contrib/format-excel/src/main/java/org/apache/drill/exec/store/excel/ExcelFormatPlugin.java

/*
 * 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.drill.exec.store.excel;

import org.apache.drill.common.exceptions.ExecutionSetupException;
import org.apache.drill.common.exceptions.UserException;
import org.apache.drill.common.logical.StoragePluginConfig;
import org.apache.drill.common.types.TypeProtos;
import org.apache.drill.common.types.Types;
import org.apache.drill.exec.physical.impl.scan.file.FileScanFramework.FileReaderFactory;
import org.apache.drill.exec.physical.impl.scan.file.FileScanFramework.FileScanBuilder;
import org.apache.drill.exec.physical.impl.scan.file.FileScanFramework.FileSchemaNegotiator;

import org.apache.drill.exec.physical.impl.scan.framework.ManagedReader;
import org.apache.drill.exec.proto.UserBitShared;
import org.apache.drill.exec.server.DrillbitContext;
import org.apache.drill.exec.server.options.OptionManager;
import org.apache.drill.exec.store.dfs.easy.EasyFormatPlugin;
import org.apache.drill.exec.store.dfs.easy.EasySubScan;
import org.apache.hadoop.conf.Configuration;
import org.apache.drill.exec.store.excel.ExcelBatchReader.ExcelReaderConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


public class ExcelFormatPlugin extends EasyFormatPlugin<ExcelFormatConfig> {

  protected static final String DEFAULT_NAME = "excel";
  private static final Logger logger = LoggerFactory.getLogger(ExcelFormatPlugin.class);

  private static class ExcelReaderFactory extends FileReaderFactory {
    private final ExcelBatchReader.ExcelReaderConfig readerConfig;
    private final int maxRecords;

    public ExcelReaderFactory(ExcelReaderConfig config, int maxRecords) {
      readerConfig = config;
      this.maxRecords = maxRecords;
    }

    @Override
    public ManagedReader<? extends FileSchemaNegotiator> newReader() {
      return new ExcelBatchReader(readerConfig, maxRecords);
    }
  }

  public ExcelFormatPlugin(String name, DrillbitContext context,
                         Configuration fsConf, StoragePluginConfig storageConfig,
                         ExcelFormatConfig formatConfig) {
    super(name, easyConfig(fsConf, formatConfig), context, storageConfig, formatConfig);
  }

  private static EasyFormatConfig easyConfig(Configuration fsConf, ExcelFormatConfig pluginConfig) {
    EasyFormatConfig config = new EasyFormatConfig();
    config.readable = true;
    config.writable = false;
    config.blockSplittable = false;
    config.compressible = true;
    config.supportsProjectPushdown = true;
    config.extensions = pluginConfig.getExtensions();
    config.fsConf = fsConf;
    config.defaultName = DEFAULT_NAME;
    config.readerOperatorType = UserBitShared.CoreOperatorType.EXCEL_SUB_SCAN_VALUE;
    config.useEnhancedScan = true;
    config.supportsLimitPushdown = true;
    return config;
  }

  @Override
  public ManagedReader<? extends FileSchemaNegotiator> newBatchReader(
    EasySubScan scan, OptionManager options) throws ExecutionSetupException {
    return new ExcelBatchReader(formatConfig.getReaderConfig(this), scan.getMaxRecords());
  }

  @Override
  protected FileScanBuilder frameworkBuilder(OptionManager options, EasySubScan scan) throws ExecutionSetupException {
    FileScanBuilder builder = new FileScanBuilder();
    ExcelReaderConfig readerConfig = new ExcelReaderConfig(this);

    verifyConfigOptions(readerConfig);
    builder.setReaderFactory(new ExcelReaderFactory(readerConfig, scan.getMaxRecords()));

    initScanBuilder(builder, scan);
    builder.nullType(Types.optional(TypeProtos.MinorType.VARCHAR));
    return builder;
  }

  /**
   * This function verifies that the user entered valid user configuration options.  Specifically it verifies that:
   * <ul>
   * <li>the lastColumn is greater than the first column</li>
   * <li>The lastColumn is not zero</li>
   * <li>firstColumn is greater than zero</li>
   * <li>lastColumn is greater than zero</li>
   * <li>The headerRow index is less than the lastRow index</li>
   * </ul>
   *
   * @param readerConfig The readerConfig object for which the function will verify the config options
   */
  private void verifyConfigOptions(ExcelReaderConfig readerConfig) {
    // Validate the config variables
    if ((readerConfig.lastColumn < readerConfig.firstColumn) && readerConfig.lastColumn != 0) {
      throw UserException
        .validationError()
        .message("Invalid column configuration. The first column index is greater than the last column index.")
        .build(logger);
    }

    if (readerConfig.firstColumn < 0) {
      throw UserException
        .validationError()
        .message("Invalid value for first column. Index must be greater than zero.")
        .build(logger);
    }

    if (readerConfig.lastColumn < 0) {
      throw UserException
        .validationError()
        .message("Invalid value for last column. Index must be greater than zero.")
        .build(logger);
    }

    if (readerConfig.headerRow > readerConfig.lastRow) {
      throw UserException
        .validationError()
        .message("Invalid value for headerRow. Header row must be less than last row.")
        .build(logger);
    }
  }
}