// NeoPixel Ring simple sketch (c) 2013 Shae Erisson
// released under the GPLv3 license to match the rest of the AdaFruit NeoPixel library

#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
  #include <avr/power.h>
#endif

// Which pin on the Arduino is connected to the NeoPixels?
// On a Trinket or Gemma we suggest changing this to 1
#define PIN            2

// How many NeoPixels are attached to the Arduino?
#define NUMPIXELS      20

// defines ultrasonic pins numbers
const int trigPin = 3;
const int echoPin = 4;

// defines variables
long duration;
int distance;
int ledValue;

// When we setup the NeoPixel library, we tell it how many pixels, and which pin to use to send signals.
// Note that for older NeoPixel strips you might need to change the third parameter--see the strandtest
// example for more information on possible values.
Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_RGBW + NEO_KHZ800);

int delayval = 83; // delay for half a second

void setup()
{
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); // Sets the echoPin as an Input
  Serial.begin(9600); // Starts the serial communication
  pixels.begin(); // This initializes the NeoPixel library.
  pinMode(2, OUTPUT); 
}

void loop()
{
  // Clears the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);

  // Calculating the distance
  distance = duration*0.034/2;

   // map the sensor reading to a range for the LED
  ledValue = map(distance, 0, 150, 0, 255);
  if (ledValue < 0) {
    ledValue = 0;
  }
  digitalWrite(2, ledValue);

  // Prints the distance on the Serial Monitor to know its range
  Serial.print("Distance: ");
  Serial.println(distance);

  // Prints the LED value on the Serial Monitor to know its range
  Serial.print("LED Value: ");
  Serial.println(ledValue);


  for(int i=0;i<NUMPIXELS;i++){

    // pixels.Color takes RGB values, from 0,0,0 up to 255,255,255
    pixels.setPixelColor(i, pixels.Color(ledValue,255,ledValue)); // Colour based sensor value.

    pixels.show(); // This sends the updated pixel color to the hardware.
    pixels.show(); // This sends the updated pixel color to the hardware.

    delay(delayval); // Delay for a period of time (in milliseconds).

   // For a set of NeoPixels the first NeoPixel is 0, second is 1, all the way up to the count of pixels minus one.

  }
}