Added config post-processor which sets proper allowed methods based on redirect status codes

module/Core/src/Config/PostProcessor/ShortUrlMethodsProcessor.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Core\Config\PostProcessor;
+
+use Fig\Http\Message\RequestMethodInterface;
+use Mezzio\Router\Route;
+use Shlinkio\Shlink\Core\Action\RedirectAction;
+use Shlinkio\Shlink\Core\Util\RedirectStatus;
+
+use function array_values;
+use function count;
+use function Functional\partition;
+
+use const Shlinkio\Shlink\DEFAULT_REDIRECT_STATUS_CODE;
+
+class ShortUrlMethodsProcessor
+{
+    public function __invoke(array $config): array
+    {
+        [$redirectRoutes, $rest] = partition(
+            $config['routes'] ?? [],
+            static fn (array $route) => $route['name'] === RedirectAction::class,
+        );
+        if (count($redirectRoutes) === 0) {
+            return $config;
+        }
+
+        [$redirectRoute] = array_values($redirectRoutes);
+        $redirectStatus = RedirectStatus::tryFrom(
+            $config['redirects']['redirect_status_code'] ?? 0,
+        ) ?? DEFAULT_REDIRECT_STATUS_CODE;
+        $redirectRoute['allowed_methods'] = $redirectStatus->isLegacyStatus()
+            ? [RequestMethodInterface::METHOD_GET]
+            : Route::HTTP_METHOD_ANY;
+
+        $config['routes'] = [...$rest, $redirectRoute];
+        return $config;
+    }
+}