#!/usr/bin/env perl -w
#use strict;
use utf8;

# utf-8 definitions, some extra (file opens etc.) to be on the safe side.
binmode( STDIN, ':utf8' );
binmode( STDOUT, ':utf8' );
binmode( STDERR, ':utf8' );
use open 'utf8';
use Encode;

# kwic.pl
# K. Koskenniemi, 36.2.2000
# Modified 1.8.2005 to UTF-8 by Seppo Nyrkkö and Trond Trosterud
# Modified 28.9.2007 utf-8 compatibility check by Saara Huhmarniemi

require "getopts.pl";

&Getopts('m:w:l:bh');

if ($opt_h) {
    print "
usage:
  kwic-snt <options> <regexp> file...

options:
  -m nnn : at most first nnn occurences taken (default 100)
  -w nnn : total width of the kwic listing (default 80)
  -l nnn : width reserved for the left context (default 0.6 of total)
  -b : sort identical keys according to characters before
  -h : this help text

regexp:
  a regular expression for identifying keys in sentences

file...:
  zero or more input text files (one sentence per line)

";
    exit;
}

$maxocc = $opt_m ? $opt_m : 100;
$columns = $opt_w ? $opt_w : 80;
$leftcols = $opt_l ? $opt_l : (int(0.6 * $columns));

#print "columns=$columns\n";
#print "leftcols=$leftcols\n";

sub revutf8($){
    my ($slr)=@_;
    my $srl="";
    my $ci;
    for($ci=0;$ci<length($slr);$ci++) {
	$srl .= substr($slr,length($slr)-1-$ci,1); }
    return $srl;
}

$PAT = $ARGV[0];
shift @ARGV;
# Command line arguments have to be explicitely
# decoded to utf8.
$PAT = Encode::decode_utf8($PAT);
print $PAT, "\n";

$occurences = 0;
SENT:
while (<>) {
    chop;
    while (m/($PAT)/go) {
	$key = $1;
	$rest = substr($_, pos());
	$start = substr($_, 0, pos() - length($key));
	if ($opt_b) {
	    $r[$occurences] = $key . "&" .  revutf8($start) . "&" . $rest;
	}
	else {
	    $r[$occurences] = $key . "&" . $rest . "&" .  $start;
	}
#	print $start, ":", $key, ":", $rest, "\n";
#	print $r[$occurences], "\n";
	last SENT if ++$occurences > $maxocc;
    }
}

@s = sort(@r);

$rightcols = $columns - $leftcols;
$fmt = "%$leftcols". "s%-" . "$rightcols" . "s\n";
#print $fmt;

for ($j = 0; $j < $occurences; $j++) {
    if ($opt_b) {
	($mid, $leftr, $right) = ($s[$j] =~ /^([^&]*)&([^&]*)&([^&]*)/o);
	$left = revutf8($leftr);
    }
    else {
	($mid, $right, $left) = ($s[$j] =~ /^([^&]*)&([^&]*)&([^&]*)/o);
    }
    $leftpart = substr($left,-$leftcols,$leftcols);
    $rightpart = substr($mid . $right, 0, $rightcols);
    printf($fmt, $leftpart, $rightpart);
}