// Data reader interface for uniform access

// File_Extractor 0.4.0

#ifndef DATA_READER_H

#define DATA_READER_H

#include "blargg_common.h"

#ifdef HAVE_ZLIB_H

#include <zlib.h>

#endif

// Supports reading and finding out how many bytes are remaining

class Data_Reader {

public:

  virtual ~Data_Reader() { }

  static const char eof_error []; // returned by read() when request goes beyond end

  // Read at most count bytes and return number actually read, or <= 0 if error

  virtual long read_avail( void*, long n ) = 0;

  // Read exactly count bytes and return error if they couldn't be read

  virtual blargg_err_t read( void*, long count );

  // Number of bytes remaining until end of file

  virtual long remain() const = 0;

  // Read and discard count bytes

  virtual blargg_err_t skip( long count );

public:

  Data_Reader() { }

  typedef blargg_err_t error_t; // deprecated

private:

  // noncopyable

  Data_Reader( const Data_Reader& );

  Data_Reader& operator = ( const Data_Reader& );

};

// Supports seeking in addition to Data_Reader operations

class File_Reader : public Data_Reader {

public:

  // Size of file

  virtual long size() const = 0;

  // Current position in file

  virtual long tell() const = 0;

  // Go to new position

  virtual blargg_err_t seek( long ) = 0;

  long remain() const;

  blargg_err_t skip( long n );

};

// Disk file reader

class Std_File_Reader : public File_Reader {

public:

  blargg_err_t open( const char* path );

  void close();

public:

  Std_File_Reader();

  ~Std_File_Reader();

  long size() const;

  blargg_err_t read( void*, long );

  long read_avail( void*, long );

  long tell() const;

  blargg_err_t seek( long );

private:

  void* file_; // Either FILE* or zlib's gzFile

#ifdef HAVE_ZLIB_H

  long size_; // TODO: Fix ABI compat

#endif /* HAVE_ZLIB_H */

};

// Treats range of memory as a file

class Mem_File_Reader : public File_Reader {

public:

  Mem_File_Reader( const void*, long size );

#ifdef HAVE_ZLIB_H

  ~Mem_File_Reader( );

#endif /* HAVE_ZLIB_H */

public:

  long size() const;

  long read_avail( void*, long );

  long tell() const;

  blargg_err_t seek( long );

private:

#ifdef HAVE_ZLIB_H

  bool gz_decompress();

#endif /* HAVE_ZLIB_H */

  const char* m_begin;

  long m_size;

  long m_pos;

#ifdef HAVE_ZLIB_H

  bool m_ownedPtr = false; // set if we must free m_begin

#endif /* HAVE_ZLIB_H */

};

// Makes it look like there are only count bytes remaining

class Subset_Reader : public Data_Reader {

public:

  Subset_Reader( Data_Reader*, long count );

public:

  long remain() const;

  long read_avail( void*, long );

private:

  Data_Reader* in;

  long remain_;

};

// Joins already-read header and remaining data into original file (to avoid seeking)

class Remaining_Reader : public Data_Reader {

public:

  Remaining_Reader( void const* header, long size, Data_Reader* );

public:

  long remain() const;

  long read_avail( void*, long );

  blargg_err_t read( void*, long );

private:

  char const* header;

  char const* header_end;

  Data_Reader* in;

  long read_first( void* out, long count );

};

// Invokes callback function to read data. Size of data must be specified in advance.

class Callback_Reader : public Data_Reader {

public:

  typedef const char* (*callback_t)( void* data, void* out, int count );

  Callback_Reader( callback_t, long size, void* data = 0 );

public:

  long read_avail( void*, long );

  blargg_err_t read( void*, long );

  long remain() const;

private:

  callback_t const callback;

  void* const data;

  long remain_;

};

#endif