Customizing the WordPress Body Class: http://darrinb.com/customizing-the-wordpress-body_class-function/

body_class.php

<?php
/**
 * Add dynamic classes to the WP body_class() function
 *
 * updated: 01/06/16
 */
function _dbdb_body_classes( $classes ) {
    global $wp_query, $post;

    // if it's the front page of the site
    if ( is_front_page() ) {
        $classes[] = 'front-page';
    }
    
    // url paths
    if ( is_singular() ) {
        // Get the queried post        
        $post_id   = get_queried_object_id();
        $post_type = get_post_type( $post_id );
        $post_type_object = get_post_type_object( $post_type );
        if ( 'post' !== $post_type ) {
            if ( false !== $post_type_object->rewrite ){
                if ( !empty( $post_type_object->rewrite['slug'] ) ){
                    $path = $post_type_object->rewrite['slug'];
                    $path = trim( $path, '/' );
                    if ( !empty( $path ) ) {
                        $matches = explode('/', $path);                        
                        if ( is_array( $matches ) ) {
                            $matches = array_reverse( $matches );
                            $parent_title = sanitize_title( $matches[0] );
                            $classes[] = 'parent-pagename-'.$parent_title;
                            if ( count($matches) > 1 ) {
                                $is_first = true;
                                foreach ( $matches as $ancestor ){
                                    if ( $is_first ) {
                                        $is_first = false;
                                        continue;
                                    }
                                    $ancestor_title = sanitize_title( $ancestor );
                                    $classes[] = 'ancestor-pagename-'.$ancestor_title;
                                }
                            }
                        }
                    }
                }
            }
        }    
    }
        
    // the $post object
    $post_obj = ( property_exists( $wp_query, 'post' ) && isset( $wp_query->post ) ) ? true : false;
    $post_obj_parent = ( $post_obj && property_exists( $wp_query->post, 'post_parent' ) ) ? true : false;    
    
    // if there is no parent ID and it's not a single post page, category page, or 404 page, give it a class of "parent-page"
    if ( $post_obj_parent && $wp_query->post->post_parent < 1  && !is_single() && !is_archive() && !is_404() ) {
        $classes[] = 'parent-page';
    };

    // if the page/post has a parent, it's a child, give it a class of its parent name
    if ( $post_obj_parent && $wp_query->post->post_parent > 0 ) {
        $parent_title = get_the_title($wp_query->post->post_parent);
        $parent_title = sanitize_title($parent_title);
        $classes[] = 'parent-pagename-'.$parent_title;
    };

    // if the page/post has ancestors, get all ancestors' names
    $ancestors = array();
    if ( isset($wp_query->queried_object) && isset($wp_query->queried_object->ancestors) ) {
        $ancestors = $wp_query->queried_object->ancestors;
    }

    if ( is_array($ancestors) && !empty($ancestors) ) {
        foreach($ancestors as $ancestor) {
            $ancestor_title = get_the_title($ancestor);
            $ancestor_title = sanitize_title($ancestor_title);

            $classes[] = 'ancestor-pagename-'.$ancestor_title;
        }
    } else {
        $classes[] = 'top-level-ancestor';
    }


    // get the post categories
    $categories = ( isset($wp_query->queried_object) ) ? get_the_category($wp_query->queried_object_id) : false;
    if ( $categories ) {
        foreach ( $categories as $category ) {
            $classes[] = 'in-category-'.$category->category_nicename;
        }
    }

    // add a class equal to the name of post or page
    if ( isset($wp_query->queried_object) && isset($wp_query->queried_object->post_name) ) {
        $classes[] = 'pagename-'.$wp_query->queried_object->post_name;
    }

	// author
    if ( function_exists( 'is_multi_author' ) && ! is_multi_author() ) {
        $classes[] = 'single-author';
    }

	// single pages
    if ( is_singular() && ! is_home() && ! is_page_template( 'showcase.php' ) && ! is_page_template( 'sidebar-page.php' ) ) {
        $classes[] = 'singular';
    }

    $classes = array_filter($classes);

    return array_unique($classes);
};

add_filter('body_class','_dbdb_body_classes');