WordPress - Remove the front permastruct / base slug from a custom post type (CPT)

cpt-remove-front.php

<?php
class Plugin
{
    /**
     * This will let a CPT with the slug 'story' be used without a base slug, ie:
     * Before:
     * /story/hello
     * 
     * After:
     * /hello
     */
    function __construct()
    {
    }
    
    function initialize()
    {
        //Handle CPT rewrites for Story to remove base
        add_filter('post_type_link', array(
            &$this,
            'story_preview_url_remove_base'
        ), 10, 3);
        add_action('pre_get_posts', array(
            &$this,
            'story_modify_query_remove_base'
        ));
        add_filter('wp_unique_post_slug', array(
            &$this,
            'story_fix_slug'
        ), 100, 6);
        
        //Add the Story post type to the front page static page dropdown under Settings > Reading
        add_filter('get_pages', array(
            &$this,
            'story_add_to_frontpage_dropdown'
        ), 10, 2);
        
        //Let story be used as the front page on the routing level
        add_action('pre_get_posts', array(
            &$this,
            'story_enable_frontpage'
        ), 11);
    }
    
    /**
     * Let's the Story CPT be used as the front page properly.
     *
     * @param $query
     */
    function story_enable_frontpage($query)
    {
        // Only touch the main query
        if (!$query->is_main_query())
            return;
        
        //Look for empty post_type, meaning start page (?) TODO: Really?
        //http://wordpress.stackexchange.com/questions/18013/how-do-you-use-a-cpt-as-the-default-home-page
        if (empty($query->query_vars['post_type']) && 0 != $query->query_vars['page_id']) {
            $query->set('post_type', array(
                'story',
                'page'
            ));
        }
    }
    
    /**
     * Add the Story post type to the front page static page dropdown under Settings > Reading
     *
     * http://wordpress.stackexchange.com/questions/18013/how-do-you-use-a-cpt-as-the-default-home-page
     *
     * @param $pages
     * @param $r
     *
     * @return array
     */
    function story_add_to_frontpage_dropdown($pages, $r)
    {
        if ((isset($r['name']) && ('page_on_front' === $r['name']))) {
            $args   = array(
                'post_type' => 'story'
            );
            $stacks = get_posts($args);
            $pages  = array_merge($pages, $stacks);
        }
        
        return $pages;
    }
    
    
    /**
     * Fix the Story CPT slug so it does not conflict with pages or posts.
     *
     * @param $slug
     * @param $post_ID
     * @param $post_status
     * @param $post_type
     * @param $post_parent
     * @param $original_slug
     *
     * @return mixed
     */
    function story_fix_slug($slug, $post_ID, $post_status, $post_type, $post_parent, $original_slug)
    {
        global $wpdb;
        
        //These post types will never clash
        $post_types_no_conflict = array(
            'story',
            'post',
            'page',
            'attachment'
        );
        $post_types_sql = function() use ($post_types_no_conflict)
        {
            $ret = '';
            foreach ($post_types_no_conflict as $post_type)
                $ret .= "'{$post_type}', ";
            
            return substr($ret, 0, -2);
        };
        
        //If we are creating the unique slug for an affected post type
        if (in_array($post_type, $post_types_no_conflict)) {
            $unique = false;
            
            //While we haven't found a unique link
            while ($unique !== true) {
                $post_name_check = $wpdb->get_var($wpdb->prepare("SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN (" . $post_types_sql() . ") AND ID != %d LIMIT 1", $slug, $post_ID));
                
                //Not unique? Append some numbers and let's try again!
                if ($post_name_check) {
                    $slug = "{$slug}-2";
                } else {
                    //If unique, we're done
                    $unique = true;
                }
            }
            return $slug;
        } else
            return $slug;
    }
    
    /**
     * Remove the slug from published post permalinks. Only affect our CPT though.
     *
     * http://kellenmace.com/remove-custom-post-type-slug-from-permalinks/
     */
    function story_preview_url_remove_base($post_link, $post)
    {
        if ('story' != $post->post_type || 'publish' != $post->post_status) {
            return $post_link;
        }
        $post_link = str_replace('/' . $post->post_type . '/', '/', $post_link);
        return $post_link;
    }
    
    /**
     * Have WordPress match postname to any of our public post types (page, post, race)
     * All of our public post types can have /post-name/ as the slug, so they better be unique across all posts
     * By default, core only accounts for posts and pages where the slug is /post-name/
     *
     * TODO: Make sure this is 100% safe, especially the "2 != count( $query->query )"
     *
     * @param $query
     */
    function story_modify_query_remove_base($query)
    {
        // Only touch the main query
        if (!$query->is_main_query())
            return;
        // Only noop our very specific rewrite rule match
        if (2 != count($query->query) || !isset($query->query['page'])) {
            return;
        }
        // 'name' will be set if post permalinks are just post_name, otherwise the page rule will match
        if (!empty($query->query['name'])) {
            $query->set('post_type', array(
                'story',
                'page',
                'post'
            ));
        }
    }
}