Default rating only at first publish

Hi!

First of all I would like to thank you for this awesome plugin.

I however have a small problem with setting default rating on my posts. I found your solution from another support ticket on how to set a default rating when publishing a post.

This is the code I talk about:

add_action('save_post', 'auto_rate_post');

function auto_rate_post($post_id)
{
	if(defined('DOING_AUTOSAVE') && DOING_AUTOSAVE)
	{
		return $post_id;
	}

	if(!isset($_POST['post_type']) || !current_user_can('edit_post', $post_id))
	{
		return $post_id;
	}

	$stars = 4;

	$total_stars = is_numeric(get_option('kksr_stars')) ? get_option('kksr_stars') : 5;

	if(!get_post_meta($post_id, '_kksr_ratings', true))
	{
		$ratings = $stars / ($total_stars/5);
		$avg = $ratings ? number_format((float)$ratings, 2, '.', '') : 0;

		update_post_meta($post_id, '_kksr_ratings', $ratings);
		update_post_meta($post_id, '_kksr_casts', 1);
		update_post_meta($post_id, '_kksr_avg', $avg);
	}

	return $post_id;
}

This code works perfectly when I publish a post for the first time. My problem is that when I update a post the current rating is getting overwritten by the rating (4) in the example code above.

I also have a few posts with rating 0 that are saved as draft for now. I want them to get the rating “3” when I publish them.

So I only want to put this default rating on new posts or on posts that have rating = 0. In other cases I want to keep the current rating.

I can´t seem to figure out how to modify your code example to fix this.

Thanks in advance for your help!

http://wordpress.org/extend/plugins/kk-star-ratings/