feature #50264 [AssetMapper] Flexible public paths + relative path imports + possibility of "building" assets (weaverryan)

This PR was squashed before being merged into the 6.3 branch.

Discussion
----------

[AssetMapper] Flexible public paths + relative path imports + possibility of "building" assets

| Q             | A
| ------------- | ---
| Branch?       | 6.3
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | no
| Tickets       | None
| License       | MIT
| Doc PR        | Still a TODO in general

Hi!

Working hard to see where AssetMapper adjustments need to be made. 3 changes proposed here:

1) AssetMapper's "public output path" awareness was moved to a new `PublicAssetsPathResolver` service
2) The asset compilers were updated to use relative paths when adjusting paths in files.
3) Drop the "mime type" stuff entirely - except for the "dev server" so it can set the content-type. Asset compiler's can use `$mappedAsset->getPublicExtension()` instead.

### Why these changes?

1) **Allow public/assets/ structure to flatten/change**

The new `PublicAssetsPathResolver` + the "adjustment" of import/url paths in the compilers allows the "output" directory structure to be decoupled from the source structure. Currently the output structure matches your "source" structure, so you get things like `public/assets/styles/app.css` or `public/assets/bundles/easyadmin/foo.css`. We could add an option in the future (or the user could decorate `PublicAssetsPathResolver` immediately) to "flatten" everything into just `public/assets/`.

2) **Allow for building of certain files, like `.scss` or `.jsx`**

These changes allow users to create... more controversial functionality that could build certain files automatically. For example, you could have:

```twig
<link rel="stylesheet" href="{{ asset('styles/app.scss') }}">
```

Locally, I have a custom compiler that executes the `dart-sass` binary to convert this to CSS. Then, by decorating `PublicAssetsPathResolver`, I'm changing the public path for `styles/app.scss` so that it ends with `.css`. This is about 50 lines of code that results in the sass-compiled CSS file being properly rendered onto the page.

I have a similar compiler + path decorator locally that compiles `.jsx` => `.js` using the babel binary. Usage:

```javascript
// assets/app.js
import HelloWorldComponent from './HelloReact.jsx';

// ... render like normal
```

I realize usage like this is more controversial... however it's also super pragmatic if you DO use Sass or have some React components. The alternative would be to run the `sass` binary manually, import the built `.css` file and probably ignore that file from `git`.

Thanks for your consideration :).

Cheers!

Commits
-------

53e297db92 [AssetMapper] Flexible public paths + relative path imports + possibility of "building" assets

Author: fabpot

DependencyInjection/FrameworkExtension.php

@@ -1271,13 +1271,6 @@ private function registerAssetMapperConfiguration(array $config, ContainerBuilde
             $container->removeDefinition('asset_mapper.asset_package');
         }
 
-        $publicDirName = $this->getPublicDirectoryName($container);
-        $container->getDefinition('asset_mapper')
-            ->setArgument(3, $config['public_prefix'])
-            ->setArgument(4, $publicDirName)
-            ->setArgument(5, $config['extensions'])
-        ;
-
         $paths = $config['paths'];
         foreach ($container->getParameter('kernel.bundles_metadata') as $name => $bundle) {
             if ($container->fileExists($dir = $bundle['path'].'/Resources/public') || $container->fileExists($dir = $bundle['path'].'/public')) {
@@ -1287,11 +1280,20 @@ private function registerAssetMapperConfiguration(array $config, ContainerBuilde
         $container->getDefinition('asset_mapper.repository')
             ->setArgument(0, $paths);
 
+        $publicDirName = $this->getPublicDirectoryName($container);
+        $container->getDefinition('asset_mapper.public_assets_path_resolver')
+            ->setArgument(1, $config['public_prefix'])
+            ->setArgument(2, $publicDirName);
+
         $container->getDefinition('asset_mapper.command.compile')
-            ->setArgument(4, $publicDirName);
+            ->setArgument(5, $publicDirName);
 
         if (!$config['server']) {
             $container->removeDefinition('asset_mapper.dev_server_subscriber');
+        } else {
+            $container->getDefinition('asset_mapper.dev_server_subscriber')
+                ->setArgument(1, $config['public_prefix'])
+                ->setArgument(2, $config['extensions']);
         }
 
         $container->getDefinition('asset_mapper.compiler.css_asset_url_compiler')
@@ -1302,9 +1304,9 @@ private function registerAssetMapperConfiguration(array $config, ContainerBuilde
 
         $container
             ->getDefinition('asset_mapper.importmap.manager')
-            ->replaceArgument(1, $config['importmap_path'])
-            ->replaceArgument(2, $config['vendor_dir'])
-            ->replaceArgument(3, $config['provider'])
+            ->replaceArgument(2, $config['importmap_path'])
+            ->replaceArgument(3, $config['vendor_dir'])
+            ->replaceArgument(4, $config['provider'])
         ;
 
         $container

Resources/config/asset_mapper.php

@@ -28,6 +28,7 @@
 use Symfony\Component\AssetMapper\ImportMap\ImportMapManager;
 use Symfony\Component\AssetMapper\ImportMap\ImportMapRenderer;
 use Symfony\Component\AssetMapper\MapperAwareAssetPackage;
+use Symfony\Component\AssetMapper\Path\PublicAssetsPathResolver;
 use Symfony\Component\HttpKernel\Event\RequestEvent;
 
 return static function (ContainerConfigurator $container) {
@@ -36,17 +37,23 @@
             ->args([
                 service('asset_mapper.repository'),
                 service('asset_mapper_compiler'),
-                param('kernel.project_dir'),
-                abstract_arg('asset public prefix'),
-                abstract_arg('public directory name'),
-                abstract_arg('extensions map'),
+                service('asset_mapper.public_assets_path_resolver'),
             ])
         ->alias(AssetMapperInterface::class, 'asset_mapper')
+
         ->set('asset_mapper.repository', AssetMapperRepository::class)
             ->args([
                 abstract_arg('array of asset mapper paths'),
                 param('kernel.project_dir'),
             ])
+
+        ->set('asset_mapper.public_assets_path_resolver', PublicAssetsPathResolver::class)
+            ->args([
+                param('kernel.project_dir'),
+                abstract_arg('asset public prefix'),
+                abstract_arg('public directory name'),
+            ])
+
         ->set('asset_mapper.asset_package', MapperAwareAssetPackage::class)
             ->decorate('assets._default_package')
             ->args([
@@ -57,11 +64,14 @@
         ->set('asset_mapper.dev_server_subscriber', AssetMapperDevServerSubscriber::class)
             ->args([
                 service('asset_mapper'),
+                abstract_arg('asset public prefix'),
+                abstract_arg('extensions map'),
             ])
             ->tag('kernel.event_subscriber', ['event' => RequestEvent::class])
 
         ->set('asset_mapper.command.compile', AssetMapperCompileCommand::class)
             ->args([
+                service('asset_mapper.public_assets_path_resolver'),
                 service('asset_mapper'),
                 service('asset_mapper.importmap.manager'),
                 service('filesystem'),
@@ -102,6 +112,7 @@
         ->set('asset_mapper.importmap.manager', ImportMapManager::class)
             ->args([
                 service('asset_mapper'),
+                service('asset_mapper.public_assets_path_resolver'),
                 abstract_arg('importmap.php path'),
                 abstract_arg('vendor directory'),
                 abstract_arg('provider'),

Tests/DependencyInjection/XmlFrameworkExtensionTest.php

@@ -78,9 +78,11 @@ public function testAssetMapper()
     {
         $container = $this->createContainerFromFile('asset_mapper');
 
-        $definition = $container->getDefinition('asset_mapper');
-        $this->assertSame('/assets_path/', $definition->getArgument(3));
-        $this->assertSame(['zip' => 'application/zip'], $definition->getArgument(5));
+        $definition = $container->getDefinition('asset_mapper.public_assets_path_resolver');
+        $this->assertSame('/assets_path/', $definition->getArgument(1));
+
+        $definition = $container->getDefinition('asset_mapper.dev_server_subscriber');
+        $this->assertSame(['zip' => 'application/zip'], $definition->getArgument(2));
 
         $definition = $container->getDefinition('asset_mapper.importmap.renderer');
         $this->assertSame(['data-turbo-track' => 'reload'], $definition->getArgument(3));