Start work on endpoints - at this point just validating urls

src/Endpoint.php

@@ -6,4 +6,29 @@ use Lewisdale\Webmentions\Gateways\WebmentionGatewayInterface;
 
 class Endpoint {
     private readonly WebmentionGatewayInterface $gateway;
+
+    public function validateUrl(string $url) : bool {
+        return !!filter_var($url, FILTER_VALIDATE_URL);
+    }
+
+    public function receiveWebmention(string $source, string $target) : void
+    {
+        // Validate that both source and target are actual domains
+        if (!$this->validateUrl($source) || !$this->validateUrl($target))
+        {
+            return;
+        }
+
+        // Validate that the webmention target is a domain I care about
+        if (!str_contains($target, "https://lewisdale.dev")) {
+            // Should throw a Bad Request error
+            return;  
+        }
+
+        // Parse content from the source
+
+        // Store the webmention
+
+        // Send the appropriate response
+    }
 }