[AsseticBundle] added a --watch option to the assetic:dump command

src/Symfony/Bundle/AsseticBundle/Command/DumpCommand.php

@@ -11,9 +11,12 @@
 
 namespace Symfony\Bundle\AsseticBundle\Command;
 
+use Assetic\Asset\AssetInterface;
+use Assetic\Factory\LazyAssetManager;
 use Symfony\Bundle\FrameworkBundle\Command\Command;
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
 /**
@@ -29,6 +32,7 @@ class DumpCommand extends Command
             ->setName('assetic:dump')
             ->setDescription('Dumps all assets to the filesystem')
             ->addArgument('base_dir', InputArgument::OPTIONAL, 'The base directory')
+            ->addOption('watch', null, InputOption::VALUE_NONE, 'Check for changes every second')
         ;
     }
 
@@ -39,18 +43,95 @@ class DumpCommand extends Command
         }
 
         $am = $this->container->get('assetic.asset_manager');
-        foreach ($am->all() as $name => $asset) {
-            $output->writeln('<info>[asset]</info> '.$name);
-            $asset->load();
-
-            $target = $baseDir . '/' . $asset->getTargetUrl();
-            if (!is_dir($dir = dirname($target))) {
-                $output->writeln('<info>[dir+]</info> '.$dir);
-                mkdir($dir);
+
+        if ($input->getOption('watch')) {
+            return $this->watch($am, $baseDir, $output, $this->container->getParameter('kernel.debug'));
+        }
+
+        foreach ($am->getNames() as $name) {
+            $this->dumpAsset($am->get($name), $baseDir, $output);
+        }
+    }
+
+    /**
+     * Watches a asset manager for changes.
+     *
+     * This method includes an infinite loop the continuously polls the asset
+     * manager for changes.
+     *
+     * @param LazyAssetManager $am      The asset manager
+     * @param string           $baseDir The base directory to write to
+     * @param OutputInterface  $output  The command output
+     * @param Boolean          $debug   Debug mode
+     */
+    protected function watch(LazyAssetManager $am, $baseDir, OutputInterface $output, $debug = false)
+    {
+        $previously = array();
+
+        while (true) {
+            // reload formulae when in debug
+            if ($debug) {
+                $am->load();
+            }
+
+            foreach ($am->getNames() as $name) {
+                if ($asset = $this->checkAsset($am, $name, $previously)) {
+                    $this->dumpAsset($asset, $baseDir, $output);
+                }
+            }
+
+            sleep(1);
+        }
+    }
+
+    /**
+     * Checks if an asset should be dumped.
+     *
+     * @param LazyAssetManager $am         The asset manager
+     * @param string           $name       The asset name
+     * @param array            $previously An array of previous visits
+     *
+     * @return AssetInterface|Boolean The asset if it should be dumped
+     */
+    protected function checkAsset(LazyAssetManager $am, $name, array &$previously)
+    {
+        $formula = serialize($am->getFormula($name));
+        $asset = $am->get($name);
+        $mtime = $asset->getLastModified();
+
+        if (isset($previously[$name])) {
+            $changed = $previously[$name]['mtime'] != $mtime || $previously[$name]['formula'] != $formula;
+        } else {
+            $changed = true;
+        }
+
+        $previously[$name] = array('mtime' => $mtime, 'formula' => $formula);
+
+        return $changed ? $asset : false;
+    }
+
+    /**
+     * Writes an asset.
+     *
+     * @param AssetInterface  $asset   An asset
+     * @param string          $baseDir The base directory to write to
+     * @param OutputInterface $output  The command output
+     *
+     * @throws RuntimeException If there is a problem writing the asset
+     */
+    protected function dumpAsset(AssetInterface $asset, $baseDir, OutputInterface $output)
+    {
+        $target = rtrim($baseDir, '/') . '/' . $asset->getTargetUrl();
+        if (!is_dir($dir = dirname($target))) {
+            $output->writeln('<info>[dir+]</info> '.$dir);
+            if (false === @mkdir($dir)) {
+                throw new \RuntimeException('Unable to create directory '.$dir);
             }
+        }
 
-            $output->writeln('<info>[file+]</info> '.$asset->getTargetUrl());
-            file_put_contents($target, $asset->dump());
+        $output->writeln('<info>[file+]</info> '.$target);
+        if (false === @file_put_contents($target, $asset->dump())) {
+            throw new \RuntimeException('Unable to write file '.$target);
         }
     }
 }