#!/usr/bin/perl -wn


BEGIN {

  $LINE_WIDTH = 75;
  $METHOD     = \&middle_out;
  $CONDENSE   = 1;

  use Getopt::Long;
  Getopt::Long::Configure('bundling');

  GetOptions(
    'c|condense'   => sub { $CONDENSE = 1             },
    'C|nocondense' => sub { $CONDENSE = 1             },
    'm|middle'     => sub { $METHOD = \&middle_out    },
    'l|left'       => sub { $METHOD = \&left_to_right },
    'r|right'      => sub { $METHOD = \&right_to_left },
    'w|width=i'    => sub {
      $LINE_WIDTH = $_[1];
      die "$0: invalid WIDTH (must be between 1 and 255)\n"
      if($LINE_WIDTH < 1 or $LINE_WIDTH > 255);
    },
    'help'         => sub {
      my $self = $0; $self =~ s/^.*\///;
      print << "USAGE";
Usage: $self [OPTION]... [FILE]...
Fully justifies a stream of text using one of three different methods.

  -c, --condense        condense multiple spaces before justifying (default)
  -C, --nocondense
  -m, --middle          use the middle-out method (default)
  -l, --left            use the left-to-right method
  -r, --right           use the right-to-left method
  -w, --width=WIDTH     set the line-width to WIDTH (default is 75)

      --help            display this help and exit

The different methods  describe  where  it  starts expanding spaces to
get lines to be the appropriate width.  For example, middle-out starts
in the middle of the line,  expanding  spaces in both directions.  The
middle-out method usually looks  best, although right-to-left is some-
times better.
USAGE
      exit(0);
    },
  );

}


if($CONDENSE and !/^ /) {
  s/ +$//g;
  s/(?<!\.) {2,}/ /g;
}

if(defined $last_line) {

  if($last_line !~ /^( |$)/ and $_ !~ /^$/) {

    @space_table = (1) x $last_line =~ s/(?<!\.) / /g;

    $METHOD->(\@space_table, length($last_line));

    $cntr = 0;
    $last_line =~ s/(?<!\.) /' 'x$space_table[$cntr++]/ge;

  }

  print $last_line;

}

$last_line = $_;

END { print $last_line if defined $last_line }


#*************************************************#
#*******************  METHODS  *******************#
#*************************************************#


sub middle_out {

  my $tbl_ref = shift;
  my $tbl_len = @$tbl_ref;
  my $str_len = shift;

  return unless($tbl_len);

  use integer;

  my ($pr, $pf);

  # pf and pr can't start at the same point, otherwise
  # we'll get an extra space added there (as they both
  # try to expand the same space).   We need to adjust
  # them differently  according  to  the  even-ness of
  # tbl_len to get things properly balanced.
  if($tbl_len & 1) {
    $pr = $tbl_len / 2;
    $pf = $pr + 1;
  } else {
    $pf = $tbl_len / 2;
    $pr = $pf-1;
  }

  while($str_len <= $LINE_WIDTH) {

    # reset $pr and $pf
    if($pr == -1 and $pf == $tbl_len) {
      if($tbl_len & 1) {
        $pr = $tbl_len / 2;
        $pf = $pr + 1;
      } else {
        $pf = $tbl_len / 2;
        $pr = $pf-1;
      }
    }

    # back
    unless($pr == -1) {
      $tbl_ref->[$pr--]++;
      last if(++$str_len > $LINE_WIDTH);
    }

    # forward
    unless($pf == $tbl_len) {
      $tbl_ref->[$pf++]++;
      last if(++$str_len > $LINE_WIDTH);
    }

  }

}

sub left_to_right {

  my $tbl_ref = shift;
  my $tbl_len = @$tbl_ref;
  my $str_len = shift;

  return unless($tbl_len);

  my $pf = 0;

  while($str_len <= $LINE_WIDTH) {

    $pf = 0 if($pf == $tbl_len);

    $tbl_ref->[$pf++]++;
    ++$str_len;

  }

}

sub right_to_left {

  my $tbl_ref = shift;
  my $tbl_len = @$tbl_ref;
  my $str_len = shift;

  return unless($tbl_len);

  my $pr = $tbl_len-1;

  while($str_len <= $LINE_WIDTH) {

    $pr = $tbl_len-1 if($pr == -1);

    $tbl_ref->[$pr--]++;
    ++$str_len;

  }

}