Terpaksa Membuat Plugin SEO Wordpress (Tahap 0)

<?php
/*
Plugin Name: WP Meta Tag Description
Plugin URI: http://www.elangsakti.com/tabung-reaksi
Description: Simple plugin to write meta tag description
Author: haripinter
Version: 1.0
Author URI: http://www.elangsakti.com
License: A "Slug" license name e.g. GPL2
*/

add_action( 'add_meta_boxes', 'elangsakti_box' );
 function elangsakti_box(){
 add_meta_box( 'elangsakti_box_id', 'WP Meta Tag Description', 'cd_meta_box_cb', 'post', 'normal', 'high' );
}

function cd_meta_box_cb(){
 global $post;
 $values = get_post_custom( $post->ID );
 $text = isset( $values['elangsakti_text'] ) ? $values['elangsakti_text'] : '';

 wp_nonce_field( 'my_meta_box_nonce', 'meta_box_nonce' );

 $etxt = get_post_meta($post->ID, 'elangsakti_text', true);
 ?>
 <script type="text/javascript">
  function hahihu(t){
   document.getElementById('the_count_text').innerHTML = 160-t.length;
  }
 </script>
 <textarea name="elangsakti_text" id="elangsakti_text" style="width:550px; height:70px;" onKeyUp="hahihu(this.value)" maxlength="160"><?php echo $etxt; ?></textarea><br/>
 <div>Sisa jumlah karakter (dari maksimal 160 karakter) : <label id="the_count_text" style="color:green;">160</label></div>
 <?php
}

add_action( 'save_post', 'elangsakti_save' );
 function elangsakti_save( $post_id ){
 if( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) return;
 if( !isset( $_POST['meta_box_nonce'] ) || !wp_verify_nonce( $_POST['meta_box_nonce'], 'my_meta_box_nonce' ) ) return;
 if( !current_user_can( 'edit_post' ) ) return;

 $allowed = array('a' => array(
     'href' => array()));

if( isset( $_POST['elangsakti_text'] ) )
 update_post_meta( $post_id, 'elangsakti_text', wp_kses( $_POST['elangsakti_text'], $allowed ) );
}
?>