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

typedef enum{ 
  FAM_R, 
  FAM_W 
} FileAccessMode;

class SDHelper {
private:
  uint8_t _cs;
  FileAccessMode _fam;
  File _stream;
  String _filename;
  bool _available = false;
  SPIClass _spi(HSPI);

  String getNewFilename() {
    static unsigned long i = 0;
    String name;
    do {
      name = "coords" + String(i++) + ".txt";
    } while (SD.exists(name.c_str()));
    return name;
  }

public:
  SDHelper(uint8_t csPin, FileAccessMode fam, String filename = "") : _cs(csPin), _fam(fam) {
    _spi.begin(14, 2, 15, 13);
    if(!SD.begin(_cs, _spi)){ 
      _available = false; 
      return;
    }

    if(_fam == FAM_W){
      _filename = filename.length() ? filename : getNewFilename();
      _stream = SD.open(_filename.c_str(), FILE_WRITE);
    } 
    else {
      _filename = filename;
      _stream = SD.open(_filename.c_str(), FILE_READ);
    }
    _available = (bool)_stream;
  }

  ~SDHelper(){ 
    if(_stream) _stream.close();
  }

  bool Available() const { return _available; }
  const String& filename() const { return _filename; }

  void Log(const String& msg) {
    if(_fam != FAM_W || !_stream) return;
    _stream.println(msg);
    _stream.flush();
  }
};