#pragma once

#include <cstdint>
#include <istream>
#include <ostream>
#include <string>

#include <glob.h>

namespace Gudhi_laplacian
{ 
  // FIXME: Read from PETSc headers.
  static const int32_t PETSC_MAT_FILE_CLASSID = 1211216;
  static const int32_t PETSC_VEC_FILE_CLASSID = 1211214;

  bool preexisting_files(const std::string & prefix, const std::string & postfix)
  {
    glob_t globbuf;
    std::string pattern = prefix + std::string(".*.") + postfix;
    bool ret = (glob(pattern.c_str(), GLOB_ERR | GLOB_NOSORT, NULL, &globbuf) != GLOB_NOMATCH);
    globfree(&globbuf);
    return ret;
  }


  template <typename T> inline void reverse_endianness(T & x)
  {
    uint8_t * p = reinterpret_cast<uint8_t *>(&x);
    std::reverse(p, p + sizeof(T));
  }
  
  template <typename T> inline T read_le(std::istream & s)
  {
    T result;
    s.read(reinterpret_cast<char *>(&result), sizeof(T));
    #ifdef BIGENDIAN
    reverse_endianness(result);
    #endif
    return result;
  }

  template <typename T> inline void write_le(std::ostream & s, T value)
  {
    #ifdef BIGENDIAN
    reverse_endianness(value);
    #endif
    s.write(reinterpret_cast<char *>(&value), sizeof(T));
  }

  template <typename T> inline T read_be(std::istream & s)
  {
    T result;
    s.read(reinterpret_cast<char *>(&result), sizeof(T));
    #ifndef BIGENDIAN
    reverse_endianness(result);
    #endif
    return result;
  }

  template <typename T> inline void write_be(std::ostream & s, T value)
  {
    #ifndef BIGENDIAN
    reverse_endianness(value);
    #endif
    s.write(reinterpret_cast<char *>(&value), sizeof(T));
  }   
}