Self-Hosted WordPress Plugin Updates (Client Plugin)

self-hosted-plugin-updates-client.php

<?php

/*
Plugin Name: Self-Hosted WordPress Plugin Updates - Client
Description: Demo plugin showcasing a client plugin which updates from a custom update server.
Version: 1.0.0
Author: Drazen Bebic
Author URI: https://drazen.bebic.dev
Text Domain: shwpuc
Domain Path: /languages
*/

// Current plugin version.
define( "SHWPUC_PLUGIN_VERSION", "1.0.0" );

// Output of this will be
// "self-hosted-plugin-updates/self-hosted-plugin-updates.php".
define( "SHWPUC_PLUGIN_SLUG", plugin_basename( __FILE__ ) );

// Set the server base URL. This should
// be replaced with the actual URL of
// your update server.
define( "SHWPUC_API_BASE_URL", "https://example.com/wp-json/shwpus/v1" );

/**
 * Returns the plugin slug: self-hosted-plugin-updates
 *
 * @return string
 */
function shwpuc_get_plugin_slug() {
	// We split this string because we need the
	// slug without the fluff.
	list ( $t1, $t2 ) = explode( '/', SHWPUC_PLUGIN_SLUG );

	// This will remove the ".php" from the
	// "self-hosted-plugin-updates.php" string
	// and leave us with the slug only.
	return str_replace( '.php', '', $t2 );
}

/**
 * Add our self-hosted auto-update plugin
 * to the filter transient.
 *
 * @param $transient
 *
 * @return object $transient
 */
function shwpuc_check_for_update( $transient ) {
	// This will be "self-hosted-plugin-updates-client"
	$slug = shwpuc_get_plugin_slug();

	// Set the server base URL. This should be replaced
	// with the actual URL of your update server.
	$api_base = SHWPUC_API_BASE_URL;

	// This needs to be obtained from the
	// site settings. Somewhere set by a
	// setting your plugin provides.
	$license_i_surely_paid_for = 'XXX-YYY-ZZZ';

	// Get the remote version.
	$remote_version = shwpuc_get_remote_version( $slug );

	// This is the URL the new plugin
	// version will be downloaded from.
	$download_url = "$api_base/package/$slug.$remote_version.zip?license=$license_i_surely_paid_for";

	// If a newer version is available, add the update.
	if ( $remote_version
		&& version_compare( SHWPUC_PLUGIN_VERSION, $remote_version, '<' )
	) {
		$obj              = new stdClass();
		$obj->slug        = $slug;
		$obj->new_version = $remote_version;
		$obj->url         = $download_url;
		$obj->package     = $download_url;

		$transient->response[ SHWPUC_PLUGIN_SLUG ] = $obj;
	}

	return $transient;
}

// Define the alternative API for updating checking
add_filter( 'pre_set_site_transient_update_plugins', 'shwpuc_check_for_update' );

/**
 * Return the latest version of a plugin on
 * the remote update server.
 *
 * @return string|null $remote_version
 */
function shwpuc_get_remote_version( $slug ) {
	$api_base = SHWPUC_API_BASE_URL;
	$license  = 'XXX-YYY-ZZZ';
	$url      = "$api_base/version/$slug?license=$license";
	$request  = wp_remote_get( $url );

	if ( ! is_wp_error( $request )
	     || wp_remote_retrieve_response_code( $request ) === 200
	) {
		return $request['body'];
	}

	return null;
}

/**
 * Add our self-hosted description to the filter
 *
 * @param boolean  $false
 * @param array    $action
 * @param stdClass $arg
 *
 * @return bool|stdClass
 */
function shwpuc_check_info( $false, $action, $arg ) {
	// This will be "self-hosted-plugin-updates"
	$slug = shwpuc_get_plugin_slug();

	// Abort early if this isn't our plugin.
	if ( $arg->slug !== $slug ) {
		return false;
	}

	// Set the server base URL. This should be replaced
	// with the actual URL of your update server.
	$api_base = SHWPUC_API_BASE_URL;
	$license  = 'XXX-YYY-ZZZ';
	$url      = "$api_base/info/$slug?license=$license";
	$request  = wp_remote_get( $url );

	if ( ! is_wp_error( $request )
		|| wp_remote_retrieve_response_code( $request ) === 200
	) {
		return unserialize( $request['body'] );
	}

	return null;
}

// Define the alternative response for information checking
add_filter( 'plugins_api', 'shwpuc_check_info', 10, 3 );