<?php
/*
Plugin Name:Similar Posts
Plugin URI: http://rmarsh.com/plugins/similar-posts/
Description: Displays a <a href="options-general.php?page=similar-posts.php">highly configurable</a> list of related posts. Similarity can be based on any combination of word usage in the content, title, or tags. Don't be disturbed if it takes a few moments to complete the installation -- the plugin is indexing your posts. <a href="http://rmarsh.com/plugins/post-options/">Instructions and help online</a>. Requires the latest version of the <a href="http://wordpress.org/extend/plugins/post-plugin-library/">Post-Plugin Library</a> to be installed.
Version: 2.6.2.0
Author: Rob Marsh, SJ
Author URI: http://rmarsh.com/
*/

/*
Copyright 2008  Rob Marsh, SJ  (http://rmarsh.com)

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details: http://www.gnu.org/licenses/gpl.txt
*/

$similar_posts_version = $similar_posts_feed_version= '2.6.2.0';

/*
    Template Tag: Displays the posts most similar to the current post.
        e.g.: <?php similar_posts(); ?>
    Full help and instructions at http://rmarsh.com/plugins/post-options/
*/

function similar_posts($args = '') {
    echo SimilarPosts::execute($args);
}

function similar_posts_mark_current(){
    global $post, $similar_posts_current_ID;
    $similar_posts_current_ID = $post->ID;
}

/*

    'innards'
   
*/


if (!defined('DSEP')) define('DSEP', DIRECTORY_SEPARATOR);
if (!defined('POST_PLUGIN_LIBRARY')) SimilarPosts::install_post_plugin_library();

$similar_posts_current_ID = -1;

class SimilarPosts {
   
    function execute($args='', $default_output_template='<li>{link}</li>', $option_key='similar-posts'){
        if (!SimilarPosts::check_post_plugin_library('<a href="http://downloads.wordpress.org/plugin/post-plugin-library.zip">'.__('Post-Plugin Library missing').'</a>')) return '';
        global $table_prefix, $wpdb, $wp_version, $similar_posts_current_ID;
        $start_time = ppl_microtime();
        $postid = ppl_current_post_id($similar_posts_current_ID);
        if (defined('POC_CACHE_4')) {
            $cache_key = $option_key.$postid.$args;
            $result = poc_cache_fetch($cache_key);
            if ($result !== false) return $result . sprintf("<!-- Similar Posts took %.3f ms (cached) -->", 1000 * (ppl_microtime() - $start_time));
        }
        $table_name = $table_prefix . 'similar_posts';
        // First we process any arguments to see if any defaults have been overridden
        $options = ppl_parse_args($args);
        // Next we retrieve the stored options and use them unless a value has been overridden via the arguments
        $options = ppl_set_options($option_key, $options, $default_output_template);
        if (0 < $options['limit']) {
            $match_tags = ($options['match_tags'] !== 'false' && $wp_version >= 2.3);
            $exclude_cats = ($options['excluded_cats'] !== '');
            $include_cats = ($options['included_cats'] !== '');
            $exclude_authors = ($options['excluded_authors'] !== '');
            $include_authors = ($options['included_authors'] !== '');
            $exclude_posts = (trim($options['excluded_posts']) !== '');
            $include_posts = (trim($options['included_posts']) !== '');
            $match_category = ($options['match_cat'] === 'true');
            $match_author = ($options['match_author'] === 'true');
            $use_tag_str = ('' != trim($options['tag_str']) && $wp_version >= 2.3);
            $omit_current_post = ($options['omit_current_post'] !== 'false');
            $hide_pass = ($options['show_private'] === 'false');
            $check_age = ('none' !== $options['age']['direction']);
            $check_custom = (trim($options['custom']['key']) !== '');
            $limit = $options['skip'].', '.$options['limit'];

             //get the terms to do the matching
            if ($options['term_extraction'] === 'pagerank') {
                list( $contentterms, $titleterms, $tagterms) = sp_terms_by_textrank($postid, $options['num_terms']);
            } else {
                list( $contentterms, $titleterms, $tagterms) = sp_terms_by_freq($postid, $options['num_terms']);
            }   
             // these should add up to 1.0
            $weight_content = $options['weight_content'];
            $weight_title = $options['weight_title'];
            $weight_tags = $options['weight_tags'];
            // below a threshold we ignore the weight completely and save some effort
            if ($weight_content < 0.001) $weight_content = (int) 0;
            if ($weight_title < 0.001) $weight_title = (int) 0;
            if ($weight_tags < 0.001) $weight_tags = (int) 0;
           
            $count_content = substr_count($contentterms, ' ') + 1;
            $count_title = substr_count($titleterms, ' ') + 1;
            $count_tags  = substr_count($tagterms, ' ') + 1;
            if ($weight_content) $weight_content = 57.0 * $weight_content / $count_content;
            if ($weight_title) $weight_title = 18.0 * $weight_title / $count_title;
            if ($weight_tags) $weight_tags = 24.0 * $weight_tags / $count_tags;
            if ($options['hand_links'] === 'true') {
                // check custom field for manual links
                $forced_ids = $wpdb->get_var("SELECT meta_value FROM $wpdb->postmeta WHERE post_id = $postid AND meta_key = 'sp_similar' ") ;
            }   
            // the workhorse...
            $sql = "SELECT *, ";
            $sql .= score_fulltext_match($table_name, $weight_title, $titleterms, $weight_content, $contentterms, $weight_tags, $tagterms, $forced_ids);
           
            if ($check_custom) $sql .= "LEFT JOIN $wpdb->postmeta ON post_id = ID ";
           
            // build the 'WHERE' clause
            $where = array();
            $where[] = where_fulltext_match($weight_title, $titleterms, $weight_content, $contentterms, $weight_tags, $tagterms);
            if (!function_exists('get_post_type')) {
                $where[] = where_hide_future();
            } else {
                $where[] = where_show_status($options['status'], $options['show_attachments']);
            }
            if ($match_category) $where[] = where_match_category();
            if ($match_tags) $where[] = where_match_tags($options['match_tags']);
            if ($match_author) $where[] = where_match_author();
            $where[] = where_show_pages($options['show_pages'], $options['show_attachments']);   
            if ($include_cats) $where[] = where_included_cats($options['included_cats']);
            if ($exclude_cats) $where[] = where_excluded_cats($options['excluded_cats']);
            if ($exclude_authors) $where[] = where_excluded_authors($options['excluded_authors']);
            if ($include_authors) $where[] = where_included_authors($options['included_authors']);
            if ($exclude_posts) $where[] = where_excluded_posts(trim($options['excluded_posts']));
            if ($include_posts) $where[] = where_included_posts(trim($options['included_posts']));
            if ($use_tag_str) $where[] = where_tag_str($options['tag_str']);
            if ($omit_current_post) $where[] = where_omit_post($similar_posts_current_ID);
            if ($hide_pass) $where[] = where_hide_pass();
            if ($check_age) $where[] = where_check_age($options['age']['direction'], $options['age']['length'], $options['age']['duration']);
            if ($check_custom) $where[] = where_check_custom($options['custom']['key'], $options['custom']['op'], $options['custom']['value']);
            $sql .= "WHERE ".implode(' AND ', $where);
            if ($check_custom) $sql .= " GROUP BY $wpdb->posts.ID";   
            $sql .= " ORDER BY score DESC LIMIT $limit";
            //echo $sql;
            $results = $wpdb->get_results($sql);
        } else {
            $results = false;
        }
        if ($results) {
            $translations = ppl_prepare_template($options['output_template']);
            foreach ($results as $result) {
                $items[] = ppl_expand_template($result, $options['output_template'], $translations, $option_key);
            }
            if ($options['sort']['by1'] !== '') $items = ppl_sort_items($options['sort'], $results, $option_key, $options['group_template'], $items);       
            $output = implode(($options['divider']) ? $options['divider'] : "\n", $items);
            $output = $options['prefix'] . $output . $options['suffix'];
        } else {
            // if we reach here our query has produced no output ... so what next?
            if ($options['no_text'] !== 'false') {
                $output = ''; // we display nothing at all
            } else {
                // we display the blank message, with tags expanded if necessary
                $translations = ppl_prepare_template($options['none_text']);
                $output = $options['prefix'] . ppl_expand_template(array(), $options['none_text'], $translations, $option_key) . $options['suffix'];
            }
        }
        if (defined('POC_CACHE_4')) poc_cache_store($cache_key, $output);
        return ($output) ? $output . sprintf("<!-- Similar Posts took %.3f ms -->", 1000 * (ppl_microtime() - $start_time)) : '';
    }

    // tries to install the post-plugin-library plugin
    function install_post_plugin_library() {
        $plugin_path = 'post-plugin-library/post-plugin-library.php';
        $current = get_option('active_plugins');
        if (!in_array($plugin_path, $current)) {
            $current[] = $plugin_path;
            update_option('active_plugins', $current);
            do_action('activate_'.$plugin_path);
        }
    }

    function check_post_plugin_library($msg) {
        $exists = function_exists('ppl_microtime');
        if (!$exists) echo $msg;
        return $exists;
    }
   
}

function sp_terms_by_freq($ID, $num_terms = 20) {
    if (!$ID) return array('', '', '');
    global $wpdb, $table_prefix;
    $table_name = $table_prefix . 'similar_posts';
    $terms = '';
    $results = $wpdb->get_results("SELECT title, content, tags FROM $table_name WHERE pID=$ID LIMIT 1", ARRAY_A);
    if ($results) {
        $word = strtok($results[0]['content'], ' ');
        $n = 0;
        $wordtable = array();
        while ($word !== false) {
            $wordtable[$word] += 1;
            $word = strtok(' ');
        }
        arsort($wordtable);
        if ($num_terms < 1) $num_terms = 1;
        $wordtable = array_slice($wordtable, 0, $num_terms);
       
        foreach ($wordtable as $word => $count) {
            $terms .= ' ' . $word;
        }
       
        $res[] = $terms;
        $res[] = $results[0]['title'];   
        $res[] = $results[0]['tags'];
     }
    return $res;
}


// adapted PageRank algorithm see http://www.cs.unt.edu/~rada/papers/mihalcea.emnlp04.pdf
// and the weighted version http://www.cs.unt.edu/~rada/papers/hassan.ieee07.pdf
function sp_terms_by_textrank($ID, $num_terms = 20) {
    global $wpdb, $table_prefix;
    $table_name = $table_prefix . 'similar_posts';
    $terms = '';
    $results = $wpdb->get_results("SELECT title, content, tags FROM $table_name WHERE pID=$ID LIMIT 1", ARRAY_A);
    if ($results) {
        // build a directed graph with words as vertices and, as edges, the words which precede them
         $prev_word = 'aaaaa';
        $graph = array();
        $word = strtok($results[0]['content'], ' ');
        while ($word !== false) {
            $graph[$word][$prev_word] += 1; // list the incoming words and keep a tally of how many times words co-occur
            $out_edges[$prev_word] += 1; // count the number of different words that follow each word
            $prev_word = $word;
            $word = strtok(' ');
        }
         // initialise the list of PageRanks-- one for each unique word
        reset($graph);
        while (list($vertex, $in_edges) =  each($graph)) {
            $oldrank[$vertex] = 0.25;
        }
        $n = count($graph);
        if ($n > 0) {
            $base = 0.15 / $n;
            $error_margin = $n * 0.005;
            do {
                $error = 0.0;
                // the edge-weighted PageRank calculation
                reset($graph);
                while (list($vertex, $in_edges) =  each($graph)) {
                    $r = 0;
                    reset($in_edges);
                    while (list($edge, $weight) =  each($in_edges)) {
                        $r += ($weight * $oldrank[$edge]) / $out_edges[$edge];
                    }
                    $rank[$vertex] = $base + 0.95 * $r;
                    $error += abs($rank[$vertex] - $oldrank[$vertex]);       
                }
                $oldrank = $rank;
                //echo $error . '<br>';
            } while ($error > $error_margin);
            arsort($rank);
            if ($num_terms < 1) $num_terms = 1;
            $rank = array_slice($rank, 0, $num_terms);
            foreach ($rank as $vertex => $score) {
                $terms .= ' ' . $vertex;
            }
        }   
        $res[] = $terms;
        $res[] = $results[0]['title'];   
        $res[] = $results[0]['tags'];
     }
    return $res;
}

function sp_save_index_entry($postID) {
    global $wpdb, $table_prefix;
    $table_name = $table_prefix . 'similar_posts';
    $post = $wpdb->get_row("SELECT post_content, post_title, post_type FROM $wpdb->posts WHERE ID = $postID", ARRAY_A);
    if ($post['post_type'] === 'revision') return $postid;
    //extract its terms
    $options = get_option('similar-posts');
    $utf8 = ($options['utf8'] === 'true');
    $cjk = ($options['cjk'] === 'true');
    $content = sp_get_post_terms($post['post_content'], $utf8, $options['use_stemmer'], $cjk);
    $title = sp_get_title_terms($post['post_title'], $utf8, $options['use_stemmer'], $cjk);
    $tags = sp_get_tag_terms($postID, $utf8);
    //check to see if the field is set
    $pid = $wpdb->get_var("SELECT pID FROM $table_name WHERE pID=$postID limit 1");
    //then insert if empty
    if (is_null($pid)) {
        $wpdb->query("INSERT INTO $table_name (pID, content, title, tags) VALUES ($postID, \"$content\", \"$title\", \"$tags\")");
    } else {
        $wpdb->query("UPDATE $table_name SET content=\"$content\", title=\"$title\", tags=\"$tags\" WHERE pID=$postID" );   
    }
    return $postID;
}

function sp_delete_index_entry($postID) {
    global $wpdb, $table_prefix;
    $table_name = $table_prefix . 'similar_posts';
    $wpdb->query("DELETE FROM $table_name WHERE pID = $postID ");
    return $postID;
}

function sp_clean_words($text) {
    $text = strip_tags($text);
    $text = strtolower($text);
    $text = str_replace("’", "'", $text); // convert MSWord apostrophe
    $text = preg_replace(array('/\[(.*?)\]/', '/&[^\s;]+;/', '/‘|’|—|“|”|–|…/', "/'\W/"), ' ', $text); //anything in [..] or any entities or MS Word droppings
    return $text;
}

function sp_mb_clean_words($text) {
    mb_regex_encoding('UTF-8');
    mb_internal_encoding('UTF-8');
    $text = strip_tags($text);
    $text = mb_strtolower($text);
    $text = str_replace("’", "'", $text); // convert MSWord apostrophe
    $text = preg_replace(array('/\[(.*?)\]/u', '/&[^\s;]+;/u', '/‘|’|—|“|”|–|…/u', "/'\W/u"), ' ', $text); //anything in [..] or any entities
    return     $text;
}

function sp_mb_str_pad($text, $n, $c) {
    mb_internal_encoding('UTF-8');
    $l = mb_strlen($text);
    if ($l > 0 && $l < $n) {
        $text .= str_repeat($c, $n-$l);
    }
    return $text;
}

function sp_cjk_digrams($string) {
    mb_internal_encoding("UTF-8");
    $strlen = mb_strlen($string);
    $ascii = '';
    $prev = '';
    $result = array();
    for ($i = 0; $i < $strlen; $i++) {
        $c = mb_substr($string, $i, 1);
        // single-byte chars get combined
        if (strlen($c) > 1) {
            if ($ascii) {
                $result[] = $ascii;
                $ascii = '';
                $prev = $c;
            } else {   
                $result[] = sp_mb_str_pad($prev.$c, 4, '_');
                $prev = $c;
            }   
        } else {
            $ascii .= $c;
        }
    }
    if ($ascii) $result[] = $ascii;
    return implode(' ', $result);
}

function sp_get_post_terms($text, $utf8, $use_stemmer, $cjk) {
    global $overusedwords;
    if ($utf8) {
        mb_regex_encoding('UTF-8');
        mb_internal_encoding('UTF-8');
        $wordlist = mb_split("\W+", sp_mb_clean_words($text));
        $words = '';
        reset($wordlist);
        while (list($n, $word) =  each($wordlist)) {
            if ( mb_strlen($word) > 3 && !isset($overusedwords[$word])) {
                switch ($use_stemmer) {
                case 'true':
                    $words .= sp_mb_str_pad(stem($word), 4, '_') . ' ';
                    break;
                case 'fuzzy':
                    $words .= sp_mb_str_pad(metaphone($word), 4, '_') . ' ';
                    break;
                case 'false':
                default:   
                    $words .= $word . ' ';       
                }
            }   
        }   
    } else {
        $wordlist = str_word_count(sp_clean_words($text), 1);
        $words = '';
        reset($wordlist);
        while (list($n, $word) =  each($wordlist)) {
            if ( strlen($word) > 3 && !isset($overusedwords[$word])) {
                switch ($use_stemmer) {
                case 'true':
                    $words .= str_pad(stem($word), 4, '_') . ' ';
                    break;
                case 'fuzzy':
                    $words .= str_pad(metaphone($word), 4, '_') . ' ';
                    break;
                case 'false':
                default:   
                    $words .= $word . ' ';       
                }
            }   
        }   
    }
    if ($cjk) $words = sp_cjk_digrams($words);   
    return $words;
}

$tinywords = array('the' => 1, 'and' => 1, 'of' => 1, 'a' => 1, 'for' => 1, 'on' => 1);

function sp_get_title_terms($text, $utf8, $use_stemmer, $cjk) {
    global $tinywords;
    if ($utf8) {
        mb_regex_encoding('UTF-8');
        mb_internal_encoding('UTF-8');
        $wordlist = mb_split("\W+", sp_mb_clean_words($text));
        $words = '';
        foreach ($wordlist as $word) {
            if (!isset($tinywords[$word])) {
                switch ($use_stemmer) {
                case 'true':
                    $words .= sp_mb_str_pad(stem($word), 4, '_') . ' ';
                    break;
                case 'fuzzy':
                    $words .= sp_mb_str_pad(metaphone($word), 4, '_') . ' ';
                    break;
                case 'false':
                default:   
                    $words .= sp_mb_str_pad($word, 4, '_') . ' ';
                }
            }   
        }   
    } else {
        $wordlist = str_word_count(sp_clean_words($text), 1);
        $words = '';
        foreach ($wordlist as $word) {
            if (!isset($tinywords[$word])) {
                switch ($use_stemmer) {
                case 'true':
                    $words .= str_pad(stem($word), 4, '_') . ' ';
                    break;
                case 'fuzzy':
                    $words .= str_pad(metaphone($word), 4, '_') . ' ';
                    break;
                case 'false':
                default:   
                    $words .= str_pad($word, 4, '_') . ' ';
                }
            }
        }
    }
    if ($cjk) $words = sp_cjk_digrams($words);   
    return $words;
}

function sp_get_tag_terms($ID, $utf8) {
    global $wpdb;
    if (!function_exists('get_object_term_cache')) return '';
    $tags = array();
    $query = "SELECT t.name FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy AS tt ON tt.term_id = t.term_id INNER JOIN $wpdb->term_relationships AS tr ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy = 'post_tag' AND tr.object_id = '$ID'";
    $tags = $wpdb->get_col($query);
    if (!empty ($tags)) {
        if ($utf8) {
            mb_internal_encoding('UTF-8');
            foreach ($tags as $tag) {
                $newtags[] = sp_mb_str_pad(mb_strtolower(str_replace('"', "'", $tag)), 4, '_');
            }   
        } else {
            foreach ($tags as $tag) {
                $newtags[] = str_pad(strtolower(str_replace('"', "'", $tag)), 4, '_');
            }   
        }   
        $newtags = str_replace(' ', '_', $newtags);   
        $tags = implode (' ', $newtags);
    } else {
        $tags = '';
    }   
    return $tags;       
}

if ( is_admin() ) {
    require(dirname(__FILE__).'/similar-posts-admin.php');
}

function widget_rrm_similar_posts_init() {
    if (! function_exists("register_sidebar_widget")) {
        return;
    }
    function widget_rrm_similar_posts($args) {
        extract($args);
        $options = get_option('widget_rrm_similar_posts');
        $opt = get_option('similar-posts');
        $widget_condition = $opt['widget_condition'];
        // the condition specified in the widget control overrides  the placement setting screen
        if ($options['condition']) {
            $condition = $options['condition'];
        } else {
            if ($widget_condition) {
                $condition = $widget_condition;
            } else {
                $condition = 'true';
            }
        }
        $condition = (stristr($condition, "return")) ? $condition : "return ".$condition;
        $condition = rtrim($condition, '; ') . ' || is_admin();';
        if (eval($condition)) {
            $title = empty($options['title']) ? __('Similar Posts', 'similar_posts') : $options['title'];
            if ( !$number = (int) $options['number'] )
                $number = 10;
            else if ( $number < 1 )
                $number = 1;
            else if ( $number > 15 )
                $number = 15;
            $options = get_option('recent-posts');   
            $widget_parameters = $options['widget_parameters'];
            $output = SimilarPosts::execute('limit='.$number.'&'.$widget_parameters);
            if ($output) {
                echo $before_widget;
                echo $before_title.$title.$after_title;
                echo $output;
                echo $after_widget;
            }
        }
    }
    function widget_rrm_similar_posts_control() {
        if ( $_POST['widget_rrm_similar_posts_submit'] ) {
            $options['title'] = strip_tags(stripslashes($_POST['widget_rrm_similar_posts_title']));
            $options['number'] = (int) $_POST["widget_rrm_similar_posts_number"];
            $options['condition'] = stripslashes(trim($_POST["widget_rrm_similar_posts_condition"], '; '));
            update_option("widget_rrm_similar_posts", $options);
        } else {
            $options = get_option('widget_rrm_similar_posts');
        }       
        $title = attribute_escape($options['title']);
        if ( !$number = (int) $options['number'] )
            $number = 5;
        $condition = attribute_escape($options['condition']);
        ?>
        <p><label for="widget_rrm_similar_posts_title"> <?php _e('Title:', 'similar_posts'); ?> <input style="width: 200px;" id="widget_rrm_similar_posts_title" name="widget_rrm_similar_posts_title" type="text" value="<?php echo $title; ?>" /></label></p>
        <p><label for="widget_rrm_similar_posts_number"> <?php _e('Number of posts to show:', 'similar_posts'); ?> <input style="width: 25px; text-align: center;" id="widget_rrm_similar_posts_number" name="widget_rrm_similar_posts_number" type="text" value="<?php echo $number; ?>" /></label> <?php _e('(at most 15)', 'similar_posts'); ?> </p>
        <p><label for="widget_rrm_similar_posts_condition"> <?php echo sprintf(__('Show only if page: (e.g., %sis_single()%s)', 'similar_posts'), '<a href="http://codex.wordpress.org/Conditional_Tags" title="help">', '</a>'); ?> <input style="width: 200px;" id="widget_rrm_similar_posts_condition" name="widget_rrm_similar_posts_condition" type="text" value="<?php echo $condition; ?>" /></label></p>
        <input type="hidden" id="widget_rrm_similar_posts_submit" name="widget_rrm_similar_posts_submit" value="1" />
        There are many more <a href="options-general.php?page=similar-posts.php">options</a> available.
        <?php
    }
    register_sidebar_widget(__('Similar Posts +', 'similar_posts'), 'widget_rrm_similar_posts');
    register_widget_control(__('Similar Posts +', 'similar_posts'), 'widget_rrm_similar_posts_control', 300, 100);
}

add_action('plugins_loaded', 'widget_rrm_similar_posts_init');


/*
    now some language specific stuff
*/

//the next lines find the language WordPress is using
$language = substr(WPLANG, 0, 2);
//if no language is specified make it the default which is 'en'
if ($language == '') {
    $language = 'en';
}
$languagedir = dirname(__FILE__).DSEP.'languages'.DSEP.$language.DSEP;
//see if the directory exists and if not revert to the default English dir
if (!file_exists($languagedir)) {
    $languagedir = dirname(__FILE__).DSEP.'languages'.DSEP.'en'.DSEP;
}

// import the stemming algorithm ... a single function called 'stem'
require_once($languagedir.'stemmer.php');
require_once($languagedir.'stopwords.php');
global $overusedwords;
$overusedwords = array_flip($overusedwords);

// do not try and use this function directly -- it is automatically installed when the option is set to show similar posts in feeds  // moreover it is deprecated and going soon
function similar_posts_for_feed($content) {
    return (is_feed()) ? $content . SimilarPosts::execute('', '<li>{link}</li>', 'similar-posts-feed') : $content;
}

function similar_posts_init () {
    global $overusedwords, $wp_db_version;
    load_plugin_textdomain('similar_posts');
   
    $options = get_option('similar-posts');
    if ($options['feed_active'] === 'true') add_filter('the_content', 'similar_posts_for_feed');
    if ($options['content_filter'] === 'true' && function_exists('ppl_register_content_filter')) ppl_register_content_filter('SimilarPosts');
    if ($options['feed_on'] === 'true' && function_exists('ppl_register_post_filter')) ppl_register_post_filter('feed', 'similar-posts', 'SimilarPosts');
    if ($options['append_condition']) {
        $condition = $options['append_condition'];
    } else {
        $condition = 'true';
    }
    $condition = (stristr($condition, "return")) ? $condition : "return ".$condition;
    $condition = rtrim($condition, '; ') . ';';
    if ($options['append_on'] === 'true' && function_exists('ppl_register_post_filter')) ppl_register_post_filter('append', 'similar-posts', 'SimilarPosts', $condition);

    //install the actions to keep the index up to date
    add_action('save_post', 'sp_save_index_entry', 1);
    add_action('delete_post', 'sp_delete_index_entry', 1);
    if ($wp_db_version < 3308 ) {
        add_action('edit_post', 'sp_save_index_entry', 1);
        add_action('publish_post', 'sp_save_index_entry', 1);
    }
}

add_action ('init', 'similar_posts_init', 1);

?>

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