Allow using custom PostCSS configuration file

config/services.php

@@ -1,12 +1,11 @@
 <?php
 
 use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
-
 use Symfonycasts\TailwindBundle\AssetMapper\TailwindCssAssetCompiler;
 use Symfonycasts\TailwindBundle\Command\TailwindBuildCommand;
 use Symfonycasts\TailwindBundle\Command\TailwindInitCommand;
-use Symfonycasts\TailwindBundle\TailwindBinary;
 use Symfonycasts\TailwindBundle\TailwindBuilder;
+
 use function Symfony\Component\DependencyInjection\Loader\Configurator\abstract_arg;
 use function Symfony\Component\DependencyInjection\Loader\Configurator\param;
 use function Symfony\Component\DependencyInjection\Loader\Configurator\service;
@@ -26,11 +25,12 @@
                 abstract_arg('path to tailwind binary'),
                 abstract_arg('Tailwind binary version'),
                 abstract_arg('path to Tailwind CSS config file'),
+                abstract_arg('path to PostCSS config file'),
             ])
 
         ->set('tailwind.command.build', TailwindBuildCommand::class)
             ->args([
-                service('tailwind.builder')
+                service('tailwind.builder'),
             ])
             ->tag('console.command')
 
@@ -42,11 +42,10 @@
 
         ->set('tailwind.css_asset_compiler', TailwindCssAssetCompiler::class)
             ->args([
-                service('tailwind.builder')
+                service('tailwind.builder'),
             ])
             ->tag('asset_mapper.compiler', [
                 // run before core CssAssetUrlCompiler that resolves url() references
                 'priority' => 10,
-            ])
-    ;
+            ]);
 };

doc/index.rst

@@ -189,7 +189,7 @@ the default directories, for example, in the ``vendor/`` directory like the
 .. code-block:: yaml
 
     # config/packages/twig.yaml
-    twig:    
+    twig:
         form_themes:
             - 'tailwind_2_layout.html.twig'
 
@@ -234,6 +234,25 @@ if you want to use a different version, you can specify the version to use,
 set ``binary_version`` option:
 
 .. code-block:: yaml
+
     # config/packages/symfonycasts_tailwind.yaml
     symfonycasts_tailwind:
         binary_version: 'v3.3.0'
+
+Using a PostCSS config file
+------------------------
+
+If you want to use additional PostCSS plugins, you can specify the
+PostCSS config file to use, set ``postcss_config_file`` option or
+pass the ``--postcss`` option to the ``tailwind:build`` command.
+
+.. code-block:: yaml
+
+    # config/packages/symfonycasts_tailwind.yaml
+    symfonycasts_tailwind:
+        postcss_config_file: 'postcss.config.js'
+
+
+.. code-block:: terminal
+
+    $ php bin/console tailwind:build --postcss='postcss.config.js'

src/Command/TailwindBuildCommand.php

@@ -37,6 +37,7 @@ protected function configure(): void
             ->addOption('watch', 'w', null, 'Watch for changes and rebuild automatically')
             ->addOption('poll', null, null, 'Use polling instead of filesystem events when watching')
             ->addOption('minify', 'm', InputOption::VALUE_NONE, 'Minify the output CSS')
+            ->addOption('postcss', null, InputOption::VALUE_REQUIRED, 'Load custom PostCSS configuration')
         ;
     }
 
@@ -50,6 +51,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             poll: $input->getOption('poll'),
             minify: $input->getOption('minify'),
             inputFile: $input->getArgument('input_css'),
+            postCssConfigFile: $input->getOption('postcss'),
         );
         $process->wait(function ($type, $buffer) use ($io) {
             $io->write($buffer);

src/DependencyInjection/TailwindExtension.php

@@ -32,6 +32,7 @@ public function load(array $configs, ContainerBuilder $container): void
             ->replaceArgument(4, $config['binary'])
             ->replaceArgument(5, $config['binary_version'])
             ->replaceArgument(6, $config['config_file'])
+            ->replaceArgument(7, $config['postcss_config_file'])
         ;
     }
 
@@ -71,6 +72,10 @@ public function getConfigTreeBuilder(): TreeBuilder
                     ->info('Tailwind CLI version to download - null means the latest version')
                     ->defaultNull()
                 ->end()
+                ->scalarNode('postcss_config_file')
+                    ->info('Path to PostCSS config file which is passed to the Tailwind CLI')
+                    ->defaultNull()
+                ->end()
             ->end();
 
         return $treeBuilder;

src/TailwindBuilder.php

@@ -34,6 +34,7 @@ public function __construct(
         private readonly ?string $binaryPath = null,
         private readonly ?string $binaryVersion = null,
         private readonly string $configPath = 'tailwind.config.js',
+        private readonly ?string $postCssconfigPath = null,
     ) {
         $paths = [];
         foreach ($inputPaths as $inputPath) {
@@ -48,6 +49,7 @@ public function runBuild(
         bool $poll,
         bool $minify,
         ?string $inputFile = null,
+        ?string $postCssConfigFile = null,
     ): Process {
         $binary = $this->createBinary();
 
@@ -66,6 +68,12 @@ public function runBuild(
         if ($minify) {
             $arguments[] = '--minify';
         }
+
+        $postCssConfigPath = $this->validatePostCssConfigFile($postCssConfigFile ?? $this->postCssconfigPath);
+        if ($postCssConfigPath) {
+            $arguments[] = '--postcss';
+            $arguments[] = $postCssConfigPath;
+        }
         $process = $binary->createProcess($arguments);
         if ($watch) {
             $process->setTimeout(null);
@@ -145,6 +153,23 @@ private function validateInputFile(string $inputPath): string
         throw new \InvalidArgumentException(\sprintf('The input CSS file "%s" does not exist.', $inputPath));
     }
 
+    private function validatePostCssConfigFile(?string $postCssConfigPath): ?string
+    {
+        if (null === $postCssConfigPath) {
+            return null;
+        }
+
+        if (is_file($postCssConfigPath)) {
+            return realpath($postCssConfigPath);
+        }
+
+        if (is_file($this->projectRootDir.'/'.$postCssConfigPath)) {
+            return realpath($this->projectRootDir.'/'.$postCssConfigPath);
+        }
+
+        throw new \InvalidArgumentException(\sprintf('The PostCSS config file "%s" does not exist.', $postCssConfigPath));
+    }
+
     private function createBinary(): TailwindBinary
     {
         return new TailwindBinary($this->tailwindVarDir, $this->projectRootDir, $this->binaryPath, $this->binaryVersion, $this->cache, $this->output);

tests/TailwindBuilderTest.php

@@ -106,4 +106,26 @@ public function testBuildProvidedInputFile(): void
         $outputFileContents = file_get_contents(__DIR__.'/fixtures/var/tailwind/second.built.css');
         $this->assertStringContainsString('body{background-color:blue}', $outputFileContents, 'The output file should contain minified CSS.');
     }
+
+    public function testIntegrationWithPostcss(): void
+    {
+        $builder = new TailwindBuilder(
+            __DIR__.'/fixtures',
+            [__DIR__.'/fixtures/assets/styles/app.css'],
+            __DIR__.'/fixtures/var/tailwind',
+            new ArrayAdapter(),
+            null,
+            null,
+            __DIR__.'/fixtures/tailwind.config.js',
+            __DIR__.'/fixtures/postcss.config.js',
+        );
+        $process = $builder->runBuild(watch: false, poll: false, minify: false);
+        $process->wait();
+
+        $this->assertTrue($process->isSuccessful());
+        $this->assertFileExists(__DIR__.'/fixtures/var/tailwind/app.built.css');
+
+        $outputFileContents = file_get_contents(__DIR__.'/fixtures/var/tailwind/app.built.css');
+        $this->assertStringContainsString('.dummy {}', $outputFileContents, 'The output file should contain the dummy CSS added by the dummy plugin.');
+    }
 }

tests/fixtures/postcss.config.js

@@ -0,0 +1,10 @@
+module.exports = {
+  plugins: [
+    {
+      postcssPlugin: 'dummy',
+      Once (root) {
+        root.append('.dummy {}')
+      },
+    },
+  ],
+}