// https://forum.arduino.cc/t/room-light-control-with-two-laser-beam-in-arduino/1414689

#define outPin 2
#define inPin 3
int inLED = 4, outLED = 5;
int occupants = 0, occupantsOld, entered, exited;
bool entering = false, exiting = false;
int debounce = 150;

void setup() {
  Serial.begin(115200);
  pinMode(outPin, INPUT_PULLUP);
  pinMode(inPin, INPUT_PULLUP);
  pinMode(inLED, OUTPUT);
  pinMode(outLED, OUTPUT);
  Serial.println("Hello, World!");
}

void loop() {
  if (entering == false && exiting == false) { // no sequence started
    if (digitalRead(outPin) == LOW) {
      entering = true;
      exiting = false;
      digitalWrite(outLED, HIGH);
      Serial.print("Entering. ");
    }
    if (digitalRead(inPin) == LOW) {
      entering = false;
      exiting = true;
      digitalWrite(inLED, HIGH);
      Serial.print("Exiting.  ");
    }
    delay(debounce);
  }

  if (entering == true && exiting == false) { // enter sequence started
    if (digitalRead(inPin) == LOW) {
      digitalWrite(inLED, HIGH);
      Serial.print("Entered. ");
      delay(debounce);
      occupants++;
      entered++;
    }
  }

  if (entering == false && exiting == true) { // exit sequence started
    if (digitalRead(outPin) == LOW) {
      digitalWrite(outLED, HIGH);
      Serial.print("Exited.  ");
      delay(debounce);
      occupants--;
      exited++;
    }
  }

  if (occupants != occupantsOld) { // if count changes
    occupantsOld = occupants; // store current count
    Serial.print("Occupants: ");
    Serial.print(occupants);
    Serial.print(" Entered: ");
    Serial.print(entered);
    Serial.print(" Exited: ");
    Serial.print(exited);
    Serial.println();
    entering = false; // reset sequences
    exiting = false;
      digitalWrite(inLED, LOW);
      digitalWrite(outLED, LOW);
  }
}