#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#define BUTTON_MENU 2 
#define BUTTON_UP 3 
#define BUTTON_DOWN 4 
#define BUTTON_LEFT 5 

LiquidCrystal_I2C lcd(0x27, 16, 2);
byte second_final, minute_final, hour_final;
byte alarm1[3] = {2, 4 ,5};
byte alarm2[3] = {1, 1, 1};
byte change1[3] = {0, 0, 0};
byte menu = 0;

byte readSecond(){
  byte second, second1, second10;
  
  Wire.beginTransmission(0x68);
  Wire.write(0x00);
  Wire.endTransmission(1);

  Wire.requestFrom(0x68, 1, 1);
  second = Wire.read();
  second1 = second << 4;
  second1 = second1 >> 4;
  second10 = second << 1;
  second10 = second10 >> 5;
  second10 *= 10;
  return (second10 + second1);
}

byte readMinute(){
  byte minute, minute1, minute10;
  Wire.beginTransmission(0x68);
  Wire.write(0x01);
  Wire.endTransmission(1);
  
  Wire.requestFrom(0x68, 1, 1);
  minute = Wire.read();
  minute1 = minute << 4;
  minute1 = minute1 >> 4;
  minute10 = minute >> 4;
  minute10 *= 10;
  return (minute10 + minute1);
}

byte readHour(){

  byte hour, hour1, hour10;
  Wire.beginTransmission(0x68);
  Wire.write(0x02);
  Wire.endTransmission(1);

  Wire.requestFrom(0x68, 1, 1);
  hour = Wire.read();
  hour1 = hour << 4;
  hour1 = hour1 >> 4;
  hour10 = hour << 1;
  hour10 = hour10 >> 5;
  hour10 *= 10;
  return (hour10 + hour1);
}

void printClock(byte second, byte minute, byte hour){
  lcd.setCursor(4,0);
  (hour >= 10) ? lcd.print(hour) : lcd.print("0") && lcd.print(hour);
  lcd.print(":");
  (minute >= 10) ? lcd.print(minute) : lcd.print("0") && lcd.print(minute);
  lcd.print(":");
  (second >= 10) ? lcd.print(second) : lcd.print("0") && lcd.print(second);
}

void buttonRecognizing(){
  for(int i = 2; i <= 5; i++){
    pinMode(i, INPUT);
  }
}

void setup() {
  Wire.begin();
  lcd.init();
  lcd.backlight();
  Serial.begin(9600);
  buttonRecognizing();
}

void loop(){
  if(digitalRead(BUTTON_MENU)){
    Serial.print(":");
    while(digitalRead(BUTTON_MENU));
    (menu < 3) ? menu++ : menu = 0;
    Serial.println(menu);
  }
  switch(menu){
    case 0 :
      second_final = readSecond();
      minute_final = readMinute();
      hour_final = readHour();
      printClock(second_final, minute_final, hour_final);
      break;
    case 1 :
      printClock(alarm1[0], alarm1[1], alarm1[2]);
      break;
    case 2 :
      printClock(alarm2[0], alarm2[1], alarm2[2]);
      break;
    case 3 :
      change1[0] = readSecond();
      change1[1] = readMinute();
      change1[2] = readHour();
      printClock(change1[0], change1[1], change1[2]);
      break;
    default :
      break;
  }
  

  delay(100);
}