/*
 * Copyright 2015 Google LLC
 *
 * 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.cloud.datastore;

import java.util.List;

/**
 * An interface to represent Google Cloud Datastore write operations.
 */
public interface DatastoreWriter {

  /**
   * Datastore add operation: inserts the provided entity. This method will automatically allocate
   * an id if necessary.
   *
   * @param entity the entity to add
   * @return an {@code Entity} with the same properties and a key that is either newly allocated
   *     or the same one if key is already complete
   * @throws DatastoreException upon failure
   * @throws IllegalArgumentException if the given entity is missing a key
   */
  Entity add(FullEntity<?> entity);

  /**
   * Datastore add operation: inserts the provided entities. This method will automatically allocate
   * id for any entity with an incomplete key.
   *
   * @return a list of {@code Entity} ordered by input with the same properties and a key that
   *     is either newly allocated or the same one if was already complete
   * @throws DatastoreException upon failure
   * @throws IllegalArgumentException if any of the given entities is missing a key
   * @see #add(FullEntity)
   */
  List<Entity> add(FullEntity<?>... entities);

  /**
   * A Datastore update operation. The operation will fail if an entity with the same key does not
   * already exist.
   *
   * @throws DatastoreException upon failure
   */
  void update(Entity... entities);

  /**
   * A Datastore put (a.k.a upsert) operation: inserts an entity if it does not exist, updates it
   * otherwise. This method will automatically allocate an id if necessary.
   *
   * @param entity the entity to put
   * @return an {@code Entity} with the same properties and a key that is either newly allocated
   *     or the same one if key is already complete
   * @throws DatastoreException upon failure
   * @throws IllegalArgumentException if the given entity is missing a key
   */
  Entity put(FullEntity<?> entity);

  /**
   * A Datastore put (a.k.a upsert) operation: creates an entity if it does not exist, updates it
   * otherwise. This method will automatically allocate id for any entity with an incomplete key.
   *
   * @return a list of updated or inserted {@code Entity}, ordered by input. Returned keys are
   *     either newly allocated or the same one if was already complete.
   * @throws DatastoreException upon failure
   * @throws IllegalArgumentException if any of the given entities is missing a key
   */
  List<Entity> put(FullEntity<?>... entities);

  /**
   * A datastore delete operation. It is OK to request the deletion of a non-existing key.
   */
  void delete(Key... keys);
}
