Faceted Search Widget

<?php
/*
Plugin Name: Faceted Search Widget
Description: Sidebar Widget to allow filtering indexes by builtin and custom taxonomies
Version: 2.0
Author: The Federal Communications Commission
Author URI: http://fcc.gov/developers
License: GPL2
*/

class FCC_Refine_Widget extends WP_Widget {

    private $defaults = array(
            'title' => '',
            'depth' => '0',
            'contentdiv' => false,
            'orderby' => 'name',
        );

    /**
     * Constructor
     */
    Function FCC_Refine_Widget() {

        parent::WP_Widget(false, $name = 'Faceted Search Widget');

        //can't i18n outside of function
        $this->defaults['title'] = __( 'Refine', 'faceted-search-widget' );

    }

    /**
     * Widget to propegate sidebar list of taxonomies and terms
     * @param array $args args passed to widget
     * @param reference $instance the widget instance
     */
    function widget( $args, $instance ) {

        //verify that this is either an archive or search results
        if ( is_404() || is_single() || is_attachment() || is_page() )
            return;

        //enqueue ajax scripts, if necessary
        if ( $instance['contentdiv'] ) {

            $file = ( WP_DEBUG ) ? 'js/faceted-search-widget.dev.js' : 'js/faceted-search-widget.js';

            wp_enqueue_script( 'faceted-search-widget', plugins_url( $file, __FILE__ ), array( 'jquery' ), filemtime( dirname( __FILE__ ) . '/' . $file ), true );

            $data = array( '.' . $this->widget_options['classname'], $instance['contentdiv'] );

            wp_localize_script( 'faceted-search-widget', 'faceted_search_widget', $data );

        }

        //grab widget args and wp_query
        global $wp_query;
        extract( $args );

        $title = apply_filters( 'widget_title', $instance['title'] );
        ?>
            <?php echo $before_widget; ?>
                <?php if ( $title )
                    echo $before_title . $title . $after_title;

        $taxs = get_taxonomies( array( 'public' => true, 'query_var' => true ),  'objects' ); ?>
        <ul>
        <?php foreach ($taxs as $tax) {

        //Non-Hierarchical taxonomy with term already filtered (no futher filtering)
        if ( !$tax->hierarchical && $this->tax_in_query( $tax->name ) ) {
            continue;

        //Hierarchical taxonomy with term filtered (filter down to children)
        } else if ( $tax->hierarchical && $this->tax_in_query( $tax->name ) ) {
            $termID = term_exists( get_query_var( $tax->query_var ) );
            $terms = get_terms( $tax->name, array( 'child_of' => $termID ) );

        //No filters, get all terms
        } else {
            $terms = get_terms( $tax->name );
        }

        //verify taxonomy has terms associated with it
        if ( sizeof( $terms ) == 0 )
            continue;

        add_filter( 'term_link', array( &$this, 'term_link_filter'), 10, 3 );
        add_filter( 'get_terms', array( &$this, 'get_terms_filter'), 10, 3 );

        wp_list_categories( array(
                                'taxonomy' => $tax->name,
                                'show_count' => true,
                                'depth' => $instance['depth'],
                                'title_li' => $tax->labels->name,
                                'orderby' => $instance['orderby'],
                                'order' => ( $instance['orderby'] == 'count' ) ? 'DESC' : 'ASC',
                            ) );

        remove_filter( 'term_link', array( &$this, 'term_link_filter' ) );
        remove_filter( 'get_terms', array( &$this, 'get_terms_filter') );

        } ?>
        </ul>
        <?php  echo $after_widget;
    }

    /**
     * Function to process changes to the widge title
     * @param array $old the old title
     * @param array $new the new title
     * @return array the new title array
     */
    function update( $new, $old ) {
        $instance = $old;
        $instance['title'] = strip_tags( $new['title'] );
        $instance['contentdiv'] = strip_tags( $new['contentdiv'] );
        $instance['depth'] = (int) $new['depth'];
        $instance['orderby'] = $new['orderby'];
        return $instance;
    }

    /**
     * Callback to generate the title form for widgets.php
     * @param reference $instance the widget instance
     */
    function form( $instance ) {

        foreach ( $this->defaults as $key => $value )
            if ( !isset( $instance[ $key ] ) )
                $instance[ $key ] = $value;
    ?>
         <p>
          <label for="<?php echo $this->get_field_id('title'); ?>"><?php _e('Title:', 'faceted-search-widget' ); ?></label>
          <input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo esc_attr( $instance['title'] ); ?>" /><br />
          <span class="description"><?php _e( 'Title to display above the widget', 'faceted-search-widget' ); ?></span>
        </p>
        <p>
          <label for="<?php echo $this->get_field_id('depth'); ?>"><?php _e('Depth:', 'faceted-search-widget' ); ?></label>
          <input class="small-text" id="<?php echo $this->get_field_id('depth'); ?>" name="<?php echo $this->get_field_name('depth'); ?>" type="text" value="<?php echo esc_attr( $instance['depth'] );; ?>" /><br />
          <span class="description"><?php _e( 'Maximum number of levels to show within hierarchical taxonomies like categories', 'faceted-search-widget' ); ?></span>
        </p>
        <p>
            <label for="<?php echo $this->get_field_id('orderby'); ?>"><?php _e('Order terms by:', 'faceted-search-widget' ); ?></label>
            <select class="widefat" id="<?php echo $this->get_field_id('orderby'); ?>" name="<?php echo $this->get_field_name('orderby'); ?>">
                <?php foreach ( array( 'name' => __( 'Name', 'faceted-search-widget' ), 'count' => __( 'Count', 'faceted-search-widget' )) as $option => $label ) { ?>
                    <option value="<?php echo $option; ?>" <?php selected( $option, $instance['orderby'] ); ?>><?php echo $label; ?></option>
                <?php } ?>
            </select>
        </p>
        <p>
          <label for="<?php echo $this->get_field_id('contentdiv'); ?>"><?php _e('Content Div:', 'faceted-search-widget' ); ?></label>
          <input class="widefat" id="<?php echo $this->get_field_id('contentdiv'); ?>" name="<?php echo $this->get_field_name('contentdiv'); ?>" type="text" value="<?php echo esc_attr( $instance['contentdiv'] );; ?>" /><br />
          <span class="description"><?php _e( 'jQuery selector of DIV containing your template\'s posts, leave blank to disable ajax search', 'faceted-search-widget' ); ?></span>
        </p>

        <?php
    }

    /**
     * Makes term links query args rather than absolute links
     * @param string $termlink the original link
     * @param array $term the term object
     * @param string $taxonomy the taxonomy slug
     * @return string the modified link
     */
    function term_link_filter( $termlink, $term, $taxonomy ) {
        $tax = get_taxonomy( $taxonomy );
        return esc_url( add_query_arg( $tax->query_var, $term->slug ) );
    }

    /**
     * Filters term list to only terms within current view, and modifies post count
     * @param array $terms the original terms list
     * @param array $taxonomies the taxonomy
     * @param array $args args originally passed
     * @return array the modified terms list
     */
    function get_terms_filter( $terms, $taxonomies, $args ) {

        global $wp_query;

        //safe to assume one because filter is added immediately before use
        $tax = get_taxonomy( $taxonomies[0] );

        $post_type = get_post_type();

        foreach ( $terms as $id => &$term ) {

            $tax_query = $wp_query->tax_query->queries;
            $tax_query['relationship'] = 'AND';

            $tax_query[] =  array(
                                'taxonomy'  =>  $tax->name,
                                'field'     =>  'slug',
                                'terms'     =>  $term->slug,
                                );
            /*Added by Chuck - Adds post type to query*/
            $query = new WP_Query( array( 'post_type' => $post_type, 'tax_query' => $tax_query ) );

            //If this term has no posts, don't display the link
            if ( !$query->found_posts )
                unset( $terms[ $id ] );
            else
                $terms[$id]->count = $query->found_posts;

        }

        return $terms;
    }

    /**
     * Checks the global WP_Query Object to see if the taxonomy query is being queried
     * Used to prevent already filtered taxonomies from being displayed
     * @param string $tax the taxonomy slug
     * @return bool true if in the query, otherwise false
     * @since 1.4
     */
    function tax_in_query( $tax ) {
        global $wp_query;

        if ( !isset( $wp_query->tax_query ) || !isset( $wp_query->tax_query->queries ) )
            return false;

        foreach ( $wp_query->tax_query->queries as $query )
            if ( $query['taxonomy'] == $tax )
                return true;

        return false;

    }
}

/**
 * Register the sidebar widget
 */
add_action('widgets_init', create_function('', 'return register_widget("FCC_Refine_Widget");'));