/*
 * 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.common.model;

import org.apache.hudi.common.util.Option;

import java.io.Serializable;
import java.util.List;
import java.util.Objects;
import java.util.TreeSet;
import java.util.stream.Stream;

/**
 * Within a file group, a slice is a combination of data file written at a commit time and list of log files, containing
 * changes to the data file from that commit time.
 */
public class FileSlice implements Serializable {

  /**
   * File Group Id of the Slice.
   */
  private final HoodieFileGroupId fileGroupId;

  /**
   * Point in the timeline, at which the slice was created.
   */
  private final String baseInstantTime;

  /**
   * data file, with the compacted data, for this slice.
   */
  private HoodieBaseFile baseFile;

  /**
   * List of appendable log files with real time data - Sorted with greater log version first - Always empty for
   * copy_on_write storage.
   */
  private final TreeSet<HoodieLogFile> logFiles;

  public FileSlice(FileSlice fileSlice) {
    this.baseInstantTime = fileSlice.baseInstantTime;
    this.baseFile = fileSlice.baseFile != null ? new HoodieBaseFile(fileSlice.baseFile) : null;
    this.fileGroupId = fileSlice.fileGroupId;
    this.logFiles = new TreeSet<>(HoodieLogFile.getReverseLogFileComparator());
    fileSlice.logFiles.forEach(lf -> this.logFiles.add(new HoodieLogFile(lf)));
  }

  public FileSlice(String partitionPath, String baseInstantTime, String fileId) {
    this(new HoodieFileGroupId(partitionPath, fileId), baseInstantTime);
  }

  public FileSlice(HoodieFileGroupId fileGroupId, String baseInstantTime) {
    this.fileGroupId = fileGroupId;
    this.baseInstantTime = baseInstantTime;
    this.baseFile = null;
    this.logFiles = new TreeSet<>(HoodieLogFile.getReverseLogFileComparator());
  }

  public FileSlice(HoodieFileGroupId fileGroupId, String baseInstantTime,
                   HoodieBaseFile baseFile, List<HoodieLogFile> logFiles) {
    this.fileGroupId = fileGroupId;
    this.baseInstantTime = baseInstantTime;
    this.baseFile = baseFile;
    this.logFiles = new TreeSet<>(HoodieLogFile.getReverseLogFileComparator());
    this.logFiles.addAll(logFiles);
  }

  public void setBaseFile(HoodieBaseFile baseFile) {
    this.baseFile = baseFile;
  }

  public void addLogFile(HoodieLogFile logFile) {
    this.logFiles.add(logFile);
  }

  public Stream<HoodieLogFile> getLogFiles() {
    return logFiles.stream();
  }

  public String getBaseInstantTime() {
    return baseInstantTime;
  }

  public String getPartitionPath() {
    return fileGroupId.getPartitionPath();
  }

  public String getFileId() {
    return fileGroupId.getFileId();
  }

  public HoodieFileGroupId getFileGroupId() {
    return fileGroupId;
  }

  public Option<HoodieBaseFile> getBaseFile() {
    return Option.ofNullable(baseFile);
  }

  public Option<HoodieLogFile> getLatestLogFile() {
    return Option.fromJavaOptional(logFiles.stream().findFirst());
  }

  public long getTotalFileSize() {
    return getBaseFile().map(HoodieBaseFile::getFileSize).orElse(0L)
        + getLogFiles().mapToLong(HoodieLogFile::getFileSize).sum();
  }

  /**
   * Returns true if there is no data file and no log files. Happens as part of pending compaction
   * 
   * @return
   */
  public boolean isEmpty() {
    return (baseFile == null) && (logFiles.isEmpty());
  }

  @Override
  public String toString() {
    final StringBuilder sb = new StringBuilder("FileSlice {");
    sb.append("fileGroupId=").append(fileGroupId);
    sb.append(", baseCommitTime=").append(baseInstantTime);
    sb.append(", baseFile='").append(baseFile).append('\'');
    sb.append(", logFiles='").append(logFiles).append('\'');
    sb.append('}');
    return sb.toString();
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    FileSlice slice = (FileSlice) o;
    return Objects.equals(fileGroupId, slice.fileGroupId) && Objects.equals(baseInstantTime, slice.baseInstantTime)
        && Objects.equals(baseFile, slice.baseFile) && Objects.equals(logFiles, slice.logFiles);
  }

  @Override
  public int hashCode() {
    return Objects.hash(fileGroupId, baseInstantTime);
  }
}
