// Key definitions
#define BUTTON_KEY1 KEY_F13
#define BUTTON_KEY2 KEY_F14
#define BUTTON_KEY3 KEY_F15
#define BUTTON_KEY4 KEY_F16
#define BUTTON_KEY5 KEY_F17
#define BUTTON_KEY6 KEY_F18
#define BUTTON_KEY7 KEY_F19
#define BUTTON_KEY8 KEY_F20

#define BUTTON_KEY9 KEY_F21
#define BUTTON_KEY10 KEY_F22
#define BUTTON_KEY11 KEY_F23
#define BUTTON_KEY12 KEY_F24

// Pin definitions
#define BUTTON_PIN1 2
#define BUTTON_PIN2 3
#define BUTTON_PIN3 4
#define BUTTON_PIN4 5
#define BUTTON_PIN5 6
#define BUTTON_PIN6 7
#define BUTTON_PIN7 8
#define BUTTON_PIN8 9

#define BUTTON_PIN9 10
#define BUTTON_PIN10 15
#define BUTTON_PIN11 14
#define BUTTON_PIN12 16

// ---------------------------------

#include "Keyboard.h"

// Button helper class for handling press/release and debouncing
class button {
  public:
  const char key;
  const uint8_t pin;

  button(uint8_t k, uint8_t p) : key(k), pin(p){}

  void press(boolean state){
    if(state == pressed || (millis() - lastPressed  <= debounceTime)){
      return; // Nothing to see here, folks
    }

    lastPressed = millis();

    state ? Keyboard.press(key) : Keyboard.release(key);    
    pressed = state;
  }

  void update(){
    press(!digitalRead(pin));
  }

  private:
  const unsigned long debounceTime = 30;
  unsigned long lastPressed = 0;
  boolean pressed = 0;
} ;

// Button objects, organized in array
button buttons[] = {
  {BUTTON_KEY1, BUTTON_PIN1},
  {BUTTON_KEY2, BUTTON_PIN2},
  {BUTTON_KEY3, BUTTON_PIN3},
  {BUTTON_KEY4, BUTTON_PIN4},
  {BUTTON_KEY5, BUTTON_PIN5},
  {BUTTON_KEY6, BUTTON_PIN6},
  {BUTTON_KEY7, BUTTON_PIN7},
  {BUTTON_KEY8, BUTTON_PIN8},
  {BUTTON_KEY9, BUTTON_PIN9},
  {BUTTON_KEY10, BUTTON_PIN10},
  {BUTTON_KEY11, BUTTON_PIN11},
  {BUTTON_KEY12, BUTTON_PIN12},
};

const uint8_t NumButtons = sizeof(buttons) / sizeof(button);
const uint8_t ledPin = 17;

void setup() { 
  // Safety check. Ground pin #1 (RX) to cancel keyboard inputs.
  pinMode(1, INPUT_PULLUP);
  if(!digitalRead(1)){
    failsafe();
  }

  // Set LEDs Off. Active low.
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, HIGH);
  TXLED0;

  for(int i = 0; i < NumButtons; i++){
    pinMode(buttons[i].pin, INPUT_PULLUP);
  }
}

void loop() {
  for(int i = 0; i < NumButtons; i++){
    buttons[i].update();
  }
}

void failsafe(){
  for(;;){} // Just going to hang out here for awhile :D
}