/*  GNU Ocrad - Optical Character Recognition program
    Copyright (C) 2003-2019 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/>.
*/
/*
    Exit status: 0 for a normal exit, 1 for environmental problems
    (file not found, invalid flags, I/O errors, etc), 2 to indicate a
    corrupt or invalid input file, 3 for an internal consistency error
    (eg, bug) which caused ocrad to panic.
*/

#include <cctype>
#include <cerrno>
#include <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <stdint.h>
#include <unistd.h>
#if defined(__MSVCRT__) || defined(__OS2__) || defined(__DJGPP__)
#include <fcntl.h>
#include <io.h>
#endif

#include "arg_parser.h"
#include "common.h"
#include "rational.h"
#include "rectangle.h"
#include "user_filter.h"
#include "page_image.h"
#include "textpage.h"


namespace {

const char * const program_name = "ocrad";
const char * const program_year = "2019";
const char * invocation_name = 0;

struct Input_control
  {
  Transformation transformation;
  int scale;
  Rational threshold, ltwh[4];
  bool copy, cut, invert, layout;

  Input_control()
    : scale( 0 ), threshold( -1 ),
      copy( false ), cut( false ), invert( false ), layout( false ) {}

  bool parse_cut_rectangle( const char * const s );
  bool parse_threshold( const char * const s );
  };


void show_error( const char * const msg, const int errcode = 0,
                 const bool help = false )
  {
  if( verbosity < 0 ) return;
  if( msg && msg[0] )
    std::fprintf( stderr, "%s: %s%s%s\n", program_name, msg,
                  ( errcode > 0 ) ? ": " : "",
                  ( errcode > 0 ) ? std::strerror( errcode ) : "" );
  if( help )
    std::fprintf( stderr, "Try '%s --help' for more information.\n",
                  invocation_name );
  }


bool Input_control::parse_cut_rectangle( const char * const s )
  {
  int c = ltwh[0].parse( s );				// left
  if( c && s[c] == ',' && ltwh[0] >= -1 )
    {
    int i = c + 1;
    c = ltwh[1].parse( &s[i] );				// top
    if( c && s[i+c] == ',' && ltwh[1] >= -1 )
      {
      i += c + 1; c = ltwh[2].parse( &s[i] );		// width
      if( c && s[i+c] == ',' && ltwh[2] > 0 )
        {
        i += c + 1; c = ltwh[3].parse( &s[i] );		// height
        if( c && ltwh[3] > 0 ) { cut = true; return true; }
        }
      }
    }
  show_error( "invalid cut rectangle.", 0, true );
  return false;
  }


bool Input_control::parse_threshold( const char * const s )
  {
  Rational tmp;
  if( tmp.parse( s ) && tmp >= 0 && tmp <= 1 )
    { threshold = tmp; return true; }
  show_error( "threshold out of limits (0.0 - 1.0).", 0, true );
  return false;
  }


void show_help()
  {
  std::printf( "GNU Ocrad is an OCR (Optical Character Recognition) program based on a\n"
               "feature extraction method. It reads images in pbm (bitmap), pgm\n"
               "(greyscale) or ppm (color) formats and produces text in byte (8-bit) or\n"
               "UTF-8 formats. The pbm, pgm and ppm formats are collectively known as pnm.\n"
               "\nOcrad includes a layout analyser able to separate the columns or blocks\n"
               "of text normally found on printed pages.\n"
               "\nFor best results the characters should be at least 20 pixels high. If\n"
               "they are smaller, try the --scale option. Scanning the image at 300 dpi\n"
               "usually produces a character size good enough for ocrad.\n"
               "Merged, very bold or very light (broken) characters are normally not\n"
               "recognized correctly. Try to avoid them.\n"
               "\nUsage: %s [options] [files]\n", invocation_name );
  std::printf( "\nOptions:\n"
               "  -h, --help                display this help and exit\n"
               "  -V, --version             output version information and exit\n"
               "  -a, --append              append text to output file\n"
               "  -c, --charset=<name>      try '--charset=help' for a list of names\n"
               "  -e, --filter=<name>       try '--filter=help' for a list of names\n"
               "  -E, --user-filter=<file>  user-defined filter, see manual for format\n"
               "  -f, --force               force overwrite of output file\n"
               "  -F, --format=<fmt>        output format (byte, utf8)\n"
               "  -i, --invert              invert image levels (white on black)\n"
               "  -l, --layout              perform layout analysis\n"
               "  -o, --output=<file>       place the output into <file>\n"
               "  -q, --quiet               suppress all messages\n"
               "  -s, --scale=[-]<n>        scale input image by [1/]<n>\n"
               "  -t, --transform=<name>    try '--transform=help' for a list of names\n"
               "  -T, --threshold=<n%%>      threshold for binarization (0-100%%)\n"
               "  -u, --cut=<l,t,w,h>       cut input image by given rectangle\n"
               "  -v, --verbose             be verbose\n"
               "  -x, --export=<file>       export results in ORF format to <file>\n" );
  if( verbosity >= 1 )
    {
    std::printf( "  -1..6                     pnm output file type (debug)\n"
                 "  -C, --copy                'copy' input to output (debug)\n"
                 "  -D, --debug=<level>       (0-100) output intermediate data (debug)\n" );
    }
  std::printf( "\nIf no files are specified, ocrad reads the image from standard input.\n"
               "If the -o option is not specified, ocrad sends text to standard output.\n"
               "\nExit status: 0 for a normal exit, 1 for environmental problems (file\n"
               "not found, invalid flags, I/O errors, etc), 2 to indicate a corrupt or\n"
               "invalid input file, 3 for an internal consistency error (eg, bug) which\n"
               "caused ocrad to panic.\n"
               "\nReport bugs to bug-ocrad@gnu.org\n"
               "Ocrad home page: http://www.gnu.org/software/ocrad/ocrad.html\n"
               "General help using GNU software: http://www.gnu.org/gethelp\n" );
  }


void show_version()
  {
  std::printf( "GNU %s %s\n", program_name, PROGVERSION );
  std::printf( "Copyright (C) %s Antonio Diaz Diaz.\n", program_year );
  std::printf( "License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>\n"
               "This is free software: you are free to change and redistribute it.\n"
               "There is NO WARRANTY, to the extent permitted by law.\n" );
  }


const char * my_basename( const char * filename )
  {
  const char * c = filename;
  while( *c ) { if( *c == '/' ) { filename = c + 1; } ++c; }
  return filename;
  }


int process_file( FILE * const infile, const char * const infile_name,
                  const Input_control & input_control,
                  const Control & control )
  {
  try
    {
    Page_image page_image( infile, input_control.invert );

    if( input_control.cut )
      {
      if( page_image.cut( input_control.ltwh ) )
        {
        if( verbosity >= 1 )
          std::fprintf( stderr, "file cut to %dw x %dh\n",
                        page_image.width(), page_image.height() );
        }
      else
        {
        if( verbosity >= 1 )
          std::fprintf( stderr, "file '%s' totally cut away.\n", infile_name );
        return 1;
        }
      }

    page_image.transform( input_control.transformation );
    page_image.change_scale( input_control.scale );
    page_image.threshold( input_control.threshold );
    if( verbosity >= 1 )
      {
      const Rational th( page_image.threshold(), page_image.maxval() );
      std::fprintf( stderr, "maxval = %d, threshold = %d (%s)\n",
                    page_image.maxval(), page_image.threshold(),
                    th.to_decimal( 1, -3 ).c_str() );
      }

    if( input_control.copy )
      {
      if( control.outfile ) page_image.save( control.outfile, control.filetype );
      return 0;
      }

    Textpage textpage( page_image, my_basename( infile_name ), control,
                       input_control.layout );
    if( control.debug_level == 0 )
      {
      if( control.outfile ) textpage.print( control );
      if( control.exportfile ) textpage.xprint( control );
      }
    }
  catch( Page_image::Error & e ) { show_error( e.msg ); return 2; }
  if( verbosity >= 1 ) std::fputc( '\n', stderr );
  return 0;
  }

int process_full_file( FILE * const infile, const char * const infile_name,
                       const Input_control & input_control,
                       const Control & control )
  {
  if( verbosity >= 1 )
    std::fprintf( stderr, "processing file '%s'\n", infile_name );
  int retval = 0;
  while( true )
    {
    const int tmp = process_file( infile, infile_name, input_control, control );
    if( retval < tmp ) retval = tmp;
    if( control.outfile ) std::fflush( control.outfile );
    if( control.exportfile ) std::fflush( control.exportfile );
    if( infile != stdin ) break;
    if( tmp <= 1 )		// detect EOF
      {
      int ch;
      do ch = std::fgetc( infile ); while( ch == 0 || std::isspace( ch ) );
      std::ungetc( ch, infile );
      }
    if( tmp > 1 || std::feof( infile ) || std::ferror( infile ) ) break;
    }
  if( std::fclose( infile ) != 0 )
    {
    show_error( ( infile != stdin ) ? "Error closing input file" :
                                      "Error closing stdin", errno );
    if( retval < 1 ) retval = 1;
    }
  return retval;
  }

} // end namespace


// 'infile' contains the scanned image (in pnm format) to be converted
// to text.
// 'outfile' is the destination for the text version of the scanned
// image. (or for a pnm file if debugging).
// 'exportfile' is the Ocr Results File.
//
int main( const int argc, const char * const argv[] )
  {
  Input_control input_control;
  Control control;
  const char * outfile_name = 0, * exportfile_name = 0;
  bool append = false, force = false;
  invocation_name = argv[0];

  const Arg_parser::Option options[] =
    {
    { '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  },
    { 'a', "append",      Arg_parser::no  },
    { 'c', "charset",     Arg_parser::yes },
    { 'C', "copy",        Arg_parser::no  },
    { 'D', "debug",       Arg_parser::yes },
    { 'e', "filter",      Arg_parser::yes },
    { 'E', "user-filter", Arg_parser::yes },
    { 'f', "force",       Arg_parser::no  },
    { 'F', "format",      Arg_parser::yes },
    { 'h', "help",        Arg_parser::no  },
    { 'i', "invert",      Arg_parser::no  },
    { 'l', "layout",      Arg_parser::no  },
    { 'o', "output",      Arg_parser::yes },
    { 'q', "quiet",       Arg_parser::no  },
    { 's', "scale",       Arg_parser::yes },
    { 't', "transform",   Arg_parser::yes },
    { 'T', "threshold",   Arg_parser::yes },
    { 'u', "cut",         Arg_parser::yes },
    { 'v', "verbose",     Arg_parser::no  },
    { 'V', "version",     Arg_parser::no  },
    { 'x', "export",      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; }

  int retval = 0;
  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 )
      {
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6': control.filetype = code; break;
      case 'a': append = true; break;
      case 'c': if( !control.charset.enable( arg ) )
                  { control.charset.show_error( program_name, arg ); return 1; }
                break;
      case 'C': input_control.copy = true; break;
      case 'D': control.debug_level = std::strtol( arg, 0, 0 ); break;
      case 'e': if( !control.add_filter( program_name, arg ) ) return 1;
                break;
      case 'E': retval = control.add_user_filter( program_name, arg );
                if( retval != 0 ) return retval;
                break;
      case 'f': force = true; break;
      case 'F': if( !control.set_format( arg ) )
                  { show_error( "bad output format.", 0, true ); return 1; }
                break;
      case 'h': show_help(); return 0;
      case 'i': input_control.invert = true; break;
      case 'l': input_control.layout = true; break;
      case 'o': outfile_name = arg; break;
      case 'q': verbosity = -1; break;
      case 's': input_control.scale = std::strtol( arg, 0, 0 ); break;
      case 't': if( !input_control.transformation.set( arg ) )
                  { input_control.transformation.show_error( program_name, arg );
                  return 1; }
                break;
      case 'T': if( !input_control.parse_threshold( arg ) ) return 1; break;
      case 'u': if( !input_control.parse_cut_rectangle( arg ) ) return 1; break;
      case 'v': if( verbosity < 4 ) ++verbosity; break;
      case 'V': show_version(); return 0;
      case 'x': exportfile_name = arg; break;
      default : Ocrad::internal_error( "uncaught option." );
      }
    } // end process options

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

  if( outfile_name && std::strcmp( outfile_name, "-" ) != 0 )
    {
    if( append ) control.outfile = std::fopen( outfile_name, "a" );
    else if( force ) control.outfile = std::fopen( outfile_name, "w" );
    else if( ( control.outfile = std::fopen( outfile_name, "wx" ) ) == 0 )
      {
      if( verbosity >= 0 )
        std::fprintf( stderr, "Output file %s already exists.\n", outfile_name );
      return 1;
      }
    if( !control.outfile )
      {
      if( verbosity >= 0 )
        std::fprintf( stderr, "Can't open '%s'\n", outfile_name );
      return 1;
      }
    }

  if( exportfile_name && control.debug_level == 0 && !input_control.copy )
    {
    if( std::strcmp( exportfile_name, "-" ) == 0 )
      { control.exportfile = stdout; if( !outfile_name ) control.outfile = 0; }
    else
      {
      control.exportfile = std::fopen( exportfile_name, "w" );
      if( !control.exportfile )
        {
        if( verbosity >= 0 )
          std::fprintf( stderr, "Can't open '%s'\n", exportfile_name );
        return 1;
        }
      }
    std::fprintf( control.exportfile,
                  "# Ocr Results File. Created by GNU Ocrad version %s\n",
                  PROGVERSION );
    }

  // process any remaining command line arguments (input files)
  bool stdin_used = false;
  for( bool first = true; first || argind < parser.arguments(); first = false )
    {
    const char * infile_name = ( argind < parser.arguments() ) ?
                               parser.argument( argind++ ).c_str() : "-";
    FILE * infile;
    if( std::strcmp( infile_name, "-" ) == 0 )
      {
      if( stdin_used ) continue; else stdin_used = true;
      infile = stdin;
      }
    else
      {
      infile = std::fopen( infile_name, "rb" );
      if( !infile )
        {
        if( verbosity >= 0 )
          std::fprintf( stderr, "Can't open '%s'\n", infile_name );
        if( retval < 1 ) retval = 1;
        continue;
        }
      }
    const int tmp = process_full_file( infile, infile_name, input_control, control );
    if( retval < tmp ) retval = tmp;
    }
  if( control.outfile ) std::fclose( control.outfile );
  if( control.exportfile ) std::fclose( control.exportfile );
  return retval;
  }