Add plugin extension and servlet for avatar images

Avatar images are provided by a single plugin and requested from the
/avatar/* URL.  If no plugin is provided, a 404 is returned.

Change-Id: Icfc35ce713b34381bb1afc3691dd7e84e54da86e

gerrit-httpd/src/main/java/com/google/gerrit/httpd/UrlModule.java

@@ -18,6 +18,7 @@ import static com.google.inject.Scopes.SINGLETON;
 
 import com.google.common.base.Strings;
 import com.google.gerrit.common.PageLinks;
+import com.google.gerrit.httpd.raw.AvatarServlet;
 import com.google.gerrit.httpd.raw.CatServlet;
 import com.google.gerrit.httpd.raw.HostPageServlet;
 import com.google.gerrit.httpd.raw.LegacyGerritServlet;
@@ -78,6 +79,7 @@ class UrlModule extends ServletModule {
     serve("/ssh_info").with(SshInfoServlet.class);
     serve("/static/*").with(StaticServlet.class);
     serve("/tools/*").with(ToolServlet.class);
+    serve("/avatar/*").with(AvatarServlet.class);
 
     serve("/Main.class").with(notFound());
     serve("/com/google/gerrit/launcher/*").with(notFound());

gerrit-httpd/src/main/java/com/google/gerrit/httpd/raw/AvatarServlet.java

@@ -0,0 +1,103 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.httpd.raw;
+
+import com.google.gerrit.extensions.registration.DynamicItem;
+import com.google.gerrit.reviewdb.client.Account;
+import com.google.gerrit.server.account.AccountResolver;
+import com.google.gerrit.server.avatar.AvatarProvider;
+import com.google.gwtorm.server.OrmException;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * Serves avatars based on the installed avatar plugin. If no plugin is
+ * installed, serves 404s.
+ */
+@Singleton
+public class AvatarServlet extends HttpServlet {
+  private static final long serialVersionUID = 1L;
+  private static final Logger log = LoggerFactory
+      .getLogger(AvatarServlet.class);
+
+  private final AccountResolver accountResolver;
+  private final DynamicItem<AvatarProvider> avatarProviderItem;
+
+  @Inject
+  AvatarServlet(AccountResolver accountResolver,
+      DynamicItem<AvatarProvider> avatarProvider) {
+    this.accountResolver = accountResolver;
+    this.avatarProviderItem = avatarProvider;
+  }
+
+  @Override
+  protected void doGet(HttpServletRequest req, HttpServletResponse rsp)
+      throws IOException {
+    AvatarProvider avatarProvider = avatarProviderItem.get();
+    if (avatarProvider == null) {
+      rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
+      return;
+    }
+
+    String user = req.getPathInfo();
+    if (user == null) {
+      rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
+      return;
+    }
+    // Hack off leading '/'
+    user = user.substring(1);
+
+    final Account account;
+    try {
+      account = accountResolver.find(user);
+    } catch (OrmException e1) {
+      log.error("Exception while looking up avatar for user: " + user, e1);
+      rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
+      return;
+    }
+
+    if (account == null) {
+      // Account was not found.
+      rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
+      return;
+    }
+
+    String size = req.getParameter("size");
+    int imageSize = 0;
+    if (size != null) {
+      try {
+        imageSize = Integer.parseInt(size);
+      } catch (NumberFormatException e) {
+        // Ignore, keep size at 0.
+      }
+    }
+
+    final String url = avatarProvider.getUrl(account, imageSize);
+    if (url == null) {
+      rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
+    } else {
+      rsp.sendRedirect(rsp.encodeRedirectURL(url));
+    }
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/avatar/AvatarProvider.java

@@ -0,0 +1,51 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.avatar;
+
+import com.google.gerrit.extensions.annotations.ExtensionPoint;
+import com.google.gerrit.reviewdb.client.Account;
+import com.google.gerrit.reviewdb.client.UserIdentity;
+
+/**
+ * Provide avatar URLs for specified user.
+ *
+ * Invoked by Gerrit when Avatar image requests are made.
+ */
+@ExtensionPoint
+public interface AvatarProvider {
+  /**
+   * Get avatar URL.
+   *
+   * @param account The user for which to load an avatar image
+   * @param imageSize A requested image size, in pixels. An imageSize of 0
+   *        indicates to use whatever default size the provider determines.
+   *        AvatarProviders may ignore the requested image size. The web
+   *        interface will resize any image to match imageSize, so ideally the
+   *        provider should return an image sized correctly.
+   * @return a URL of an avatar image for the specified user. A return value of
+   *         {@code null} is acceptable, and results in the server responding
+   *         with a 404. This will hide the avatar image in the web UI.
+   */
+  public String getUrl(Account account, int imageSize);
+
+  /**
+   * Gets a URL for a user to modify their avatar image.
+   *
+   * @param user The user wishing to change their avatar image
+   * @return a URL the user should visit to modify their avatar, or null if
+   *         modification is not possible.
+   */
+  public String getChangeAvatarUrl(UserIdentity user);
+}

gerrit-server/src/main/java/com/google/gerrit/server/config/GerritGlobalModule.java

@@ -21,6 +21,7 @@ import com.google.gerrit.audit.AuditModule;
 import com.google.gerrit.common.data.ApprovalTypes;
 import com.google.gerrit.extensions.events.GitReferenceUpdatedListener;
 import com.google.gerrit.extensions.events.NewProjectCreatedListener;
+import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.extensions.registration.DynamicMap;
 import com.google.gerrit.extensions.registration.DynamicSet;
 import com.google.gerrit.reviewdb.client.AuthType;
@@ -55,6 +56,7 @@ import com.google.gerrit.server.auth.AuthBackend;
 import com.google.gerrit.server.auth.InternalAuthBackend;
 import com.google.gerrit.server.auth.UniversalAuthBackend;
 import com.google.gerrit.server.auth.ldap.LdapModule;
+import com.google.gerrit.server.avatar.AvatarProvider;
 import com.google.gerrit.server.cache.CacheRemovalListener;
 import com.google.gerrit.server.events.EventFactory;
 import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
@@ -209,10 +211,11 @@ public class GerritGlobalModule extends FactoryModule {
     DynamicSet.setOf(binder(), NewProjectCreatedListener.class);
     DynamicSet.bind(binder(), GitReferenceUpdatedListener.class).to(ChangeCache.class);
     DynamicSet.setOf(binder(), CommitValidationListener.class);
-    factory(CommitValidators.Factory.class);
+    DynamicItem.itemOf(binder(), AvatarProvider.class);
 
     bind(AnonymousUser.class);
 
+    factory(CommitValidators.Factory.class);
     factory(NotesBranchUtil.Factory.class);
   }
 }