#define echoPin A0
#define trigPin A1
#define greenLED A4
#define orangeLED A3
#define redLED A2
#define switchPin D1
#define buzzerPin D2
#define SHCP D5
#define STCP D4
#define DS D3
int sound, time_delay;
int switchState;
float distance_meters;
long duration, distance;

byte digits[] = {
  0b01111110, // digit 0
  0b00001010, // digit 1
  0b10110110, // digit 2
  0b10011110, // digit 3
  0b11001010, // digit 4
  0b11011100, // digit 5
  0b11111100, // digit 6
  0b00001110, // digit 7
  0b11111110, // digit 8
  0b11011110  // digit 9
};

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(greenLED, OUTPUT);
  pinMode(redLED, OUTPUT);
  pinMode(orangeLED, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(switchPin, INPUT_PULLUP);

  pinMode(DS, OUTPUT);
  pinMode(SHCP, OUTPUT);
  pinMode(STCP, OUTPUT);
}

void loop() {
  switchState = digitalRead(switchPin);
  if (switchState == LOW) {
    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);

    duration = pulseIn(echoPin, HIGH);
    distance = duration / 2 * 0.0343;
    Serial.print("Distance in CM: ");
    Serial.println(distance);
    distance_meters = distance * 0.01;
    Serial.print("Distance in metre: ");
    Serial.println(distance_meters);

    int distanceCategory;

    if (distance >= 120) {
      distanceCategory = 3;
    } else if (distance > 30 && distance < 120) {
      distanceCategory = 2;
    } else if (distance <= 30) {
      distanceCategory = 1;
    }

    switch (distanceCategory) {
      case 3:
        digitalWrite(greenLED, HIGH);
        digitalWrite(orangeLED, LOW);
        digitalWrite(redLED, LOW);
        sound = 0;
        time_delay = 0;
        break;
      case 2:
        digitalWrite(greenLED, LOW);
        digitalWrite(orangeLED, HIGH);
        digitalWrite(redLED, LOW);
        sound = 440;
        time_delay = map(distance, -30, 90, 0, 1000);
        Serial.print("time delay = ");
        Serial.println(time_delay);
        break;
      case 1:
        digitalWrite(greenLED, LOW);
        digitalWrite(orangeLED, LOW);
        digitalWrite(redLED, HIGH);
        sound = 440;
        time_delay = 0;
        break;
      default:
        digitalWrite(greenLED, LOW);
        digitalWrite(orangeLED, LOW);
        digitalWrite(redLED, HIGH);
        sound = 0;
        time_delay = 0;
        break;
    }

    tone(buzzerPin, sound, time_delay);

    int distance_integer = int(distance_meters * 10); 

    int digit1 = distance_integer / 10; 

   int digit2 = distance_integer % 10; 
    
    digitalWrite(STCP, LOW);
    
    shiftOut(DS, SHCP, MSBFIRST, digits[digit2]);
    
    shiftOut(DS, SHCP, MSBFIRST, digits[digit1]| 0b00000001);
    
    digitalWrite(STCP, HIGH);
 
    delay(500);
  } else {
    // turn off all LEDs and displays
    digitalWrite(greenLED, LOW);
    digitalWrite(orangeLED, LOW);
    digitalWrite(redLED, LOW);
    digitalWrite(buzzerPin, LOW);
    
  }
}