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package com.hfg.util.io;


import com.hfg.util.StringUtil;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.List;

//------------------------------------------------------------------------------
/**
 Base class for CSV (comma-separated value) and TSV (tab-separated value).
 
 @author J. Alex Taylor, hairyfatguy.com
 
 */
//------------------------------------------------------------------------------
// com.hfg Library
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// J. Alex Taylor, President, Founder, CEO, COO, CFO, OOPS hairyfatguy.com
// [email protected]
//------------------------------------------------------------------------------
public class DelimitedTextParser
{
   private char mDelimiter;

   //###########################################################################
   // CONSTRUCTORS
   //###########################################################################

   //---------------------------------------------------------------------------
   public DelimitedTextParser(char inDelimiter)
   {
      mDelimiter = inDelimiter;
   }

   //###########################################################################
   // PUBLIC METHODS
   //###########################################################################

   //---------------------------------------------------------------------------
   public String escapeField(String inField)
   {
      String result = inField;

      if (StringUtil.isSet(result)
            && (result.contains("\"") || result.contains(mDelimiter + "")))
      {
         result = "\"" + result.replaceAll("\"", "\"\"") + "\"";
      }

      return result;
   }

   //---------------------------------------------------------------------------
   public List parse(Reader inReader)
      throws IOException
   {
      List parsedLines = new ArrayList<>();

      BufferedReader bufferedReader = null;
      try
      {
         if (inReader instanceof BufferedReader)
         {
            bufferedReader = (BufferedReader) inReader;
         }
         else
         {
            bufferedReader = new BufferedReader(inReader);
         }

         String line;
         while ((line = bufferedReader.readLine()) != null)
         {
            parsedLines.add(parseLine(line));
         }
      }
      finally
      {
         StreamUtil.close(bufferedReader);
      }

      return parsedLines;
   }

   //---------------------------------------------------------------------------
   public String[] parseLine(String inLine)
         throws IOException
   {
      List fields = new ArrayList<>();

      boolean inQuotedValue = false;
      int quoteCount = 0;
      char currentQuoteChar = ' ';
      StringBuilder currentValue = new StringBuilder();

      int index = 0;
      while (index < inLine.length())
      {
         int theChar = inLine.charAt(index);

         if (inQuotedValue)
         {
            if (theChar == currentQuoteChar)
            {
               quoteCount++;

               if (2 == quoteCount)
               {
                  // Skip
                  quoteCount = 0;
               }
               else if ((index == inLine.length() - 1 || inLine.charAt(index + 1) != currentQuoteChar)
                     && (0 == currentValue.length() || currentValue.charAt(currentValue.length() - 1) != '\\'))
               {
                  inQuotedValue = false;
                  String unescapedValue = StringUtil.replaceAll(currentValue, "\\" + currentQuoteChar, currentQuoteChar + "");
                  currentValue.setLength(0);
                  currentValue.append(unescapedValue);
               }
               else
               {
                  currentValue.append((char) theChar);
               }
            }
            else
            {
               currentValue.append((char) theChar);
               quoteCount = 0;
            }
         }
         else if (theChar == mDelimiter)
         {
            fields.add(currentValue.length() > 0 ? currentValue.toString().trim() : null);
            currentValue.setLength(0);
         }
         else if (Character.isWhitespace(theChar)
               && 0 == currentValue.length())
         {
            // Skip whitespace between the comma and the value
         }
         else if ((theChar == '\''
               || theChar == '\"')
               && 0 == currentValue.length())
         {  // Start of a quoted value
            inQuotedValue = true;
            quoteCount = 0;
            currentQuoteChar = (char) theChar;
         }
         else
         {
            currentValue.append((char) theChar);
         }

         index++;
      }

      fields.add(currentValue.length() > 0 ? currentValue.toString().trim() : null);

      return fields.toArray(new String[] {});
   }
}