Filtering plugin for Polylang

<?php
/*
Plugin Name: pll_filter for Polylang
Description: Obsolete since the feature has been included in Polylang v0.9
*/

class pll_filter {
    function __construct() {
        // FIXME will be useless since everything will go in admin-filters.php
        if (!is_admin())
            return;

        add_filter('terms_clauses', array(&$this, 'terms_clauses'), 10, 3);
        add_filter('comments_clauses', array(&$this, 'comments_clauses'), 10, 2);

        add_action('admin_bar_menu', array(&$this, 'admin_bar_menu'), 100); // 100 determines the position
        add_action('admin_init', array(&$this, 'admin_init'));
        // FIXME enlever parse_query (remplacé par celui-ci) et restrict_manage_posts dans admin-filters.php
        add_filter('parse_query',array(&$this,'parse_query'));
    }

    // filter tag cloud and list table in 'tags' screen
    function terms_clauses($clauses, $taxonomies, $args) {

        // FIXME remplacer $polylang par $this
        global $polylang;

        if (function_exists('get_current_screen'))
            $screen = get_current_screen();

        // only on the 'Tags' or 'Categories' screen
        // and the 'Posts' or 'Pages' screen for the quick edit
        if (!isset($screen) || !in_array($screen->base, array('edit-tags', 'edit')) || isset($_GET['action']))
            return $clauses;

        // FIXME this complex test allows not to filter the 'get_terms_not_translated'
        // maybe it's more robust to add a new arg to the function in polylang and to test it
        if ($screen->base == 'edit-tags' && !isset($args['page']) && $args['fields'] != 'count' && !isset($args['class']) && !$args['hide_empty'])
            return $clauses;

        // parent drowdown already filtered in polylang
        if (isset($args['class']))
            return $clauses;

        // when adding a new translation. FIXME : filtrer ou non ? -> filtrer contredit le filtre général
        // FIXME add ajax to manage tag cloud and list table when changing language ?
        // already done for parent dropdown list
        if (isset($_GET['new_lang']) && $_GET['new_lang'])
            $lang = $polylang->get_language($_GET['new_lang']);

        elseif (isset($_GET['lang']) && $_GET['lang']) {
            if ($_GET['lang'] != 'all')
                $lang = $polylang->get_language($_GET['lang']);
        }

        elseif ($lg = get_user_meta(get_current_user_id(), 'pll_filter_content', true))
            $lang = $polylang->get_language($lg);

        return isset($lang) ? $polylang->_terms_clauses($clauses, $lang) : $clauses;
    }

    // filters comments by language
    function comments_clauses($clauses, $query) {

        // FIXME remplacer $polylang par $this
        global $polylang;

        if (isset($_GET['lang']) && $_GET['lang']) {
            if ($_GET['lang'] != 'all')
                $lang = $polylang->get_language($_GET['lang']);
        }

        elseif ($lg = get_user_meta(get_current_user_id(), 'pll_filter_content', true))
            $lang = $polylang->get_language($lg);

        if (isset($lang))
            $clauses = $this->_comments_clauses($clauses, $lang);

        return $clauses;
    }

    // FIXME fonction comments_clauses de core.php doit appeler _comments_clauses qui doit passer dans base.php
    function _comments_clauses($clauses, $lang) {
        global $wpdb;

        // if this clause is not already added by WP
        if (!strpos($clauses['join'], '.ID'))
            $clauses['join'] .= " JOIN $wpdb->posts ON $wpdb->posts.ID = $wpdb->comments.comment_post_ID";

        $clauses['join'] .= " INNER JOIN $wpdb->term_relationships AS pll_tr ON pll_tr.object_id = ID";
        $clauses['where'] .= $wpdb->prepare(" AND pll_tr.term_taxonomy_id = %d", $lang->term_taxonomy_id);

        return $clauses;
    }

    // adds the languages in admin bar
    function admin_bar_menu($wp_admin_bar) {

        if (function_exists('get_current_screen'))
            $screen = get_current_screen();
/*
        // only on relevant admin panels
        if (!isset($screen) || !in_array($screen->base, array('edit', 'upload', 'edit-comments', 'edit-tags')) || ($screen->base == 'edit-tags' && isset($_GET['action'])))
            return;
*/
        global $polylang;

        $url = ( is_ssl() ? 'https://' : 'http://' ) . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];

        $selected = isset($_GET['lang']) && $_GET['lang'] ? $_GET['lang'] :
            (($lg = get_user_meta(get_current_user_id(), 'pll_filter_content', true)) ? $lg : 'all');

        $wp_admin_bar->add_menu(array(
            'id'     => 'languages',
            'title'  => __('Languages', 'polylang'),
            'meta'  => array('title' => __('Filters content by language', 'polylang')),
        ));

        $wp_admin_bar->add_menu(array(
            'parent' => 'languages',
            'id'     => 'all',
            'title'  => sprintf('<input name="all" type="radio" value="1" %s /> %s',
                $selected == 'all' ? 'checked="checked"' : '', __('Show all languages', 'polylang')),
            'href'   => add_query_arg('lang', 'all', $url),
        ));

        foreach ($polylang->get_languages_list() as $lang) {
            $wp_admin_bar->add_menu(array(
                'parent' => 'languages',
                'id'     => $lang->slug,
                'title'  => sprintf('<input name="%s" type="radio" value="1" %s /> %s',
                    $lang->slug, $selected == $lang->slug ? 'checked="checked"' : '', $lang->name),
                'href'   => add_query_arg('lang', $lang->slug, $url),
            ));
        }
    }

    // set user meta when choosing to filter content by language
    function admin_init() {
        if (isset($_GET['lang']) && $_GET['lang'])
            update_user_meta(get_current_user_id(), 'pll_filter_content', $_GET['lang'] == 'all' ? '' : $_GET['lang']);
    }

    // filters posts, pages and media by language
    function parse_query($query) {
        $qvars = &$query->query_vars;

        // do not filter post types such nav_menu_item for example
        if (in_array($qvars['post_type'], array('nav_menu_item','attachment')))
            return;

        if (!isset($qvars['lang']) && $lg = get_user_meta(get_current_user_id(), 'pll_filter_content', true))
            $qvars['lang'] = $lg;

        if (isset($qvars['lang']) &&  $qvars['lang'] == 'all')
            unset ($qvars['lang']);
    }

}

new pll_filter();