#include <LiquidCrystal_I2C.h>

#define I2C_ADDR 0x27
#define I2C_COLUMNS 16
#define I2C_ROWS 2

#define koda1 777111
#define koda2 777333
#define koda3 777330
#define koda4 777444

int LED3 = 3;
int LED4 = 4;
int blinkTime = 300;

bool led3_on = LOW;
bool led4_on = LOW;
bool blinking4 = false;

unsigned long changeTime;

LiquidCrystal_I2C lcd(I2C_ADDR, I2C_COLUMNS, I2C_ROWS);


void setup() {
  Serial.begin(9600);
  Serial.println("Vpisi kodo:");
  lcd.init();
  pinMode(LED3, OUTPUT);
  pinMode(LED4, OUTPUT);
}

void loop() {
  if(Serial.available()){
    char vpis[6];
    int stevilo_znakov = Serial.readBytes(vpis, 6);
    if(stevilo_znakov == 6){
      vpis[6] = '\0';
      int stevilka = atol(vpis);
      lcd.clear();
      lcd.setCursor(0,0);
      switch(stevilka){
        case koda1:
          led3_on = !led3_on;
          if(led3_on == HIGH){
            lcd.print("LED3 vklop");
          }
          else{
            lcd.print("LED3 izklop");
          }
          digitalWrite(LED3, led3_on);
          break;
        case koda2:
          blinking4 = true;
          lcd.print("LED4 utripa");
          break;
        case koda3:
          blinking4 = false;
          led4_on = LOW;
          digitalWrite(LED4, LOW);
          lcd.print("LED4 izklop");
          break;
        case koda4:
          lcd.print("LED4 utripa 10x");
          for(int i = 0; i < 20; i++){
            utripanje();
            delay(blinkTime + 5);
          }
          led4_on = LOW;
          digitalWrite(LED4, LOW);
          break;
        default:
          Serial.println("Napaka, ponovni vnos.");
          break;
      }
    }
  }
  if(blinking4){
    utripanje();
  }
}

void utripanje(){
  if((millis() - changeTime) > blinkTime){
    led4_on = !led4_on;
    changeTime = millis();
    digitalWrite(LED4, led4_on);
  }
}