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/*
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */

package ai.preferred.regression.pe;

import ai.preferred.regression.io.CSVInputData;
import ai.preferred.regression.io.CSVUtils;
import org.apache.commons.csv.CSVPrinter;
import org.kohsuke.args4j.CmdLineException;
import org.kohsuke.args4j.CmdLineParser;
import org.kohsuke.args4j.Option;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;

public abstract class ProcessingElement {

  private static final Logger LOGGER = LoggerFactory.getLogger(ProcessingElement.class);

  @Option(name = "-i", aliases = {"--input"}, usage = "the path to the input CSV file", required = true)
  private File input;

  @Option(name = "-o", aliases = {"--output"}, usage = "the path to the output CSV file", required = true)
  private File output;

  @Option(name = "-h", aliases = {"--header"}, usage = "specifies if the input CSV files have headers")
  private boolean header = true;

  public ProcessingElement() {
  }

  protected abstract void process(CSVInputData data, CSVPrinter printer) throws Exception;

  protected static void parseArgsAndRun(Class clazz, String[] args) {
    ProcessingElement processingElement = null;
    try {
      processingElement = clazz.newInstance();
    } catch (IllegalAccessException | InstantiationException e) {
      System.err.println("Please check if there is the public default constructor for the class: " + clazz.getCanonicalName());
      System.exit(1);
    }

    if (args == null) {
      System.out.println("=========== HELP ===========");
      System.out.println();
      System.out.println("Processing Element: " + clazz.getSimpleName() + ".class");
      System.out.println();
      System.out.println("Shell.run(" + clazz.getSimpleName() + ".class, \"\");");
      final CmdLineParser parser = new CmdLineParser(processingElement);
      System.out.println();
      parser.printUsage(System.out);
      System.out.println();
      System.out.println("============================");
      System.out.println();
      System.out.println();
      return;
    }

    final CmdLineParser parser = new CmdLineParser(processingElement);
    try {
      parser.parseArgument(args);
    } catch (CmdLineException e) {
      System.err.println("ProcessingElement: " + clazz.getCanonicalName());
      System.err.println(e.getMessage());
      System.err.println();
      parser.printUsage(System.err);
      System.exit(1);
    }

    if (processingElement.input.equals(processingElement.output)) {
      LOGGER.error("The input and output files point to the same location: {}", processingElement.input);
      System.exit(1);
    }

    try (final CSVPrinter printer = CSVUtils.printer(processingElement.output);
         final CSVInputData reader = CSVUtils.reader(processingElement.input, processingElement.header)) {
      try {
        processingElement.process(reader, printer);
      } catch (Exception e) {
        LOGGER.error("Unexpected error: ", e);
        System.exit(1);
      }
    } catch (IOException e) {
      LOGGER.error("Unable to process files: ", e);
      System.exit(1);
    }
  }

}