/*  Zupdate - recompress bzip2, gzip, xz files to lzip files
    Copyright (C) 2013 Antonio Diaz Diaz.

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#define _FILE_OFFSET_BITS 64

#include <cerrno>
#include <climits>
#include <csignal>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <list>
#include <string>
#include <vector>
#include <dirent.h>
#include <fcntl.h>
#include <stdint.h>
#include <unistd.h>
#include <utime.h>
#include <sys/stat.h>
#if defined(__MSVCRT__) || defined(__OS2__)
#include <io.h>
#endif

#include "arg_parser.h"
#include "zutils.h"
#include "rc.h"

#if CHAR_BIT != 8
#error "Environments where CHAR_BIT != 8 are not supported."
#endif


namespace {

#ifdef O_BINARY
const int o_binary = O_BINARY;
#else
const int o_binary = 0;
#endif


void show_zupdate_help()
  {
  std::printf( "Zupdate recompresses files from bzip2, gzip, and xz formats to lzip format.\n"
               "The originals are compared with the new files and then deleted.\n"
               "Only regular files with standard file name extensions are recompressed,\n"
               "other files are ignored.\n"
               "Compressed files are decompressed and then recompressed on the fly; no\n"
               "temporary files are created.\n"
               "The lzip format is chosen as destination because it is by far the most\n"
               "appropriate for long-term data archiving.\n"
               "\nIf the lzip compressed version of a file already exists, the file is\n"
               "skipped unless the '--force' option is given. In this case, if the\n"
               "comparison fails, an error is returned and the original file is not\n"
               "deleted. The operation of zupdate is meant to be safe and not produce\n"
               "any data loss. Therefore, existing lzip compressed files are never\n"
               "overwritten nor deleted.\n"
               "\nUsage: zupdate [options] [files]\n"
               "\nExit status is 0 if all the compressed files were successfully\n"
               "recompressed (if needed), compared and deleted. Non-zero otherwise.\n"
               "\nOptions:\n"
               "  -h, --help                 display this help and exit\n"
               "  -V, --version              output version information and exit\n"
               "  -f, --force                do not skip a file even if the .lz exists\n"
               "  -l, --lzip-verbose         pass a -v option to the lzip compressor\n"
               "  -N, --no-rcfile            don't read runtime configuration file\n"
               "  -q, --quiet                suppress all messages\n"
               "  -r, --recursive            operate recursively on directories\n"
               "  -v, --verbose              be verbose (a 2nd -v gives more)\n"
               "  -0 .. -9                   set compression level [default 9]\n"
               "      --bz2=<command>        set compressor and options for bzip2 format\n"
               "      --gz=<command>         set compressor and options for gzip format\n"
               "      --lz=<command>         set compressor and options for lzip format\n"
               "      --xz=<command>         set compressor and options for xz format\n" );
  show_help_addr();
  }


int cant_execute( const std::string & command, const int status )
  {
  if( verbosity >= 0 )
    {
    if( WIFEXITED( status ) )
      std::fprintf( stderr, "%s: Error executing '%s'. Exit status = %d.\n",
                    util_name, command.c_str(), WEXITSTATUS( status ) );
    else
      std::fprintf( stderr, "%s: Can't execute '%s'.\n",
                    util_name, command.c_str() );
    }
  return 1;
  }


     // Set permissions, owner and times.
void set_permissions( const char * const rname, const struct stat & in_stats )
  {
  bool warning = false;
  // fchown will in many cases return with EPERM, which can be safely ignored.
  if( ( chown( rname, in_stats.st_uid, in_stats.st_gid ) != 0 &&
        errno != EPERM ) ||
      chmod( rname, in_stats.st_mode ) != 0 ) warning = true;
  struct utimbuf t;
  t.actime = in_stats.st_atime;
  t.modtime = in_stats.st_mtime;
  if( utime( rname, &t ) != 0 ) warning = true;
  if( warning && verbosity >= 2 )
    show_error( "Can't change output file attributes." );
  }


struct { const char * from; const char * to; int format_index; } const
  known_extensions[] = {
  { ".bz2",  "",     fmt_bz2 },
  { ".tbz",  ".tar", fmt_bz2 },
  { ".tbz2", ".tar", fmt_bz2 },
  { ".gz",   "",     fmt_gz },
  { ".tgz",  ".tar", fmt_gz },
  { ".lz",   "",     fmt_lz },
  { ".tlz",  ".tar", fmt_lz },
  { ".xz",   "",     fmt_xz },
  { ".txz",  ".tar", fmt_xz },
  { 0,       0,      -1 } };


    // Returns 0 for success, -1 for file skipped, 1 for error.
int zupdate_file( const std::string & name, const char * const lzip_name,
                  const std::vector< std::string > & lzip_args2,
                  const bool force )
  {
  int format_index = -1;
  std::string dname;					// decompressed_name

  for( int i = 0; known_extensions[i].from; ++i )	// search extension
    {
    const std::string from( known_extensions[i].from );
    if( name.size() > from.size() &&
        name.compare( name.size() - from.size(), from.size(), from ) == 0 )
      {
      dname.assign( name, 0, name.size() - from.size() );
      dname += known_extensions[i].to;
      format_index = known_extensions[i].format_index;
      if( format_index == fmt_lz )
        {
        if( verbosity >= 2 )
          std::fprintf( stderr, "%s: Input file '%s' already has '%s' suffix.\n",
                        util_name, name.c_str(), known_extensions[i].from );
        return 0;					// ignore this file
        }
      break;
      }
    }
  const char * const compressor_name = get_compressor_name( format_index );
  if( !compressor_name || !compressor_name[0] )
    {
    if( verbosity >= 2 )
      std::fprintf( stderr, "%s: Unknown extension in file name '%s' -- ignored.\n",
                    util_name, name.c_str() );
    return 0;						// ignore this file
    }

  struct stat in_stats;
  if( stat( name.c_str(), &in_stats ) != 0 )		// check input file
    {
    if( verbosity >= 0 )
      std::fprintf( stderr, "%s: Can't stat input file '%s': %s.\n",
                    util_name, name.c_str(), std::strerror( errno ) );
    return 1;
    }
  if( !S_ISREG( in_stats.st_mode ) )
    {
    if( verbosity >= 0 )
      std::fprintf( stderr, "%s: Input file '%s' is not a regular file.\n",
                    util_name, name.c_str() );
    return 1;
    }

  struct stat st;
  std::string rname( dname ); rname += ".lz";		// recompressed_name
  const bool lz_exists = ( stat( rname.c_str(), &st ) == 0 );
  if( lz_exists && !force )
    {
    if( verbosity >= 0 )
      std::fprintf( stderr, "%s: Output file '%s' already exists, skipping.\n",
                    util_name, rname.c_str() );
    return -1;
    }

  if( !lz_exists )					// recompress
    {
    if( verbosity >= 1 )
      std::fprintf( stderr, "Recompressing file '%s'.\n", name.c_str() );
    int fda[2];			// pipe between decompressor and compressor
    if( pipe( fda ) < 0 )
      { show_error( "Can't create pipe", errno ); return 1; }

    const pid_t pid = fork();
    if( pid == 0 )				// child1 (decompressor)
      {
      if( dup2( fda[1], STDOUT_FILENO ) >= 0 &&
          close( fda[0] ) == 0 && close( fda[1] ) == 0 )
        {
        const std::vector< std::string > & compressor_args =
          get_compressor_args( format_index );
        const int size = compressor_args.size();
        const char ** const argv = new const char *[size+5];
        argv[0] = compressor_name;
        for( int i = 0; i < size; ++i ) argv[i+1] = compressor_args[i].c_str();
        argv[size+1] = "-cd";
        argv[size+2] = "--";
        argv[size+3] = name.c_str();
        argv[size+4] = 0;
        execvp( argv[0], (char **)argv );
        }
      show_exec_error( compressor_name );
      _exit( 1 );
      }
    if( pid < 0 )				// parent
      { show_fork_error( compressor_name ); return 1; }

    const pid_t pid2 = fork();
    if( pid2 == 0 )				// child2 (lzip compressor)
      {
      if( dup2( fda[0], STDIN_FILENO ) >= 0 &&
          close( fda[0] ) == 0 && close( fda[1] ) == 0 )
        {
        const std::vector< std::string > & lzip_args =
          get_compressor_args( fmt_lz );
        const int size = lzip_args.size();
        const int size2 = lzip_args2.size();
        const char ** const argv = new const char *[size+size2+5];
        argv[0] = lzip_name;
        argv[1] = "-9";
        for( int i = 0; i < size; ++i ) argv[i+2] = lzip_args[i].c_str();
        for( int i = 0; i < size2; ++i ) argv[i+size+2] = lzip_args2[i].c_str();
        argv[size+size2+2] = "-o";
        argv[size+size2+3] = dname.c_str();
        argv[size+size2+4] = 0;
        execvp( argv[0], (char **)argv );
        }
      show_exec_error( lzip_name );
      _exit( 1 );
      }
    if( pid2 < 0 )				// parent
      { show_fork_error( lzip_name ); return 1; }

    close( fda[0] ); close( fda[1] );
    int retval = wait_for_child( pid, compressor_name );
    int retval2 = wait_for_child( pid2, lzip_name );
    if( retval || retval2 ) { std::remove( rname.c_str() ); return 1; }
    set_permissions( rname.c_str(), in_stats );
    }

  {
  if( lz_exists && verbosity >= 1 )
    std::fprintf( stderr, "Comparing file '%s'.\n", name.c_str() );
  std::string zcmp_command( invocation_name );
  unsigned i =  zcmp_command.size();
  while( i > 0 && zcmp_command[i-1] != '/' ) --i;
  zcmp_command.resize( i );
  zcmp_command += "zcmp ";				// ${bindir}zcmp
  zcmp_command += name; zcmp_command += ' '; zcmp_command += rname;
  int status = std::system( zcmp_command.c_str() );
  if( status != 0 )
    { if( !lz_exists ) std::remove( rname.c_str() );
      return cant_execute( zcmp_command, status ); }
  }

  if( std::remove( name.c_str() ) != 0 && errno != ENOENT )
    {
    if( verbosity >= 0 )
      std::fprintf( stderr, "%s: Can't delete input file '%s': %s.\n",
                    util_name, name.c_str(), std::strerror( errno ) );
    return 1;
    }
  return 0;
  }

} // end namespace


int main( const int argc, const char * const argv[] )
  {
  enum { bz2_opt = 256, gz_opt, lz_opt, xz_opt };
  std::string input_filename;
  std::list< std::string > filenames;
  std::vector< std::string > lzip_args2;	// args to lzip, maybe empty
  bool force = false;
  bool recursive = false;
  invocation_name = argv[0];
  util_name = "zupdate";

  const Arg_parser::Option options[] =
    {
    { '0',  0,              Arg_parser::no  },
    { '1',  0,              Arg_parser::no  },
    { '2',  0,              Arg_parser::no  },
    { '3',  0,              Arg_parser::no  },
    { '4',  0,              Arg_parser::no  },
    { '5',  0,              Arg_parser::no  },
    { '6',  0,              Arg_parser::no  },
    { '7',  0,              Arg_parser::no  },
    { '8',  0,              Arg_parser::no  },
    { '9',  0,              Arg_parser::no  },
    { 'f', "force",         Arg_parser::no  },
    { 'h', "help",          Arg_parser::no  },
    { 'l', "lzip-verbose",  Arg_parser::no  },
    { 'N', "no-rcfile",     Arg_parser::no  },
    { 'q', "quiet",         Arg_parser::no  },
    { 'r', "recursive",     Arg_parser::no  },
    { 'v', "verbose",       Arg_parser::no  },
    { 'V', "version",       Arg_parser::no  },
    { bz2_opt,    "bz2",    Arg_parser::yes },
    { gz_opt,     "gz",     Arg_parser::yes },
    { lz_opt,     "lz",     Arg_parser::yes },
    { xz_opt,     "xz",     Arg_parser::yes },
    {  0 ,  0,              Arg_parser::no  } };

  const Arg_parser parser( argc, argv, options );
  if( parser.error().size() )				// bad option
    { show_error( parser.error().c_str(), 0, true ); return 1; }

  maybe_process_config_file( parser );

  int argind = 0;
  for( ; argind < parser.arguments(); ++argind )
    {
    const int code = parser.code( argind );
    if( !code ) break;					// no more options
    const char * const arg = parser.argument( argind ).c_str();
    switch( code )					// common options
      {
      case '0': case '1': case '2': case '3': case '4':
      case '5': case '6': case '7': case '8': case '9':
                lzip_args2.push_back( "-" ); lzip_args2.back() += code; break;
      case 'f': force = true; break;
      case 'h': show_zupdate_help(); return 0;
      case 'l': lzip_args2.push_back( "-v" ); break;
      case 'N': continue;
      case 'q': verbosity = -1; lzip_args2.push_back( "-q" ); break;
      case 'r': recursive = true; break;
      case 'v': if( verbosity < 4 ) ++verbosity; break;
      case 'V': show_version( "Zupdate" ); return 0;
      case bz2_opt: parse_compressor( arg, fmt_bz2, 1 ); continue;
      case gz_opt: parse_compressor( arg, fmt_gz, 1 ); continue;
      case lz_opt: parse_compressor( arg, fmt_lz, 1 ); continue;
      case xz_opt: parse_compressor( arg, fmt_xz, 1 ); continue;
      default : internal_error( "uncaught option" );
      }
    } // end process options

#if defined(__MSVCRT__) || defined(__OS2__)
  setmode( STDIN_FILENO, O_BINARY );
  setmode( STDOUT_FILENO, O_BINARY );
#endif

  const char * const lzip_name = get_compressor_name( fmt_lz );
  if( !lzip_name || !lzip_name[0] )
    { show_error( "Missing name of compressor for lzip format." ); return 1; }

  for( ; argind < parser.arguments(); ++argind )
    filenames.push_back( parser.argument( argind ) );

  int retval = 0;
  while( !filenames.empty() )
    {
    input_filename = filenames.front();
    filenames.pop_front();
    if( !input_filename.size() || input_filename == "-" ) continue;
    if( recursive )
      {
      struct stat st;
      if( stat( input_filename.c_str(), &st ) == 0 && S_ISDIR( st.st_mode ) )
        {
        DIR * const dirp = opendir( input_filename.c_str() );
        if( !dirp )
          {
          show_error2( "Can't open directory", input_filename.c_str() );
          if( retval < 1 ) retval = 1; continue;
          }
        std::list< std::string > tmp_list;
        while( true )
          {
          const struct dirent * const entryp = readdir( dirp );
          if( !entryp ) { closedir( dirp ); break; }
          std::string tmp_name( entryp->d_name );
          if( tmp_name != "." && tmp_name != ".." )
            tmp_list.push_back( input_filename + "/" + tmp_name );
          }
        filenames.splice( filenames.begin(), tmp_list );
        continue;
        }
      }

    int tmp = zupdate_file( input_filename, lzip_name, lzip_args2, force );
    if( tmp < 0 && retval < 1 ) retval = 1;
    if( tmp > retval ) retval = tmp;
    if( tmp > 0 ) break;
    }
  return retval;
  }