/*
  STM32 Reaction Timer Game (Group 6) - Wokwi, Nucleo C031C6
  D10 -> 220R -> LED -> GND   : reaction signal
  D2  -> START button -> GND
  D3  -> REACT button -> GND
  Type 's' in the Serial Monitor to start a round as well.
*/

const int LED_PIN   = D10;
const int START_PIN = D2;
const int REACT_PIN = D3;

enum State { IDLE, WAITING, SIGNAL_ON };
State state = IDLE;

unsigned long waitStart = 0, waitTime = 0, signalTime = 0, bestTime = 0;
int rounds = 0;

bool pressed(int pin) {
  if (digitalRead(pin) == LOW) {
    delay(20);
    if (digitalRead(pin) == LOW) return true;
  }
  return false;
}

void waitRelease(int pin) {
  while (digitalRead(pin) == LOW) { }
  delay(30);
}

void printMenu() {
  Serial.println();
  Serial.println("=== STM32 REACTION TIMER ===");
  Serial.println("Press START button (or send 's') to begin.");
}

void startRound() {
  rounds++;
  Serial.print("\nRound ");
  Serial.println(rounds);
  Serial.println("Get ready... wait for the LED!");
  digitalWrite(LED_PIN, LOW);
  waitTime  = random(2000, 6000);
  waitStart = millis();
  state = WAITING;
}

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  pinMode(START_PIN, INPUT_PULLUP);
  pinMode(REACT_PIN, INPUT_PULLUP);
  digitalWrite(LED_PIN, LOW);
  randomSeed(analogRead(A0));
  printMenu();
}

void loop() {
  switch (state) {

    case IDLE:
      if (pressed(START_PIN)) {
        waitRelease(START_PIN);
        startRound();
      } else if (Serial.available()) {
        char c = Serial.read();
        if (c == 's' || c == 'S') startRound();
      }
      break;

    case WAITING:
      if (pressed(REACT_PIN)) {                       // early press
        waitRelease(REACT_PIN);
        Serial.println("TOO EARLY! You pressed before the LED. Round restarted.");
        delay(1000);
        startRound();
        break;
      }
      if (millis() - waitStart >= waitTime) {         // delay over
        digitalWrite(LED_PIN, HIGH);
        signalTime = micros();
        state = SIGNAL_ON;
      }
      break;

    case SIGNAL_ON:
      if (digitalRead(REACT_PIN) == LOW) {
        unsigned long reaction = (micros() - signalTime) / 1000;   // ms
        digitalWrite(LED_PIN, LOW);
        waitRelease(REACT_PIN);

        Serial.print("Reaction time: ");
        Serial.print(reaction);
        Serial.println(" ms");

        if (bestTime == 0 || reaction < bestTime) {
          bestTime = reaction;
          Serial.println("New best time!");
        }
        Serial.print("Best time: ");
        Serial.print(bestTime);
        Serial.println(" ms");

        if (reaction < 200)      Serial.println("Rating: Excellent!");
        else if (reaction < 300) Serial.println("Rating: Good");
        else if (reaction < 500) Serial.println("Rating: Average");
        else                     Serial.println("Rating: Slow, try again");

        state = IDLE;
        printMenu();
      }
      break;
  }
}