/*  Zgrep - search compressed files for a regular expression
    Copyright (C) 2010-2019 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 2 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 <sys/stat.h>
#if defined(__MSVCRT__) || defined(__OS2__)
#include <io.h>
#endif

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


namespace {

#include "recursive.cc"
#include "zcatgrep.cc"

void show_help()
  {
  std::printf( "Zgrep is a front end to the grep program that allows transparent search\n"
               "on any combination of compressed and uncompressed files. If any given\n"
               "file is compressed, its decompressed content is used. If a given file\n"
               "does not exist, and its name does not end with one of the known\n"
               "extensions, zgrep tries the compressed file names corresponding to the\n"
               "formats supported.\n"
               "\nIf a file is specified as '-', data are read from standard input,\n"
               "decompressed if needed, and fed to grep. Data read from standard input\n"
               "must be of the same type; all uncompressed or all in the same\n"
               "compression format.\n"
               "\nIf no files are specified, recursive searches examine the current\n"
               "working directory, and nonrecursive searches read standard input.\n"
               "\nThe formats supported are bzip2, gzip, lzip and xz.\n"
               "\nUsage: zgrep [options] <pattern> [files]\n"
               "\nExit status is 0 if match, 1 if no match, 2 if trouble.\n"
               "\nOptions:\n"
               "      --help                   display this help and exit\n"
               "  -V, --version                output version information and exit\n"
               "  -a, --text                   treat all files as text\n"
               "  -A, --after-context=<n>      print <n> lines of trailing context\n"
               "  -b, --byte-offset            print the byte offset of each line\n"
               "  -B, --before-context=<n>     print <n> lines of leading context\n"
               "  -c, --count                  only print a count of matching lines per file\n"
               "  -C, --context=<n>            print <n> lines of output context\n"
               "      --color[=<when>]         show matched strings in color\n"
               "  -e, --regexp=<pattern>       use <pattern> as the pattern to match\n"
               "  -E, --extended-regexp        <pattern> is an extended regular expression\n"
               "  -f, --file=<file>            obtain patterns from <file>\n"
               "  -F, --fixed-strings          <pattern> is a set of newline-separated strings\n"
               "  -h, --no-filename            suppress the prefixing filename on output\n"
               "  -H, --with-filename          print the filename for each match\n"
               "  -i, --ignore-case            ignore case distinctions\n"
               "  -I                           ignore binary files\n"
               "  -l, --files-with-matches     only print names of files containing matches\n"
               "  -L, --files-without-match    only print names of files containing no matches\n"
               "  -m, --max-count=<n>          stop after <n> matches\n"
               "  -M, --format=<list>          process only the formats in <list>\n"
               "  -n, --line-number            print the line number of each line\n"
               "  -N, --no-rcfile              don't read runtime configuration file\n"
               "  -o, --only-matching          show only the part of a line matching <pattern>\n"
               "  -O, --force-format=<fmt>     force given format (bz2, gz, lz, xz)\n"
               "  -q, --quiet                  suppress all messages\n"
               "  -r, --recursive              operate recursively on directories\n"
               "  -R, --dereference-recursive  recursively follow symbolic links\n"
               "  -s, --no-messages            suppress error messages\n"
               "  -v, --invert-match           select non-matching lines\n"
               "      --verbose                verbose mode (show error messages)\n"
               "  -w, --word-regexp            match only whole words\n"
               "  -x, --line-regexp            match only whole lines\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"
               "Numbers may be followed by a multiplier: k = kB = 10^3 = 1000,\n"
               "Ki = KiB = 2^10 = 1024, M = 10^6, Mi = 2^20, G = 10^9, Gi = 2^30, etc...\n" );
  show_help_addr();
  }


int zgrep_stdin( int infd, const int format_index,
                 const std::vector< const char * > & grep_args )
  {
  Children children;
  if( !set_data_feeder( "", &infd, children, format_index ) ) return 2;
  const pid_t grep_pid = fork();
  if( grep_pid == 0 )			// child (grep)
    {
    if( dup2( infd, STDIN_FILENO ) >= 0 && close( infd ) == 0 )
      {
      const char ** const argv = new const char *[grep_args.size()+2];
      argv[0] = GREP;
      for( unsigned i = 0; i < grep_args.size(); ++i )
        argv[i+1] = grep_args[i];
      argv[grep_args.size()+1] = 0;
      execvp( argv[0], (char **)argv );
      }
    show_exec_error( GREP );
    _exit( 2 );
    }
  if( grep_pid < 0 )			// parent
    { show_fork_error( GREP ); return 2; }

  int retval = wait_for_child( grep_pid, GREP );

  if( !good_status( children, retval == 1 ) ) retval = 2;

  if( close( infd ) != 0 )
    { show_close_error(); return 2; }
  return retval;
  }


int zgrep_file( int infd, const int format_index,
                const std::string & input_filename,
                const std::vector< const char * > & grep_args,
                const int list_mode, const bool show_name )
  {
  Children children;
  if( !set_data_feeder( input_filename, &infd, children, format_index ) )
    return 2;
  int fda[2];				// pipe from grep
  if( pipe( fda ) < 0 )
    { show_error( "Can't create pipe", errno ); return 2; }
  const pid_t grep_pid = fork();
  if( grep_pid == 0 )			// child (grep)
    {
    if( dup2( infd, STDIN_FILENO ) >= 0 &&
        dup2( fda[1], STDOUT_FILENO ) >= 0 &&
        close( infd ) == 0 && close( fda[0] ) == 0 && close( fda[1] ) == 0 )
      {
      const char ** const argv = new const char *[grep_args.size()+2];
      argv[0] = GREP;
      for( unsigned i = 0; i < grep_args.size(); ++i )
        argv[i+1] = grep_args[i];
      argv[grep_args.size()+1] = 0;
      execvp( argv[0], (char **)argv );
      }
    show_exec_error( GREP );
    _exit( 2 );
    }
  if( grep_pid < 0 )			// parent
    { show_fork_error( GREP ); return 2; }

  close( fda[1] );
  enum { buffer_size = 256 };
  uint8_t buffer[buffer_size];
  bool line_begin = true;
  while( true )
    {
    const int size = readblock( fda[0], buffer, buffer_size );
    if( size != buffer_size && errno )
      { show_error( "Read error", errno ); return 2; }
    if( size > 0 && !list_mode )
      {
      if( show_name )
        for( int i = 0; i < size; ++i )
          {
          if( line_begin )
            { line_begin = false; std::printf( "%s:", input_filename.c_str() ); }
          if( buffer[i] == '\n' ) line_begin = true;
          putchar( buffer[i] );
          }
      else if( std::fwrite( buffer, 1, size, stdout ) != (unsigned)size )
        { std::fflush( stdout ); show_error( "Write error", errno ); return 2; }
      std::fflush( stdout );
      }
    if( size < buffer_size ) break;
    }

  int retval = wait_for_child( grep_pid, GREP );

  if( !good_status( children, retval == 1 ) ) retval = 2;

  if( list_mode && (retval == 0) == (list_mode == 1) )
    { std::printf( "%s\n", input_filename.c_str() ); std::fflush( stdout ); }
  if( close( infd ) != 0 )
    { show_close_error(); return 2; }
  if( close( fda[0] ) != 0 )
    { show_close_error( GREP ); return 2; }
  return retval;
  }

} // end namespace


int main( const int argc, const char * const argv[] )
  {
  enum { help_opt = 256, verbose_opt, color_opt,
         bz2_opt, gz_opt, lz_opt, xz_opt };
  int format_index = -1;
  int list_mode = 0;		// 1 = list matches, -1 = list non matches
  int recursive = 0;		// 1 = '-r', 2 = '-R'
  int show_name = -1;		// tri-state bool
  bool no_messages = false;
  std::list< std::string > filenames;
  std::vector< const char * > grep_args;	// args to grep, maybe empty
  std::string color_option;		// needed because of optional arg
  invocation_name = argv[0];
  program_name = "zgrep";

  const Arg_parser::Option options[] =
    {
    { 'a', "text",                  Arg_parser::no  },	// grep GNU
    { 'A', "after-context",         Arg_parser::yes },	// grep GNU
    { 'b', "byte-offset",           Arg_parser::no  },	// grep GNU
    { 'B', "before-context",        Arg_parser::yes },	// grep GNU
    { 'c', "count",                 Arg_parser::no  },	// grep
    { 'C', "context",               Arg_parser::yes },	// grep GNU
    { 'e', "regexp",                Arg_parser::yes },	// grep
    { 'E', "extended-regexp",       Arg_parser::no  },	// grep
    { 'f', "file ",                 Arg_parser::yes },	// grep
    { 'F', "fixed-strings",         Arg_parser::no  },	// grep
    { 'h', "no-filename",           Arg_parser::no  },	// grep GNU
    { 'H', "with-filename",         Arg_parser::no  },	// grep GNU
    { 'i', "ignore-case",           Arg_parser::no  },	// grep
    { 'I',  0,                      Arg_parser::no  },	// grep GNU
    { 'l', "files-with-matches",    Arg_parser::no  },	// grep
    { 'L', "files-without-match",   Arg_parser::no  },	// grep GNU
    { 'm', "max-count",             Arg_parser::yes },	// grep GNU
    { 'M', "format",                Arg_parser::yes },
    { 'n', "line-number",           Arg_parser::no  },	// grep
    { 'N', "no-rcfile",             Arg_parser::no  },
    { 'o', "only-matching",         Arg_parser::no  },	// grep
    { 'O', "force-format",          Arg_parser::yes },
    { 'q', "quiet",                 Arg_parser::no  },
    { 'r', "recursive",             Arg_parser::no  },
    { 'R', "dereference-recursive", Arg_parser::no  },
    { 's', "no-messages",           Arg_parser::no  },	// grep
    { 'v', "invert-match",          Arg_parser::no  },	// grep
    { 'V', "version",               Arg_parser::no  },
    { 'w', "word-regexp",           Arg_parser::no  },	// grep GNU
    { 'x', "line-regexp",           Arg_parser::no  },	// grep
    { help_opt,    "help",          Arg_parser::no  },
    { verbose_opt, "verbose",       Arg_parser::no  },
    { color_opt,   "color",         Arg_parser::maybe },
    { 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 2; }

  maybe_process_config_file( parser );

  int argind = 0;
  bool pattern_found = false;
  for( ; argind < parser.arguments(); ++argind )
    {
    const int code = parser.code( argind );
    if( !code ) break;					// no more options
    const std::string & arg = parser.argument( argind );
    switch( code )
      {
      case 'a': grep_args.push_back( "-a" ); break;
      case 'A': grep_args.push_back( "-A" );
                grep_args.push_back( arg.c_str() ); break;
      case 'b': grep_args.push_back( "-b" ); break;
      case 'B': grep_args.push_back( "-B" );
                grep_args.push_back( arg.c_str() ); break;
      case 'c': grep_args.push_back( "-c" ); break;
      case 'C': grep_args.push_back( "-C" );
                grep_args.push_back( arg.c_str() ); break;
      case 'e': grep_args.push_back( "-e" );
                grep_args.push_back( arg.c_str() ); pattern_found = true; break;
      case 'E': grep_args.push_back( "-E" ); break;
      case 'f': grep_args.push_back( "-f" );
                grep_args.push_back( arg.c_str() ); pattern_found = true; break;
      case 'F': grep_args.push_back( "-F" ); break;
      case 'h': show_name = false; break;
      case 'H': show_name = true; break;
      case 'i': grep_args.push_back( "-i" ); break;
      case 'I': grep_args.push_back( "-I" ); break;
      case 'l': grep_args.push_back( "-l" ); list_mode = 1; break;
      case 'L': grep_args.push_back( "-L" ); list_mode = -1; break;
      case 'm': grep_args.push_back( "-m" );
                grep_args.push_back( arg.c_str() ); break;
      case 'M': parse_format_list( arg ); break;
      case 'n': grep_args.push_back( "-n" ); break;
      case 'N': break;
      case 'o': grep_args.push_back( "-o" ); break;
      case 'O': format_index = parse_format_type( arg ); break;
      case 'q': grep_args.push_back( "-q" ); verbosity = -1; break;
      case 'r': recursive = 1; break;
      case 'R': recursive = 2; break;
      case 's': grep_args.push_back( "-s" ); no_messages = true; break;
      case 'v': grep_args.push_back( "-v" ); break;
      case 'V': show_version(); return 0;
      case 'w': grep_args.push_back( "-w" ); break;
      case 'x': grep_args.push_back( "-x" ); break;
      case help_opt   : show_help(); return 0;
      case verbose_opt: if( verbosity < 4 ) ++verbosity;
                        no_messages = false; break;
      case color_opt: color_option = "--color";
        if( !arg.empty() ) { color_option += '='; color_option += arg; }
        break;
      case bz2_opt: parse_compressor( arg, fmt_bz2 ); break;
      case gz_opt: parse_compressor( arg, fmt_gz ); break;
      case lz_opt: parse_compressor( arg, fmt_lz ); break;
      case xz_opt: parse_compressor( arg, fmt_xz ); break;
      default : internal_error( "uncaught option." );
      }
    } // end process options

  if( !color_option.empty() )		// push the last value set
    grep_args.push_back( color_option.c_str() );

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

  if( !pattern_found )
    {
    if( argind >= parser.arguments() )
      { show_error( "Pattern not found." ); return 2; }
    const std::string & arg = parser.argument( argind++ );
    if( arg.size() && arg[0] == '-' ) grep_args.push_back( "-e" );
    grep_args.push_back( arg.c_str() );
    }

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

  if( filenames.empty() ) filenames.push_back( recursive ? "." : "-" );

  if( show_name < 0 ) show_name = ( filenames.size() != 1 || recursive );

  std::string input_filename;
  int retval = 1;
  bool error = false;
  bool stdin_used = false;
  while( next_filename( filenames, input_filename, error, recursive,
                        false, no_messages ) )
    {
    int infd;
    if( input_filename.empty() )
      {
      if( stdin_used ) continue; else stdin_used = true;
      infd = STDIN_FILENO;
      }
    else
      {
      infd = open_instream( input_filename, format_index < 0, no_messages );
      if( infd < 0 ) { error = true; continue; }
      }

    int tmp;
    if( infd == STDIN_FILENO )
      tmp = zgrep_stdin( infd, format_index, grep_args );
    else tmp = zgrep_file( infd, format_index, input_filename, grep_args,
                           list_mode, show_name );
    if( tmp == 0 || ( tmp == 2 && retval == 1 ) ) retval = tmp;

    if( input_filename.size() ) close( infd );
    if( retval == 0 && verbosity < 0 ) break;
    }

  if( std::fclose( stdout ) != 0 )
    {
    show_error( "Error closing stdout", errno );
    error = true;
    }
  if( error && ( retval != 0 || verbosity >= 0 ) ) retval = 2;
  return retval;
  }