//Adapted from ahmedebeed555
//  https://www.youtube.com/watch?v=1wWdtkLxMaQ
// https://www.instructables.com/Arduino-Digital-Clock-Without-RTC-Real-Time-Clock-/

//PLEASE NOTE: If we use delays at all in this code, we could lose entire minutes in time!

#include <LiquidCrystal_I2C.h>
#include <Keypad.h>

/* Keypad setup */
const byte KEYPAD_ROWS = 4;
const byte KEYPAD_COLS = 4;
byte rowPins[KEYPAD_ROWS] = {12, 11, 10, 9};
byte colPins[KEYPAD_COLS] = {8, 7, 6, 5};
char keys[KEYPAD_ROWS][KEYPAD_COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, KEYPAD_ROWS, KEYPAD_COLS);

LiquidCrystal_I2C lcd(0x27, 20, 4); // I2C address 0x27, 20 column and 4 rows


int RTCHour = 23;
int RTCMinute = 59;
int RTCSecond = 40;
int flag = 0;
int TIME = 0;
const int hourSet = 0;
const int minuteSet = 1;
int hourSetState = 0;
int minuteSetState = 0;

//millis controllers
int prevSecond;

//---------------------- KEY INPUTS ---------------------------
char getKeyInput(){
  char key = 0;
  while (key == 0) {
    key = keypad.getKey();
    if (key >= '0' && key <= '9') {
      //lcd.print(key);
    }    
  }
  return key;
}

void printTimeHeader(){
  lcd.setCursor(0, 0);
  prevSecond = (millis()/1000)%60;
  RTCSecond = prevSecond;
  //RTCSecond = RTCSecond + 1;
  lcd.print("TIME:" );
  //print leading 0 if necessary
  lcd.setCursor(5,0);
  if (RTCHour < 10) lcd.print("0");
  lcd.print(RTCHour);
  lcd.print(":");
  lcd.setCursor(8,0);
  //print leading 0 if necessary
  if (RTCMinute < 10) lcd.print("0");
  lcd.print(RTCMinute);
  lcd.print(":");
  lcd.setCursor(11,0);
  //print leading 0 if necessary
  if (RTCSecond < 10) lcd.print("0");
  lcd.print(RTCSecond);
}

void correctTime(){
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("TIME:" );
  //print leading 0 if necessary
  lcd.setCursor(5,0);
  lcd.print("--");
  lcd.print(":");
  lcd.setCursor(8,0);
  lcd.print("--");
  lcd.print(":");
  //no need to correct seconds
  // lcd.setCursor(11,0);
  // lcd.print("--");

  //starting with hours:
  int i = 0; //to count number of keys pressed. expecting 6
  int j = 0; //to move the cursor to the right position
  String keys = "";
  int timevals[6];
  while (keys.length() < 4){
    keys += getKeyInput();
    if(i == 2) j = 1; //move it to the correct position
    lcd.setCursor((i + j + 5),0);
    lcd.print(keys[i]);
    //convert to int
    timevals[i] = keys[i] - '0';
    i++;
  }
  lcd.setCursor(0,1);
  //untidy combination into the actual time: and lazy wrap around of time:
  RTCHour = (timevals[0])*10 + timevals[1];
  if (RTCHour >= 24) RTCHour -= 24;
  RTCMinute = (timevals[2])*10 + timevals[3];
  if (RTCMinute >= 60) RTCMinute -=60;
  // RTCSecond = (timevals[4])*10 + timevals[5];
}

void updateLCDTime(){
 prevSecond = RTCSecond;

    //minutes
    if (RTCSecond == 0)
    {
      RTCMinute ++;
    }

    if (RTCMinute >= 60)
    {
      RTCMinute = 0;
      RTCHour = RTCHour + 1;
      flag = flag + 1;
    }

    if (RTCHour >= 24)
    {
      RTCHour = 0;
    }

    //print leading 0 if necessary
    lcd.setCursor(5,0);
    if (RTCHour < 10) lcd.print("0");
    lcd.print(RTCHour);
    lcd.print(":");
    lcd.setCursor(8,0);
    //print leading 0 if necessary
    if (RTCMinute < 10) lcd.print("0");
    lcd.print(RTCMinute);
    lcd.print(":");
    lcd.setCursor(11,0);
    //print leading 0 if necessary
    if (RTCSecond < 10) lcd.print("0");
    lcd.print(RTCSecond);
}

//---------------------------- SETUP ---------------------------------

void setup()
{
  lcd.begin(16, 2);
  pinMode(hourSet, INPUT_PULLUP);
  pinMode(minuteSet, INPUT_PULLUP);
  //RTCSecond = millis()/1000;
  //give it time to settle before we start
  //delay(1000);

  RTCHour = 23;
  RTCMinute = 59;

  //initialise time screen
  printTimeHeader();
  

}

//----------------------------------- LOOP ----------------------------
void loop()
{
  
  RTCSecond = (millis()/1000)%60;
  
  if (flag == 24) flag = 0;

  //only change the necessary fields
  //if (RTCSecond > prevSecond){ //until we solve the 0 issue
  if (RTCSecond != prevSecond){
    updateLCDTime();
  }
  
  //TODO: use keypad for correcting time
    
  if (keypad.getKey() == '*'){
    correctTime();
  }
}