<?php
/*
Plugin Name: Post Levels
Plugin URI: http://fortes.com/projects/wordpress/postlevels
Description: Show private posts if user's level is greater than or equal to the post level.
Version: 0.2.1
Author: Filipe Fortes
Author URI: http://fortes.com/

Known Issues:
 - Archive / Category listing do not include private posts
*/

// Name of the custom field used to store level
$postlevel_key = "post_level";

if (function_exists('get_currentuserinfo'))
{
  // WP 1.5, get_currentuserinfo already loaded
  postlevel_setup();
}
else
{
  // Need to wait until pluggable functions have been loaded
  add_action('init', 'postlevel_setup');
}


function postlevel_setup()
{
  // In case we're running standalone, for some odd reason
  if (function_exists('add_filter'))
  {
    global $user_level; get_currentuserinfo();

    // Don't bother unless someone is logged in
    if (!empty($user_level))
    {
      add_filter('posts_join', 'postlevel_posts_join');
      add_filter('posts_where', 'postlevel_posts_where');
      // Make sure private pages aren't cached publicly
      header('Cache-Control: private');
      header('Pragma: no-cache');

      // Whether the current post is private (i.e. not level 0)
      function is_private()
      {
        global $post; 
        return ($post->post_status == 'private');
      }

      // Whether the current posts is of the given level
      function is_post_level($level = 0)
      {
        global $postlevel_key;
        $val = get_post_custom_values($postlevel_key);
        if (!empty($val))
          return ($val == $level);
        else
          return ($level == 0);
      }
    }
    else
    {
      // Not logged in, use define fast functions that don't use the DB
      function is_private() { return false; }
      function is_post_level($level = 0) { return ($level == 0); }
    }  
  }
}

// Left join with the custom fields table so we can filter
// based on level in the where clause
function postlevel_posts_join($join)
{
	global $wpdb;
	return " LEFT JOIN {$wpdb->postmeta} ON {$wpdb->posts}.ID = {$wpdb->postmeta}.post_id " . $join;
}

// Change where clause to accept published posts and private posts
// with a post level less than or equal to the user's level
function postlevel_posts_where($where)
{
	global $user_level, $postlevel_key, $wpdb;
	return str_replace('post_status = "publish"', '(post_status = "publish" OR (post_status = "private" ' .
										 "AND ({$wpdb->postmeta}.meta_key = '$postlevel_key' " .
										 "AND {$wpdb->postmeta}.meta_value <= $user_level )))", $where);
}

?>