sub main {
    if ($mode ne 'EDIT') {
        return;
    }

    # Receive an array reference
    my $countries = _getData();
    if ( 0 == scalar @$countries ) {
        return "";
    }

    my $html = "";

    # $#{$countries} is last index of array reference $countries
    for (my $i = 0 ; $i <= $#{$countries} ; $i++) {
        if (defined $countries->[$i]->{"id"}) {
            # option selection will be automatically set by Imperia
            $html .= sprintf(
                '<option value="%s">%s</option>',
                $countries->[$i]->{"id"},
                encode_utf8($countries->[$i]->{"label"}),
            );
        }
    }

    return $html;
}

sub _getData {
    my $url = sprintf(
        "%s%s",
        $ENV{'API_BASE_URL'},
        "/ajax/imperia/countrylist/de"
    );
 
    my $ua = LWP::UserAgent->new(ssl_opts => { verify_hostname => 1 });
    my $header = HTTP::Request->new(GET => $url);
    my $request = HTTP::Request->new('GET', $url, $header);
    my $response = $ua->request($request);

    if (!$response || $response->is_error || !$response->is_success) {
        return;
    }

    my $response = decode_json($response->content);
    return $response->{"countries"};
}