// https://wokwi.com/projects/354478377898627073
// https://forum.arduino.cc/t/humidity-temp-ventilation-control-for-frog-paludarium-2nd-3rd-or-even-4th-pair-of-eyes-on-whether-im-on-the-right-track/1078600

# define buttonPin    6
# define fanLED       7   // fan running lamp/relay

unsigned long fanTimer;

void setup() {
  Serial.begin(115200);
  Serial.println("paludarium thing\n");

  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(fanLED, OUTPUT);

  turnOnFan();
  delay(777);
  turnOffFan();
}

unsigned long now;      // time for all non-blocked functions

unsigned long counter;

void loop()
{
  counter++;    // just count the loops as they go by

  now = millis();

  setFan();     // turn on for random time maybe
  handleFan();  // turn off fan maybe
  report();     // whassup?
}

int fanOnTime;
bool fanIsOn;

void setFan()
{
  if (!digitalRead(buttonPin)) {

    fanOnTime = random(3000, 7000);

    Serial.print("                           fans starting for ");
    Serial.println(fanOnTime);

    turnOnFan();
    fanTimer = now;

// crude button denouncing:
    do {
      delay(20);
    } while (!digitalRead(buttonPin));

    delay(20);
  }
}

void handleFan()
{
  if (now - fanTimer > fanOnTime) {
    turnOffFan();
  }
}

void turnOnFan()
{
  if (!fanIsOn) {
    fanIsOn = true;    
    Serial.println("                           turn fan ON");
    digitalWrite(fanLED, HIGH);    // and do whatever else needs be done 
  }
}

void turnOffFan()
{
  if (fanIsOn) {
    fanIsOn = false;
    Serial.println("                           turn fan OFF");
    digitalWrite(fanLED, LOW);   // and do whatever else needs be done 
  }
}

// reporting only - adjust for taste
void report()
{
  static unsigned long lastPrint;

  if (now - lastPrint > 1777) {
    Serial.print(counter); counter++;
    Serial.print(" the fan is ");
    Serial.println(fanIsOn ? "running..." : "not running.");

    lastPrint = now;
  }
}