Add REST API for /restore

Changes can be restored via REST api.  The web UI now uses this API,
and the ssh command line uses the same backend.

Change-Id: I7a7e8706a52289f87ace5a60ef3bcd6dd2a2dbde

gerrit-server/src/main/java/com/google/gerrit/server/change/Restore.java

@@ -0,0 +1,120 @@
+// Copyright (C) 2012 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.change;
+
+import com.google.common.base.Strings;
+import com.google.gerrit.common.ChangeHooks;
+import com.google.gerrit.extensions.restapi.AuthException;
+import com.google.gerrit.extensions.restapi.DefaultInput;
+import com.google.gerrit.extensions.restapi.ResourceConflictException;
+import com.google.gerrit.extensions.restapi.RestModifyView;
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.Change.Status;
+import com.google.gerrit.reviewdb.client.ChangeMessage;
+import com.google.gerrit.reviewdb.client.PatchSet;
+import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.ChangeUtil;
+import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.change.Restore.Input;
+import com.google.gerrit.server.mail.RestoredSender;
+import com.google.gerrit.server.project.ChangeControl;
+import com.google.gwtorm.server.AtomicUpdate;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+
+public class Restore implements RestModifyView<ChangeResource, Input> {
+  private final ChangeHooks hooks;
+  private final RestoredSender.Factory restoredSenderFactory;
+  private final Provider<ReviewDb> dbProvider;
+  private final ChangeJson json;
+
+  public static class Input {
+    @DefaultInput
+    public String message;
+  }
+
+  @Inject
+  Restore(ChangeHooks hooks,
+      RestoredSender.Factory restoredSenderFactory,
+      Provider<ReviewDb> dbProvider,
+      ChangeJson json) {
+    this.hooks = hooks;
+    this.restoredSenderFactory = restoredSenderFactory;
+    this.dbProvider = dbProvider;
+    this.json = json;
+  }
+
+  @Override
+  public Class<Input> inputType() {
+    return Input.class;
+  }
+
+  @Override
+  public Object apply(ChangeResource req, Input input)
+      throws Exception {
+    ChangeControl control = req.getControl();
+    Change change = req.getChange();
+    if (!control.canRestore()) {
+      throw new AuthException("restore not permitted");
+    } else if (change.getStatus() != Status.ABANDONED) {
+      throw new ResourceConflictException("change is " + status(change));
+    }
+
+    // Create a message to accompany the restore change
+    ReviewDb db = dbProvider.get();
+    PatchSet.Id patchSetId = change.currentPatchSetId();
+    IdentifiedUser currentUser = (IdentifiedUser) control.getCurrentUser();
+    String message = Strings.emptyToNull(input.message);
+    final ChangeMessage cmsg = new ChangeMessage(
+        new ChangeMessage.Key(change.getId(), ChangeUtil.messageUUID(db)),
+        currentUser.getAccountId(), patchSetId);
+    StringBuilder msg = new StringBuilder();
+    msg.append(String.format("Patch Set %d: Restored", patchSetId.get()));
+    if (message != null) {
+      msg.append("\n\n");
+      msg.append(message);
+    }
+    cmsg.setMessage(msg.toString());
+
+    // Restore the change
+    final Change updatedChange = db.changes().atomicUpdate(
+      change.getId(),
+      new AtomicUpdate<Change>() {
+        @Override
+        public Change update(Change change) {
+          if (change.getStatus() == Change.Status.ABANDONED) {
+            change.setStatus(Change.Status.NEW);
+            ChangeUtil.updated(change);
+            return change;
+          }
+          return null;
+        }
+      });
+    if (updatedChange == null) {
+      throw new ResourceConflictException("change is "
+          + status(db.changes().get(change.getId())));
+    }
+
+    ChangeUtil.updatedChange(db, currentUser, updatedChange, cmsg,
+                             restoredSenderFactory);
+    hooks.doChangeRestoredHook(updatedChange, currentUser.getAccount(),
+                                message, db);
+    return json.format(change.getId());
+  }
+
+  private static String status(Change change) {
+    return change != null ? change.getStatus().name().toLowerCase() : "deleted";
+  }
+}