Allow interactive resets or stash/apply cycles when updating dirty packages instead of failing hard

src/Composer/Downloader/GitDownloader.php

@@ -19,6 +19,8 @@ use Composer\Package\PackageInterface;
  */
 class GitDownloader extends VcsDownloader
 {
+    private $hasStashedChanges = false;
+
     /**
      * {@inheritDoc}
      */
@@ -76,6 +78,86 @@ class GitDownloader extends VcsDownloader
         return trim($output) ?: null;
     }
 
+    /**
+     * {@inhertiDoc}
+     */
+    protected function cleanChanges($path, $update)
+    {
+        if (!$this->io->isInteractive()) {
+            return parent::cleanChanges($path, $update);
+        }
+
+        if (!$changes = $this->getLocalChanges($path)) {
+            return;
+        }
+
+        $changes = array_map(function ($elem) {
+            return '    '.$elem;
+        }, preg_split('{\s*\r?\n\s*}', $changes));
+        $this->io->write('    <error>The package has modified files:</error>');
+        $this->io->write(array_slice($changes, 0, 10));
+        if (count($changes) > 10) {
+            $this->io->write('    <info>'.count($changes) - 10 . ' more files modified, choose "v" to view the full list</info>');
+        }
+
+        while (true) {
+            switch ($this->io->ask('    <info>Discard changes [y,n,v,'.($update ? 's,' : '').'?]?</info> ', '?')) {
+                case 'y':
+                    if (0 !== $this->process->execute('git reset --hard', $output, $path)) {
+                        throw new \RuntimeException("Could not reset changes\n\n:".$this->process->getErrorOutput());
+                    }
+                    break 2;
+
+                case 's':
+                    if (!$update) {
+                        goto help;
+                    }
+
+                    if (0 !== $this->process->execute('git stash', $output, $path)) {
+                        throw new \RuntimeException("Could not stash changes\n\n:".$this->process->getErrorOutput());
+                    }
+
+                    $this->hasStashedChanges = true;
+                    break 2;
+
+                case 'n':
+                    throw new \RuntimeException('Update aborted');
+                    break;
+
+                case 'v':
+                    $this->io->write($changes);
+                    break;
+
+                case '?':
+                default:
+                    help:
+                    $this->io->write(array(
+                        '    y - discard changes and apply the '.($update ? 'update' : 'uninstall'),
+                        '    n - abort the '.($update ? 'update' : 'uninstall').' and let you manually clean things up',
+                        '    v - view modified files',
+                    ));
+                    if ($update) {
+                        $this->io->write('    s - stash changes and try to reapply them after the update');
+                    }
+                    $this->io->write('    ? - print help');
+                    break;
+            }
+        }
+    }
+
+    /**
+     * {@inhertiDoc}
+     */
+    protected function reapplyChanges($path)
+    {
+        if ($this->hasStashedChanges) {
+            $this->io->write('    <info>Re-applying stashed changes');
+            if (0 !== $this->process->execute('git stash pop', $output, $path)) {
+                throw new \RuntimeException("Failed to apply stashed changes:\n\n".$this->process->getErrorOutput());
+            }
+        }
+    }
+
     protected function updateToCommit($path, $reference, $branch, $date)
     {
         $template = 'git checkout %s && git reset --hard %1$s';

src/Composer/Downloader/SvnDownloader.php

@@ -79,6 +79,57 @@ class SvnDownloader extends VcsDownloader
         }
     }
 
+    /**
+     * {@inhertiDoc}
+     */
+    protected function cleanChanges($path, $update)
+    {
+        if (!$this->io->isInteractive()) {
+            return parent::cleanChanges($path, $update);
+        }
+
+        if (!$changes = $this->getLocalChanges($path)) {
+            return;
+        }
+
+        $changes = array_map(function ($elem) {
+            return '    '.$elem;
+        }, preg_split('{\s*\r?\n\s*}', $changes));
+        $this->io->write('    <error>The package has modified files:</error>');
+        $this->io->write(array_slice($changes, 0, 10));
+        if (count($changes) > 10) {
+            $this->io->write('    <info>'.count($changes) - 10 . ' more files modified, choose "v" to view the full list</info>');
+        }
+
+        while (true) {
+            switch ($this->io->ask('    <info>Discard changes [y,n,v,?]?</info> ', '?')) {
+                case 'y':
+                    if (0 !== $this->process->execute('svn revert -R .', $output, $path)) {
+                        throw new \RuntimeException("Could not reset changes\n\n:".$this->process->getErrorOutput());
+                    }
+                    break 2;
+
+                case 'n':
+                    throw new \RuntimeException('Update aborted');
+                    break;
+
+                case 'v':
+                    $this->io->write($changes);
+                    break;
+
+                case '?':
+                default:
+                    $this->io->write(array(
+                        '    y - discard changes and apply the '.($update ? 'update' : 'uninstall'),
+                        '    n - abort the '.($update ? 'update' : 'uninstall').' and let you manually clean things up',
+                        '    v - view modified files',
+                        '    ? - print help',
+                    ));
+                    break;
+            }
+        }
+    }
+
     /**
      * {@inheritDoc}
      */

src/Composer/Downloader/VcsDownloader.php

@@ -86,8 +86,16 @@ abstract class VcsDownloader implements DownloaderInterface
 
         $this->io->write("  - Updating <info>" . $name . "</info> (<comment>" . $from . "</comment> => <comment>" . $to . "</comment>)");
 
-        $this->enforceCleanDirectory($path);
-        $this->doUpdate($initial, $target, $path);
+        $this->cleanChanges($path, true);
+        try {
+            $this->doUpdate($initial, $target, $path);
+        } catch (\Exception $e) {
+            // in case of failed update, try to reapply the changes before aborting
+            $this->reapplyChanges($path);
+
+            throw $e;
+        }
+        $this->reapplyChanges($path);
 
         //print the commit logs if in verbose mode
         if ($this->io->isVerbose()) {
@@ -117,25 +125,39 @@ abstract class VcsDownloader implements DownloaderInterface
      */
     public function remove(PackageInterface $package, $path)
     {
-        $this->enforceCleanDirectory($path);
         $this->io->write("  - Removing <info>" . $package->getName() . "</info> (<comment>" . $package->getPrettyVersion() . "</comment>)");
+        $this->cleanChanges($path, false);
         if (!$this->filesystem->removeDirectory($path)) {
             throw new \RuntimeException('Could not completely delete '.$path.', aborting.');
         }
     }
 
     /**
-     * Guarantee that no changes have been made to the local copy
+     * Prompt the user to check if changes should be stashed/removed or the operation aborted
      *
-     * @throws \RuntimeException if the directory is not clean
+     * @param  string            $path
+     * @param  bool              $stash if true (update) the changes can be stashed and reapplied after an update,
+     *                                  if false (remove) the changes should be assumed to be lost if the operation is not aborted
+     * @throws \RuntimeException in case the operation must be aborted
      */
-    protected function enforceCleanDirectory($path)
+    protected function cleanChanges($path, $update)
     {
+        // the default implementation just fails if there are any changes, override in child classes to provide stash-ability
         if (null !== $this->getLocalChanges($path)) {
             throw new \RuntimeException('Source directory ' . $path . ' has uncommitted changes.');
         }
     }
 
+    /**
+     * Guarantee that no changes have been made to the local copy
+     *
+     * @param  string            $path
+     * @throws \RuntimeException in case the operation must be aborted or the patch does not apply cleanly
+     */
+    protected function reapplyChanges($path)
+    {
+    }
+
     /**
      * Downloads specific package into specific folder.
      *