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

config/config.php

@@ -50,4 +50,5 @@ return (new ConfigAggregator\ConfigAggregator([
 ], 'data/cache/app_config.php', [
     Core\Config\PostProcessor\BasePathPrefixer::class,
     Core\Config\PostProcessor\MultiSegmentSlugProcessor::class,
+    Core\Config\PostProcessor\ShortUrlMethodsProcessor::class,
 ]))->getMergedConfig();

config/constants.php

@@ -9,7 +9,7 @@ use Shlinkio\Shlink\Core\Util\RedirectStatus;
 const DEFAULT_DELETE_SHORT_URL_THRESHOLD = 15;
 const DEFAULT_SHORT_CODES_LENGTH = 5;
 const MIN_SHORT_CODES_LENGTH = 4;
-const DEFAULT_REDIRECT_STATUS_CODE = RedirectStatus::STATUS_302;
+const DEFAULT_REDIRECT_STATUS_CODE = RedirectStatus::STATUS_302; // Deprecated. Default to 307 for Shlink v4
 const DEFAULT_REDIRECT_CACHE_LIFETIME = 30;
 const LOCAL_LOCK_FACTORY = 'Shlinkio\Shlink\LocalLockFactory';
 const TITLE_TAG_VALUE = '/<title[^>]*>(.*?)<\/title>/i'; // Matches the value inside a html title tag

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;
+    }
+}

module/Core/test/Config/PostProcessor/ShortUrlMethodsProcessorTest.php

@@ -0,0 +1,105 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ShlinkioTest\Shlink\Core\Config\PostProcessor;
+
+use Mezzio\Router\Route;
+use PHPUnit\Framework\TestCase;
+use Shlinkio\Shlink\Core\Action\RedirectAction;
+use Shlinkio\Shlink\Core\Config\PostProcessor\ShortUrlMethodsProcessor;
+
+class ShortUrlMethodsProcessorTest extends TestCase
+{
+    private ShortUrlMethodsProcessor $processor;
+
+    protected function setUp(): void
+    {
+        $this->processor = new ShortUrlMethodsProcessor();
+    }
+
+    /**
+     * @test
+     * @dataProvider provideConfigs
+     */
+    public function onlyFirstRouteIdentifiedAsRedirectIsEditedWithProperAllowedMethods(
+        array $config,
+        ?array $expectedRoutes,
+    ): void {
+        self::assertEquals($expectedRoutes, ($this->processor)($config)['routes'] ?? null);
+    }
+
+    public function provideConfigs(): iterable
+    {
+        $buildConfigWithStatus = static fn (int $status, ?array $expectedAllowedMethods) => [[
+            'routes' => [
+                ['name' => 'foo'],
+                ['name' => 'bar'],
+                ['name' => RedirectAction::class],
+            ],
+            'redirects' => [
+                'redirect_status_code' => $status,
+            ],
+        ], [
+            ['name' => 'foo'],
+            ['name' => 'bar'],
+            [
+                'name' => RedirectAction::class,
+                'allowed_methods' => $expectedAllowedMethods,
+            ],
+        ]];
+
+        yield 'empty config' => [[], null];
+        yield 'empty routes' => [['routes' => []], []];
+        yield 'no redirects route' => [['routes' => $routes = [
+            ['name' => 'foo'],
+            ['name' => 'bar'],
+        ]], $routes];
+        yield 'one redirects route' => [['routes' => [
+            ['name' => 'foo'],
+            ['name' => 'bar'],
+            ['name' => RedirectAction::class],
+        ]], [
+            ['name' => 'foo'],
+            ['name' => 'bar'],
+            [
+                'name' => RedirectAction::class,
+                'allowed_methods' => ['GET'],
+            ],
+        ]];
+        yield 'one redirects route in different location' => [['routes' => [
+            [
+                'name' => RedirectAction::class,
+                'allowed_methods' => ['POST'],
+            ],
+            ['name' => 'foo'],
+            ['name' => 'bar'],
+        ]], [
+            ['name' => 'foo'],
+            ['name' => 'bar'],
+            [
+                'name' => RedirectAction::class,
+                'allowed_methods' => ['GET'],
+            ],
+        ]];
+        yield 'multiple redirects routes' => [['routes' => [
+            ['name' => RedirectAction::class],
+            ['name' => 'foo'],
+            ['name' => 'bar'],
+            ['name' => RedirectAction::class],
+            ['name' => RedirectAction::class],
+        ]], [
+            ['name' => 'foo'],
+            ['name' => 'bar'],
+            [
+                'name' => RedirectAction::class,
+                'allowed_methods' => ['GET'],
+            ],
+        ]];
+        yield 'one redirects route with invalid status code' => $buildConfigWithStatus(500, ['GET']);
+        yield 'one redirects route with 302 status code' => $buildConfigWithStatus(302, ['GET']);
+        yield 'one redirects route with 301 status code' => $buildConfigWithStatus(301, ['GET']);
+        yield 'one redirects route with 307 status code' => $buildConfigWithStatus(307, Route::HTTP_METHOD_ANY);
+        yield 'one redirects route with 308 status code' => $buildConfigWithStatus(308, Route::HTTP_METHOD_ANY);
+    }
+}