Update the javascript tracker on several events:

- when Piwik updates
- when a plugin is enabled or disabled
- when the plugin settings are updated

CustomTrackerJs.php

@@ -8,14 +8,20 @@
 
 namespace Piwik\Plugins\CustomTrackerJs;
 
+use Piwik\Log;
 use Piwik\Plugin;
 
 class CustomTrackerJs extends Plugin
 {
     public function getListHooksRegistered()
     {
         return array(
-            'CustomTrackerJs.getTrackerJsAdditions' => 'getTrackerJsAdditions',
+            'CustomTrackerJs.getTrackerJsAdditions'    => 'getTrackerJsAdditions',
+            // Update the tracker when one of these events is raised
+            'Settings.CustomTrackerJs.settingsUpdated' => 'updateTracker',
+            'CoreUpdater.update.end'                   => 'updateTracker',
+            'PluginManager.pluginDeactivated'          => 'updateTracker',
+            'PluginManager.pluginActivated'            => 'updateTracker',
         );
     }
 
@@ -34,4 +40,14 @@ public function getTrackerJsAdditions(&$code)
             $code .= PHP_EOL . $addition;
         }
     }
+
+    public function updateTracker()
+    {
+        try {
+            $trackerUpdater = new TrackerUpdater();
+            $trackerUpdater();
+        } catch (\Exception $e) {
+            Log::error('There was an error while updating the javascript tracker: ' . $e->getMessage());
+        }
+    }
 }

TrackerUpdater.php

@@ -29,6 +29,10 @@ public function __construct($file = null)
 
     public function __invoke()
     {
+        if (! (file_exists($this->file) && is_readable($this->file) && is_writable($this->file))) {
+            throw new \InvalidArgumentException("The file '$this->file' doesn't exist or is not writable");
+        }
+
         $originalJs = file_get_contents($this->file);
         $addition = $this->getCustomJsAdditions();
 

tests/Integration/TrackerUpdaterTest.php

@@ -97,4 +97,14 @@ public function testMultipleEventListeners()
 
         $this->assertEquals($expected, file_get_contents($this->file));
     }
+
+    /**
+     * @expectedException \InvalidArgumentException
+     * @expectedExceptionMessage The file 'foobar' doesn't exist or is not writable
+     */
+    public function testUnknownFile()
+    {
+        $updater = new TrackerUpdater('foobar');
+        $updater();
+    }
 }