/*
 * 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.source.split;

import org.apache.hudi.common.table.cdc.HoodieCDCFileSplit;
import org.apache.hudi.common.util.ValidationUtils;
import org.apache.hudi.source.IncrementalInputSplits;
import org.apache.hudi.table.format.cdc.CdcInputSplit;

import lombok.Getter;

import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

/**
 * Result from continuous enumerator. It has the same semantic to the {@link org.apache.hudi.source.IncrementalInputSplits.Result}.
 */
@Getter
public class HoodieContinuousSplitBatch {
  public static final HoodieContinuousSplitBatch EMPTY = new HoodieContinuousSplitBatch(Collections.emptyList(), "", "");
  private final Collection<HoodieSourceSplit> splits;
  private final String endInstant; // end instant to consume to
  private final String offset;     // monotonic increasing consumption offset

  /**
   * @param splits should never be null. But it can be an empty collection
   * @param endInstant should never be null, end instant to consume to
   * @param offset could be null. monotonic increasing consumption offset
   */
  public HoodieContinuousSplitBatch(
      Collection<HoodieSourceSplit> splits,
      String endInstant,
      String offset) {

    ValidationUtils.checkArgument(splits != null, "Invalid to splits collection: null");
    ValidationUtils.checkArgument(endInstant != null, "Invalid end instant: null");
    this.splits = splits;
    this.endInstant = endInstant;
    this.offset = offset;
  }

  public static HoodieContinuousSplitBatch fromResult(IncrementalInputSplits.Result result) {
    List<HoodieSourceSplit> splits = result.getInputSplits().stream().map(split -> {
      if (split instanceof CdcInputSplit) {
        CdcInputSplit cdcSplit = (CdcInputSplit) split;
        HoodieCDCFileSplit[] changes = cdcSplit.getChanges();
        // CdcInputSplit does not carry a latestCommit; derive it from the last (largest instant)
        // CDC file split, falling back to the batch end instant when the array is empty.
        String latestCommit = changes.length > 0
            ? changes[changes.length - 1].getInstant()
            : result.getEndInstant();
        return (HoodieSourceSplit) new HoodieCdcSourceSplit(
            HoodieSourceSplit.SPLIT_ID_GEN.incrementAndGet(),
            cdcSplit.getTablePath(),
            cdcSplit.getMaxCompactionMemoryInBytes(),
            cdcSplit.getFileId(),
            cdcSplit.getPartitionPath(),
            changes,
            split.getMergeType(),
            latestCommit);
      }
      return new HoodieSourceSplit(
          HoodieSourceSplit.SPLIT_ID_GEN.incrementAndGet(),
          split.getBasePath().orElse(null),
          split.getLogPaths(),
          split.getTablePath(),
          split.getPartitionPath(),
          split.getMergeType(),
          split.getLatestCommit(),
          split.getFileId(),
          split.getInstantRange()
      );
    }).collect(Collectors.toList());

    return new HoodieContinuousSplitBatch(splits, result.getEndInstant(), result.getOffset());
  }
}
