int Led_blue = 12;
int Led_green = 7;
int Led_red = 10;
int btn_pin = 5;
int btn_up = 3;
int btn_down = 4;
bool btn_state = false;
int counter = 0;
int brightness = 0;
int change_btn = 2;


void setup() {
  pinMode(Led_red, OUTPUT);
  pinMode(Led_green, OUTPUT);
  pinMode(Led_blue, OUTPUT);
  pinMode(btn_pin, INPUT);
  pinMode(btn_up, INPUT);
  pinMode(btn_down, INPUT);
  pinMode(change_btn, INPUT);
  Serial.begin(9600);
}

void loop() {
bool btn_status = digitalRead(btn_pin);
if (btn_status){
  delay(150);
  btn_state = !btn_state;
}
if (btn_state){
  if (counter == 1){
  analogWrite(Led_blue, brightness);
}
  if (counter == 2) {
  analogWrite(Led_red, brightness);
}
  if (counter == 3){
  analogWrite(Led_green, brightness);
}
  
  bool btn_up_status = digitalRead(btn_up);
  if (btn_up_status) {
    delay(100);
    brightness = brightness + 15;
    if (brightness > 255) {
      brightness = 255;
    }
  }

  bool btn_dn_status = digitalRead(btn_down);
  if (btn_dn_status) {
    delay(100);
    brightness = brightness - 15;
    if (brightness < 0) {
      brightness = 0;
    }
  }
  bool btn_changeOn = digitalRead(change_btn);
  if (btn_changeOn){
    delay(100);
    counter = counter + 1;
    if (counter == 1) {
    analogWrite(Led_red, false);
    analogWrite(Led_blue, brightness);
    analogWrite(Led_green, false);
  }
  if (counter == 2) {
    analogWrite(Led_red, brightness);
    analogWrite(Led_blue, false);
    analogWrite(Led_green, false);
  }
  if (counter == 3) {
    analogWrite(Led_red, false);
    analogWrite(Led_blue, false);
    analogWrite(Led_green, brightness);
  }
  }
}else{
  delay(100);
    if (Led_red){
  analogWrite(Led_red, 0);
}
  if (Led_blue) {
  analogWrite(Led_blue, 0);
}
  if (Led_green){
  analogWrite(Led_green, 0);
}
}
if (counter > 3) {
    counter = 0;
  }
  Serial.println(counter);
  Serial.println(btn_state);
}