#include <SPI.h>

void setup() {
  // put your setup code here, to run once:
  SPI_initialization(9600);

  // Using STRCAT() ---------------------------------
  // int32_t session = 45;
  // int32_t fileIndex = 10; 
  // char formatted_NUM[5];
  // char fileName[13]; 

  // strcat(fileName,fourDigits(session,formatted_NUM)); 
  // strcat(fileName,fourDigits(fileIndex,formatted_NUM));
  // strcat(fileName, ".txt");

  // Serial.println(fileName);
  //---------------------------------

  int32_t session = 5555;
  int32_t fileIndex = 1;
  char fileName[13];  // Increased size to accommodate null terminator

  // Use the same buffer for formatting to avoid unnecessary memory allocation
  // and improve performance
  fourDigits(session, fileName);
  fourDigits(fileIndex, fileName + 4);  // Move the pointer to the next available position

  // Use snprintf for better readability and to avoid potential buffer overflows
  snprintf(fileName + 8, 5, ".txt");

  Serial.println(fileName);

}

void loop() {
  
}

/* Format function; adds leading zeros;
retruns 4 digits*/
char* fourDigits(int32_t digits, char* result) 
{
  if (digits < 10)
  {
    sprintf(result, "000%d", digits);
  }
  else if (digits < 100)
  {
    sprintf(result, "00%d", digits);
  }
  else if (digits < 1000)
  {
    sprintf(result, "0%d", digits);
  }
  else
  {
    sprintf(result, "%d", digits);
  }

  return result;
}

/* Format function:  adds leading zeros
** Required input: 
*** char formattedNumber[3]; ensures space for format & null
** retruns formattedNumber*/
char* twoDigits(int32_t digits, char* result) // used to format file name
{
  if (digits < 10)
  {
    sprintf(result, "0%d", digits);
  }
  else
  {
    sprintf(result, "%d", digits);
  }
  return result; 
}

/* Open serial communications by initializing serial obj @ baudRate
    - Standard baudRate = 9600
    - Speed of printing to serial monitor 
*/
void SPI_initialization(const int baudRate)
{

  Serial.begin(baudRate);

  // Will wait up to 15 seconds for Arduino Serial Monitor / serial port to connect
  //  - Needed for native USB port only
  //  - Ensure only one monitor is open
  while (!Serial && millis() < 15000)
  {
    ;
  }
  Serial.println("\n\n-----New Serial Communication Secured-----");
}