Use composer API instead of checking explicit paths (#3)

* Use composer to find installed packages, and determine the directory to write config and service files to

* Add an explicit require_once for ExtenderManager

* Move require for ExtenderManager

* Fix variable name

* Fix CS

* Fix duplicate call to addConfigFile

src/Extender.php

@@ -10,6 +10,11 @@
 use Composer\EventDispatcher\EventSubscriberInterface;
 use Symfony\Component\Yaml\Yaml;
 
+// Explicitly require ExtenderManager here.
+// When this package is uninstalled, ExtenderManager needs to be available any
+// time this class is available.
+require_once 'ExtenderManager.php';
+
 class Extender implements PluginInterface, EventSubscriberInterface
 {
     /**
@@ -53,16 +58,29 @@ public static function getSubscribedEvents()
     public function processPackages(PackageEvent $event)
     {
         $extenderManager = new ExtenderManager();
-        $directory = realpath(__DIR__.'/../../../../');
-        $extenderManager->processProjectPackages($directory);
-
-        if (is_dir($directory.'/vendor/drupal/console')) {
-            $directory = $directory.'/vendor/drupal/console';
-        } else {
-            $configFile = $directory.'/console.config.yml';
-            $servicesFile = $directory.'/console.services.yml';
-            $extenderManager->addConfigFile($configFile);
-            $extenderManager->addServicesFile($servicesFile);
+
+        $composer = $event->getComposer();
+        $installationManager = $composer->getInstallationManager();
+        $repositoryManager = $composer->getRepositoryManager();
+        $localRepository = $repositoryManager->getLocalRepository();
+
+        foreach ($localRepository->getPackages() as $package) {
+          if ($installationManager->isPackageInstalled($localRepository, $package)) {
+            if ($package->getType() === 'drupal-console-library') {
+              $extenderManager->addServicesFile($installationManager->getInstallPath($package) . '/console.services.yml');
+              $extenderManager->addConfigFile($installationManager->getInstallPath($package) . '/console.config.yml');
+            }
+          }
+        }
+
+        if ($consolePackage = $localRepository->findPackage('drupal/console', '*')) {
+          if ($localRepository->hasPackage($consolePackage)) {
+            $directory = $installationManager->getInstallPath($consolePackage);
+          }
+        }
+        if (empty($directory)) {
+          // cwd should be the project root.  This is the same logic Symfony uses.
+          $directory = getcwd();
         }
 
         $configFile = $directory . '/extend.console.config.yml';