#!/usr/bin/perl -wp -00

use Getopt::Std;
use strict;
use vars qw(%opts);

BEGIN {
    %opts = (
	y => 6,
    );
    getopts('y:', \%opts);
}

my ($g_id, $p_opts) =
    m#<g id="(\w+)" class="edge">.*<path (.*?)/>#s;
next unless $p_opts;
s#<path #<path id="${g_id}_p" #;
my (@lines) = m#(<text .*?>.*?</text>)#sg;
my ($collect) = "";
my $dy = - int($#lines/2) * $opts{y} - 1;
foreach (@lines) {
    # http://stackoverflow.com/questions/5185699/multiple-lines-of-curved-text-in-svg
    my ($t_opts, $t_str) = m#<text( .*?)>(.*?)</text>#;
    $t_opts =~ s# x=".*?"##;
    $t_opts =~ s# y=".*?"##;
    $collect .= qq(<text $t_opts><textPath xlink:href="#${g_id}_p" startOffset="50%"><tspan x="0" dy="$dy">$t_str</tspan></textPath></text>\n);
    $dy += $opts{y};
}
s#(<text .*?>.*?</text>\s*)+#$collect#;