#!/usr/bin/perl
#
# Adapted from https://stackoverflow.com/a/68057031

use strict;

my $usage = "setdotlabelwidth [char-width] < [dotfile]";
my $width = shift() or die("Usage: $usage $!");

while(<STDIN>)
{
  if (m/label="(.*?)"/)
  {
    my $labeltext = $1;
    my @words = split(/ +|(?=\\n)/, $labeltext);
    my @newtext = ();
    my $newline = "";
    foreach my $word(@words)
    {
      if (length($newline) > 0 and
          length($newline) + length($word) > $width)
      {
        push(@newtext, $newline);
        $newline = "";
      }

      $newline .= " " if (length($newline) > 0);
      $newline .= $word;
    }

    push(@newtext, $newline) if (length($newline) > 0);
    my $newlabel = join("\\n", @newtext);
    s/label=".*?"/label="$newlabel"/;
  }

  print;
}