// GPU Fan Controller — Delta QFR1212GHE (4-pin PWM, 12V)
// 6 режимов: 1=STOP, 2=STANDBY, 3=LOW, 4=MED, 5=HIGH, 6=FULL(2 мин)
// RPM читается через тахометр (жёлтый → D2), PWM на синий → D9
// PWM инвертирован: 0 = стоп, 99 = полная (Delta QFR1212GHE)
// Фан не гаснет полностью — минимум 1000 (10%)

const int FAN_PIN = 9;
const int TACH_PIN = 2;

volatile unsigned long tachPulses = 0;
unsigned long lastRpm = 0;
unsigned long lastDataTime = 0;

const int MODE_STOP    = 10000;
const int MODE_STANDBY = 8000;
const int MODE_LOW     = 5000;
const int MODE_MED     = 3000;
const int MODE_HIGH    = 2500;
const int MODE_FULL    = 0;
const int MODE_FULL_TIME = 60000;

int currentPWM = MODE_STANDBY;
unsigned long modeFullStart = 0;
bool inModeFull = false;

char buf[16];

void setup() {
  pinMode(FAN_PIN, OUTPUT);
  pinMode(TACH_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(TACH_PIN), tachISR, FALLING);
  Serial.begin(115200);

  // Timer1: Fast PWM, ICR1=10000, prescaler 64 → 10Hz
  TCCR1A = _BV(COM1A1) | _BV(COM1A0) | _BV(WGM11);
  TCCR1B = _BV(WGM12) | _BV(WGM13) | _BV(CS12);
  ICR1 = 10000;
  OCR1A = MODE_STANDBY;
  lastDataTime = millis();
  lastRpm = millis();
  Serial.println("FAN CONTROLLER READY - modes 1-6 + RPM");
}

void tachISR() { tachPulses++; }

void applyPWM(int pwm) {
  if (pwm < MODE_FULL) pwm = MODE_FULL;
  if (pwm > MODE_STOP) pwm = MODE_STOP;
  OCR1A = pwm;
  currentPWM = pwm;
}

void loop() {
  unsigned long now = millis();

  if (Serial.available()) {
    int n = Serial.readBytesUntil('\n', buf, 15);
    if (n > 0) {
      buf[n] = '\0';
      char c = buf[0];

      if (c >= '1' && c <= '6') {
        lastDataTime = now;
        inModeFull = false;
        modeFullStart = 0;

        switch (c) {
          case '1': applyPWM(MODE_STOP);    Serial.println("MODE: 1 STOP"); break;
          case '2': applyPWM(MODE_STANDBY); Serial.println("MODE: 2 STANDBY"); break;
          case '3': applyPWM(MODE_LOW);     Serial.println("MODE: 3 LOW"); break;
          case '4': applyPWM(MODE_MED);     Serial.println("MODE: 4 MED"); break;
          case '5': applyPWM(MODE_HIGH);    Serial.println("MODE: 5 HIGH"); break;
          case '6':
            applyPWM(MODE_FULL);
            inModeFull = true;
            modeFullStart = now;
            Serial.println("MODE: 6 FULL (60s)");
            break;
        }
      }

      if (c == 'R' || c == 'r') {
        noInterrupts();
        unsigned long p = tachPulses;
        tachPulses = 0;
        interrupts();
        Serial.print("RPM:"); Serial.println(p * 60);
      }

      if (c == 's' || c == 'S') {
        Serial.print("PWM:"); Serial.println(currentPWM);
        if (inModeFull) Serial.print("FULL:"); Serial.println((now - modeFullStart) / 1000);
        Serial.print("DATA:"); Serial.println((now - lastDataTime) / 1000);
      }
    }
  }

  if (inModeFull && (now - modeFullStart >= MODE_FULL_TIME)) {
    applyPWM(MODE_MED);
    inModeFull = false;
    Serial.println("FULL TIMEOUT -> MODE_MED");
  }

  if (now - lastRpm >= 1000) {
    noInterrupts();
    unsigned long p = tachPulses;
    tachPulses = 0;
    interrupts();
    Serial.print("RPM:"); Serial.println(p * 60);
    lastRpm = now;
  }
}