#!/usr/local/bin/perl
use warnings;
use 5.012;
use CGI;
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);

my $cgi = new CGI();
my $step = $cgi->param('step') // 0;

my @functions = ( \&eins, \&zwei, \&drei );
my $function = $functions[$step] or die "invalid $step";
$function->();

sub eins {
        print $cgi->header();
        print $cgi->start_html();
        print $cgi->p('eins');
        print $cgi->startform();
        print $cgi->hidden( -name => 'step', -value => 1 );
        print $cgi->submit( 'OK' );
        print $cgi->endform();       
        print $cgi->end_html();
}

sub zwei {
        print $cgi->header();
        print $cgi->start_html();
        print $cgi->p('zwei');
        print $cgi->startform();
        print $cgi->hidden( -name => 'step', -value => 2 );
        print $cgi->submit( 'OK' );
        print $cgi->endform();   
        print $cgi->end_html();
}

sub drei {
        print $cgi->header();
        print $cgi->start_html();
        print $cgi->p('drei');
        print $cgi->startform();
        print $cgi->hidden( -name => 'step', -value => 0 );
        print $cgi->submit( 'OK' );
        print $cgi->endform();   
        print $cgi->end_html();
}