#include <Adafruit_NeoPixel.h>

#define DIN 6
#define LEDS 50
#define SPEED 40 // 0-50
#define TRIG 4
#define ECHO 5
#define TRIG_DIST 100 // min trigger distance
#define SOUND 7

long duration, cm;
long oldDist = 0;

Adafruit_NeoPixel led = Adafruit_NeoPixel(LEDS, DIN, NEO_GRB + NEO_KHZ800);

void setup() {
  Serial.begin(9600);
  led.begin();
  led.show();
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(SOUND, OUTPUT);
}

void loop() {
  
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);
  duration = pulseIn(ECHO, HIGH);
  cm = duration / 58;

  Serial.println(cm);

  if(cm <= TRIG_DIST) {

    Serial.print(TRIG_DIST);
    Serial.print("\t");

    digitalWrite(SOUND, HIGH);
    delay(100);


    for(int d=0; d<20; d++){
      led.setBrightness(255);
    
      for(int i=0; i<=LEDS; i++) { 
        led.setPixelColor(i, 255, 255, 255);
        led.show();
        if(oldDist <= TRIG_DIST) {
          delay((50-(d/2))-SPEED);
        } else { 
          delay(5); 
        }
      }

      if(oldDist <= TRIG_DIST) {
        for(int i=0; i<=LEDS; i++) { 
          led.setPixelColor(0, 0, 0, 0);
          led.setBrightness(0);
          led.show();
        }
      }
    }
  
    oldDist = cm;
    
  } else {

    for(int i=0; i<=LEDS; i++) { 
      led.setPixelColor(0, 0, 0, 0);
      led.setBrightness(0);
      led.show();
      digitalWrite(SOUND, LOW);
    }
  }
  
}