Initial commit of sime's work

Closes #3457682

src/InstallReadiness.php

@@ -2,21 +2,36 @@
 
 namespace Drupal\project_browser;
 
+use Drupal\Component\Datetime\TimeInterface;
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\package_manager\Event\PreApplyEvent;
 use Drupal\package_manager\StatusCheckTrait;
+use Drupal\package_manager\ValidationResult;
 use Drupal\project_browser\ComposerInstaller\Installer;
 use Drupal\system\SystemManager;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
 /**
- * Defines Installer service.
+ * Performs status checks before installing projects.
  */
-class InstallReadiness {
+class InstallReadiness implements EventSubscriberInterface {
 
   use StatusCheckTrait;
 
+  /**
+   * The cache key for the status check results.
+   *
+   * @var string
+   */
+  private const CACHE_KEY = 'status_check_results';
+
   public function __construct(
     private readonly Installer $installer,
     private readonly EventDispatcherInterface $eventDispatcher,
+    private readonly TimeInterface $time,
+    private readonly CacheBackendInterface $cache,
+    private readonly int $cacheTimeToLive = 300,
   ) {}
 
   /**
@@ -26,10 +41,24 @@ class InstallReadiness {
    *   errors - an array of messages with severity 2
    *   messages - all other messages below severity 2 (warnings)
    */
-  public function validatePackageManager() {
-    $errors = [];
-    $warnings = [];
-    foreach ($this->runStatusCheck($this->installer, $this->eventDispatcher) as $result) {
+  public function validatePackageManager(): array {
+    if ($cache = $this->cache->get(self::CACHE_KEY)) {
+      $validation_results = $cache->data;
+    }
+    else {
+      $validation_results = $this->runStatusCheck($this->installer, $this->eventDispatcher);
+
+      // Cache the validation results if there were no errors.
+      if (ValidationResult::getOverallSeverity($validation_results) !== SystemManager::REQUIREMENT_ERROR) {
+        $this->cache->set(self::CACHE_KEY, $validation_results, $this->time->getRequestTime() + $this->cacheTimeToLive);
+      }
+    }
+
+    $return = [
+      'errors' => [],
+      'warnings' => [],
+    ];
+    foreach ($validation_results as $result) {
       $messages = $result->messages;
       $summary = $result->summary;
       if ($summary) {
@@ -38,16 +67,14 @@ class InstallReadiness {
       $text = implode("\n", $messages);
 
       if ($result->severity === SystemManager::REQUIREMENT_ERROR) {
-        $errors[] = $text;
+        $return['errors'][] = $text;
       }
       else {
-        $warnings[] = $text;
+        $return['warnings'][] = $text;
       }
     }
-    return [
-      'errors' => $errors,
-      'warnings' => $warnings,
-    ];
+
+    return $return;
   }
 
   /**
@@ -60,4 +87,21 @@ class InstallReadiness {
     return $this->installer->isAvailable();
   }
 
+  /**
+   * Invalidate the readiness check.
+   */
+  public function clearReadinessCheckCache(): void {
+    // @todo Under what conditions should we clear the cache?
+    $this->cache->delete(self::CACHE_KEY);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents(): array {
+    return [
+      PreApplyEvent::class => ['clearReadinessCheckCache'],
+    ];
+  }
+
 }