/* Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.activiti.engine.impl.calendar;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;

import org.activiti.engine.ActivitiException;
import org.activiti.engine.impl.util.ClockUtil;


/**
 * @author Tom Baeyens
 */
public class DefaultBusinessCalendar implements BusinessCalendar {

  private static Map<String, Integer> units = new HashMap<String, Integer>();
  static {
    units.put("millis", Calendar.MILLISECOND);
    units.put("seconds", Calendar.SECOND);
    units.put("second", Calendar.SECOND);
    units.put("minute", Calendar.MINUTE);
    units.put("minutes", Calendar.MINUTE);
    units.put("hour", Calendar.HOUR);
    units.put("hours", Calendar.HOUR);
    units.put("day", Calendar.DAY_OF_YEAR);
    units.put("days", Calendar.DAY_OF_YEAR);
    units.put("week", Calendar.WEEK_OF_YEAR);
    units.put("weeks", Calendar.WEEK_OF_YEAR);
    units.put("month", Calendar.MONTH);
    units.put("months", Calendar.MONTH);
    units.put("year", Calendar.YEAR);
    units.put("years", Calendar.YEAR);
  }
  
  public Date resolveDuedate(String duedate) {
    Date resolvedDuedate = ClockUtil.getCurrentTime();
    
    String[] tokens = duedate.split(" and ");
    for (String token : tokens) {
      resolvedDuedate = addSingleUnitQuantity(resolvedDuedate, token);      
    }

    return resolvedDuedate;
  }

  protected Date addSingleUnitQuantity(Date startDate, String singleUnitQuantity) {
    int spaceIndex = singleUnitQuantity.indexOf(" ");
    if (spaceIndex==-1 || singleUnitQuantity.length() < spaceIndex+1) {
      throw new ActivitiException("invalid duedate format: "+singleUnitQuantity);
    }
    
    String quantityText = singleUnitQuantity.substring(0, spaceIndex);
    Integer quantity = new Integer(quantityText);
    
    String unitText = singleUnitQuantity
      .substring(spaceIndex+1)
      .trim()
      .toLowerCase();
    
    int unit = units.get(unitText);

    GregorianCalendar calendar = new GregorianCalendar(); 
    calendar.setTime(startDate);
    calendar.add(unit, quantity);
    
    return calendar.getTime();
  }
}