// BSD License (http://www.galagosearch.org/license)

 package org.galagosearch.core.parse;

 import java.io.IOException;

 import java.util.Calendar;

 import java.util.GregorianCalendar;

 import java.util.HashMap;

 import java.util.List;

 import org.galagosearch.tupleflow.InputClass;

 import org.galagosearch.tupleflow.OutputClass;

 import org.galagosearch.tupleflow.StandardStep;

 /**

  * A very crude extractor of dates from text.

  * 

  * This class searches for anything that looks like a year (1000-2999), then

  * searches around that year for a month name.  A year is sufficient to emit

  * a date.  Day of the month is currently not supported.

  * 

  * @author trevor

  */

 @InputClass(className = "org.galagosearch.core.parse.Document")

 @OutputClass(className = "org.galagosearch.core.types.DateExtent")

 public class DateExtractor extends StandardStep<Document, Document> {

     HashMap<String, Integer> months = new HashMap<String, Integer>();

     public DateExtractor() {

         addMonth("January", "Jan", Calendar.JANUARY);

         addMonth("February", "Feb", Calendar.FEBRUARY);

         addMonth("March", "Mar", Calendar.MARCH);

         addMonth("April", "Apr", Calendar.APRIL);

         addMonth("May", "May", Calendar.MAY);

         addMonth("June", "Jun", Calendar.JUNE);

         addMonth("July", "Jul", Calendar.JULY);

         addMonth("August", "Aug", Calendar.AUGUST);

         addMonth("September", "Sep", Calendar.SEPTEMBER);

         addMonth("October", "Oct", Calendar.OCTOBER);

         addMonth("November", "Nov", Calendar.NOVEMBER);

         addMonth("December", "Dec", Calendar.DECEMBER);        

     }

     public void addMonth(String longMonth, String shortMonth, int value) {

         months.put(longMonth, value);

         months.put(shortMonth, value);

     }

     public boolean isMonth(String month) {

         return months.containsKey(month);

     }

     public boolean isYear(String year) {

         if (year.length() != 4)

             return false;

         char first = year.charAt(0);

         if (first != '1' && first != '2')

             return false;

         return Character.isDigit(year.charAt(1)) &&

                Character.isDigit(year.charAt(2)) &&

                Character.isDigit(year.charAt(3));

     }

     public int getMonth(List<String> terms, int i) {

         if (i > 0 && isMonth(terms.get(i-1))) {

             return months.get(terms.get(i-1));

         }

         if (i > 0 && isMonth(terms.get(i-2))) {

             return months.get(terms.get(i-2));

         }

         if (i < terms.size()-1 && isMonth(terms.get(i+1))) {

             return months.get(terms.get(i+1));

         }

         return 0;

     }

     @Override

     public void process(Document object) throws IOException {

         for (int i = 0; i < object.terms.size(); ++i) {

             String term = object.terms.get(i);

             if (isYear(term)) {

                 int year = Integer.parseInt(term);

                 int month = getMonth(object.terms, i);

                 Calendar calendar = new GregorianCalendar();

                 calendar.set(year, month, 1);

                 // TODO(trevor): add date extent

                 // processor.process(new DateExtent(i, calendar.getTime()));

             }

         }

     }

 }