// 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.change;

import com.google.auto.value.AutoValue;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableSet;
import com.google.gerrit.reviewdb.client.Account;
import com.google.gerrit.reviewdb.client.PatchSet;
import com.google.gwtorm.server.OrmException;

import java.util.Collection;

/**
 * Store for reviewed flags on changes.
 *
 * A reviewed flag is a tuple of (patch set ID, file, account ID) and records
 * whether the user has reviewed a file in a patch set. Each user can easily
 * have thousands of reviewed flags and the number of reviewed flags is growing
 * without bound. The store must be able handle this data volume efficiently.
 *
 * For a multi-master setup the store must replicate the data between the
 * masters.
 */
public interface AccountPatchReviewStore {

  /**
   * Represents patch set id with reviewed files.
   */
  @AutoValue
  abstract class PatchSetWithReviewedFiles {
    abstract PatchSet.Id patchSetId();
    abstract ImmutableSet<String> files();

    public static PatchSetWithReviewedFiles create(
        PatchSet.Id id, ImmutableSet<String> files) {
      return new AutoValue_AccountPatchReviewStore_PatchSetWithReviewedFiles(
          id, files);
    }
  }

  /**
   * Marks the given file in the given patch set as reviewed by the given user.
   *
   * @param psId patch set ID
   * @param accountId account ID of the user
   * @param path file path
   * @return {@code true} if the reviewed flag was updated, {@code false} if the
   *         reviewed flag was already set
   * @throws OrmException thrown if updating the reviewed flag failed
   */
  boolean markReviewed(PatchSet.Id psId, Account.Id accountId, String path)
      throws OrmException;

  /**
   * Marks the given files in the given patch set as reviewed by the given user.
   *
   * @param psId patch set ID
   * @param accountId account ID of the user
   * @param paths file paths
   * @throws OrmException thrown if updating the reviewed flag failed
   */
  void markReviewed(PatchSet.Id psId, Account.Id accountId,
      Collection<String> paths) throws OrmException;

  /**
   * Clears the reviewed flag for the given file in the given patch set for the
   * given user.
   *
   * @param psId patch set ID
   * @param accountId account ID of the user
   * @param path file path
   * @throws OrmException thrown if clearing the reviewed flag failed
   */
  void clearReviewed(PatchSet.Id psId, Account.Id accountId, String path)
      throws OrmException;

  /**
   * Clears the reviewed flags for all files in the given patch set for all
   * users.
   *
   * @param psId patch set ID
   * @throws OrmException thrown if clearing the reviewed flags failed
   */
  void clearReviewed(PatchSet.Id psId) throws OrmException;

  /**
   * Find the latest patch set, that is smaller or equals to the given patch set,
   * where at least, one file has been reviewed by the given user.
   *
   * @param psId patch set ID
   * @param accountId account ID of the user
   * @return optionally, all files the have been reviewed by the given user
   * that belong to the patch set that is smaller or equals to the given patch set
   * @throws OrmException thrown if accessing the reviewed flags failed
   */
  Optional<PatchSetWithReviewedFiles> findReviewed(PatchSet.Id psId,
      Account.Id accountId) throws OrmException;
}