// LED PINS
int led_pins[5] = {13,12,11,10,9};
int led_pins_length = sizeof(led_pins)/sizeof(led_pins[0]);
int led_anim_delay = 100;
int led_index = 0;

// Button setup
int btn_pin = 6;
int btn_value = 0;
int btn_prev_value = 0;
int btn_switch = false;

// Slowdown Animation
int anim_init_slowdown = 300;
int anim_total_slowdowns_max = 4;
int anim_total_slowdowns_count = 999;
bool anim_switch = false;

void setup() {
	// Set led pin modes
  for (int i = 0; i < led_pins_length; i++){
    pinMode(led_pins[i], OUTPUT);
  }

  // set button
  pinMode(btn_pin, INPUT);
}

void loop() {
  btn_value = digitalRead(btn_pin);

  // Detect button press transition
  if (btn_value == HIGH && btn_prev_value == 0) {
    btn_switch = !btn_switch; // Toggle the LED animation state
    btn_prev_value = 1; // Remember current state
    anim_total_slowdowns_count = 0;
    delay(50); // Debouncing delay
  } else if (btn_value == LOW && btn_prev_value == 1) {
    btn_prev_value = 0; // Remember current state
    led_index = 0 + rand() % led_pins_length; // randomise position
  }

  // LED Cycle Animation
  if (btn_switch){
      digitalWrite(led_pins[led_index], HIGH);
      delay(led_anim_delay);
      digitalWrite(led_pins[led_index], LOW);

      // Play LED animation cycle
      led_animation_cycle();
  } else {
    // Make LED animation slowdown before stopping
    if (anim_total_slowdowns_count <= anim_total_slowdowns_max) { 
      for (int i = 0; i < anim_total_slowdowns_max; i++){
      digitalWrite(led_pins[led_index], HIGH);
      delay(anim_init_slowdown + 50);
      digitalWrite(led_pins[led_index], LOW);

      // Reuse led animation cycle for this slowdown
      led_animation_cycle();

      // Increment total slowdowns
      anim_total_slowdowns_count++;
      }
    }
    else {
      // Stop and light up specific LED
      digitalWrite(led_pins[led_index], HIGH);
    }
  }
}

// Function for making LED animation switch between left and right
void led_animation_cycle(){
  if (anim_switch){
    // Make LED animation go left
    if (led_index <= 0){
      anim_switch = !anim_switch;
    } else {
      led_index--;
    } 
  } else {
    // Make LED animation go right
    if (led_index >= led_pins_length-1){
      anim_switch = !anim_switch;
    } else {
      led_index++;
    } 
  }
}