[WordPress] Do multiple featured-image-esque meta boxes

multi-feat-img.php

<?php
/*
Plugin Name: Multiple Featured Images
Description: NOT production ready. May cause tears.
Version: 2012.12.13
Author: Kailey Lampert
Author URI: kaileylampert.com
*/

new MFI_Meta_Box( 'derp', 'Derp Image', '200', '400', 'post' );
new MFI_Meta_Box( 'herp', 'Herp Image', '600', '150', 'page' );
new MFI_Meta_Box( 'berp', 'Berp Image', '300', '300', 'post' );

class MFI_Meta_Box {

  //size_name should be alphanumeric withOUT dashes. underscores okay
	function __construct( $size_name, $size_title, $size_width, $size_height, $post_type ) {

		if ( empty( $size_name ) || empty( $size_width ) || empty( $size_height ) || empty( $post_type ) )
			return false;

		$this->size_name = $size_name;
		$this->size_title = $size_title;
		$this->size_width = $size_width;
		$this->size_height = $size_height;
		$this->post_type = $post_type;
		$this->meta_key = "_{$this->size_name}_thumbnail_id";

		add_image_size( $this->size_name, $this->size_width, $this->size_height, true );

		add_filter( 'MFI_Sizes', array( &$this, 'MFI_Sizes' ) );
		add_action( 'add_meta_boxes', array( &$this, 'add_meta_boxes' ) );
		add_action( 'save_post', array( &$this, 'save_post' ), 10, 2 );

		add_action( 'wp_ajax_set_post_thumbnail_'.$this->size_name, array( &$this, 'set_post_thumbnail' ) );
		add_action( 'admin_footer-post.php', array( &$this, 'admin_footer' ) );
		add_action( 'admin_footer-post-new.php', array( &$this, 'admin_footer' ) );
		// apply_filters( "postbox_classes_{$page}_{$id}", $classes );
		add_filter( "postbox_classes_{$this->post_type}_mfi_postimagediv-{$this->size_name}", array( &$this, 'postbox_class' ) );

	}

	function MFI_Sizes( $sizes ) {
		$sizes[] = $this->size_name;
		return $sizes;
	}

	function postbox_class( $classes ) {
		$classes[] = 'mfi-feat-image';
		return $classes;
	}

	function add_meta_boxes() {
		add_meta_box( 'mfi_postimagediv-'. $this->size_name, __( $this->size_title ), array( &$this, 'mfi_post_thumbnail_meta_box' ), $this->post_type, 'side', 'low');
	}

	function mfi_post_thumbnail_meta_box( $post ) {

		$thumbnail_id = get_post_meta( $post->ID, $this->meta_key, true );
		echo $this->_wp_post_thumbnail_html_2( $thumbnail_id, $post->ID );

	}

	//hijacked from wp-admin/includes/post.php
	function _wp_post_thumbnail_html_2( $thumbnail_id = null, $post = null ) {
		global $content_width, $_wp_additional_image_sizes;

		$post = get_post( $post );

		$upload_iframe_src = esc_url( get_upload_iframe_src('image', $post->ID ) );
		$set_thumbnail_link = '<p class="hide-if-no-js"><a title="' . esc_attr__( 'Set '.$this->size_title ) . '" href="%s" id="set-'. $this->size_name .'" class="thickbox">%s</a></p>';
		$content = sprintf( $set_thumbnail_link, $upload_iframe_src, esc_html__( 'Set '.$this->size_title ) );

		if ( $thumbnail_id && get_post( $thumbnail_id ) ) {
			$old_content_width = $content_width;
			$content_width = 266;
			if ( !isset( $_wp_additional_image_sizes[ $this->size_name ] ) )
				$thumbnail_html = wp_get_attachment_image( $thumbnail_id, array( $content_width, $content_width ) );
			else
				$thumbnail_html = wp_get_attachment_image( $thumbnail_id, $this->size_name );
			if ( !empty( $thumbnail_html ) ) {
				$ajax_nonce = wp_create_nonce( 'set_'.$this->size_name.'-' . $post->ID );
				$content = sprintf( $set_thumbnail_link, $upload_iframe_src, $thumbnail_html );
				$content .= '<p class="hide-if-no-js"><a href="#" id="remove-'.$this->size_name.'" onclick="WPRemoveThumbnail_2(\'' . $ajax_nonce . '\', \''.$this->size_name .'\');return false;">' . esc_html__( 'Remove '.$this->size_title ) . '</a></p>';
			}
			$content_width = $old_content_width;
		}
		return $content;
	}

	function save_post( $post_id, $post ) {
		if ( empty( $_POST ) ) return;

		if ( ! isset( $_POST[ 'nn-save-mfi-'.$this->size_name ] ) )
			return $post_id;
		if ( ! wp_verify_nonce( $_POST[ 'nn-save-mfi-'.$this->size_name ], 'na-save-mfi-'.$this->size_name ) ) //verify intent 
			return $post_id;
		if ( ! isset( $_POST[ $this->meta_key ] ) )
			return $post_id;

		// die( "$post_id, {$this->meta_key}, {$_POST[ $this->meta_key ]}" );
		update_post_meta( $post_id, $this->meta_key, intval( $_POST[ $this->meta_key ] ) );

	}

	//hijacked from wp-admin/ajax-actions.php
	function set_post_thumbnail() {
		$json = ! empty( $_REQUEST['json'] ); // New-style request

		$post_ID = intval( $_POST['post_id'] );
		if ( ! current_user_can( 'edit_post', $post_ID ) )
			wp_die( -1 );

		$thumbnail_id = intval( $_POST['thumbnail_id'] );

		if ( $json )
			check_ajax_referer( "update-post_$post_ID" );
		else
			check_ajax_referer( "set_{$this->size_name}-$post_ID" );

		if ( $thumbnail_id == '-1' ) {
			if ( delete_post_meta( $post_ID, $this->meta_key ) ) {
				$return = $this->_wp_post_thumbnail_html_2( null, $post_ID );
				$json ? wp_send_json_success( $return ) : wp_die( $return );
			} else {
				wp_die( 0 );
			}
		}

		if ( update_post_meta( $post_ID, $this->meta_key, $thumbnail_id ) ) {
			$return = $this->_wp_post_thumbnail_html_2( $thumbnail_id, $post_ID );
			$json ? wp_send_json_success( $return ) : wp_die( $return );
		}

		wp_die( 0 );
	}

	function admin_footer() {

		if ( $this->post_type != get_post_type() ) return;

		//this will probably make you cry
		echo '<script>';
		$file = file_get_contents( plugin_dir_path( __FILE__) .'multi-feat.js' );
		$file = str_replace( 'multi_feat.size', "'{$this->size_name}'", $file );
		$file = str_replace( 'secondaryFeaturedImage', "{$this->size_name}FeaturedImage", $file );
		echo $file;
		echo '</script>';
	}

}
new MFI_Meta_Box_once();
class MFI_Meta_Box_once {
	function __construct() {
		$this->sizes = apply_filters( 'MFI_Sizes', array() );
		if ( empty( $this->sizes ) ) return;

		add_action( 'admin_enqueue_scripts', array( &$this, 'admin_scripts' ) );
		add_action( 'admin_footer-post.php', array( &$this, 'admin_footer' ) );
		add_action( 'admin_footer-post-new.php', array( &$this, 'admin_footer' ) );
	}
	function admin_scripts( $hook ) {
		if ( $hook != 'post.php' && $hook != 'post-new.php' ) return;
		?><style>
			.mfi-feat-image img { max-width: 100%; height: auto;}
		</style><?php
	}
	function admin_footer() {
		?><script>
(function($){
WPRemoveThumbnail_2 = function(nonce, size_name){
	$.post(ajaxurl, {
		action:"set_post_thumbnail_"+size_name, post_id: $('#post_ID').val(), thumbnail_id: -1, _ajax_nonce: nonce, cookie: encodeURIComponent(document.cookie)
	}, function(str){
		if ( str == '0' ) {
			alert( setPostThumbnailL10n.error );
		} else {
			$('.inside', '#mfi_postimagediv-'+size_name).html(str);
		}
	}
	);
};
}(jQuery));
		</script><?php
	}

}

multi-feat.js

(function($){
  wp.media.secondaryFeaturedImage = {
		get: function() {
			return wp.media.view.settings.post.featuredImageId;
		},

		set: function( id ) {
			var settings = wp.media.view.settings;

			settings.post.featuredImageId = id;

			wp.media.post( 'set_post_thumbnail_'+multi_feat.size, {
				json:         true,
				post_id:      settings.post.id,
				thumbnail_id: settings.post.featuredImageId,
				_wpnonce:     settings.post.nonce
			}).done( function( html ) {
				$( '.inside', '#mfi_postimagediv-'+multi_feat.size ).html( html );
			});
		},

		frame: function() {
			if ( this._frame )
				return this._frame;

			this._frame = wp.media({
				state: 'featured-image',
				states: [ new wp.media.controller.FeaturedImage() ]
			});

			this._frame.on( 'toolbar:create:featured-image', function( toolbar ) {
				this.createSelectToolbar( toolbar, {
					text: wp.media.view.l10n.setFeaturedImage
				});
			}, this._frame );

			this._frame.state('featured-image').on( 'select', this.select );
			return this._frame;
		},

		select: function() {
			var settings = wp.media.view.settings,
				selection = this.get('selection').single();

			if ( ! settings.post.featuredImageId )
				return;

			wp.media.secondaryFeaturedImage.set( selection ? selection.id : -1 );
		},

		init: function() {
			// Open the content media manager to the 'featured image' tab when
			// the post thumbnail is clicked.
			$('#mfi_postimagediv-'+multi_feat.size).on( 'click', '#set-'+multi_feat.size, function( event ) {
				event.preventDefault();
				// Stop propagation to prevent thickbox from activating.
				event.stopPropagation();

				wp.media.secondaryFeaturedImage.frame().open();

			// Update the featured image id when the 'remove' link is clicked.
			}).on( 'click', '#remove-'+multi_feat.size, function() {
				wp.media.view.settings.post.featuredImageId = -1;
			});
		}
	};
				// alert( '#mfi_postimagediv-'+multi_feat.size );

	$( wp.media.secondaryFeaturedImage.init );

}(jQuery));