feat: resolve IPN secret key by merchant when currency missing

Author: hegedustibor

src/Http/Middleware/VerifySimplePaySignature.php

@@ -26,17 +26,33 @@ public function handle(Request $request, Closure $next): Response
         $body = $request->getContent();
         $data = json_decode($body, true);
 
-        if (! is_array($data) || ! isset($data['currency'])) {
+        if (! is_array($data)) {
             abort(401, 'Invalid SimplePay request body');
         }
 
-        $currency = Currency::from($data['currency']);
-        $secretKey = $this->merchantResolver->getSecretKey($currency);
+        $secretKey = $this->resolveSecretKey($data);
+
+        if (! $secretKey) {
+            abort(401, 'Cannot resolve SimplePay merchant for request');
+        }
 
         if (! Signature::verify($secretKey, $body, $signature)) {
             abort(401, 'Invalid SimplePay signature');
         }
 
         return $next($request);
     }
+
+    private function resolveSecretKey(array $data): ?string
+    {
+        if (isset($data['currency'])) {
+            return $this->merchantResolver->getSecretKey(Currency::from($data['currency']));
+        }
+
+        if (isset($data['merchant'])) {
+            return $this->merchantResolver->getSecretKeyByMerchant($data['merchant']);
+        }
+
+        return null;
+    }
 }

src/Support/MerchantResolver.php

@@ -31,4 +31,17 @@ public function getSecretKey(Currency $currency): string
     {
         return $this->resolve($currency)['secret_key'];
     }
+
+    public function getSecretKeyByMerchant(string $merchant): string
+    {
+        $merchants = config('simplepay.merchants');
+
+        foreach ($merchants as $config) {
+            if (isset($config['merchant'], $config['secret_key']) && $config['merchant'] === $merchant) {
+                return $config['secret_key'];
+            }
+        }
+
+        throw new InvalidArgumentException("SimplePay merchant not configured: {$merchant}");
+    }
 }