#include <LiquidCrystal.h>

const int RED_BUTTON_PIN = 4;
const int GREEN_BUTTON_PIN = 3;
const int BLUE_BUTTON_PIN = 2;
uint16_t BLUE_BUTTON_BUFFER = 0;
unsigned long LAST_TIMESTAMP = 0;
uint16_t DISPLAY_STATE = 0;
const String WELCOME_MSG = "Welcome!";
char buffer[40];

LiquidCrystal lcd(12, 11, 10, 9, 8, 7);

uint16_t debounce_high(uint16_t *state, uint16_t raw_event) {
  *state = (*state << (uint16_t) 1) | !raw_event | 0xE000;
  //sprintf(buffer, "%#08x", *state);
  //Serial.println(buffer);
  if (*state == 0xF000)
    return 1;
  return 0;
}

void setup() {
  pinMode(RED_BUTTON_PIN, INPUT);
  pinMode(GREEN_BUTTON_PIN, INPUT);
  pinMode(BLUE_BUTTON_PIN, INPUT);
  Serial.begin(115200);
  lcd.begin(16, 1);
  lcd.print(WELCOME_MSG);
  lcd.setCursor(0, 1);
}

void loop() {
  digitalWrite(LED_BUILTIN,
               digitalRead(RED_BUTTON_PIN) | digitalRead(GREEN_BUTTON_PIN) | digitalRead(BLUE_BUTTON_PIN)
              );

  if (debounce_high(&BLUE_BUTTON_BUFFER, digitalRead(BLUE_BUTTON_PIN))) {
    lcd.print(":)      ");
    lcd.setCursor(0, 1);
    Serial.println("ONCE!");
    LAST_TIMESTAMP = micros();
    DISPLAY_STATE = 1;
  } else if (DISPLAY_STATE && micros() - LAST_TIMESTAMP >= 500000) {
    Serial.println("RESET...");
    lcd.print(WELCOME_MSG);
    lcd.setCursor(0, 1);
    DISPLAY_STATE = 0;
  }
}