1 files changed, 59 insertions, 0 deletions
diff --git a/middlewares/CacheMiddleware.php b/middlewares/CacheMiddleware.php
new file mode 100644
index 00000000..ae0d0d33
--- /dev/null
+++ b/middlewares/CacheMiddleware.php
@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+class CacheMiddleware implements Middleware
+{
+    private CacheInterface $cache;
+
+    public function __construct(CacheInterface $cache)
+    {
+        $this->cache = $cache;
+    }
+
+    public function __invoke(Request $request, $next): Response
+    {
+        $action = $request->attribute('action');
+
+        if ($action !== 'DisplayAction') {
+            // We only cache DisplayAction (for now)
+            return $next($request);
+        }
+
+        // TODO: might want to remove som params from query
+        $cacheKey = 'http_' . json_encode($request->toArray());
+        $cachedResponse = $this->cache->get($cacheKey);
+
+        if ($cachedResponse) {
+            $ifModifiedSince = $request->server('HTTP_IF_MODIFIED_SINCE');
+            $lastModified = $cachedResponse->getHeader('last-modified');
+            if ($ifModifiedSince && $lastModified) {
+                $lastModified = new \DateTimeImmutable($lastModified);
+                $lastModifiedTimestamp = $lastModified->getTimestamp();
+                $modifiedSince = strtotime($ifModifiedSince);
+                // TODO: \DateTimeImmutable can be compared directly
+                if ($lastModifiedTimestamp <= $modifiedSince) {
+                    $modificationTimeGMT = gmdate('D, d M Y H:i:s ', $lastModifiedTimestamp);
+                    return new Response('', 304, ['last-modified' => $modificationTimeGMT . 'GMT']);
+                }
+            }
+            return $cachedResponse;
+        }
+
+        /** @var Response $response */
+        $response = $next($request);
+
+        if (in_array($response->getCode(), [403, 429, 500, 503])) {
+            // Cache these responses for about ~20 mins on average
+            $this->cache->set($cacheKey, $response, 60 * 15 + rand(1, 60 * 10));
+        }
+
+        // For 1% of requests, prune cache
+        if (rand(1, 100) === 1) {
+            // This might be resource intensive!
+            $this->cache->prune();
+        }
+
+        return $response;
+    }
+}
+\ No newline at end of file