const int redPin   = 2;   // Pin for controlling red LED
const int greenPin = 0;   // Pin for controlling green LED
const int bluePin  = 4;   // Pin for controlling blue LED
const bool invert = false;  // Set to true for common anode, false for common cathode

int color = 0;  // Hue value from 0 to 255
int R, G, B;    // Red, Green, Blue color components

void setup() {
  Serial.begin(9600);         // Initialize serial communication
  pinMode(redPin, OUTPUT);    // Set pins as outputs
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
}

void loop() {
  int brightness = 255;  // Maximum brightness

  hueToRGB(color, brightness);  // Convert hue to RGB components

  // Set RGB values to the corresponding PWM pins
  analogWrite(redPin,   R);
  analogWrite(greenPin, G);
  analogWrite(bluePin,  B);

  Serial.print("R: "); Serial.print(R);
  Serial.print(" G: "); Serial.print(G);
  Serial.print(" B: "); Serial.println(B);

  color++;  // Increment color hue
  if (color > 255)
    color = 0;
  delay(10);  // Delay for smooth color transitions
}

// Function to convert hue to RGB components
void hueToRGB(int hue, int brightness) {
  unsigned int scaledHue = (hue * 6);  // Scale hue to 0-1535

  // Determine segment of color wheel
  unsigned int segment = scaledHue / 256;

  // Offset within the segment
  unsigned int segmentOffset = scaledHue - (segment * 256);

  unsigned int complement = 0;
  unsigned int prev = (brightness * (255 - segmentOffset)) / 256;
  unsigned int next = (brightness * segmentOffset) / 256;
  
  // Adjust for common anode configuration
  if (invert) {
    brightness = 255 - brightness;
    complement = 255;
    prev = 255 - prev;
    next = 255 - next;
  }

  // Set RGB values based on color segment
  switch (segment) {
    case 0:  // Red
      R = brightness;
      G = next;
      B = complement;
      break;
    case 1:  // Yellow
      R = prev;
      G = brightness;
      B = complement;
      break;
    case 2:  // Green
      R = complement;
      G = brightness;
      B = next;
      break;
    case 3:  // Cyan
      R = complement;
      G = prev;
      B = brightness;
      break;
    case 4:  // Blue
      R = next;
      G = complement;
      B = brightness;
      break;
    case 5:  // Magenta
    default:
      R = brightness;
      G = complement;
      B = prev;
      break;
  }
}