improve plugin installation and backup installed archives

scm-webapp/src/main/java/sonia/scm/plugin/Plugins.java

@@ -10,12 +10,19 @@ package sonia.scm.plugin;
 
 //~--- non-JDK imports --------------------------------------------------------
 
+import com.google.common.base.Charsets;
 import com.google.common.base.Function;
 import com.google.common.collect.Iterables;
-import java.io.File;
+import com.google.common.io.Files;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import sonia.scm.util.IOUtil;
 
 //~--- JDK imports ------------------------------------------------------------
 
+import java.io.File;
 import java.io.IOException;
 
 import java.nio.file.Path;
@@ -29,6 +36,13 @@ import java.util.Set;
 public final class Plugins
 {
 
+  /**
+   * the logger for Plugins
+   */
+  private static final Logger logger = LoggerFactory.getLogger(Plugins.class);
+
+  //~--- constructors ---------------------------------------------------------
+
   /**
    * Constructs ...
    *
@@ -56,11 +70,68 @@ public final class Plugins
 
     return processor.collectPlugins(classLoader);
   }
-  
-  public static File createPluginDirectory(File parent, PluginId id){
+
+  /**
+   * Method description
+   *
+   *
+   * @param parent
+   * @param id
+   *
+   * @return
+   */
+  public static File createPluginDirectory(File parent, PluginId id)
+  {
     return new File(new File(parent, id.getGroupId()), id.getArtifactId());
   }
 
+    /** Field description */
+  private static final String FILE_CHECKSUM = "checksum";
+
+  
+  
+  /**
+   * Method description
+   *
+   *
+   * @param archive
+   * @param checksum
+   * @param directory
+   * @param checksumFile
+   * @param core
+   *
+   * @throws IOException
+   */
+  public static void extract(SmpArchive archive, String checksum,
+    File directory, File checksumFile, boolean core)
+    throws IOException
+  {
+    if (directory.exists())
+    {
+      logger.debug("delete directory {} for plugin extraction",
+        archive.getPluginId());
+      IOUtil.delete(directory);
+    }
+
+    IOUtil.mkdirs(directory);
+
+    logger.debug("extract plugin {}", archive.getPluginId());
+    archive.extract(directory);
+    Files.write(checksum, checksumFile, Charsets.UTF_8);
+
+    if (core)
+    {
+      if (!new File(directory, "core").createNewFile())
+      {
+        throw new IOException("could not create core plugin marker");
+      }
+    }
+  }
+  
+  public static File getChecksumFile(File pluginDirectory){
+    return new File(pluginDirectory, FILE_CHECKSUM);
+  }
+
   /**
    * Method description
    *