Custom META Tags for WordPress

<?php
/*
	Plugin Name: Custom META Tags
	Description: Add custom META tags on a per-page/post basis using custom fields.
	Author: Keith Solomon
	Version: 1.0
	Author URI: http://solowebdesigns.net/
*/


/*
	Custom head META tags

	This plugin will build cutom META (descripton and keyword) tags for your site.  You can set defaults for both using the settings below.
	It will also use the custom fields defined below to fill in this data.  If you choose not to use custom fields, it will build per-post/page
	tags using post tags for keywords and either the post/page content or excerpt for the description.
*/

function head_meta() {
	// Change the settings below to suit your needs.
	$default_blog_desc = '';			// Default blog description
	$default_blog_kw = '';				// Default blog keywords

	$post_desc_length  = 20;			// description length in # words for post/Page
	$post_use_excerpt  = 0; 			// 0 (zero) to force content as description for post/Page
	$custom_desc_key   = 'description'; // custom field key; if used, overrides excerpt/content
	$custom_kw_key   = 'keywords'; 		// custom field key; if used, overrides post tags
	// Stop editing here.

	global $cat, $cache_categories, $wp_query, $wp_version;

	if (is_single() || is_page()) {
		$post = $wp_query->post;
		$post_custom = get_post_custom($post->ID);
		$custom_desc_value = $post_custom["$custom_desc_key"][0];
		$custom_kw_value = $post_custom["$custom_kw_key"][0];

		if ($custom_kw_value) {
			$keywords = $custom_kw_value;
		} else {
			$posttags = get_the_tags();
			if ($posttags) {
				foreach ($posttags as $tag) {
					$keywords .= $tag->name.','; 
				}
			}
		}

		if ($custom_desc_value) {
			$text = $custom_desc_value;
		} elseif ($post_use_excerpt) {
			$text = $post->post_excerpt;
		} else {
			$text = $post->post_content;
		}

		$text = str_replace(array("\r\n", "\r", "\n", "  "), " ", $text);
		$text = str_replace(array("\""), "", $text);
		$text = trim(strip_tags($text));
		$text = explode(' ', $text);

		if (count($text) > $post_desc_length) {
			$l = $post_desc_length;
			$ellipsis = '...';
		} else {
			$l = count($text);
			$ellipsis = '';
		}

		$description = '';

		for ($i=0; $i<$l; $i++)
			$description .= $text[$i] . ' ';

		$description .= $ellipsis;
	} elseif (is_category()) {
		$category = $wp_query->get_queried_object();
		$description = trim(strip_tags($category->category_description));
	} else {
		$description = (empty($default_blog_desc)) ? trim(strip_tags(get_bloginfo('description'))) : $default_blog_desc;
		$keywords = $default_blog_kw;
	}

	echo "<!-- Meta tags built by Custom META Tags -->\n";
	
	if ($keywords) {
		echo "<meta name=\"keywords\" content=\"$keywords\" />\n";
	}

	if ($description) {
		echo "<meta name=\"description\" content=\"$description\" />\n";
	}
}

add_action('wp_head', 'head_meta');
?>