uc-js.php

<?php
/**
 * Plugin Name: UC JavaScript
 * Description: Allow super admin's to add arbitrary JavaScript to each site on a site by site basis
 * Author: Josh Roy
 * Version: 1.0
 * Text Domain: ucjs
 */
 
function ucjs_scripts() {	
	wp_enqueue_script( 'ucjs-js', plugin_dir_url( __FILE__ ) . '/uc-js.js', array( 'jquery' ));
}
add_action( 'admin_enqueue_scripts', 'ucjs_scripts' );

/**
 * Register text domain
 *
 * @since 1.0
 */
function ucjs_textdomain() {
	load_plugin_textdomain( 'ucjs' );
}
add_action( 'init', 'ucjs_textdomain' );


/**
 * Delete Options on Uninstall
 *
 * @since 1.1
 */
function ucjs_uninstall() {
	delete_option( 'ucjs_settings' );
}
register_uninstall_hook( __FILE__, 'ucjs_uninstall' );


/**
 * Enqueue link to add JS through PHP
 *
 * This is a typical WP Enqueue statement,
 * except that the URL of the script is simply a query var.
 * This query var is passed to the URL, and when it is detected by ucjs_add_trigger(),
 * It fires ucjs_trigger_check, which writes its PHP/JS to the browser.
 *
 * Credit for this technique: @Otto http://ottopress.com/2010/dont-include-wp-load-please/
 *
 * @since 1.1
 */
function ucjs_register_style() {

	$options     = get_option( 'ucjs_settings' );
	if(strlen($options['ucjs-content']) == 0) return;

	wp_register_script( 'ucjs', home_url( '/?ucjs=1' ) );
	wp_enqueue_script( 'ucjs' );
}
add_action( 'wp_enqueue_scripts', 'ucjs_register_style', 999 );

/**
 * Add Query Var Script trigger
 *
 * Adds a query var to our script, so it can trigger our psuedo-script
 *
 * @since 1.1
 * @param string $vars
 * @return array $vars
 */
function ucjs_add_trigger( $vars ) {
	$vars[] = 'ucjs';
	return $vars;
}
add_filter( 'query_vars', 'ucjs_add_trigger' );

/**
 * If trigger (query var) is tripped, load our pseudo-script
 *
 * I'd prefer to esc $content at the very last moment, but we need to allow the > character.
 *
 * @since 1.1
 */
function ucjs_trigger_check() {
	if ( intval( get_query_var( 'ucjs' ) ) == 1 ) {
		ob_start();
		header( 'Content-type: text/javascript' );
		$options     = get_option( 'ucjs_settings' );
		$raw_content = isset( $options['ucjs-content'] ) ? $options['ucjs-content'] : '';
		$content     = str_replace( '&gt;', '>', $raw_content );
		echo $content; //xss okay
		exit;
		ob_clean();
	}
}
add_action( 'template_redirect', 'ucjs_trigger_check' );


/**
 * Register "Custom JS" submenu in "Appearance" Admin Menu
 *
 * @since 1.0
 */
function ucjs_register_submenu_page() {
	add_theme_page( __( 'JavaScript', 'ucjs' ), __( 'JavaScript', 'ucjs' ), 'manage_network', basename( __FILE__ ), 'ucjs_render_submenu_page' );
}
add_action( 'admin_menu', 'ucjs_register_submenu_page' );


/**
 * Register settings
 *
 * @since 1.0
 */
function ucjs_register_settings() {
	register_setting( 'ucjs_settings_group', 'ucjs_settings' );
}
add_action( 'admin_init', 'ucjs_register_settings' );

/**
 * Render Admin Menu page
 *
 * @since 1.0
 */
function ucjs_render_submenu_page() {

	$options = get_option( 'ucjs_settings' );
	$content = isset( $options['ucjs-content'] ) && ! empty( $options['ucjs-content'] ) ? $options['ucjs-content'] : '/* Enter Your Custom JS Here */';
	$content_back = isset( $options['ucjs-content-back'] ) && ! empty( $options['ucjs-content-back'] ) ? $options['ucjs-content-back'] : $options['ucjs-content'];

	if ( isset( $_GET['settings-updated'] ) ) : ?>
		<div id="message" class="updated"><p><?php _e( 'Custom JS updated successfully.', 'ucjs' ); ?></p></div>
	<?php endif; ?>
	<div class="wrap">
		<h2 style="margin-bottom: 1em;"><?php _e( 'JavaScript', 'ucjs' ); ?></h2>
		<form name="ucjs-form" action="options.php" method="post" enctype="multipart/form-data">
			<?php settings_fields( 'ucjs_settings_group' ); ?>
			<div id="template">
				<?php do_action( 'ucjs-form-top' ); ?>
				<div>
					<textarea cols="70" rows="30" name="ucjs_settings[ucjs-content]" id="ucjs_settings[ucjs-content]" class="ucjs-content" ><?php echo esc_html( $content ); ?></textarea>
					<input type="hidden" name="ucjs_settings[ucjs-content-back]" id="ucjs_settings[ucjs-content-back]" value="<?php echo esc_html( $content ); ?>">
					<input type="hidden" class="ucjs-content-back" value="<?php echo esc_html( $content_back ); ?>">
				</div>
				<?php do_action( 'ucjs-textarea-bottom' ); ?>
				<div>
                <div>
                	<a href="#" id="revertucjs">Revert to previous version</a>
                </div>
					<?php submit_button( __( 'Update JavaScript', 'ucjs' ), 'primary', 'submit', true, array('disabled' => true) ); ?>
				</div>
				<?php do_action( 'ucjs-form-bottom' ); ?>
			</div>
		</form>
	</div>
	<?php
}