#define DELAY 200

const int LED[] = {11, 10, 9, 8, 7, 6, 5, 4};
const int BUTTON[] = {A0, A1, A2, A3};

int clk = 0;  // 定義每個模式中的計數器

void setup() {
  for (int i = 0; i < 8; i++) {
    pinMode(LED[i], OUTPUT);
    digitalWrite(LED[i], HIGH);
  }
  for (int i = 0; i < 4; i++) {
    pinMode(BUTTON[i], INPUT);
  }
}

void call_interval( void (*f)(unsigned int) ) {
  static unsigned long checkpoint = 0;
  if (millis() - checkpoint > DELAY) {
    for (int i = 0; i < 8; i++) {
      digitalWrite(LED[7 - i], !((value >> i) % 2));
    }
    clk += 1;
    checkpoint = millis();
  }
}

/*
 * Function: get_mode
 * Return the current mode from buttons input
 * 
 * Side effects: reset the clk on button pressed
 */
unsigned int get_mode() {
  static int last = 0;
  for (int i = 0; i < 4; i++) {
    if (!digitalRead(BUTTON[i])) {
      last = i + 1;
      clk = 0;
      return last;
    }
  }
  return last;
}

/*
 * Function: binary
 * Display the LED as binary of clk
 * 
 * increase clk per DELAY
 * Side effect: increase clk per DELAY
 */
void binary(unsigned int value) {
  static unsigned long checkpoint = 0;
  if (millis() - checkpoint > DELAY) {
    for (int i = 0; i < 8; i++) {
      digitalWrite(LED[7 - i], !((value >> i) % 2));
    }
    clk += 1;
    checkpoint = millis();
  }
}

void gray_code(unsigned int value) {
  binary(value ^ (value >> 1));
}

/*
 * Function: random_popup
 * Randomly blink LED
 * 
 * Randomly select LED. Each LED will turn on for 3 clk
 * Side effect: increase clk per DELAY
 */
void random_popup() {
  static unsigned long checkpoint = 0;
  static int hp[] = {0, 0, 0, 0, 0, 0, 0, 0};
  
  // Reset hp on mode changing
  if (clk == 0) {
    for (int i = 0; i < 8; i++) {
      hp[i] = 0;
    }
  }

  if (millis() - checkpoint > DELAY) {
    for (int i = 0; i < 8; i++) {

      // Decrease hp
      if (hp[i] > 0) {
        hp[i] -= 1;
      }
      digitalWrite(LED[i], !(hp[i]));
    }

    // randomly select LED which is not turned on
    int choice;
    do {
      choice = random(8);
    } while (hp[choice] > 0);
    hp[choice] = 4;
    
    checkpoint = millis();
    clk++;
  }
}

void clear_all() {
  for (int i = 0; i < 8; i++) {
    digitalWrite(LED[i], HIGH);
  }
}

void loop() {
  const int mode = get_mode();
  if (mode == 1) {
    binary(clk);
  }
  if (mode == 2) {
    gray_code(clk);
  }
  if (mode == 3) {
    random_popup();
  }
  if (mode == 4) {
    clear_all();
  }
  delay(1);
}