#!/usr/bin/perl -w

#
# Copyright (C) 2007-2008 ...
#   Alex Linke <alinke@lingua-systems.com>
#   Rona Linke <rlinke@lingua-systems.com>
# Copyright (C) 2009-2016 Lingua-Systems Software GmbH
# Copyright (C) 2016-2017 Netzum Sorglos, Lingua-Systems Software GmbH
# Copyright (C) 2017 Netzum Sorglos Software GmbH
#

use strict;
use Getopt::Long;

require 5.008;

use Lingua::Translit;
use Lingua::Translit::Tables qw/:all/;

my $VERSION = '0.5';

=pod

=head1 NAME

translit - transliterate text between various writing systems

=head1 SYNOPSIS

translit B<-t> I<name> B<-r> B<-i> I<file> B<-o> I<file> -l -v -h

=head1 DESCRIPTION

B<translit> transliterates B<UTF-8> encoded natural language text from one
writing system to another.

It utilizes the Perl module L<Lingua::Translit> to accomplish this task and
follows the provided transliteration standards as strict as possible.

B<translit> regards the following commandline switches:

=over 4

=item B<--trans>, B<-t> I<name>

Use the transliteration standard named I<name>.

=item B<--reverse>, B<-r>

Transliterate in reverse direction.

B<NOTE>: Not every transliteration is capable of being reversed.
If unsure, have a look at the list of supported transliterations using the
B<--list> switch.

=item B<--infile>, B<-i> I<FILE>

Read text from I<FILE>. Defaults to STDIN.

=item B<--outfile>, B<-o> I<FILE>

Write the transliterated text to I<FILE>. Defaults to STDOUT.

=item B<--list>, B<-l>

Print a list of supported transliterations showing their

=over 4

=item *

name

=item *

reversibility

=item *

description

=back

=item B<--verbose>, B<-v>

Print verbose status messages to STDERR.

=item B<--help>, B<-h>

Show a short help text introducing command line switches only.

=back

=cut

# Set defaults where possible
my %opt = (
    trans   => "",
    infile  => "",
    outfile => "",
    reverse => 0,
    list    => 0,
    verbose => 0,    # off
    help    => 0
);

show_help(1)
  unless GetOptions(
    "trans|t=s"   => \$opt{trans},
    "infile|i=s"  => \$opt{infile},
    "outfile|o=s" => \$opt{outfile},
    "reverse|r"   => \$opt{reverse},
    "list|l"      => \$opt{list},
    "verbose|v"   => \$opt{verbose},
    "help|h"      => \$opt{help}
  );
show_help(0) if $opt{help};
show_list()  if $opt{list};
show_help(1) unless $opt{trans};

# Assure the requested transliteration is supported...
die "$opt{trans} is not supported.\n" unless translit_supported( $opt{trans} );

# ...and reverse transliteration is supported, too - if requested
die "$opt{trans} cannot be reversed.\n"
  if ( $opt{reverse} && !translit_reverse_supported( $opt{trans} ) );

# If no input file was specified, use STDIN as a fallback. This way, translit
# may also be used in pipes!
my $in;

if ( $opt{infile} ) {
    print STDERR "Reading input from $opt{infile}...\n" if $opt{verbose};

    open IN, "$opt{infile}" or die "$opt{infile}: $!\n";

    $in = *IN;
}
else {
    print STDERR "Reading input from STDIN...\n" if $opt{verbose};

    $in = *STDIN;
}

# If no output file was specified, use STDOUT as a fallback.
my $out;

if ( $opt{outfile} ) {
    print STDERR "Writing output to $opt{outfile}...\n" if $opt{verbose};

    open OUT, "> $opt{outfile}" or die "$opt{outfile}: $!\n";

    $out = *OUT;
}
else {
    print STDERR "Writing output to STDOUT...\n" if $opt{verbose};

    $out = *STDOUT;
}

# Slurp in all the input and close filehandle
local $/;
my $text = <$in>;
close($in);

# Transliterate
my $tr = new Lingua::Translit( $opt{trans} );
my $text_tr;

unless ( $opt{reverse} ) {
    print STDERR "Transliterating according to ", $tr->name(), "...\n"
      if $opt{verbose};

    $text_tr = $tr->translit($text);
}
else {
    print STDERR "Transliterating according to ", $tr->name(), " (reverse)...\n"
      if $opt{verbose};

    $text_tr = $tr->translit_reverse($text);
}

# Write the transliterated text to the filehandle and close it
print $out $text_tr;
close($out);

sub show_help {
    my $retval = shift();

    print "translit v$VERSION  --  ",
      "(c) 2009-2016 Lingua-Systems Software GmbH\n\n",
      "usage: $0 -i FILE -o FILE -t NAME -r -l -v -h\n\n",
      "  --infile   -i  FILE       read input from FILE\n",
      "  --outfile  -o  FILE       write output to FILE\n",
      "  --trans    -t  NAME       use transliteration NAME\n",
      "  --reverse  -r             transliterate in reverse direction\n",
      "  --list     -l             list all supported transliterations\n\n",
      "  --verbose  -v             print verbose status messages\n",
      "  --help     -h             show this help\n\n",
      "Read translit(1) for details.\n";

    exit($retval);
}

sub show_list {
    print "Transliterations supported by Lingua::Translit v"
      . $Lingua::Translit::VERSION . ":\n\n";

    translit_list_supported();

    exit(0);
}

=head1 RESTRICTIONS

The input has to be UTF-8 encoded.

=head1 BUGS

None known.

Please report bugs using CPAN's request tracker at
L<https://rt.cpan.org/Public/Dist/Display.html?Name=Lingua-Translit>.

=head1 SEE ALSO

L<Lingua::Translit>, L<Lingua::Translit::Tables>

=head1 AUTHORS

Alex Linke <alinke@netzum-sorglos.de>

Rona Linke <rlinke@netzum-sorglos.de>

=head1 LICENSE AND COPYRIGHT

Copyright (C) 2007-2008 Alex Linke and Rona Linke

Copyright (C) 2009-2016 Lingua-Systems Software GmbH

Copyright (C) 2016-2017 Netzum Sorglos, Lingua-Systems Software GmbH

Copyright (C) 2017 Netzum Sorglos Software GmbH

This module is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.

=cut

# vim: set ft=perl sts=4 sw=4 ts=4 ai et: