//uncomment this line if using a Common Anode LED
//#define COMMON_ANODE

// constants won't change. They're used here to set pin numbers:
const int buttonPin = 21;  // the number of the pushbutton pin
const int redPin = 19;
const int greenPin = 18;
const int bluePin = 5;

enum color {
	RED,
	GREEN,
  BLUE
};

color ledColor = RED;

int ledState = HIGH;        // the current state of the output pin
int buttonState;            // the current reading from the input pin
int lastButtonState = LOW;  // the previous reading from the input pin

// the following variables are unsigned longs because the time, measured in
// milliseconds, will quickly become a bigger number than can be stored in an int.
unsigned long lastDebounceTime = 0;  // the last time the output pin was toggled
unsigned long debounceDelay = 50;    // the debounce time; increase if the output flickers

void setup() {
  pinMode(buttonPin, INPUT);
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT); 

  // set initial LED state
  setColor(255, 0, 0);  // red
}

void loop() {
  int reading = digitalRead(buttonPin);

  if (reading != lastButtonState) {
    // reset the debouncing timer
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > debounceDelay) {
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == HIGH) {
        switch(ledColor) {
          case RED:         
            ledColor = GREEN;
            break;
          case GREEN:
            ledColor = BLUE;
            break;
          case BLUE:
            ledColor = RED;
            break;
        }
      }
    }
  }

  // set the LED color  
  switch(ledColor) {
          case RED:
            setColor(255, 0, 0);  // red
            break;
          case GREEN:
            setColor(0, 255, 0);  // green
            break;
          case BLUE:
            setColor(0, 0, 255);  // blue
            break;
        }

  // save the reading. Next time through the loop, it'll be the lastButtonState:
  lastButtonState = reading;
}


void setColor(int red, int green, int blue)
{
  #ifdef COMMON_ANODE
    red = 255 - red;
    green = 255 - green;
    blue = 255 - blue;
  #endif
  analogWrite(redPin, red);
  analogWrite(greenPin, green);
  analogWrite(bluePin, blue);  
}