzzerPin = 17;                  // Buzzer pin

// RGB LED pins
const int redPin = 5;
const int greenPin = 18;
const int bluePin = 19;

const int TOTAL_QUESTIONS = 20;

int currentQuestion = 0;
int score = 0;
int selectedOption = -1;

unsigned long lastDebounceTime = 0;
const unsigned long debounceDelay = 50;

struct Question {
  String question;
  int options[4];
  int answerIndex;
};

Question questions[TOTAL_QUESTIONS];

// Generate random math question with 4 options
Question generateQuestion() {
  Question q;
  int a = random(1, 21);
  int b = random(1, 21);
  int op = random(0, 3);

  if (op == 0) {
    q.question = String(a) + " + " + String(b) + " = ?";
    q.options[0] = a + b;
  } else if (op == 1) {
    if (a < b) { int t = a; a = b; b = t; }
    q.question = String(a) + " - " + String(b) + " = ?";
    q.options[0] = a - b;
  } else {
    q.question = String(a) + " * " + String(b) + " = ?";
    q.options[0] = a * b;
  }

  for (int i = 1; i < 4; i++) {
    int val;
    do {
      val = q.options[0] + random(-10, 11);
    } while (val == q.options[0] || val < 0);
    q.options[i] = val;
  }

  // Shuffle options
  for (int i = 3; i > 0; i--) {
    int j = random(0, i + 1);
    int temp = q.options[i];
    q.options[i] = q.options[j];
    q.options[j] = temp;
  }

  for (int i = 0; i < 4; i++) {
    if (q.options[i] == q.options[0]) {
      q.answerIndex = i;
      break;
    }
  }

  return q;
}

void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();

  for (int i = 0; i < 4; i++) {
    pinMode(buttonPins[i], INPUT_PULLUP);
  }
  pinMode(buzzerPin, OUTPUT);
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);

  digitalWrite(redPin, LOW);
  digitalWrite(greenPin, LOW);
  digitalWrite(bluePin, LOW);

  randomSeed(analogRead(0));

  for (int i = 0; i < TOTAL_QUESTIONS; i++) {
    questions[i] = generateQuestion();
  }

  displayQuestion();
}

void displayQuestion() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Q"); lcd.print(currentQuestion + 1);
  lcd.print(": ");
  lcd.print(questions[currentQuestion].question);

  for (int i = 0; i < 4; i++) {
    lcd.setCursor(0, i + 1);
    lcd.print(char('A' + i));
    lcd.print(") ");
    lcd.print(questions[currentQuestion].options[i]);
    if (i == selectedOption) lcd.print(" <");
  }
}

void beep(int freq, int duration) {
  tone(buzzerPin, freq, duration);
  delay(duration);
  noTone(buzzerPin);
}

void setRGB(bool r, bool g, bool b) {
  digitalWrite(redPin, r ? HIGH : LOW);
  digitalWrite(greenPin, g ? HIGH : LOW);
  digitalWrite(bluePin, b ? HIGH : LOW);
}

void showFeedback(bool correct) {
  if (correct) {
    setRGB(false, true, false);  // Green ON
    beep(1000, 200);
  } else {
    setRGB(true, false, false);  // Red ON
    beep(400, 500);
  }
  delay(1000);
  setRGB(false, false, false); // Turn off all
}

void loop() {
  for (int i = 0; i < 4; i++) {
    if (digitalRead(buttonPins[i]) == LOW) {
      if (millis() - lastDebounceTime > debounceDelay) {
        selectedOption = i;
        displayQuestion();
        delay(200);
        lastDebounceTime = millis();
      }
    }
  }

  static unsigned long selectStart = 0;
  static bool timing = false;

  if (selectedOption != -1) {
    if (!timing) {
      selectStart = millis();
      timing = true;
    }
    if (millis() - selectStart > 1000) {
      bool correct = (selectedOption == questions[currentQuestion].answerIndex);
      if (correct) score++;
      showFeedback(correct);

      currentQuestion++;
      if (currentQuestion >= TOTAL_QUESTIONS) {
        showResults();
        while (1) {}
      }
      selectedOption = -1;
      displayQuestion();
      timing = false;
    }
  } else {
    timing = false;
  }
}

void showResults() {
  lcd.clear();
  lcd.setCursor(0, 1);
  lcd.print("Quiz Completed!");
  lcd.setCursor(0, 2);
  lcd.print("Score: ");
  lcd.print(score);
  lcd.print("/");
  lcd.print(TOTAL_QUESTIONS);
}