[4.x] Add UrlInvalidated event to fire after a url has been invalidated

src/Events/UrlInvalidated.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Statamic\Events;
+
+use Statamic\StaticCaching\Cacher;
+
+class UrlInvalidated extends Event
+{
+    public $url;
+
+    public function __construct($url, $domain = null)
+    {
+        $domain ??= app(Cacher::class)->getBaseUrl();
+
+        $this->url = $domain.$url;
+    }
+}

src/StaticCaching/Cachers/ApplicationCacher.php

@@ -3,6 +3,7 @@
 namespace Statamic\StaticCaching\Cachers;
 
 use Illuminate\Http\Request;
+use Statamic\Events\UrlInvalidated;
 
 class ApplicationCacher extends AbstractCacher
 {
@@ -108,5 +109,7 @@ public function invalidateUrl($url, $domain = null)
                 $this->cache->forget($this->normalizeKey('responses:'.$key));
                 $this->forgetUrl($key);
             });
+
+        UrlInvalidated::dispatch($url, $domain);
     }
 }

src/StaticCaching/Cachers/FileCacher.php

@@ -5,6 +5,7 @@
 use Illuminate\Contracts\Cache\Repository;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Log;
+use Statamic\Events\UrlInvalidated;
 use Statamic\Facades\File;
 use Statamic\Facades\Site;
 use Statamic\StaticCaching\Replacers\CsrfTokenReplacer;
@@ -122,6 +123,8 @@ public function invalidateUrl($url, $domain = null)
                 $this->writer->delete($this->getFilePath($value, $site));
                 $this->forgetUrl($key, $domain);
             });
+
+        UrlInvalidated::dispatch($url, $domain);
     }
 
     public function getCachePaths()

src/StaticCaching/Cachers/NullCacher.php

@@ -41,4 +41,9 @@ public function getUrls($domain = null)
     {
         return collect();
     }
+
+    public function getBaseUrl()
+    {
+        //
+    }
 }

tests/StaticCaching/ApplicationCacherTest.php

@@ -4,6 +4,9 @@
 
 use Illuminate\Contracts\Cache\Repository;
 use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Event;
+use Statamic\Events\UrlInvalidated;
+use Statamic\StaticCaching\Cacher;
 use Statamic\StaticCaching\Cachers\ApplicationCacher;
 use Tests\TestCase;
 
@@ -105,6 +108,37 @@ public function invalidating_a_url_will_invalidate_all_query_string_versions_too
         $this->assertNotNull($cache->get('static-cache:responses:two'));
     }
 
+    /**
+     * @test
+     *
+     * @dataProvider invalidateEventProvider
+     */
+    public function invalidating_a_url_dispatches_event($domain, $expectedUrl)
+    {
+        Event::fake();
+
+        $cache = app(Repository::class);
+        $cacher = new ApplicationCacher($cache, ['base_url' => 'http://base.com']);
+
+        // Put it in the container so that the event can resolve it.
+        $this->instance(Cacher::class, $cacher);
+
+        $cacher->invalidateUrl('/foo', $domain);
+
+        Event::assertDispatched(UrlInvalidated::class, function ($event) use ($expectedUrl) {
+            return $event->url === $expectedUrl;
+        });
+    }
+
+    public function invalidateEventProvider()
+    {
+        return [
+            'no domain' => [null, 'http://base.com/foo'],
+            'configured base domain' => ['http://base.com', 'http://base.com/foo'],
+            'another domain' => ['http://another.com', 'http://another.com/foo'],
+        ];
+    }
+
     /** @test */
     public function it_flushes()
     {

tests/StaticCaching/FileCacherTest.php

@@ -3,7 +3,10 @@
 namespace Tests\StaticCaching;
 
 use Illuminate\Contracts\Cache\Repository;
+use Illuminate\Support\Facades\Event;
+use Statamic\Events\UrlInvalidated;
 use Statamic\Facades\Site;
+use Statamic\StaticCaching\Cacher;
 use Statamic\StaticCaching\Cachers\FileCacher;
 use Statamic\StaticCaching\Cachers\Writer;
 use Tests\TestCase;
@@ -292,6 +295,38 @@ public function invalidating_a_url_deletes_the_file_and_removes_the_url_when_usi
         $this->assertEquals(['one' => '/one'], $cacher->getUrls('http://domain.de')->all());
     }
 
+    /**
+     * @test
+     *
+     * @dataProvider invalidateEventProvider
+     */
+    public function invalidating_a_url_dispatches_event($domain, $expectedUrl)
+    {
+        Event::fake();
+
+        $writer = \Mockery::spy(Writer::class);
+        $cache = app(Repository::class);
+        $cacher = $this->fileCacher(['base_url' => 'http://base.com'], $writer, $cache);
+
+        // Put it in the container so that the event can resolve it.
+        $this->instance(Cacher::class, $cacher);
+
+        $cacher->invalidateUrl('/foo', $domain);
+
+        Event::assertDispatched(UrlInvalidated::class, function ($event) use ($expectedUrl) {
+            return $event->url === $expectedUrl;
+        });
+    }
+
+    public function invalidateEventProvider()
+    {
+        return [
+            'no domain' => [null, 'http://base.com/foo'],
+            'configured base domain' => ['http://base.com', 'http://base.com/foo'],
+            'another domain' => ['http://another.com', 'http://another.com/foo'],
+        ];
+    }
+
     private function cacheKey($domain)
     {
         return 'static-cache:'.md5($domain).'.urls';