#include <Keyboard.h>

#define PIN_BUTTON 15
#define PIN_LEFT 30
#define PIN_RIGHT 31
#define PIN_LED 5

int state_lr = 0;
int state_b = 0;

int debug = 0;

void setup() {
  pinMode(PIN_BUTTON, INPUT);
  pinMode(PIN_LEFT, INPUT);
  pinMode(PIN_RIGHT, INPUT);
  pinMode(PIN_LED, OUTPUT);
  
  if (!digitalRead(PIN_BUTTON)) {
    // debug mode
    digitalWrite(PIN_LED, HIGH);
    Serial.begin(9600);
    debug = 1;
  } else {
    // normal mode
    Keyboard.begin();
  }
}


void loop() {
  int state_lr_n;
  int state_b_n;
  state_lr_n =  (digitalRead(PIN_LEFT)<<1) | digitalRead(PIN_RIGHT);
  state_b_n = !digitalRead(PIN_BUTTON);

  if (state_b_n != state_b) {
    if (debug) {
      Serial.print("button:");
      Serial.println(state_b_n);
    } else {
      if (state_b_n) {
        Keyboard.press(' ');
      } else {
        Keyboard.release(' ');
      }
    }
  }

  if (state_lr_n != state_lr) {
    if (debug) {
      Serial.print("state:");
      Serial.println(state_lr_n);
    } else {
      if ((state_lr_n & ~state_lr) & 0b01) {
        Keyboard.press(KEY_RIGHT_ARROW);
      }
      if ((~state_lr_n & state_lr) & 0b01) {
        Keyboard.release(KEY_RIGHT_ARROW);
      }
      if ((state_lr_n & ~state_lr) & 0b10) {
        Keyboard.press(KEY_LEFT_ARROW);
      }
      if ((~state_lr_n & state_lr) & 0b10) {
        Keyboard.release(KEY_LEFT_ARROW);
      }
    }
  }

  state_lr = state_lr_n;
  state_b = state_b_n;
  delay(10);
}