#include <Keypad.h>

const int row_num = 4;
const int col_num = 4;

long int current_time = 0;
long int prev_time = 0;
int threshold = 4000;
char keypressed = '\0';
int score = 0;

char keys[row_num][col_num] = {
  {'1' , '2' , '3' , 'A'},
  {'4' , '5' , '6' , 'B'},
  {'7' , '8' , '9' , 'C'},
  {'*' , '0' , '#' , 'D'}
};

byte row_pins[] = {19,18,5,17};
byte col_pins[] = {16,4,2,15};

Keypad k = Keypad(makeKeymap(keys), row_pins, col_pins, row_num, col_num );

void setup(){
  Serial.begin(115200);
}

void loop(){
  byte random_row = random(1,5);
  byte random_column = random(1,5);
  char random_element = keys[random_row-1][random_column-1];

  String hint1 = "Row : " + String(random_row);
  String hint2 = "Column: " + String(random_column);
  byte random_hint = random(1,3);

  if(random_hint == 1)Serial.println(hint1 + "\t" +hint2);
  else Serial.println(hint2 + "\t" +hint1);


  while (true){
    char key = k.getKey();

    if(key){
      keypressed = key;
    }


  current_time = millis();

  if(current_time - prev_time == threshold){

    if(keypressed == random_element){
      score++;
      if (score > 6){
        Serial.println("You WON!");
        while(1);
      }
      Serial.println("Correct guess, score : " + String(score));
      threshold = threshold - 500;
      if (threshold < 500)threshold = 500;
  }
    else {
      Serial.println("You LOSE!");
      while(1);
    }
    prev_time = current_time;
    break;
  }
}
}