InlineEdit: Add method to read edits

This method is supposed to be used from REST endpoints and from
acceptance tests.

Change-Id: I1114acc280cb5b8235bf941b963e04bbdf5870f9

gerrit-server/src/main/java/com/google/gerrit/server/edit/ChangeEdit.java

@@ -17,7 +17,6 @@ package com.google.gerrit.server.edit;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.gerrit.reviewdb.client.Change;
-import com.google.gerrit.reviewdb.client.RefNames;
 import com.google.gerrit.reviewdb.client.RevId;
 import com.google.gerrit.server.IdentifiedUser;
 
@@ -62,8 +61,6 @@ public class ChangeEdit {
   }
 
   public String getRefName() {
-    return String.format("%s/edit-%d",
-        RefNames.refsUsers(user.getAccountId()),
-        change.getId().get());
+    return ChangeEditUtil.editRefName(user.getAccountId(), change.getId());
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/edit/ChangeEditUtil.java

@@ -0,0 +1,91 @@
+// Copyright (C) 2014 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.edit;
+
+import com.google.common.base.Optional;
+import com.google.gerrit.extensions.restapi.AuthException;
+import com.google.gerrit.reviewdb.client.Account;
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.RefNames;
+import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.git.GitRepositoryManager;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+import com.google.inject.Singleton;
+
+import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.Repository;
+
+import java.io.IOException;
+
+/**
+ * Utility functions to manipulate change edits.
+ * <p>
+ * This class contains method to retrieve edits.
+ */
+@Singleton
+public class ChangeEditUtil {
+  private final GitRepositoryManager gitManager;
+  private final Provider<IdentifiedUser> user;
+
+  @Inject
+  ChangeEditUtil(GitRepositoryManager gitManager,
+      Provider<IdentifiedUser> user) {
+    this.gitManager = gitManager;
+    this.user = user;
+  }
+
+  /**
+   * Retrieve edits for a change and user. Max. one change edit can
+   * exist per user and change.
+   *
+   * @param change
+   * @return edit for this change for this user, if present.
+   * @throws AuthException
+   * @throws IOException
+   */
+  public Optional<ChangeEdit> byChange(Change change)
+      throws AuthException, IOException {
+    if (!user.get().isIdentifiedUser()) {
+      throw new AuthException("Authentication required");
+    }
+    Repository repo = gitManager.openRepository(change.getProject());
+    try {
+      IdentifiedUser identifiedUser = (IdentifiedUser) user.get();
+      Ref ref = repo.getRefDatabase().getRef(editRefName(
+          identifiedUser.getAccountId(), change.getId()));
+      if (ref == null) {
+        return Optional.absent();
+      }
+      return Optional.of(new ChangeEdit(identifiedUser, change, ref));
+    } finally {
+      repo.close();
+    }
+  }
+
+  /**
+   * Returns reference for this change edit with sharded user and change number:
+   * refs/users/UU/UUUU/edit-CCCC.
+   *
+   * @param accountId accout id
+   * @param changeId change number
+   * @return reference for this change edit
+   */
+  static String editRefName(Account.Id accountId, Change.Id changeId) {
+    return String.format("%s/edit-%d",
+        RefNames.refsUsers(accountId),
+        changeId.get());
+  }
+}

gerrit-server/src/test/java/com/google/gerrit/server/edit/ChangeEditTest.java

@@ -0,0 +1,32 @@
+// Copyright (C) 2014 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.edit;
+
+import static org.junit.Assert.assertEquals;
+
+import com.google.gerrit.reviewdb.client.Account;
+import com.google.gerrit.reviewdb.client.Change;
+
+import org.junit.Test;
+
+public class ChangeEditTest {
+  @Test
+  public void changeEditRef() throws Exception {
+    Account.Id accountId = new Account.Id(1000042);
+    Change.Id changeId = new Change.Id(56414);
+    String refName = ChangeEditUtil.editRefName(accountId, changeId);
+    assertEquals("refs/users/42/1000042/edit-56414", refName);
+  }
+}