[5.x] Static cache response statuses (#10334)

src/StaticCaching/Middleware/Cache.php

@@ -15,6 +15,7 @@
 use Statamic\StaticCaching\NoCache\RegionNotFound;
 use Statamic\StaticCaching\NoCache\Session;
 use Statamic\StaticCaching\Replacer;
+use Statamic\StaticCaching\ResponseStatus;
 use Symfony\Component\Lock\LockFactory;
 use Symfony\Component\Lock\NoLock;
 use Symfony\Component\Lock\Store\FlockStore;
@@ -99,6 +100,8 @@ private function attemptToGetCachedResponse($request)
 
             $this->makeReplacements($response);
 
+            $response->setStaticCacheResponseStatus(ResponseStatus::HIT);
+
             return $response;
         }
     }

src/StaticCaching/ResponseStatus.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace Statamic\StaticCaching;
+
+enum ResponseStatus
+{
+    case HIT;
+    case MISS;
+    case UNDEFINED;
+}

src/StaticCaching/ResponseStatusTracker.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace Statamic\StaticCaching;
+
+use Illuminate\Http\Response;
+
+class ResponseStatusTracker
+{
+    private array $responses = [];
+
+    public function set(Response $response, ResponseStatus $status): void
+    {
+        $this->responses[spl_object_id($response)] = $status;
+    }
+
+    public function get(Response $response): ResponseStatus
+    {
+        return $this->responses[spl_object_id($response)] ?? ResponseStatus::UNDEFINED;
+    }
+
+    public function registerMacros(): void
+    {
+        $tracker = $this;
+
+        Response::macro('setStaticCacheResponseStatus', fn ($status) => $tracker->set($this, $status));
+
+        Response::macro('staticCacheResponseStatus', fn () => $tracker->get($this));
+
+        Response::macro('wasStaticallyCached', fn () => $this->staticCacheResponseStatus() === ResponseStatus::HIT);
+    }
+}

src/StaticCaching/ServiceProvider.php

@@ -62,6 +62,8 @@ public function register()
                 $urls
             );
         });
+
+        $this->app->singleton(ResponseStatusTracker::class, fn () => new ResponseStatusTracker);
     }
 
     public function boot()
@@ -87,5 +89,7 @@ public function boot()
 
             return $this;
         });
+
+        $this->app[ResponseStatusTracker::class]->registerMacros();
     }
 }