const int buttonpin = 30;
int buzzerpin = 48;

// Visual Cues
int GreenLED = 12;
int RedLED = 11;

//Distance Sensor
int triggerpin = 8;
int echopin = 7;
int distance;
int duration;

// _________________________________________________________

void setup()
{
  //Initializing inputs and outputs
  Serial.begin(9600);
  pinMode(triggerpin, OUTPUT);
  pinMode(echopin, INPUT);
  pinMode(buttonpin, INPUT_PULLUP);
  pinMode(GreenLED, OUTPUT);
  pinMode(RedLED, OUTPUT);
  pinMode(buzzerpin, OUTPUT);
}

// _________________________________________________________

void loop(){

    /* declaration of boolean presence to see if object/human has passed
    door frame or not */
  bool presence = false;

  int buttonState = HIGH; //Set buttonState to high/not pressed by default


  while(digitalRead(buttonpin) == HIGH){ // If button is not pressed,
    Serial.println("HIGH");              // display status and visual cues
    buttonState = HIGH;
    digitalWrite(RedLED,HIGH);
    digitalWrite(GreenLED, LOW);
    digitalWrite(triggerpin, LOW);
    delayMicroseconds(2);
    digitalWrite(triggerpin, HIGH);
    delayMicroseconds(10);
    digitalWrite(triggerpin, LOW);

    duration = pulseIn(echopin, HIGH);
    distance = duration/29/2; // distance in cm
    if(buttonState == HIGH && distance < 15){
      for(int i = 0; i<10; i++){
        tone(buzzerpin, 1000);
        delay(100);
        noTone(buzzerpin);
        delay(100);
      }
    }
  }

  if(digitalRead(buttonpin)==LOW){ // If button is pressed,
                                   // display status.
    Serial.println("Button Pressed");
    buttonState = LOW;

    while(presence == false){ // Loop until an object/person is detected

      /* Send and receive ultrasonic waves to detect distance 
         from foor frame to floor. */
      digitalWrite(RedLED, LOW);
      digitalWrite(GreenLED, HIGH);
      digitalWrite(triggerpin, LOW);
      delayMicroseconds(2);
      digitalWrite(triggerpin, HIGH);
      delayMicroseconds(10);
      digitalWrite(triggerpin, LOW);

      duration = pulseIn(echopin, HIGH);
      distance = duration/29/2; // distance in cm

      // print distance
      Serial.print(distance);
      Serial.println("cm");

      if(distance < 15){ //if distance from door frame to ground is
                         //cut off, meaning an object/person has crossed,
        presence = true; // set boolean presence to true
        Serial.println("True");
        while(presence == true){
          digitalWrite(RedLED, LOW);
          digitalWrite(GreenLED, HIGH);
          digitalWrite(triggerpin, LOW);
          delayMicroseconds(2);
          digitalWrite(triggerpin, HIGH);
          delayMicroseconds(10);
          digitalWrite(triggerpin, LOW);

          duration = pulseIn(echopin, HIGH);
          distance = duration/29/2; // distance in cm

          if(presence == true && distance > 15){
            Serial.println("Person has crossed");
            presence == false;
            break;
          }
        }
        delay(1000);
      }

      
    }

    if(presence = true){ // once presence of object/person has been detected,
                         // go on "lock mode" for next person
      digitalWrite(RedLED, HIGH);
      digitalWrite(GreenLED, LOW);
    }
    delay(2000);
  }

  
}