#define LED_STRIPE 29
#define MODE_BTN_PIN 14
#define BMINUS_BTN_PIN 15
#define BPLUS_BTN_PIN 26

// declare as volaile to not optimize them by the compiler and use them in interrupts
volatile int btn_state = 0;
volatile bool do_loop = true;
volatile bool debounce = false;
volatile int max_brightness = 255;

// function to adjust the delay when the max_brightness decrements
unsigned long adjustedDelay(unsigned long baseDelay) {
  const int fullRange = 255 - 10;
  int currentRange = max_brightness - 10;
  float scale = (float)fullRange / currentRange;
  return (unsigned long)(baseDelay * scale * 3.0);
}

void mode_interrupt(){
  if(debounce) return;
  btn_state++;
  do_loop = false;
  debounce = true;  // set debounce flag to prevent mode skips because of mechanical button bounces 
}

void brighness_minus_interrupt(){
  if(max_brightness <= 10) {
    max_brightness = 10;  
    return;
  }
  max_brightness -= 10;
}

void brighness_plus_interrupt(){
  if(max_brightness >= 255){
    max_brightness = 255;
    return;
  }
  max_brightness += 10;
}

void blink(){
  while(do_loop){
    analogWrite(LED_STRIPE, max_brightness);
    delay(500);
    digitalWrite(LED_STRIPE, LOW);
    delay(500);
  }
}

void bounce(){
  int direction = 1;
  int i = 10;
  int step = 20;
  const int minStep = 1;

  while(do_loop){
    i += direction * step;
    
    if(i >= max_brightness){
      i = max_brightness;
      direction = -1;
      step = 20;
    }
    if(i <= 10){
      i = 10;
      direction = 1;
      step = 20;
    }
    
    if(step > minStep){
      step--;
    }
    
    analogWrite(LED_STRIPE, i);
    delay(adjustedDelay(20));
  }
}

void bounce_fast_step(){
  int direction = 1;
  int i = 10;
  const int minStep = 1;
  const int maxStep = 20;

  while(do_loop){
    int step;
    if(direction > 0){
      step = map(i, 10, max_brightness, minStep, maxStep);
    } 
    else{
      step = map(i, max_brightness, 10, maxStep, minStep);
    }
    
    i += direction * step;
    
    if(i >= max_brightness){
      i = max_brightness;
      direction = -1;
    }
    if(i <= 10){
      i = 10;
      direction = 1;
    }
    
    analogWrite(LED_STRIPE, i);
    delay(adjustedDelay(30));
  }
}

void fade(){
  while(true){
    for(int i = 10; i < max_brightness; i++){
      if(!do_loop) return;
      analogWrite(LED_STRIPE, i);
      delay(adjustedDelay(20));
    }
    for(int i = max_brightness; i > 10; i--){
      if(!do_loop) return;
      analogWrite(LED_STRIPE, i);
      delay(adjustedDelay(20));
    }
  }
}

void on(){
  while(do_loop){
    analogWrite(LED_STRIPE, max_brightness);
    delay(10);
  }
}

void off(){
  digitalWrite(LED_STRIPE, LOW);
  while(do_loop){
    delay(10);
  }
}

void setup() {
  Serial.begin(115200);
  
  pinMode(LED_STRIPE, OUTPUT);
  pinMode(MODE_BTN_PIN, INPUT_PULLUP);
  pinMode(BMINUS_BTN_PIN, INPUT_PULLUP);
  pinMode(BPLUS_BTN_PIN, INPUT_PULLUP);


  attachInterrupt(digitalPinToInterrupt(MODE_BTN_PIN), mode_interrupt, RISING);
  attachInterrupt(digitalPinToInterrupt(BMINUS_BTN_PIN), brighness_minus_interrupt, RISING);
  attachInterrupt(digitalPinToInterrupt(BPLUS_BTN_PIN), brighness_plus_interrupt, RISING);

  Serial.println("INIT DONE!");
}

void loop() {
  debounce = false;
  do_loop = true;
  switch(btn_state){
    case 0:
      Serial.println("ON");
      on();
      break;
    case 1:
      Serial.println("FADE");
      fade();
      break;
    case 2:
      Serial.println("BOUNCE");
      bounce();
      break;
    case 3:
      Serial.println("BOUNCE (fast step)");
      bounce_fast_step();
      break;
    case 4:
      Serial.println("BLINK");
      blink();
      break;
    default:
      if(btn_state != -1){
        Serial.println("OFF");
        btn_state = -1;
        off();
      }
      break;
  }
  Serial.print("Current brightness: ");
  Serial.println(max_brightness);
}