content: /*
   * 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.carbondata.index.examples;
  
  import java.io.BufferedReader;
  import java.io.DataInputStream;
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.ArrayList;
  import java.util.BitSet;
  import java.util.List;
  
  import org.apache.log4j.Logger;
  import org.apache.carbondata.common.logging.LogServiceFactory;
  import org.apache.carbondata.core.datastore.block.SegmentProperties;
  import org.apache.carbondata.core.datastore.impl.FileFactory;
  import org.apache.carbondata.core.index.dev.IndexModel;
  import org.apache.carbondata.core.index.dev.cgindex.CoarseGrainIndex;
  import org.apache.carbondata.core.fileoperations.AtomicFileOperations;
  import org.apache.carbondata.core.fileoperations.AtomicFileOperationFactory;
  import org.apache.carbondata.core.indexstore.Blocklet;
  import org.apache.carbondata.core.indexstore.PartitionSpec;
  import org.apache.carbondata.core.memory.MemoryException;
  import org.apache.carbondata.core.scan.filter.FilterUtil;
  import org.apache.carbondata.core.scan.filter.executer.FilterExecuter;
  import org.apache.carbondata.core.scan.filter.resolver.FilterResolverIntf;
  import org.apache.carbondata.core.util.CarbonUtil;
  
  import com.google.gson.Gson;
  import org.apache.hadoop.fs.FileStatus;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.fs.PathFilter;
  
  /**
   * Index implementation for min max blocklet.
   */
  public class MinMaxIndex extends CoarseGrainIndex {
  
    private static final Logger LOGGER =
        LogServiceFactory.getLogService(MinMaxIndex.class.getName());
  
    private String[] indexFilePath;
  
    private MinMaxIndexBlockDetails[][] readMinMaxIndex;
  
    @Override
    public void init(IndexModel model) throws MemoryException, IOException {
      Path indexPath = FileFactory.getPath(model.getFilePath());
  
      FileSystem fs = FileFactory.getFileSystem(indexPath);
      if (!fs.exists(indexPath)) {
        throw new IOException(
            String.format("Path %s for MinMax index does not exist", indexPath));
      }
      if (!fs.isDirectory(indexPath)) {
        throw new IOException(
            String.format("Path %s for MinMax index must be a directory", indexPath));
      }
  
      FileStatus[] indexFileStatus = fs.listStatus(indexPath, new PathFilter() {
        @Override
        public boolean accept(Path path) {
          return path.getName().endsWith(".minmaxindex");
        }
      });
  
      this.indexFilePath = new String[indexFileStatus.length];
      this.readMinMaxIndex = new MinMaxIndexBlockDetails[indexFileStatus.length][];
      for (int i = 0; i < indexFileStatus.length; i++) {
        this.indexFilePath[i] = indexFileStatus[i].getPath().toString();
        this.readMinMaxIndex[i] = readJson(this.indexFilePath[i]);
      }
    }
  
    private MinMaxIndexBlockDetails[] readJson(String filePath) {
      Gson gsonObjectToRead = new Gson();
      DataInputStream dataInputStream = null;
      BufferedReader buffReader = null;
      InputStreamReader inStream = null;
      MinMaxIndexBlockDetails[] readMinMax = null;
      AtomicFileOperations fileOperation =
          AtomicFileOperationFactory.getAtomicFileOperations(filePath);
  
      try {
        if (!FileFactory.isFileExist(filePath)) {
          return null;
        }
        dataInputStream = fileOperation.openForRead();
        inStream = new InputStreamReader(dataInputStream, "UTF-8");
        buffReader = new BufferedReader(inStream);
        readMinMax = gsonObjectToRead.fromJson(buffReader, MinMaxIndexBlockDetails[].class);
      } catch (IOException e) {
        return null;
      } finally {
        CarbonUtil.closeStreams(buffReader, inStream, dataInputStream);
      }
      return readMinMax;
    }
  
    /**
     * Block Prunning logic for Min Max Index.
     *
     * @param filterExp
     * @param segmentProperties
     * @return
     */
    @Override
    public List<Blocklet> prune(FilterResolverIntf filterExp,
        SegmentProperties segmentProperties, List<PartitionSpec> partitions) {
      List<Blocklet> blocklets = new ArrayList<>();
  
      if (filterExp == null) {
        for (int i = 0; i < readMinMaxIndex.length; i++) {
          for (int j = 0; j < readMinMaxIndex[i].length; j++) {
            blocklets.add(new Blocklet(indexFilePath[i],
                String.valueOf(readMinMaxIndex[i][j].getBlockletId())));
          }
        }
      } else {
        FilterExecuter filterExecuter =
            FilterUtil.getFilterExecuterTree(filterExp, segmentProperties, null, false);
        for (int blkIdx = 0; blkIdx < readMinMaxIndex.length; blkIdx++) {
          for (int blkltIdx = 0; blkltIdx < readMinMaxIndex[blkIdx].length; blkltIdx++) {
  
            BitSet bitSet = filterExecuter.isScanRequired(
                readMinMaxIndex[blkIdx][blkltIdx].getMaxValues(),
                readMinMaxIndex[blkIdx][blkltIdx].getMinValues(), null);
            if (!bitSet.isEmpty()) {
              String blockFileName = indexFilePath[blkIdx].substring(
                  indexFilePath[blkIdx].lastIndexOf(File.separatorChar) + 1,
                  indexFilePath[blkIdx].indexOf(".minmaxindex"));
              Blocklet blocklet = new Blocklet(blockFileName,
                  String.valueOf(readMinMaxIndex[blkIdx][blkltIdx].getBlockletId()));
              LOGGER.info(String.format("Need to scan block#%s -> blocklet#%s, %s",
                  blkIdx, blkltIdx, blocklet));
              blocklets.add(blocklet);
            } else {
              LOGGER.info(String.format("Skip scan block#%s -> blocklet#%s",
                  blkIdx, blkltIdx));
            }
          }
        }
      }
      return blocklets;
    }
  
    @Override
    public boolean isScanRequired(FilterResolverIntf filterExp) {
      throw new UnsupportedOperationException();
    }
  
    @Override
    public void clear() {
      readMinMaxIndex = null;
    }
  
    @Override
    public void finish() {
  
    }
  
    @Override
    public int getNumberOfEntries() {
      // keep default, one record in one indexSchema
      return 1;
    }
  }
  