#include <Arduino.h>
#include <vector>
#include <SD.h>

#define CS_PIN 5

using Filenames = std::vector<String>;

Filenames getFilenames(const char * path) {
  Filenames filenames;

  File root = SD.open("/");
  if (!root) return filenames;

  File entry;
  while (entry = root.openNextFile()) {

    if (entry.isDirectory()) {
      entry.close();
      continue;
    }

    filenames.push_back(String(path) + entry.name());

    entry.close();
  }

  root.close();

  return filenames;
}

void setupSDCard() {
  Serial.print("Initializing SD card... ");

  if (!SD.begin(CS_PIN)) {
    Serial.println("Card initialization failed!");
    while (true);
  }
  Serial.println("done");
}

void listFilenames() {
  Filenames filenames = getFilenames("/");

  Serial.print(filenames.size());
  Serial.println(" file(s) found:");

  for (size_t i = 0; i < filenames.size(); i++)
    Serial.println(filenames[i]);

  // alternatively:
  // for (auto filename : filenames) Serial.println(filename);
}

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

  setupSDCard();
  listFilenames();
}

void loop() {
  delay(100); // wokwi delay
}