#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
 #include <avr/power.h> // Required for 16 MHz Adafruit Trinket
#endif

#define LED_PIN 2

#define LED_COUNT 39
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
int k;
int val;

void setup()
{
Serial.begin(9600);
#if defined(__AVR_ATtiny85__) && (F_CPU == 16000000)
  clock_prescale_set(clock_div_1);
#endif
  strip.begin();           // INITIALIZE NeoPixel strip object 
  strip.show();            // Turn OFF all pixels ASAP
  strip.setBrightness(50); // Set BRIGHTNESS to about 1/5 (max = 255)
}

void loop()
{
  if (Serial.available())
  {
   val = Serial.read();
       
       if (val == 'r') // red color
       {
        colorWipe(strip.Color(255, 0, 0), 50);    
       }
       if (val == 'g') // green color
       {
        colorWipe(strip.Color(0, 255, 0), 50);    
       }
        if (val == 'b') // blue color
       {
        colorWipe(strip.Color(0, 0, 255), 50);    
       }
        if (val == 'w') // white color
       {
        colorWipe(strip.Color(255, 255, 255), 50); 
       }
        if (val == 'y') //yellow color
       {
        colorWipe(strip.Color(255, 255, 0), 50); 
       }
        if (val == 'm') //magenta color
       {
        colorWipe(strip.Color(255, 0, 255), 50); 
       }
        if (val == 'c') //cyan color
       {
        colorWipe(strip.Color(0, 255, 255), 50); 
       }
       if (val == 'R') //Rainbow color
       {
        rainbow(10); 
       }
        if (val == 'o') //off NeoPixel
       {
        colorWipe(strip.Color(0, 0, 0), 50); 
       }
  }  
}
  
void rainbow(int wait) { //1
    for(long firstPixelHue = 0; firstPixelHue < 5*65536; firstPixelHue += 256) {
    for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip
    int pixelHue = firstPixelHue + (i * 65536L / strip.numPixels());
    strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(pixelHue)));
    }
    strip.show(); // Update NeoPixel with new contents
    delay(wait);  
  }
}

void colorWipe(uint32_t color, int wait) {
  for(int i=0; i<strip.numPixels(); i++) { // For each pixel on NeoPixel
    strip.setPixelColor(i, color);         // Set pixel's color
    strip.show();                          // Update NeoPixel 
    delay(wait);                          
  }
}