#include <Keypad.h>

#define ROW_NUM 4
#define COL_NUM 4

long int currentTime = 0;
long int previousTime = 0;
int threshold = 4000;

int score = 0;
char key = '\0';

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

byte rowPins[ROW_NUM] = { 19, 18, 5, 17 };
byte colPins[COL_NUM] = { 16, 4, 2, 15 };

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROW_NUM, COL_NUM);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  byte rand_row_num = random(1, 5);
  byte rand_col_num = random(1, 5);
  char rand_element = keys[rand_row_num-1][rand_col_num-1];

  String hintRow = "Row: " + String(rand_row_num);
  String hintCol = "Column: " + String(rand_col_num);
  
  byte rand_hint = random(1, 3);
  if (rand_hint == 1) {
    Serial.println(hintRow+"\t"+hintCol);
  } else {
    Serial.println(hintCol+"\t"+hintRow);
  }

  while (true) {
    char k = keypad.getKey();
    if (k) {
      key = k;
      Serial.println(key);
    }

    currentTime = millis();
    if (currentTime - previousTime == threshold) {
      if (key == rand_element) {
        score++;
        if (score > 5) {
          Serial.println("You win!");  
          while(true);
        }
        Serial.print("Correct! Your score is: " + String(score));
        threshold = threshold - 200;
      } else {
        Serial.println("You lost!");
        while(true);
      }
      previousTime = currentTime;
      break;
    }
  }
  
}