WP-Admin-Notice-Register - POC plugin

wp-admin-notice-register.php

<?php
/**
 * Plugin Name: WP-Admin-Notice-Register
 * Description: POC plugin. Slow deprecation of 'admin_notices' in favor of a notice registration API.
 * Version: 0.1
 */
if ( ! defined('ABSPATH') )
	wp_die( 'No soup for you!' );


/**
 * Hook onto (deprecated) 'admin_notices' - very early (-1).
 * Collect all admin_notice
 * Remove all callbacks from 'admin_notices'
 * 
 * ob_get/execute all 'admin_notice' callbacks - render to string
 * Enqueue notices onto our new hook 'admin_notie_register' using wp_admin_enqueue_notice() API
 * 
 */
add_action( 'admin_notices', 'wp_admin_notice_collector', -1 );
function wp_admin_notice_collector(){
	global $wp_filter;
	$hook_name = 'admin_notices';
	$admin_notice_hook = $wp_filter[$hook_name];

	$next = $admin_notice_hook->next();
	$the_ = $next;

	$callbacks = $admin_notice_hook->callbacks;

	/**
	 * run over all callbacks on 'admin_notices'
	 * ob_get_content()
	 * remove_filter() from 'admin_notices'
	 * 
	 * add notice as HTML using our API
	 */
	foreach ( $admin_notice_hook->callbacks as $priority => $callbacks ){
		foreach ($callbacks as $the_){

			// Don't remove our own functions from 'admin_notices'
			if ( $the_['function']=='wp_admin_notice_collector' )// && $priority == -1 
				continue;
			if ($the_['function']=='do_admin_notice_register')// && $priority == 9000 
				continue;

			

			$args = [];
			$num_args                           = count( $args );
			ob_start();
			// Avoid the array_slice if possible.
			if ( $the_['accepted_args'] == 0 ) {
				$value = call_user_func( $the_['function'] );
			} elseif ( $the_['accepted_args'] >= $num_args ) {
				$value = call_user_func_array( $the_['function'], $args );
			} else {
				$value = call_user_func_array( $the_['function'], array_slice( $args, 0, (int) $the_['accepted_args'] ) );
			}
			$notice_content = ob_get_clean();

			// Only enqueue callbacks that printed messages
			if ( ! empty($notice_content) ){
				wp_admin_enqueue_notice($notice_content, 'html', null, $priority-1);
			}


			remove_filter( $hook_name, $the_['function'], $priority );
		}
	}

}


/**
 * Add our new 'admin_notice_register' to the end of (deprecated) 'admin_notices'
 * 
 * When converting from plugin to core:
 * 
 * In wp-admin/admin-header.php
 * we will need to replace:
 * 
 * do_action( 'admin_notices' );
 * do_action( 'user_admin_notices' );
 * do_action( 'network_admin_notices' );
 * do_action( 'all_admin_notices' );
 * 
 * with:
 * 
 * do_action('admin_notice_register');
 * 
 * Hooks 'admin_notices' etc. should still exist (deprecated) for old plugins to hook their callbacks on.
 * But we will not trigger do_action() for them.
 */
add_action( 'admin_notices', 'do_admin_notice_register', 9000 ); // arbitrary number - we're removing all else anyway :P
function do_admin_notice_register(){
	do_action( 'admin_notice_register' );
}


/**
 * Our new API function
 * 
 * Wrap/format notice as html wp admin notice
 * add notice to 'admin_notice_register' hook
 * 
 * Internals are unimportant.
 * This is just a POC
 * 
 * This should be expanded to use a global class
 * like so:
 * 
 * global $wp_notice_manager
 * 
 * $wp_notice_manager->add_notice()
 * $wp_notice_manager->_render()
 * ...
 * etc.
 * 
 */
function wp_admin_notice_register( $msg, $type='info', $dismissible=false, $priority=10 ){

	if ( $type == 'html' ){
		$notice = $msg;
	}else{
		switch ($type){
			case 'info':
			case 'eror':
			case 'success':
				$notice_class = "notice-$type";
				break;
			default:
				$notice_class = '';
		}
		

		$notice = sprintf(
			'<div class="notice %s %s"><p>%s</p></div>',
			$notice_class,
			$dismissible ? 'is-dismissible' : '',
			$msg
		);
	}

	add_action('admin_notice_register',function()use($notice){echo $notice;},$priority);
}


/**
 * Our new API function
 * Wrapper function (alternative API)
 */
function wp_admin_enqueue_notice( $msg, $type='info', $dismissible=false, $priority=10 ){
	wp_admin_notice_register($msg, $type, $dismissible, $priority);
}


// Test our API functions
wp_admin_notice_register( 'wp_admin_notice_register WORKS!', 'success', true);
wp_admin_enqueue_notice( 'wp_admin_enqueue_notice works TOO!');