// Program: 1C Ex5 Q1 Lau Ngai Chun.ino

// Program: Ex5_Array.ino
/*
   Exercise 5 Array, string, and function
   Echo with some modifications
*/

char buf[100] = {0};  // this is an array
char inChar;
bool stringComplete = false;
int i = 0;

void setup()
{
  // Initialize serial and wait for port to open
  Serial.begin(115200);
}

// ** IMPORTANT **
// MUST use buf[]
// CAN'T use functions like Serial.parseInt, Serial.readString

void loop()
{
  int num;

  while (Serial.available())
  {
    inChar = (char)Serial.read();
    buf[i++] = inChar;

    if (inChar == '\n')   // change '\n' to '~' when using Tinkercad
    {
      // buf[i++] = inChar;  // last character is newline
      buf[i] = 0;        // string array should be terminated with a zero
      stringComplete = true;
    }
    else
    {
      // buf[i++] = inChar;
    }
  }

  if (stringComplete)
  {
    Serial.print(buf);    // the printing of string will be stopped when zero is reached
    // Serial.println(i);
    // Serial.println();

    if ((i == 2) && isDigit(buf[0])) {
      num = buf[0] - '0';
      PrintStars(num);
    }
    // Serial.println(num);

    // Code to handle 2 digits
    // if ((i == 3) && ...

    if ((i == 3) && isDigit(buf[0]) && isDigit(buf[1]) ) {
      num = (buf[0] - '0') * 10 + (buf[1] - '0' );
      PrintStars(num);
    }

    // Code for UI (User Interface) including 
    // message for incorrect input
    // Format the output nicely, refer to the example on the worksheet

    PrintStars(0);

    stringComplete = false;
    i = 0;
    // num = 0;
  }
}

void PrintStars(int n) {
  // Other than for, we can also use while or do-while
  // Initial value of j equals to 0 or n
  for (int j = 1; j <= n; j++) {
    Serial.print("*");

    if (j % 10 == 0) {
      Serial.println();
    }
    // Add code such that 10 stars are printed on a row
    // Hint: use % (remainder/mod operator) so that a new line 
    // is produced when j is a multiple of 10
  }
  Serial.println();
}