#include <LiquidCrystal_I2C.h>

#define R_PIN 10
#define G_PIN 9
#define B_PIN 8
#define BUTTON_PIN 3
#define RESISTOR A0

class RGB 
{
public:
  RGB(uint8_t redPin, uint8_t greenPin, uint8_t bluePin)
    : rPin(redPin)
    , gPin(greenPin)
    , bPin(bluePin)
  {
    pinMode(rPin, OUTPUT);
    pinMode(gPin, OUTPUT);
    pinMode(bPin, OUTPUT);
  }

  void setRGB(unsigned int red, unsigned int green, unsigned int blue) {
    setR(red);
    setG(green);
    setB(blue);
  }

  void setR(unsigned int red) {
    analogWrite(rPin, red);
  }

  void setG(unsigned int green) {
    analogWrite(gPin, green);
  }

  void setB(unsigned int blue) {
    analogWrite(bPin, blue);
  }
private:
  uint8_t rPin, gPin, bPin;
};

class RGBController
{
public:
  RGBController(RGB led): m_led(led){}

  setLight(unsigned int light) {
    switch (m_state)
      {
         case RGBState::RED:
            m_led.setR(light);
            m_red = light;
            break;
         case RGBState::GREEN:
            m_led.setG(light);
            m_green = light;
            break;
         default:
            m_led.setB(light);
            m_blue = light;
      }
  }

  RGBController& operator++() {
    const int i = static_cast<int>(m_state);
    m_state = static_cast<RGBState>((i + 1) % 3);

    return *this;
  }

  String getState() {
    return String(static_cast<int>(m_state));
  }

  uint16_t getR() {return m_red;}
  uint16_t getG() {return m_green;}
  uint16_t getB() {return m_blue;}
private:
  enum class RGBState {
    RED = 1,
    GREEN = 2,
    BLUE = 3,
  };

  RGB m_led;
  RGBState m_state = RGBState::RED;
  unsigned int m_red = 0;
  unsigned int m_green = 0;
  unsigned int m_blue = 0;
};

RGB led(R_PIN, G_PIN, B_PIN);
RGBController controller(led);
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(9600);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(RESISTOR, INPUT);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
}

void loop() {
  onButtonClick([]() { controller++; });
  int light = analogRead(RESISTOR);
  light = map(light, 0, 1023, 0, 255);
  controller.setLight(light);

  String r = String(controller.getR());
  String g = String(controller.getG());
  String b = String(controller.getB());

  lcd.setCursor(0, 0);
  lcd.print("R:   ");
  lcd.setCursor(2, 0);
  lcd.print(r);

  lcd.setCursor(6, 0);
  lcd.print("G:   ");
  lcd.setCursor(8, 0);
  lcd.print(g);

  lcd.setCursor(0, 1);
  lcd.print("B:   ");
  lcd.setCursor(2, 1);
  lcd.print(b);

  Serial.println(r + " " + g + " " + b);

  delay(100);
}

int lastState = HIGH;
void onButtonClick(void (*callback)()) {
  int buttonValue = digitalRead(BUTTON_PIN);
  if (lastState != buttonValue) {
    lastState = buttonValue;
    if (buttonValue == HIGH) {
      callback();
    }
  }
}