Adds header for preloading Tailwind assets

src/Http/Middleware/AddLinkHeaderForPreloadedAssets.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace Tonysm\TailwindCss\Http\Middleware;
+
+use Tonysm\TailwindCss\Manifest;
+
+class AddLinkHeaderForPreloadedAssets
+{
+    public function __construct(private Manifest $manifest)
+    {
+    }
+
+    public function handle($request, $next)
+    {
+        return tap($next($request), function ($response) {
+            if (count($assets = $this->manifest->assetsForPreloading()) > 0) {
+                $response->header('Link', trim(implode(', ', array_filter([
+                    $response->headers->get('Link', null),
+                    ...collect($assets)
+                        ->map(fn ($attributes, $asset) => implode('; ', [
+                            "<$asset>",
+                            ...collect(array_merge(['rel' => 'preload', 'as' => 'style'], $attributes))
+                                ->map(fn ($value, $key) => "{$key}={$value}")
+                                ->all(),
+                        ]))
+                        ->all(),
+                ]))));
+            }
+        });
+    }
+}

src/Manifest.php

@@ -8,6 +8,13 @@
 
 class Manifest
 {
+    protected array $preloading = [];
+
+    public function assetsForPreloading(): array
+    {
+        return $this->preloading;
+    }
+
     public static function filename(): string
     {
         return basename(self::path());
@@ -18,7 +25,7 @@ public static function path(): string
         return config('tailwindcss.build.manifest_file_path');
     }
 
-    public function __invoke(string $path)
+    public function __invoke(string $path, $preload = true)
     {
         static $manifests = [];
 
@@ -50,6 +57,12 @@ public function __invoke(string $path)
             }
         }
 
-        return new HtmlString(asset($manifest[$path]));
+        $asset = asset($manifest[$path]);
+
+        if ($preload) {
+            $this->preloading[$asset] = is_array($preload) ? $preload : [];
+        }
+
+        return new HtmlString($asset);
     }
 }

src/TailwindCssServiceProvider.php

@@ -24,4 +24,9 @@ public function configurePackage(Package $package): void
                 Commands\WatchCommand::class,
             ]);
     }
+
+    public function packageRegistered()
+    {
+        $this->app->scoped(Manifest::class);
+    }
 }

src/helpers.php

@@ -8,10 +8,11 @@
      * Get the path to a versioned TailwindCSS file.
      *
      * @param string $path
+     * @param bool|array $preload
      * @return \Illuminate\Support\HtmlString|string
      */
-    function tailwindcss(string $path): HtmlString|string
+    function tailwindcss(string $path, $preload = true): HtmlString|string
     {
-        return app(Manifest::class)($path);
+        return app(Manifest::class)($path, $preload);
     }
 }

tests/PreloadingHeaderTest.php

@@ -0,0 +1,79 @@
+<?php
+
+namespace Tonysm\TailwindCss\Tests;
+
+use Illuminate\Http\Request;
+use Tonysm\TailwindCss\Http\Middleware\AddLinkHeaderForPreloadedAssets;
+
+class PreloadingHeaderTest extends TestCase
+{
+    /** @test */
+    public function no_link_header_when_not_preloading()
+    {
+        config()->set('tailwindcss.build.manifest_file_path', __DIR__.'/stubs/test-manifest.json');
+
+        $tailwindcss = tailwindcss('css/app.css', preload: false);
+
+        $response = resolve(AddLinkHeaderForPreloadedAssets::class)->handle(
+            Request::create('/'),
+            fn () => response('hello world'),
+        );
+
+        $this->assertEquals('http://localhost/css/app-123.css', (string) $tailwindcss);
+        $this->assertEquals('hello world', $response->content());
+        $this->assertNull($response->headers->get('Link', null));
+    }
+
+    /** @test */
+    public function adds_link_header_when_preloading()
+    {
+        config()->set('tailwindcss.build.manifest_file_path', __DIR__.'/stubs/test-manifest.json');
+
+        $tailwindcss = tailwindcss('css/app.css', preload: true);
+
+        $response = resolve(AddLinkHeaderForPreloadedAssets::class)->handle(
+            Request::create('/'),
+            fn () => response('hello world'),
+        );
+
+        $this->assertEquals($asset = 'http://localhost/css/app-123.css', (string) $tailwindcss);
+        $this->assertEquals('hello world', $response->content());
+        $this->assertEquals("<{$asset}>; rel=preload; as=style", $response->headers->get('Link', null));
+    }
+
+    /** @test */
+    public function keeps_existing_preloading_link_header()
+    {
+        config()->set('tailwindcss.build.manifest_file_path', __DIR__.'/stubs/test-manifest.json');
+
+        $tailwindcss = tailwindcss('css/app.css', preload: true);
+
+        $response = resolve(AddLinkHeaderForPreloadedAssets::class)->handle(
+            Request::create('/'),
+            fn () => response('hello world')->withHeaders([
+                'Link' => '</js/app.js>; rel=modulepreload'
+            ]),
+        );
+
+        $this->assertEquals($asset = 'http://localhost/css/app-123.css', (string) $tailwindcss);
+        $this->assertEquals('hello world', $response->content());
+        $this->assertEquals("</js/app.js>; rel=modulepreload, <{$asset}>; rel=preload; as=style", $response->headers->get('Link', null));
+    }
+
+    /** @test */
+    public function adds_link_header_when_preloading_custom_attributes()
+    {
+        config()->set('tailwindcss.build.manifest_file_path', __DIR__.'/stubs/test-manifest.json');
+
+        $tailwindcss = tailwindcss('css/app.css', ['crossorigin' => 'anonymous']);
+
+        $response = resolve(AddLinkHeaderForPreloadedAssets::class)->handle(
+            Request::create('/'),
+            fn () => response('hello world'),
+        );
+
+        $this->assertEquals($asset = 'http://localhost/css/app-123.css', (string) $tailwindcss);
+        $this->assertEquals('hello world', $response->content());
+        $this->assertEquals("<{$asset}>; rel=preload; as=style; crossorigin=anonymous", $response->headers->get('Link', null));
+    }
+}

tests/TestCase.php

@@ -33,5 +33,7 @@ protected function getPackageProviders($app)
     public function getEnvironmentSetUp($app)
     {
         config()->set('database.default', 'testing');
+        config()->set('app.url', 'http://localhost');
+        config()->set('app.asset_url', 'http://localhost');
     }
 }

tests/stubs/test-manifest.json

@@ -0,0 +1,3 @@
+{
+    "/css/app.css": "/css/app-123.css"
+}