Create redirects for deleted posts to the appropriate places.

redirection_assitant.php

<?php

/*
Plugin Name: Redirection Anti-404-Assistent
Version: 1.0
Plugin URI: http://gho.nl
Author: Wouter Groenewold (GH+O)
Author URI: -
Description: Creates redirects for deleted posts to the right path.
License: Proprietary
*/

require_once( ABSPATH . 'wp-admin/includes/plugin.php' );

class RedirectionHelper
{
    public function __construct()
    {
        $this->init();
    }

    /**
     * Init function. Here we hooks all the functions at the right moment.
     */
    public function init()
    {
        register_activation_hook( __FILE__, array( $this, 'check_dependencies' ) );
        add_action('before_delete_post', array($this, 'find_redirect_location'), 10, 1);
    }

    public function check_dependencies(){
        if ( ! defined( 'REDIRECTION_VERSION' ) ){
            deactivate_plugins( plugin_basename( __FILE__ ) );
            wp_die( 'This plugin requires Redirection.' );
        }
    }

    public function get_cpt(){
        $args = array(
            'public' => true,
            '_builtin' => false,
            'has_archive' => true,
            'exclude_from_search' => false,
        );

        $cpt = get_post_types($args);
        $cpt[] = 'post'; //add posts.

        return $cpt;
    }

    public function find_redirect_location($postid){
        $type = get_post_type($postid);
        $cpt = $this->get_cpt();
        if($type !== false && in_array($type, $cpt)){
            //redirect to archive page
            $permalink = get_permalink($postid);
            $archive_link = get_post_type_archive_link($type);

            $this->create_redirect($permalink, $archive_link);
            return;
        }elseif($type == 'page'){
            //hierarchical, redirect to parent if parent != 0
            $parent = wp_get_post_parent_id($postid);
            if($parent !== 0 && $parent !== false){
                $permalink = get_permalink($postid);
                $parent_link = get_permalink($parent);

                $this->create_redirect($permalink, $parent_link);
            }else{
                return;
            }
        }else{
            return;
        }
    }

    public function create_redirect($old, $new){
        if($old && $new){
            $data = array(
	            'url' => $old,
	            'action_code' => 301,
	            'action_data' => $new,
	            'match_type' => 'url',
	            'group_id' => 1,
            );

            Red_Item::create($data);
        }else{
            return false;
        }
    }

}

$helper = new RedirectionHelper();