#include <Adafruit_NeoPixel.h>

#define PIN 6
bool has_run = false;

Adafruit_NeoPixel strip = Adafruit_NeoPixel(16, PIN, NEO_GRB + NEO_KHZ800);


void setup() {
  // put your setup code here, to run once:
  strip.begin();
  strip.show(); // Initialize pixels 'off'
}

void blink(uint8_t id_pixel){
  for(uint8_t i=0; i<6; i++){
    strip.setPixelColor(id_pixel, strip.Color(255,0,0));
    strip.show();
    delay(100);
    strip.setPixelColor(id_pixel, strip.Color(0,0,0));
    strip.show();
    delay(100);
  }
}

void scan_dig(uint16_t wait, uint8_t pixel_start, uint8_t pixel_end, 
                uint32_t color = strip.Color(255,255,255), bool forward = true){
  // Input Check
  if((pixel_start - pixel_end) * forward * -1 < 0){
    blink(0);
  }
  else{
    switch(forward){
      case true:
        for(uint8_t i=pixel_start; i<pixel_end+1; i++){
          // Disable Previous
          if(i>pixel_start){
            strip.setPixelColor(i-1,strip.Color(0,0,0));
            strip.show();
          }
          //Enable Next
          strip.setPixelColor(i,color);
          strip.show();
          delay(wait);
        }
        // Turn Off Last Pixel
        strip.setPixelColor(pixel_end, strip.Color(0,0,0));
        strip.show();
        break;
      case false:
        for(int8_t i=pixel_start; i>pixel_end-1; i--){
          // Disable Previous
          if(i<pixel_start){
            strip.setPixelColor(i+1,strip.Color(0,0,0));
            strip.show();
          }
          //Enable Next
          strip.setPixelColor(i,color);
          strip.show();
          delay(wait);
        }
        // Turn Off Last Pixel
        strip.setPixelColor(pixel_end, strip.Color(0,0,0));
        strip.show();
        break;
    }
  } 
}

void loop() {
  // put your main code here, to run repeatedly:
  if(!has_run){
    scan_dig(500, 4, 0, strip.Color(0,255,0), false);
    delay(1000);
    scan_dig(250, 0, strip.numPixels()+1, strip.Color(255,255,255), true);
    // scan_dig(1000, 5, 2, true);
    has_run = true;
  }
}

void scan(uint16_t wait){
  for(uint16_t i=0; i<strip.numPixels(); i++){
    // Disable Previous
    if(i > 0){
      strip.setPixelColor(i-1,strip.Color(0,0,0));
      strip.show();
    }
    // Enable Next
    strip.setPixelColor(i,strip.Color(255,255,255));
    strip.show();
    delay(wait);
  }
  // Turn Last Pixel Off
  strip.setPixelColor(strip.numPixels()-1,strip.Color(0,0,0));
  strip.show();
}