implemented plugin installation

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

@@ -0,0 +1,63 @@
+package sonia.scm.plugin;
+
+import com.google.common.base.Throwables;
+import com.google.common.hash.HashFunction;
+import com.google.common.hash.Hashing;
+import com.google.common.io.ByteStreams;
+import com.google.common.io.Files;
+import sonia.scm.SCMContextProvider;
+import sonia.scm.net.ahc.AdvancedHttpClient;
+import sonia.scm.util.IOUtil;
+
+import javax.inject.Inject;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.Optional;
+
+class PluginInstaller {
+
+  private final SCMContextProvider context;
+  private final AdvancedHttpClient client;
+
+  @Inject
+  public PluginInstaller(SCMContextProvider context, AdvancedHttpClient client) {
+    this.context = context;
+    this.client = client;
+  }
+
+  public void install(AvailablePlugin plugin) {
+    File file = createFile(plugin);
+    try (InputStream input = download(plugin); OutputStream output = new FileOutputStream(file)) {
+      ByteStreams.copy(input, output);
+
+      verifyChecksum(plugin, file);
+    } catch (IOException ex) {
+      throw new PluginDownloadException("failed to install plugin", ex);
+    }
+  }
+
+  private void verifyChecksum(AvailablePlugin plugin, File file) throws IOException {
+    Optional<String> checksum = plugin.getDescriptor().getChecksum();
+    if (checksum.isPresent()) {
+      String calculatedChecksum = Files.hash(file, Hashing.sha256()).toString();
+      if (!checksum.get().equalsIgnoreCase(calculatedChecksum)) {
+        throw new PluginChecksumMismatchException(
+          String.format("downloaded plugin checksum %s does not match expected %s", calculatedChecksum, checksum.get())
+        );
+      }
+    }
+  }
+
+  private InputStream download(AvailablePlugin plugin) throws IOException {
+    return client.get(plugin.getDescriptor().getUrl()).request().contentAsStream();
+  }
+
+  private File createFile(AvailablePlugin plugin) {
+    File pluginDirectory = new File(context.getBaseDirectory(), "plugins");
+    IOUtil.mkdirs(pluginDirectory);
+    return new File(pluginDirectory, plugin.getDescriptor().getInformation().getName() + ".smp");
+  }
+}