// Copyright (C) 2016 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.notedb.rebuild;

import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.reviewdb.server.ReviewDb;
import com.google.gerrit.server.notedb.ChangeBundle;
import com.google.gerrit.server.notedb.NoteDbUpdateManager;
import com.google.gerrit.server.notedb.NoteDbUpdateManager.Result;
import com.google.gwtorm.server.OrmException;
import com.google.gwtorm.server.SchemaFactory;
import java.io.IOException;
import java.util.concurrent.Callable;

public abstract class ChangeRebuilder {
  public static class NoPatchSetsException extends OrmException {
    private static final long serialVersionUID = 1L;

    NoPatchSetsException(Change.Id changeId) {
      super("Change " + changeId + " cannot be rebuilt because it has no patch sets");
    }
  }

  private final SchemaFactory<ReviewDb> schemaFactory;

  protected ChangeRebuilder(SchemaFactory<ReviewDb> schemaFactory) {
    this.schemaFactory = schemaFactory;
  }

  public final ListenableFuture<Result> rebuildAsync(
      final Change.Id id, ListeningExecutorService executor) {
    return executor.submit(
        new Callable<Result>() {
          @Override
          public Result call() throws Exception {
            try (ReviewDb db = schemaFactory.open()) {
              return rebuild(db, id);
            }
          }
        });
  }

  /**
   * Rebuild ReviewDb contents by copying from NoteDb.
   *
   * <p>Requires NoteDb to be the primary storage for the change.
   */
  public abstract void rebuildReviewDb(ReviewDb db, Project.NameKey project, Change.Id changeId)
      throws OrmException;

  // In the following methods "rebuilding" always refers to copying the state
  // from ReviewDb to NoteDb, i.e. assuming ReviewDb is the primary storage.

  public abstract Result rebuild(ReviewDb db, Change.Id changeId) throws IOException, OrmException;

  public abstract Result rebuildEvenIfReadOnly(ReviewDb db, Change.Id changeId)
      throws IOException, OrmException;

  public abstract Result rebuild(NoteDbUpdateManager manager, ChangeBundle bundle)
      throws IOException, OrmException;

  public abstract void buildUpdates(NoteDbUpdateManager manager, ChangeBundle bundle)
      throws IOException, OrmException;

  public abstract NoteDbUpdateManager stage(ReviewDb db, Change.Id changeId)
      throws IOException, OrmException;

  public abstract Result execute(ReviewDb db, Change.Id changeId, NoteDbUpdateManager manager)
      throws OrmException, IOException;
}