root/elgg/branches/elgg1.5-sql-fixes/engine/lib/tags.php

<?php
    /**
     * Elgg tags
     * Functions for managing tags and tag clouds.
     * 
     * @package Elgg
     * @subpackage Core
     * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
     * @author Curverider Ltd <info@elgg.com>
     * @copyright Curverider Ltd 2008-2009
     * @link http://elgg.org/
     */

    
    /** 
     * The algorithm working out the size of font based on the number of tags.
     * This is quick and dirty.
     */
    function calculate_tag_size($min, $max, $number_of_tags, $buckets = 6)
    {

        $delta =  (($max - $min) / $buckets);
        $thresholds = array();

        for ($n=1; $n <= $buckets; $n++) {
            $thresholds[$n-1] = ($min + $n) * $delta;
        }
    
        // Correction
        if ($thresholds[$buckets-1]>$max) $thresholds[$buckets-1] = $max;

        $size = 0;
        for ($n = 0; $n < count($thresholds); $n++) {
            if ($number_of_tags >= $thresholds[$n]) 
                $size = $n;
        }

        return $size;
    }
    
    /**
     * This function generates an array of tags with a weighting.
     *
     * @param array $tags The array of tags.
     * @return An associated array of tags with a weighting, this can then be mapped to a display class. 
     */
    function generate_tag_cloud(array $tags, $buckets = 6)
    {
        $cloud = array();
        
        $min = 65535;
        $max = 0;
        
        foreach ($tags as $tag)
        {
            $cloud[$tag]++;
            
            if ($cloud[$tag]>$max) $max = $cloud[$tag];
            if ($cloud[$tag]<$min) $min = $cloud[$tag];
        }
        
        foreach ($cloud as $k => $v)
            $cloud[$k] = calculate_tag_size($min, $max, $v, $buckets);
        
        return $cloud;
    }
    
    /**
     * Get an array of tags with weights for use with the output/tagcloud view.
     *
     * @param int $threshold Get the threshold of minimum number of each tags to bother with (ie only show tags where there are more than $threshold occurances)
     * @param int $limit Number of tags to return
     * @param string $metadata_name Optionally, the name of the field you want to grab for
     * @param string $entity_type Optionally, the entity type ('object' etc)
     * @param string $entity_subtype The entity subtype, optionally
     * @param int $owner_guid The GUID of the tags owner, optionally
     * @param int $site_guid Optionally, the site to restrict to (default is the current site)
     * @return array|false Array of objects with ->tag and ->total values, or false on failure
     */
    
    function get_tags($threshold = 1, $limit = 10, $metadata_name = "", $entity_type = "object", $entity_subtype = "", $owner_guid = "", $site_guid = -1) {
        
        global $CONFIG;
        
        $threshold = (int) $threshold;
        $limit = (int) $limit;
        
        if (!empty($metadata_name)) {
            $metadata_name = (int) get_metastring_id($metadata_name);
        } else {
            $metadata_name = 0;
        }
        $entity_subtype = get_subtype_id($entity_type, $entity_subtype);
        $entity_type = sanitise_string($entity_type);
        
        if ($owner_guid != "")
        if (is_array($owner_guid)) {
            foreach($owner_guid as $key => $val)
                $owner_guid[$key] = (int) $val;
        } else {
            $owner_guid = (int) $owner_guid;
        }
        
        if ($site_guid < 0) {
            $site_guid = $CONFIG->site_id;
        }
        
        //$access = get_access_list();
        
        $query = "SELECT msvalue.string as tag, count(msvalue.id) as total ";
        $query .= "FROM {$CONFIG->dbprefix}entities e join {$CONFIG->dbprefix}metadata md on md.entity_guid = e.guid ";
        $query .= " join {$CONFIG->dbprefix}entity_subtypes subtype on subtype.id = e.subtype ";
        $query .= " join {$CONFIG->dbprefix}metastrings msvalue on msvalue.id = md.value_id ";
        
        $query .= " where msvalue.string != '' ";
        
        if ($metadata_name > 0) {
            $query .= " and md.name_id = {$metadata_name} ";
        }
        if ($site_guid > 0) {
            $query .= " and e.site_guid = {$site_guid} ";
        }
        if ($entity_subtype > 0) {
            $query .= " and e.subtype = {$entity_subtype} ";
        }
        if ($entity_type != "") {
            $query .= " and e.type = '{$entity_type}' ";
        }
        if (is_array($owner_guid)) {
            $query .= " and e.container_guid in (".implode(",",$owner_guid).")";
        } else if (is_int($owner_guid)) {
            $query .= " and e.container_guid = {$owner_guid} ";
        }
        
        //$userid = get_loggedin_userid();
        //$query .= " and (e.access_id in {$access} or (e.access_id = " . ACCESS_PRIVATE . " and e.owner_guid = {$userid}))";
        $query .= ' and ' . get_access_sql_suffix("e"); // Add access controls
        
        $query .= " group by msvalue.string having count(msvalue.id) > {$threshold} order by count(msvalue.id) desc limit {$limit} ";

        return get_data($query);
        
    }

    /**
     * Loads and displays a tagcloud given particular criteria.
     *
     * @param int $threshold Get the threshold of minimum number of each tags to bother with (ie only show tags where there are more than $threshold occurances)
     * @param int $limit Number of tags to return
     * @param string $metadata_name Optionally, the name of the field you want to grab for
     * @param string $entity_type Optionally, the entity type ('object' etc)
     * @param string $entity_subtype The entity subtype, optionally
     * @param int $owner_guid The GUID of the tags owner, optionally
     * @param int $site_guid Optionally, the site to restrict to (default is the current site)
     * @return string THe HTML (or other, depending on view type) of the tagcloud.
     */
    
    function display_tagcloud($threshold = 1, $limit = 10, $metadata_name = "", $entity_type = "object", $entity_subtype = "", $owner_guid = "", $site_guid = -1) {
        
        return elgg_view("output/tagcloud",array('value' => get_tags($threshold, $limit, $metadata_name, $entity_type, $entity_subtype, $owner_guid, $site_guid),'object' => $entity_type, 'subtype' => $entity_subtype));
        
    }

?>