/*
    * (c) Copyright 2006-2020 by rapiddweller GmbH & Volker Bergmann. All rights reserved.
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, is permitted under the terms of the
    * GNU General Public License.
    *
    * For redistributing this software or a derivative work under a license other
    * than the GPL-compatible Free Software License as defined by the Free
   * Software Foundation or approved by OSI, you must first obtain a commercial
   * license to this software product from rapiddweller GmbH & Volker Bergmann.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED CONDITIONS,
   * REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE
   * HEREBY EXCLUDED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  package com.rapiddweller.benerator.util;
  
  import com.rapiddweller.common.IOUtil;
  import com.rapiddweller.common.ReaderLineIterator;
  import com.rapiddweller.common.StringUtil;
  import com.rapiddweller.common.ui.ConsoleInfoPrinter;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  import java.io.BufferedReader;
  import java.io.BufferedWriter;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Reads a text file, shuffles its lines and writes it to another file.<br/>
   * <br/>
   * Created: 16.07.2007 20:29:10
   */
  public class LineShuffler {
  
    /**
     * The constant logger.
     */
    public static final Logger logger = LogManager.getLogger(LineShuffler.class);
  
    /**
     * The entry point of application.
     *
     * @param args the input arguments
     * @throws IOException the io exception
     */
    public static void main(String[] args) throws IOException {
      if (args.length < 2) {
        printHelp();
        System.exit(-1);
      }
      String inFilename = args[0];
      String outFilename = args[1];
      int bufferSize = (args.length > 2 ? Integer.parseInt(args[2]) : 100000);
      shuffle(inFilename, outFilename, bufferSize);
    }
  
    /**
     * Shuffle.
     *
     * @param inFilename  the in filename
     * @param outFilename the out filename
     * @param bufferSize  the buffer size
     * @throws IOException the io exception
     */
    public static void shuffle(String inFilename, String outFilename, int bufferSize) throws IOException {
      logger.info("shuffling " + inFilename + " and writing to " + outFilename + " (max. " + bufferSize + " lines)");
      ReaderLineIterator iterator = new ReaderLineIterator(new BufferedReader(IOUtil.getReaderForURI(inFilename)));
      List<String> lines = read(bufferSize, iterator);
      shuffle(lines);
      save(lines, outFilename);
    }
  
    /**
     * Shuffle.
     *
     * @param lines the lines
     */
    public static void shuffle(List<String> lines) {
      int size = lines.size();
      //Generator<Integer> indexGenerator = new IntegerGenerator(0, size - 1, 1, Sequence.RANDOM);
      int iterations = size / 2;
      for (int i = 0; i < iterations; i++) {
        int i1 = RandomUtil.randomInt(0, size - 1);
       int i2;
       do {
         i2 = RandomUtil.randomInt(0, size - 1);
       } while (i1 == i2);
       String tmp = lines.get(i1);
       lines.set(i1, lines.get(i2));
       lines.set(i2, tmp);
     }
   }
 
   // private helpers -------------------------------------------------------------------------------------------------
 
   private static List<String> read(int bufferSize, ReaderLineIterator iterator) {
     List<String> lines = new ArrayList<>(Math.max(100000, bufferSize));
     int lineCount = 0;
     while (iterator.hasNext() && lineCount < bufferSize) {
       String line = iterator.next();
       if (!StringUtil.isEmpty(line)) {
         lines.add(line);
         lineCount++;
         if (lineCount % 100000 == 99999) {
           logger.info("parsed " + lineCount + " lines");
         }
       }
     }
     return lines;
   }
 
   private static void save(List<String> lines, String outputFilename) throws IOException {
     logger.info("saving " + outputFilename + "...");
     PrintWriter printer = new PrintWriter(new BufferedWriter(new FileWriter(outputFilename)));
     try {
       for (String line : lines) {
         printer.println(line);
       }
     } finally {
       IOUtil.close(printer);
     }
   }
 
   private static void printHelp() {
     ConsoleInfoPrinter.printHelp("Parameters: inFile outFile [buffer size]");
   }
 }