/*
 * 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.hudi.table.action.savepoint;

import org.apache.hudi.avro.model.HoodieSavepointMetadata;
import org.apache.hudi.common.engine.HoodieEngineContext;
import org.apache.hudi.common.fs.FSUtils;
import org.apache.hudi.common.model.HoodieLogFile;
import org.apache.hudi.common.table.timeline.HoodieInstant;
import org.apache.hudi.common.table.timeline.HoodieTimeline;
import org.apache.hudi.common.table.timeline.TimelineMetadataUtils;
import org.apache.hudi.common.table.view.TableFileSystemView;
import org.apache.hudi.common.util.Option;
import org.apache.hudi.common.util.ValidationUtils;
import org.apache.hudi.common.util.VisibleForTesting;
import org.apache.hudi.common.util.collection.ImmutablePair;
import org.apache.hudi.config.HoodieWriteConfig;
import org.apache.hudi.exception.HoodieIOException;
import org.apache.hudi.exception.HoodieSavepointException;
import org.apache.hudi.table.HoodieTable;
import org.apache.hudi.table.action.BaseActionExecutor;

import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import static org.apache.hudi.common.table.timeline.HoodieInstant.State.REQUESTED;
import static org.apache.hudi.common.table.timeline.InstantComparison.GREATER_THAN_OR_EQUALS;
import static org.apache.hudi.common.table.timeline.InstantComparison.LESSER_THAN_OR_EQUALS;
import static org.apache.hudi.common.table.timeline.InstantComparison.compareTimestamps;

@Slf4j
public class SavepointActionExecutor<T, I, K, O> extends BaseActionExecutor<T, I, K, O, HoodieSavepointMetadata> {

  private final String user;
  private final String comment;

  public SavepointActionExecutor(HoodieEngineContext context,
                                 HoodieWriteConfig config,
                                 HoodieTable<T, I, K, O> table,
                                 String instantTime,
                                 String user,
                                 String comment) {
    super(context, config, table, instantTime);
    this.user = user;
    this.comment = comment;
  }

  @Override
  public HoodieSavepointMetadata execute() {
    if (!table.getCompletedCommitsTimeline().containsInstant(instantTime)) {
      throw new HoodieSavepointException("Could not savepoint non-existing commit " + instantTime);
    }

    try {
      // Check the last commit that was not cleaned and check if savepoint time is > that commit
      String lastCommitRetained = getLastCommitRetained();

      // Cannot allow savepoint time on a commit that could have been cleaned
      ValidationUtils.checkArgument(compareTimestamps(instantTime, GREATER_THAN_OR_EQUALS, lastCommitRetained),
          () -> "Could not savepoint commit " + instantTime + " as this is beyond the lookup window " + lastCommitRetained);

      context.setJobStatus(this.getClass().getSimpleName(), "Collecting latest files for savepoint " + instantTime + " " + table.getConfig().getTableName());
      TableFileSystemView.SliceView view = table.getSliceView();

      Map<String, List<String>> latestFilesMap;
      // NOTE: for performance, we have to use different logic here for listing the latest files
      // before or on the given instant:
      // (1) using metadata-table-based file listing: instead of parallelizing the partition
      // listing which incurs unnecessary metadata table reads, we directly read the metadata
      // table once in a batch manner through the timeline server;
      // (2) using direct file system listing:  we parallelize the partition listing so that
      // each partition can be listed on the file system concurrently through Spark.
      // Note that
      if (table.getMetaClient().getTableConfig().isMetadataTableAvailable()) {
        latestFilesMap = view.getAllLatestFileSlicesBeforeOrOn(instantTime).entrySet().stream()
            .collect(Collectors.toMap(
                Map.Entry::getKey,
                entry -> {
                  List<String> latestFiles = new ArrayList<>();
                  entry.getValue().forEach(fileSlice -> {
                    if (fileSlice.getBaseFile().isPresent()) {
                      latestFiles.add(fileSlice.getBaseFile().get().getFileName());
                    }
                    latestFiles.addAll(fileSlice.getLogFiles().map(HoodieLogFile::getFileName).collect(Collectors.toList()));
                  });
                  return latestFiles;
                }));
      } else {
        List<String> partitions = FSUtils.getAllPartitionPaths(context, table.getMetaClient(), config.getMetadataConfig());
        latestFilesMap = context.mapToPair(partitions, partitionPath -> {
          // Scan all partitions files with this commit time
          log.info("Collecting latest files in partition path {}", partitionPath);
          List<String> latestFiles = new ArrayList<>();
          view.getLatestFileSlicesBeforeOrOn(partitionPath, instantTime, true).forEach(fileSlice -> {
            if (fileSlice.getBaseFile().isPresent()) {
              latestFiles.add(fileSlice.getBaseFile().get().getFileName());
            }
            latestFiles.addAll(fileSlice.getLogFiles().map(HoodieLogFile::getFileName).collect(Collectors.toList()));
          });
          return new ImmutablePair<>(partitionPath, latestFiles);
        }, null);
      }

      HoodieSavepointMetadata metadata = TimelineMetadataUtils.convertSavepointMetadata(user, comment, latestFilesMap);
      // Nothing to save in the savepoint
      table.getActiveTimeline().createNewInstant(
          instantGenerator.createNewInstant(HoodieInstant.State.INFLIGHT, HoodieTimeline.SAVEPOINT_ACTION, instantTime));
      table.getActiveTimeline()
          .saveAsComplete(
              true, instantGenerator.createNewInstant(HoodieInstant.State.INFLIGHT, HoodieTimeline.SAVEPOINT_ACTION, instantTime), Option.of(metadata),
              savepointCompletedInstant -> table.getMetaClient().getTableFormat().savepoint(savepointCompletedInstant, table.getContext(), table.getMetaClient(), table.getViewManager()));
      log.info("Savepoint {} created", instantTime);
      return metadata;
    } catch (HoodieIOException e) {
      throw new HoodieSavepointException("Failed to savepoint " + instantTime, e);
    }
  }

  @VisibleForTesting
  String getLastCommitRetained() {
    Option<HoodieInstant> cleanInstant = table.getCleanTimeline().lastInstant();
    // if there are no clean instants, we can use the first completed commit
    if (cleanInstant.isEmpty()) {
      return table.getCompletedCommitsTimeline().firstInstant().get().requestedTime();
    }
    return cleanInstant.map(instant -> {
      try {
        if (instant.isCompleted()) {
          return table.getActiveTimeline().readCleanMetadata(instant)
              .getEarliestCommitToRetain();
        } else {
          // clean is pending or inflight
          return table.getActiveTimeline().readCleanerPlan(
                  instantGenerator.createNewInstant(REQUESTED, instant.getAction(), instant.requestedTime()))
              .getEarliestInstantToRetain().getTimestamp();
        }
      } catch (IOException e) {
        throw new HoodieSavepointException("Failed to savepoint " + instantTime, e);
      }
    }).orElseGet(() ->
      // If there is no earliest commit to retain in the clean commit's metadata, but there are clean instants on the timeline,
      // we assume the last commit before the clean instant is the last commit guaranteed to be retained.
      table.getActiveTimeline().getWriteTimeline().filterCompletedInstants()
          .filter(instant -> compareTimestamps(instant.requestedTime(), LESSER_THAN_OR_EQUALS, cleanInstant.get().requestedTime()))
          .lastInstant()
          .map(HoodieInstant::requestedTime)
          .orElse(cleanInstant.get().requestedTime()));
  }
}
