#include <iostream>
#include <string>

#include <stdlib.h>

#include "FileDescriptor.hh"
#include "Exception.hh"
#include "endian.hh"

using namespace std;
using namespace pbe;


static void usage(void)
{
  cerr << "Usage: endswap [filename]\n"
       << "If no filename is given, standard input is read.\n"
       << "The input is read and endian-swapped until end-of-file,\n"
       << "with the output sent to standard output.\n"
       << "If the input terminates on a non-word boundary the\n"
       << "output will be padded to the word boundary with zeros\n"
       << "and a warning will be output to standard error.\n";
}


static void endswap(FileDescriptor& infd)
{
  string s = infd.readall();
  int padbytes=0;
  while (s.length()%4 > 0) {
    s += '\0';
    ++padbytes;
  }
  if (padbytes) {
    cerr << "Warning: " << padbytes << " bytes of padding needed at EOF.\n";
  }
  const uint32_t* p = reinterpret_cast<const uint32_t*>(s.data());
  unsigned int words = s.length()/4;
  uint32_t swapped[words];
  for (unsigned int w=0; w<words; ++w) {
    swapped[w] = swap_end_32(p[w]);
  }
  FileDescriptor outfd(1);
  outfd.writeall(reinterpret_cast<char*>(swapped),sizeof(swapped));
}


int main(int argc, char* argv[])
{
  try { try {

    if (argc>2) {
      usage();
      exit(1);
    }

    if (argc==2) {

      string arg(argv[1]);

      if (arg=="--help") {
        usage();
        exit(0);
      }

      FileDescriptor infd(arg,FileDescriptor::read_only);
      endswap(infd);
      exit(0);

    } else {

      FileDescriptor infd(0);
      endswap(infd);
      exit(0);

    }
  } RETHROW_MISC_EXCEPTIONS }
  catch (Exception& E) {
    E.report(cerr);
    exit(1);
  }
}