/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.beam.sdk.io.gcp.spanner.changestreams;

import com.google.cloud.Timestamp;
import com.google.cloud.spanner.Options.RpcPriority;
import java.util.Collections;
import org.apache.beam.sdk.io.gcp.spanner.changestreams.model.PartitionMetadata;
import org.apache.beam.sdk.io.gcp.spanner.changestreams.model.PartitionMetadata.State;
import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.Sets;

/**
 * Single place for defining the constants used in the {@code Spanner.readChangeStreams()}
 * connector.
 */
public class ChangeStreamsConstants {

  /** Represents the max end at that can be specified for a change stream. */
  public static final Timestamp MAX_INCLUSIVE_END_AT =
      Timestamp.ofTimeSecondsAndNanos(
          Timestamp.MAX_VALUE.getSeconds(), Timestamp.MAX_VALUE.getNanos() - 1);

  /** The default change stream name for a change stream query is the empty {@link String}. */
  public static final String DEFAULT_CHANGE_STREAM_NAME = "";

  /** The default start timestamp for a change stream query is {@link Timestamp#MIN_VALUE}. */
  public static final Timestamp DEFAULT_INCLUSIVE_START_AT = Timestamp.MIN_VALUE;

  /**
   * The default end timestamp for a change stream query is {@link
   * ChangeStreamsConstants#MAX_INCLUSIVE_END_AT}.
   */
  public static final Timestamp DEFAULT_INCLUSIVE_END_AT = MAX_INCLUSIVE_END_AT;

  /** The default priority for a change stream query is {@link RpcPriority#HIGH}. */
  public static final RpcPriority DEFAULT_RPC_PRIORITY = RpcPriority.HIGH;

  /** The sliding window size in seconds for throughput reporting. */
  public static final int THROUGHPUT_WINDOW_SECONDS = 10;

  /**
   * We use the following partition token to provide an estimate size of a partition token. A usual
   * partition token has around 140 characters.
   */
  private static final String SAMPLE_PARTITION_TOKEN =
      String.join("", Collections.nCopies(140, "*"));
  /**
   * We use a bogus partition here to estimate the average size of a partition metadata record.
   *
   * <p>The only dynamically allocated size field here is the "parentTokens", which is a set and can
   * expand. In practice, however, partitions have 1 to 2 parents at most.
   */
  public static final PartitionMetadata SAMPLE_PARTITION =
      PartitionMetadata.newBuilder()
          .setPartitionToken(SAMPLE_PARTITION_TOKEN)
          .setParentTokens(Sets.newHashSet(SAMPLE_PARTITION_TOKEN))
          .setStartTimestamp(Timestamp.now())
          .setHeartbeatMillis(1_000L)
          .setState(State.CREATED)
          .setWatermark(Timestamp.now())
          .setCreatedAt(Timestamp.now())
          .build();
}
