#include <SD.h>
#include <MD5Builder.h>
#include <SPI.h>

#define CS_PIN 15

File f;

String file_md5 (File & f)
{
    if (!f) {
        return String();
    }

    if (f.seek(0, SeekSet)) {

        MD5Builder md5;
        md5.begin();
        md5.addStream(f, f.size());
        md5.calculate();
        return md5.toString();
    } 
return String();

}

void setup() {
  Serial.begin(115200);
  Serial.println(sizeof(double));
  Serial.println(400/float(3600*24*100),60);
  Serial.print("Initializing SD card... ");

  SPI.begin(14, 12, 13, CS_PIN); // MOSI, MISO, SCK, CS
  
  if (!SD.begin(CS_PIN, SPI)) {
    Serial.println("Card initialization failed!");
    while (true);
  }

  Serial.println("initialization done.");

  Serial.println("Files in the card:");
  f = SD.open("/wokwi.txt","a");
  f.println("p");
  f.close();
  Serial.println("");

  // Example of reading file from the card:
  File textFile = SD.open("/wokwi.txt");
  Serial.println(file_md5(textFile));
}

void loop() {
  delay(100);
  // nothing happens after setup finishes.
}

void printDirectory(File dir, int numTabs) {
  while (true) {

    File entry =  dir.openNextFile();
    if (! entry) {
      // no more files
      break;
    }
    for (uint8_t i = 0; i < numTabs; i++) {
      Serial.print('\t');
    }
    Serial.print(entry.name());
    if (entry.isDirectory()) {
      Serial.println("/");
      printDirectory(entry, numTabs + 1);
    } else {
      // files have sizes, directories do not
      Serial.print("\t\t");
      Serial.println(entry.size(), DEC);
    }
    entry.close();
  }
}