#include <Keypad.h>
String ram[4];
int counter=0;
int counter2=0;
int phase=0;
bool stat=false;
String passcode="0000";
const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};

uint8_t colPins[COLS] = { 5, 4, 3, 2 };
uint8_t rowPins[ROWS] = { 9, 8, 7, 6 };

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {
  Serial.begin(9600);
  pinMode(10, INPUT);
}

void loop() {
  char key = keypad.getKey();
    if(stat){
    if (counter2==0){
      counter=0;
      counter2=counter2+1;
    }
    if (key != NO_KEY && counter<5) {
     ram[counter-1]=key;
     Serial.print(key);
     counter=counter+1;
  }else if (counter==0){
        Serial.println("Enter New Password");
        counter++;
  }else if (counter>4){
        passcode=ram[0]+ram[1]+ram[2]+ram[3];
        counter=0;
        counter2=0;
        phase=0;
        stat=false;
        Serial.println();
        Serial.println("Retuening to console...");
  }
  }
  else if(phase==1){
    if (counter2==0){
      counter=0;
      counter2=counter2+1;
    }
    if (key != NO_KEY && counter<5) {
     ram[counter-1]=key;
     Serial.print(key);
     counter=counter+1;
  }else if (counter==0){
         Serial.println();
        Serial.println("CHANGING PASSCODE...");
        Serial.println("Enter OLD PASSCODE");
        counter++;
  }else if (counter>4){
    if(ram[0]+ram[1]+ram[2]+ram[3]==passcode){
          Serial.println();
          stat=true;
          Serial.println("PASSCODE UPDATED!");
        }else{
          Serial.println();
          Serial.println("INCORRECT");
          Serial.println("Retuening to console...");
        }
        counter=0;
        counter2=0;
        phase=0;
        
  }
  }else if(digitalRead(10)==0){
    phase=1;
  }
  else if (key != NO_KEY && phase==0 && counter<5) {
     ram[counter-1]=key;
     Serial.print(key);
     counter=counter+1;
  }else if (counter==0){
        Serial.println("Enter passcode");
        counter=counter+1;
  }else if (counter>4){
    if(ram[0]+ram[1]+ram[2]+ram[3]==passcode){
          Serial.println();
          Serial.println("VERIFIED");
        }else{
          Serial.println();
          Serial.println("INCORRECT");
        }
        counter=0;
  }
  
}