WP-CLI: Maybe check for updates when certain WP-CLI commands run

See #558. Needs testing.

Puc/v5p3/Plugin/UpdateChecker.php

@@ -17,7 +17,7 @@ if ( !class_exists(UpdateChecker::class, false) ):
 	 */
 	class UpdateChecker extends BaseUpdateChecker {
 		protected $updateTransient = 'update_plugins';
-		protected $translationType = 'plugin';
+		protected $componentType = 'plugin';
 
 		public $pluginAbsolutePath = ''; //Full path of the main plugin file.
 		public $pluginFile = '';  //Plugin filename relative to the plugins directory. Many WP APIs use this to identify plugins.

Puc/v5p3/Theme/UpdateChecker.php

@@ -12,7 +12,7 @@ if ( !class_exists(UpdateChecker::class, false) ):
 	class UpdateChecker extends BaseUpdateChecker {
 		protected $filterSuffix = 'theme';
 		protected $updateTransient = 'update_themes';
-		protected $translationType = 'theme';
+		protected $componentType = 'theme';
 
 		/**
 		 * @var string Theme directory name.

Puc/v5p3/UpdateChecker.php

@@ -9,7 +9,16 @@ if ( !class_exists(UpdateChecker::class, false) ):
 	abstract class UpdateChecker {
 		protected $filterSuffix = '';
 		protected $updateTransient = '';
-		protected $translationType = ''; //This can be "plugin" or "theme".
+
+		/**
+		 * @var string This can be "plugin" or "theme".
+		 */
+		protected $componentType = '';
+		/**
+		 * @var string Currently the same as $componentType, but this is an implementation detail that
+		 *             depends on how WP works internally, and could therefore change.
+		 */
+		protected $translationType = '';
 
 		/**
 		 * Set to TRUE to enable error reporting. Errors are raised using trigger_error()
@@ -74,6 +83,11 @@ if ( !class_exists(UpdateChecker::class, false) ):
 		 */
 		protected $debugBarExtension = null;
 
+		/**
+		 * @var WpCliCheckTrigger|null
+		 */
+		protected $wpCliCheckTrigger = null;
+
 		public function __construct($metadataUrl, $directoryName, $slug = null, $checkPeriod = 12, $optionName = '') {
 			$this->debugMode = (bool)(constant('WP_DEBUG'));
 			$this->metadataUrl = $metadataUrl;
@@ -91,6 +105,10 @@ if ( !class_exists(UpdateChecker::class, false) ):
 				}
 			}
 
+			if ( empty($this->translationType) ) {
+				$this->translationType = $this->componentType;
+			}
+
 			$this->package = $this->createInstalledPackage();
 			$this->scheduler = $this->createScheduler($checkPeriod);
 			$this->upgraderStatus = new UpgraderStatus();
@@ -103,6 +121,10 @@ if ( !class_exists(UpdateChecker::class, false) ):
 			}
 
 			$this->installHooks();
+
+			if ( ($this->wpCliCheckTrigger === null) && defined('WP_CLI') ) {
+				$this->wpCliCheckTrigger = new WpCliCheckTrigger($this->componentType, $this->scheduler);
+			}
 		}
 
 		/**

Puc/v5p3/WpCliCheckTrigger.php

@@ -0,0 +1,87 @@
+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3;
+
+use WP_CLI;
+
+/**
+ * Triggers an update check when relevant WP-CLI commands are executed.
+ *
+ * When WP-CLI runs certain commands like "wp plugin status" or "wp theme list", it calls
+ * wp_update_plugins() and wp_update_themes() to refresh update information. This class hooks into
+ * the same commands and triggers an update check when they are executed.
+ *
+ * Note that wp_update_plugins() and wp_update_themes() do not perform an update check *every* time
+ * they are called. They use a context-dependent delay between update checks. Similarly, this class
+ * calls Scheduler::maybeCheckForUpdates(), which also dynamically decides whether to actually
+ * run a check. If you want to force an update check, call UpdateChecker::checkForUpdates() instead.
+ */
+class WpCliCheckTrigger {
+	/**
+	 * @var Scheduler
+	 */
+	private $scheduler;
+
+	/**
+	 * @var string 'plugin' or 'theme'
+	 */
+	private $componentType;
+
+	/**
+	 * @var bool Whether an update check was already triggered during the current request
+	 *           or script execution.
+	 */
+	private $wasCheckTriggered = false;
+
+	public function __construct($componentType, Scheduler $scheduler) {
+		if ( !in_array($componentType, ['plugin', 'theme']) ) {
+			throw new \InvalidArgumentException('Invalid component type. Must be "plugin" or "theme".');
+		}
+
+		$this->componentType = $componentType;
+		$this->scheduler = $scheduler;
+
+		if ( !defined('WP_CLI') || !class_exists(WP_CLI::class, false) ) {
+			return; //Nothing to do if WP-CLI is not available.
+		}
+
+		/*
+		 * We can't hook directly into wp_update_plugins(), but we can hook into the WP-CLI
+		 * commands that call it. We'll use the "before_invoke:xyz" hook to trigger update checks.
+		 */
+		foreach ($this->getRelevantCommands() as $command) {
+			WP_CLI::add_hook('before_invoke:' . $command, [$this, 'triggerUpdateCheckOnce']);
+		}
+	}
+
+	private function getRelevantCommands() {
+		$result = [];
+		foreach (['status', 'list', 'update'] as $subcommand) {
+			$result[] = $this->componentType . ' ' . $subcommand;
+		}
+		return $result;
+	}
+
+	/**
+	 * Trigger a potential update check once.
+	 *
+	 * The update transient can be read multiple times during a single WP-CLI command execution.
+	 * For performance, we only want to trigger an update check once.
+	 *
+	 * @param mixed $transient
+	 * @return mixed The input value, unchanged.
+	 * @internal This method is public so that it can be used as a WP-CLI hook callback.
+	 *           It should not be called directly.
+	 *
+	 */
+	public function triggerUpdateCheckOnce($transient) {
+		if ( $this->wasCheckTriggered ) {
+			return $transient;
+		}
+
+		$this->wasCheckTriggered = true;
+		$this->scheduler->maybeCheckForUpdates();
+
+		return $transient;
+	}
+}