/// ----------------------------------------------------------------
/// ----------------------- Type Definitions -----------------------
/// ----------------------------------------------------------------

enum State {
  WaitingForInput,
  WaitingForAck,
};

struct Button {
  const byte pin_id;
  uint8_t last_state;
};


/// ----------------------------------------------------------------
/// ----------------------- Board Specifics ------------------------
/// ----------------------------------------------------------------

const int button_count = 8;

const Button buttons[button_count] = {
  {
    .pin_id = 6,
    .last_state = LOW
  },
  {
    .pin_id = 7,
    .last_state = LOW
  },
  {
    .pin_id = 8,
    .last_state = LOW
  },
  {
    .pin_id = 9,
    .last_state = LOW
  },
  {
    .pin_id = 10,
    .last_state = LOW
  },
  {
    .pin_id = 11,
    .last_state = LOW
  },
  {
    .pin_id = 12,
    .last_state = LOW
  },
  {
    .pin_id = 13,
    .last_state = LOW
  }
};

const char message_start = '<';
const char message_end = '>';



/// ----------------------------------------------------------------
/// -------------------------- Variables ---------------------------
/// ----------------------------------------------------------------

State current_state;



/// ----------------------------------------------------------------
/// --------------------------- Startup ----------------------------
/// ----------------------------------------------------------------

void setup() {
  // enable serial port, with 9600 Baud
  Serial.begin(9600);

  // setup variables
  current_state = WaitingForInput;

  // setup pins
  for (byte i = 0; i < button_count; i++) {
    pinMode(&buttons[i], INPUT);
  }
}

void loop() {
  // check for possible input   
  if (current_state == WaitingForInput) {
    for (byte i = 0; i < button_count; i++) {
      check_pin(&buttons[i], i);
    }
  }
}

void check_pin(Button* button, byte index) {
  if (digitalRead(button->pin_id) == HIGH) {
    if (button->last_state == LOW) { 
      button->last_state = HIGH;

      /*
      // assemble message
      Serial.print(message_start);
      Serial.print(index + 1);
      Serial.print(message_end);
    
      // force new line
      Serial.print('\n');
      */
      
      debug_message(button->pin_id, "HIGH");
    }    
  } else {
    if (button->last_state == HIGH) {
      button->last_state = LOW;

      debug_message(button->pin_id, "LOW");
    }
  }
}

void debug_message(byte pin_id, char c[]) {
  // assemble message
  Serial.print(message_start);
  Serial.print(pin_id);
  Serial.print(' ');
  Serial.print(c);
  Serial.print(message_end);

  // force new line
  Serial.print('\n');
}