Add warnings to network plugins screen

src/BackgroundTask/CronBasedBackgroundTask.php

@@ -10,6 +10,7 @@
 use AmpProject\AmpWP\HasActivation;
 use AmpProject\AmpWP\HasDeactivation;
 use AmpProject\AmpWP\Service;
+use function WP_CLI\Utils\get_plugin_name;
 
 /**
  * Abstract base class for using cron to execute a background task.
@@ -33,6 +34,15 @@ abstract class CronBasedBackgroundTask implements Service, HasDeactivation {
 		self::DEFAULT_INTERVAL_DAILY,
 	];
 
+	/**
+	 * Name of the plugin as WordPress is expecting it.
+	 *
+	 * This should usually have the form "amp/amp.php".
+	 *
+	 * @var string
+	 */
+	private $plugin_file;
+
 	/**
 	 * Register the service with the system.
 	 *
@@ -41,6 +51,10 @@ abstract class CronBasedBackgroundTask implements Service, HasDeactivation {
 	public function register() {
 		add_action( 'admin_init', [ $this, 'schedule_event' ] );
 		add_action( $this->get_event_name(), [ $this, 'process' ] );
+
+		$this->plugin_file = plugin_basename( dirname( dirname( __DIR__ ) ) . '/amp.php' );
+		add_action( "network_admin_plugin_action_links_{$this->plugin_file}", [ $this, 'add_warning_sign_to_network_deactivate_action' ], 10, 1 );
+		add_action( 'plugin_row_meta', [ $this, 'add_warning_to_plugin_meta' ], 10, 2 );
 	}
 
 	/**
@@ -70,6 +84,8 @@ public function schedule_event() {
 	 *
 	 * This should be hooked up to the WordPress deactivation hook.
 	 *
+	 * @todo Needs refactoring if used for more than one cron-based task, to avoid iterating over sites multiple times.
+	 *
 	 * @param bool $network_wide Whether the deactivation was done network-wide.
 	 * @return void
 	 */
@@ -90,6 +106,49 @@ public function deactivate( $network_wide ) {
 		}
 	}
 
+	/**
+	 * Add a warning sign to the network deactivate action on the network plugins screen.
+	 *
+	 * @param string[] $actions     An array of plugin action links. By default this can include 'activate',
+	 *                              'deactivate', and 'delete'.
+	 * @return string[]
+	 */
+	public function add_warning_sign_to_network_deactivate_action( $actions ) {
+		if ( ! wp_is_large_network() ) {
+			return $actions;
+		}
+
+		if ( ! array_key_exists( 'deactivate', $actions ) ) {
+			return $actions;
+		}
+
+		$actions['deactivate'] = preg_replace( '#^(<a [^>]*>.*)(</a>)$#i', '$1 ⚠️️️︎️$2', $actions['deactivate'] );
+
+		return $actions;
+	}
+
+	/**
+	 * Add a warning to the plugin meta row on the network plugins screen.
+	 *
+	 * @param string[] $plugin_meta An array of the plugin's metadata, including the version, author, author URI, and
+	 *                              plugin URI.
+	 * @param string   $plugin_file Path to the plugin file relative to the plugins directory.
+	 * @return string[]
+	 */
+	public function add_warning_to_plugin_meta( $plugin_meta, $plugin_file ) {
+		if ( ! is_multisite() || ! wp_is_large_network() ) {
+			return $plugin_meta;
+		}
+
+		if ( $plugin_file !== $this->plugin_file ) {
+			return $plugin_meta;
+		}
+
+		$plugin_meta[] = '⚠️ Large site detected. Deactivation will leave orphaned scheduled events behind. ⚠️';
+
+		return $plugin_meta;
+	}
+
 	/**
 	 * Get the interval to use for the event.
 	 *