Dynamically reorder side navigation based on current page

functions.php

<?php
/*******************************
* SIDEBAR NAVIGATION
*******************************/
function check_for_page_tree() {
 
    //start by checking if we're on a page
    if( is_page() ) {
     
        global $post;
     
        // next check if the page has parents
        if ( $post->post_parent ){
         
            // fetch the list of ancestors
            $parents = array_reverse( get_post_ancestors( $post->ID ) );
             
            // get the top level ancestor
            return $parents[0];
             
        }
         
        // return the id  - this will be the topmost ancestor if there is one, or the current page if not
        return $post->ID;
         
    }
 
}

function sidebar_navigation() {
	 // don't run on the main blog page
    if ( is_page() ) {
     
        // run the tutsplus_check_for_page_tree function to fetch top level page
        $ancestor = check_for_page_tree();
     
        // set the arguments for children of the ancestor page
        $args = array(
            'child_of' => $ancestor,
            'depth'    => '0', 
            'title_li' => '',
            'sort_column' => 'menu_order',
        );
         
        // set a value for get_pages to check if it's empty
        $list_pages = get_pages( $args );
         // open a list with the ancestor page at the top
         ?>
			<div class="sidebar-title">
	             <a href="<?php echo get_permalink( $ancestor ); ?>"><?php echo get_the_title( $ancestor ); ?></a>
            </div>
         <?php
        // check if $list_pages has values
        if ( $list_pages ) {
        	$currentPage = get_the_ID();
            ?>
            <ul class="page-tree">
                <?php
                // use wp_list_pages to list subpages of ancestor or current page
                //wp_list_pages( $args );
                
                $childOrParent = child_or_parent();
                switch ($childOrParent) {
                	case 'parent':
                		wp_list_pages(array('child_of' => $ancestor, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		break;

                	case 'childnokids':
                		wp_list_pages(array('include' => $currentPage, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		wp_list_pages(array('child_of' => $ancestor, 'exclude' => $currentPage, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		break;

                	case 'greatgreatgrandchildwithkids':
                		$postParent = wp_get_post_parent_id($currentPage);
            			$grandParent = wp_get_post_parent_id($postParent);
            			$greatGrandParent = wp_get_post_parent_id($grandParent);
                		wp_list_pages(array('include' => $grandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		<ul class="children" style="display: block">
                		<?php
                		wp_list_pages(array('child_of' => $grandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		</ul>
                		<?php
                		wp_list_pages(array('child_of' => $ancestor, 'exclude' => $grandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
            			break;
                	case 'greatgrandchildwithkids':
                		$postParent = wp_get_post_parent_id($currentPage);
            			$grandParent = wp_get_post_parent_id($postParent);
            			$greatGrandParent = wp_get_post_parent_id($grandParent);
                		wp_list_pages(array('include' => $grandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		<ul class="children" style="display: block">
                		<?php
                		wp_list_pages(array('child_of' => $grandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		</ul>
                		<?php
                		wp_list_pages(array('child_of' => $ancestor, 'exclude' => $grandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
            			break;

                	case 'grandchildwithkids':
                		$postParent = wp_get_post_parent_id($currentPage);
            			$grandParent = wp_get_post_parent_id($postParent);
            			$greatGrandParent = wp_get_post_parent_id($grandParent);

                		wp_list_pages(array('child_of' => $ancestor, 'exclude' => $greatGrandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
            			break;

            		case 'child':
            			$postParent = wp_get_post_parent_id($currentPage);

            			wp_list_pages(array('include' => $postParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		<ul class="children" style="display: block">
                		<?php
                		wp_list_pages(array('child_of' => $postParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		</ul>
                		<?php
                		wp_list_pages(array('child_of' => $ancestor, 'exclude' => $postParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
            			break;
            		case 'childwithkids':
            			$postParent = wp_get_post_parent_id($currentPage);

            			//wp_list_pages(array('include' => $postParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		<ul class="children" style="display: block">
                		<?php
                		wp_list_pages(array('child_of' => $postParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		</ul>
                		<?php
                		//wp_list_pages(array('child_of' => $ancestor, 'exclude' => $postParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
            			break;
            		case 'greatgreatgrandchildnokids':
            			$postParent = wp_get_post_parent_id($currentPage);
            			$grandParent = wp_get_post_parent_id($postParent);
            			$greatGrandParent = wp_get_post_parent_id($grandParent);

            			wp_list_pages(array('include' => $greatGrandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		<ul class="children" style="display: block">
                		<?php
                		wp_list_pages(array('child_of' => $greatGrandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		</ul>

                		<?php
                		wp_list_pages(array('child_of' => $ancestor, 'exclude' => $greatGrandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
            			break;
            		case 'greatgrandchildnokids':
            			$postParent = wp_get_post_parent_id($currentPage);
            			$grandParent = wp_get_post_parent_id($postParent);
            			$greatGrandParent = wp_get_post_parent_id($grandParent);

            			wp_list_pages(array('include' => $grandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		<ul class="children" style="display: block">
                		<?php
                		wp_list_pages(array('child_of' => $grandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		</ul>
                		<?php
                		wp_list_pages(array('child_of' => $ancestor, 'exclude' => $grandParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
            			break;
            		case 'grandchildnokids':
            			$postParent = wp_get_post_parent_id($currentPage);
            			$grandParent = wp_get_post_parent_id($postParent);
            			wp_list_pages(array('include' => $postParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		<ul class="children" style="display: block">
                		<?php
                		wp_list_pages(array('child_of' => $postParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
                		?>
                		</ul>
                		<?php
                		wp_list_pages(array('child_of' => $ancestor, 'exclude' => $postParent, 'title_li' => '', 'sort_column' => 'menu_order', 'depth' => '0'));
            			break;
                	default:
                		# code...
                		break;
                }
            ?>
            </ul>
     
        <?php
        }
    }
}

/***************************************
*BONES CHECK IF PAGE is CHILD OR PARENT
***************************************/
function child_or_parent(){
	global $post;
	$parent = get_post_ancestors($post->ID);
	if( is_page() && $post->post_parent > 0 ) { 
	  // post has parents
	  $children = get_pages('child_of='.$post->ID);
	   if( count( $children ) != 0 && !empty($parent[3])) {
	    return "greatgreatgrandchildwithkids";
	  }
	  if( count( $children ) != 0 && !empty($parent[2])) {
	    return "greatgrandchildwithkids";
	  }
	  if( count( $children ) != 0 && !empty($parent[1])) {
	    return "grandchildwithkids";
	  }
	  
	  if( count( $children ) != 0 && empty($parent[1])) {
	    return "childwithkids";
	  }

	  if ( is_page() && (count(get_post_ancestors($post->ID)) >= 4) ) {
	 	return "greatgreatgrandchildnokids";
	  }
	  if ( is_page() && (count(get_post_ancestors($post->ID)) >= 3) ) {
	 	return "greatgrandchildnokids";
	  }
	  if ( is_page() && (count(get_post_ancestors($post->ID)) >= 2) ) {
	 	return "grandchildnokids";
	  }
	  
	  if( count( $children ) <= 0  && empty($parent[1]) ) {
	    return "childnokids";
	  } elseif ( count( $children ) <= 0  && !empty($parent[1]) )  {
	   	return "child";
	  }
	
	} else {
	  return "parent";
	}

}
?>