automatically-paginate-posts.php

<?php
/*
Plugin Name: Automatically Paginate Posts
Plugin URI: http://www.oomphinc.com/plugins-modules/automatically-paginate-posts/
Description: Automatically inserts the &lt;!--nextpage--&gt; Quicktag into WordPress posts, pages, or custom post type content.
Version: 0.2
Author: Erick Hitter & Oomph, Inc.
Author URI: http://www.oomphinc.com/

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

class Automatically_Paginate_Posts {
	/**
	 * Class variables
	 */
	private $post_types;
	private $post_types_default = array( 'post' );

	private $num_pages;
	private $paging_type_default = 'pages';
	private $num_pages_default   = 2;
	private $num_words_default   = '';

	private $paging_types_allowed = array( 'pages', 'words' );

	// Ensure option names match values in this::uninstall
	private $option_name_post_types  = 'autopaging_post_types';
	private $option_name_paging_type = 'pages';
	private $option_name_num_pages   = 'autopaging_num_pages';
	private $option_name_num_words   = 'autopaging_num_words';

	private $meta_key_disable_autopaging = '_disable_autopaging';

	/**
	 * Register actions and filters
	 *
	 * @uses add_action, register_uninstall_hook, add_filter
	 * @return null
	 */
	public function __construct() {
		//Filters
		add_action( 'init', array( $this, 'action_init' ) );

		//Admin settings
		register_uninstall_hook( __FILE__, array( 'Automatically_Paginate_Posts', 'uninstall' ) );
		add_filter( 'plugin_action_links', array( $this, 'filter_plugin_action_links' ), 10, 2 );
		add_action( 'admin_init', array( $this, 'action_admin_init' ) );

		//Post-type settings
		add_action( 'add_meta_boxes', array( $this, 'action_add_meta_boxes' ) );
		add_action( 'save_post', array( $this, 'action_save_post' ) );
		add_filter( 'the_posts', array( $this, 'filter_the_posts' ) );
	}

	/**
	 * Set post types this plugin can act on, either from Reading page or via filter
	 * Also sets default number of pages to break content over, either from Reading page or via filter