package water.parser.orc;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.ql.io.orc.OrcFile;
import org.apache.hadoop.hive.ql.io.orc.Reader;
import org.apache.hadoop.hive.ql.io.orc.StripeInformation;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
import water.DKV;
import water.H2O;
import water.Job;
import water.Key;
import water.fvec.*;
import water.parser.*;
import water.persist.PersistHdfs;

import java.io.IOException;
import java.util.List;

import static water.fvec.FileVec.getPathForKey;


/**
 * Orc parser provider.
 */
public class OrcParserProvider extends ParserProvider {

  /* Setup for this parser */
  static ParserInfo ORC_INFO = new ParserInfo("ORC", DefaultParserProviders.MAX_CORE_PRIO + 20, true);

  @Override
  public ParserInfo info() {
    return ORC_INFO;
  }

  @Override
  public Parser createParser(ParseSetup setup, Key<Job> jobKey) {
    return new OrcParser(setup, jobKey);
  }

  @Override
  public ParseSetup guessSetup(ByteVec bv, byte [] bits, byte sep, int ncols, boolean singleQuotes,
                               int checkHeader, String[] columnNames, byte[] columnTypes,
                               String[][] domains, String[][] naStrings) {
    if(bv instanceof FileVec)
      return readSetup((FileVec)bv, columnNames, columnTypes);
    throw new UnsupportedOperationException("ORC only works on Files");
  }

  /**
   * Use only the first file to setup everything.
   *
   * @param inputs  input keys
   * @param requiredSetup  user given parser setup
   * @return
   */
  @Override
  public ParseSetup createParserSetup(Key[] inputs, ParseSetup requiredSetup) {

    FileVec f;
    Object frameOrVec = DKV.getGet(inputs[0]);

    if (frameOrVec instanceof water.fvec.Frame)
      f = (FileVec) ((Frame) frameOrVec).vec(0);
    else
      f = (FileVec) frameOrVec;
    return readSetup(f, requiredSetup.getColumnNames(), requiredSetup.getColumnTypes());
  }

  private Reader getReader(FileVec f) throws IOException {
    String strPath = getPathForKey(f._key);
    Path path = new Path(strPath);
    if(f instanceof HDFSFileVec)
      return OrcFile.createReader(PersistHdfs.getFS(strPath), path);
    else
      return OrcFile.createReader(path, OrcFile.readerOptions(new Configuration()));
  }

  /**
   * This method will create the readers and others info needed to parse an orc file.
   * In addition, it will not over-ride the columnNames, columnTypes that the user
   * may want to force upon it.  However, we only allow users to set column types to
   * enum at this point and ignore all the other requests.
   *
   * @param f
   * @param columnNames
   * @param columnTypes
   * @return
   */
  public ParseSetup readSetup(FileVec f, String[] columnNames, byte[] columnTypes) {
    try {
      Reader orcFileReader = getReader(f);
      StructObjectInspector insp = (StructObjectInspector) orcFileReader.getObjectInspector();
      OrcParser.OrcParseSetup stp = OrcParser.deriveParseSetup(orcFileReader, insp);

      // change back the columnNames and columnTypes if they are specified already
      if (!(columnNames == null) && (stp.getAllColNames().length == columnNames.length)) { // copy column name
        stp.setColumnNames(columnNames);
        stp.setAllColNames(columnNames);
      }

      if (!(columnTypes == null) && (columnTypes.length == stp.getColumnTypes().length)) { // copy enum type only
        byte[] old_columnTypes = stp.getColumnTypes();
        String[] old_columnTypeNames = stp.getColumnTypesString();
        for (int index = 0; index < columnTypes.length; index++) {
          if (columnTypes[index] == Vec.T_CAT)  // only copy the enum types
            old_columnTypes[index] = columnTypes[index];
        }
        stp.setColumnTypes(old_columnTypes);
        stp.setColumnTypeStrings(old_columnTypeNames);
      }

      List<StripeInformation> stripesInfo = orcFileReader.getStripes();
      if(stripesInfo.size() == 0) { // empty file
        f.setChunkSize(stp._chunk_size = (int)f.length());
        return stp;
      }
      f.setNChunks(stripesInfo.size());
      stp._chunk_size = f._chunkSize;
      assert f.nChunks() == stripesInfo.size(); // ORC parser needs one-to one mapping between chunk and strip (just ids, offsets do not matter)
      return stp;
    } catch(IOException ioe) {
      throw new RuntimeException(ioe);
    }
  }

  @Override
  public ParseSetup setupLocal(Vec v, ParseSetup setup){
    if(!(v instanceof FileVec)) throw H2O.unimpl("ORC only implemented for HDFS / NFS files");
    try {
      ((OrcParser.OrcParseSetup)setup).setOrcFileReader(getReader((FileVec)v));

      return setup;

    } catch (IOException e) {throw new RuntimeException(e);}
  }
}