const int blinkLedPin = 13;
const int statusLedPin = 12;

int failCount = 0;
float voltage = 10.5;

unsigned long attemptStart = 0;
unsigned long lastBlink = 0;
bool alwaysValid = true;
bool done = false;

void setup() {
  pinMode(blinkLedPin, OUTPUT);
  pinMode(statusLedPin, OUTPUT);
  Serial.begin(9600);
  attemptStart = millis();
}

void loop() {
  if (done) return;

  unsigned long now = millis();

  // Blink indicator LED
  if (now - lastBlink >= 400) {
    digitalWrite(blinkLedPin, !digitalRead(blinkLedPin));
    lastBlink = now;
  }

  // Check voltage validity during 5s window
  if (now - attemptStart < 5000) {
    if (voltage < 12.0 || voltage > 14.0) alwaysValid = false;
  } else {
    if (alwaysValid) {
      Serial.println("Voltage stable for 5 seconds. Status LED ON.");
      digitalWrite(blinkLedPin, LOW);
      digitalWrite(statusLedPin, HIGH);
      failCount = 0;
      done = true;
    } else {
      failCount++;
      Serial.print("Failed attempt #");
      Serial.println(failCount);
      if (failCount >= 3) {
        Serial.println("Please contact mechanic.");
        done = true;
      } else {
        attemptStart = now;
        alwaysValid = true;
      }
    }
  }
}