/*

  * $Source$

  * $Revision$

  *

  * Copyright (C) 2001 Myles Chippendale

  * 

  * Part of Melati (http://melati.org), a framework for the rapid

  * development of clean, maintainable web applications.

  *

  * Melati is free software; Permission is granted to copy, distribute

  * and/or modify this software under the terms either:

  *

  * a) the GNU General Public License as published by the Free Software

  *    Foundation; either version 2 of the License, or (at your option)

  *    any later version,

  *

  *    or

  *

  * b) any version of the Melati Software License, as published

  *    at http://melati.org

  *

  * You should have received a copy of the GNU General Public License and

  * the Melati Software License along with this program;

  * if not, write to the Free Software Foundation, Inc.,

  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the

  * GNU General Public License and visit http://melati.org to obtain the

  * Melati Software License.

  *

  * Feel free to contact the Developers of Melati (http://melati.org),

  * if you would like to work out a different arrangement than the options

  * outlined here.  It is our intention to allow Melati to be used by as

  * wide an audience as possible.

  *

  * 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.

  *

  * Contact details for copyright holder:

  *

  *     Myles Chippendale <mylesc At paneris.org>

  */

 package org.melati.poem.csv;

 import java.io.BufferedReader;

 import java.io.File;

 import java.io.FileReader;

 import java.io.IOException;

 import java.util.NoSuchElementException;

 /**

  * A utility for tokenising a file made up of comma-separated

  * variables.  We allow for fields having returns in them.

  *

  * <PRE>

  *   foo, bar om,,"baz, ,oof",xyz,   ->

  *     "foo", " bar om", "", "baz, , oof", "xyz", ""

  *

  *   foo, "bar

  *   bar

  *   bar", baz ->

  *   "foo", "bar\u0015bar\u0015bar", "baz"

  * </PRE>

  *

  * Each record (which is usually a line, unless some fields have

  * a line break in them) is accessed one at a time by calling

  * <code>nextRecord()</code>. Within each record

  * <code>recordHasMoreFields()</code> and <code>nextField()</code>

  * can be used like an Enumeration to iterate through the fields.

  *

  * @author  mylesc, based heavily on 

  *          orginal CSVStringEnumeration williamc

  */

 public class CSVFileParser {

   private BufferedReader reader = null;

   int lineNo = 0;      // The first line will be line '1'

   private String line = "";

   private boolean emptyLastField = false;

   int p = 0;

   /**

    * Constructor.

    * @param reader file reader

    */

   public CSVFileParser(BufferedReader reader) {

     this.reader = reader;

   }

   /**

    * @return whether there is another line 

    */

   public boolean nextRecord() throws IOException {

     return nextLine();

   }

   private boolean nextLine() throws IOException {

     // Not confident about this

     // but we need to return false if we have reached end and closed the file

     if (!reader.ready()) return false;

     line = reader.readLine();

     // This should be false anyway if we're called from nextToken()

     emptyLastField = false;

     p = 0;

     if (line == null) {

       reader.close();

       return false;

     }

     lineNo++;

     return true;

   }

   /**

    * Return the line number.

    * 

    * @return the current lineNo

    */

   public int getLineNo() {

     return lineNo;

   }

   /**

    * Are there any more tokens to come?

    * @return whether there are more fields

    */

   public boolean recordHasMoreFields() {

     return emptyLastField || p < line.length();

   }

   /**

    * @return the next token as a String

    */

   public String nextField() throws IOException {

     return nextToken(false);

   }

   /**

    * @return the next token as a String

    */

   private String nextToken(boolean inUnclosedQuotes) throws IOException {

     if (emptyLastField) {

       emptyLastField = false;

       return "";

     }

     if (p >= line.length()) throw new NoSuchElementException();

     if (inUnclosedQuotes || (line.charAt(p) == '"' && (++p>0))) {

       // we need to allow for quotes inside quoted fields, so now test for ",

       int q = line.indexOf("\",", p);

       // if it is not there, we are (hopefully) at the end of a line

       if (q == -1 && (line.indexOf('"', p) == line.length()-1)) 

         q = line.length()-1;

       // If we don't find the end quote try reading in more lines

       // since fields can have \n in them

       if (q == -1) {

         String sofar = line.substring(p, line.length());

         if (!nextLine())

           throw new IllegalArgumentException("Unclosed quotes on line "

                                              + lineNo);

         return sofar + "\n" + nextToken(true);

       }

       String it = line.substring(p, q);

       ++q;

       p = q+1;

       if (q < line.length()) {

         if (line.charAt(q) != ',') {

           p = line.length();

           throw new IllegalArgumentException("No comma after quotes on line "

                                             + lineNo);

         }

         else if (q == line.length() - 1)

           emptyLastField = true;

       }

       return it;

     } else {

       int q = line.indexOf(',', p);

       if (q == -1) {

          String it = line.substring(p);

          p = line.length();

          return it;

       } else {

          String it = line.substring(p, q);

          if (q == line.length() - 1)

             emptyLastField = true;

             p = q + 1;

             return it;

       }

     }

   }

   /**

    * Test harness.

    * @param args arguments

    * @throws Exception if anything fails

    */

   public static void main(String[] args) throws Exception {

     System.out.println("***** Reading file " + args[0]);

     BufferedReader reader = new BufferedReader(

                                  new FileReader(new File(args[0])));

     CSVFileParser toks = new CSVFileParser(reader);

     int recordCount = 0;

     while(toks.nextRecord()) {

       System.out.println("*** Record " + ++recordCount);

       int i = 0;

       while (toks.recordHasMoreFields()) {

         System.out.println("Field " + ++i + ":" + toks.nextField());

       }

     }

   }

 }