/**
 * Copyright (C) 2014-2016 LinkedIn Corp. (pinot-core@linkedin.com)
 *
 * 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.linkedin.pinot.tools.segment.converter;

import com.linkedin.pinot.common.segment.SegmentMetadata;
import com.linkedin.pinot.common.utils.TarGzCompressionUtils;
import com.linkedin.pinot.core.data.readers.FileFormat;
import com.linkedin.pinot.core.data.readers.PinotSegmentRecordReader;
import com.linkedin.pinot.core.indexsegment.generator.SegmentGeneratorConfig;
import com.linkedin.pinot.core.segment.DefaultSegmentNameGenerator;
import com.linkedin.pinot.core.segment.SegmentNameGenerator;
import com.linkedin.pinot.core.segment.creator.SegmentIndexCreationDriver;
import com.linkedin.pinot.core.segment.creator.impl.SegmentIndexCreationDriverImpl;
import com.linkedin.pinot.core.segment.index.SegmentMetadataImpl;
import java.io.File;
import java.lang.reflect.Field;
import org.apache.commons.io.FileUtils;
import org.kohsuke.args4j.CmdLineParser;
import org.kohsuke.args4j.Option;


/**
 * Class to convert Pinot Columnar Segment to Pinot Star Tree Segment
 */
public class ColumnarToStarTreeConverter {
  private static final String TMP_DIR_PREFIX = "_tmp_";

  @Option(name = "-inputDir", required = true, usage = "Path to input directory containing Pinot segments")
  private String _inputDirName = null;

  @Option(name = "-outputDir", required = true, usage = "Path to output directory")
  private String _outputDirName = null;

  @Option(name = "-starTreeConfigFile", required = false, usage = "Path to Star Tree configuration file")
  private String _starTreeConfigFileName = null;

  @SuppressWarnings("FieldCanBeLocal")
  @Option(name = "-overwrite", required = false, usage = "Overwrite existing output directory.")
  private boolean _overwrite = false;

  @Option(name = "-help", required = false, help = true, aliases = {"-h"}, usage = "print this message")
  private boolean _help = false;

  /**
   * Convert the specified set of columnar segments into star tree segments.
   * @throws Exception
   */
  public void convert()
      throws Exception {
    File inputDir = new File(_inputDirName);

    if (!inputDir.exists()) {
      System.out.println("Error: Input directory " + _inputDirName + " does not exist.");
      return;
    }

    File outputDir = new File(_outputDirName);
    if (!outputDir.exists()) {
      System.out.println("Error: Output directory " + _outputDirName + " does not exist");
      return;
    }

    File[] files = inputDir.listFiles();
    if (files == null || files.length == 0) {
      System.out.println("Error: Input directory " + _inputDirName + " is empty");
      return;
    }

    for (File file : files) {
      String fileName = file.getName();

      File segment;
      boolean cleanupTempFile = false;

      if (fileName.endsWith("tar.gz") || fileName.endsWith("tgz")) {
        File untarredSegment = new File(outputDir, TMP_DIR_PREFIX + System.currentTimeMillis());
        segment = TarGzCompressionUtils.unTar(file, untarredSegment).get(0);
        cleanupTempFile = true;
      } else {
        segment = file;
      }

      convertSegment(segment);
      if (cleanupTempFile) {
        FileUtils.deleteQuietly(segment.getParentFile());
      }
    }
  }

  /**
   * Helper method to perform the conversion.
   * @param columnarSegment Columnar segment directory to convert
   * @throws Exception
   */
  private void convertSegment(File columnarSegment)
      throws Exception {
    PinotSegmentRecordReader pinotSegmentRecordReader = new PinotSegmentRecordReader(columnarSegment);
    SegmentGeneratorConfig config = new SegmentGeneratorConfig(pinotSegmentRecordReader.getSchema());

    config.setDataDir(_inputDirName);
    config.setInputFilePath(columnarSegment.getAbsolutePath());
    config.setFormat(FileFormat.PINOT);
    config.setEnableStarTreeIndex(true);
    config.setOutDir(_outputDirName);
    config.setStarTreeIndexSpecFile(_starTreeConfigFileName);
    config.setOverwrite(_overwrite);

    // Read the segment and table name from the segment's metadata.
    SegmentMetadata metadata = new SegmentMetadataImpl(columnarSegment);
    SegmentNameGenerator nameGenerator = new DefaultSegmentNameGenerator(metadata.getName());
    config.setSegmentNameGenerator(nameGenerator);
    config.setTableName(metadata.getTableName());

    SegmentIndexCreationDriver indexCreator = new SegmentIndexCreationDriverImpl();
    indexCreator.init(config);
    indexCreator.build();
  }

  /**
   * Helper method to print usage at the command line interface.
   */
  private static void printUsage() {
    System.out.println("Usage: ColumnarToStarTreeConverter");
    for (Field field : ColumnarToStarTreeConverter.class.getDeclaredFields()) {

      if (field.isAnnotationPresent(Option.class)) {
        Option option = field.getAnnotation(Option.class);

        System.out.println(
            String.format("\t%-15s: %s (required=%s)", option.name(), option.usage(), option.required()));
      }
    }
  }

  /**
   * Main driver for the converter class.
   *
   * @param args Command line arguments
   * @throws Exception
   */
  public static void main(String[] args)
      throws Exception {
    ColumnarToStarTreeConverter converter = new ColumnarToStarTreeConverter();
    CmdLineParser parser = new CmdLineParser(converter);
    parser.parseArgument(args);

    if (converter._help) {
      printUsage();
      return;
    }

    converter.convert();
  }
}