/*
    * JBoss, Home of Professional Open Source.
    * See the COPYRIGHT.txt file distributed with this work for information
    * regarding copyright ownership.  Some portions may be licensed
    * to Red Hat, Inc. under one or more contributor license agreements.
    * 
    * 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., 51 Franklin Street, Fifth Floor, Boston, MA
   * 02110-1301 USA.
   */
  
  package org.modeshape.jdbc.util;
  
  import java.sql.Date;
  import java.sql.Time;
  import java.sql.Timestamp;
  import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  import java.util.Calendar;
  import java.util.GregorianCalendar;
  import java.util.TimeZone;
  
  
  /**
   * Utility methods for SQL Timestamps, Time, and Dates with time zones as UTC 
   * 
   * This is intended to take incoming Strings or Dates that have accurate 
   * Calendar fields and give the UTC time by interpretting those fields
   * in the target time zone. 
   * 
   * Use of the Calendar object passed in will not be thread safe, but
   * it will not alter the contents of the Calendar.
   * 
   * Note that normalization occurs only for the transition from one type to another. 
   *  
   */
  public class TimestampWithTimezone {
  	
      public static DateFormat DATETIME_FORMAT = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); //$NON-NLS-1$
      public static DateFormat DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd"); //$NON-NLS-1$
      public static DateFormat TIME_FORMAT = new SimpleDateFormat("HH:mm:ss a"); //$NON-NLS-1$
  
  	
  	private static ThreadLocal<Calendar> CALENDAR = new ThreadLocal<Calendar>() {
  		@Override
  		protected Calendar initialValue() {
  			return Calendar.getInstance();
  		}
  	};
  	
  	public static Calendar getCalendar() {
  		return CALENDAR.get();
  	}
  	
  	public static void resetCalendar(TimeZone tz) {
  		TimeZone.setDefault(tz);
  		Calendar cal = Calendar.getInstance();
  		cal.setTimeZone(tz);
  		CALENDAR.set(cal);
  	}
  	
  	
      public static Timestamp createTimestamp(Calendar initial, Calendar target) {
          if (target == null) {
              target = getCalendar();
          }
  
          long time = target.getTimeInMillis(); 
          
          Calendar new_target = adjustCalendarForTimeStamp(initial, target);
                  
          Timestamp tsInTz = createTimestamp(new_target); 
                  
          target.setTimeInMillis(time);
          return tsInTz;      
      }	
      
      public static Time createTime(Calendar initial, Calendar target) {
          if (target == null) {
          	// if target is null, then obtain current calendar
          	target = getCalendar();
          }
         
          long time = target.getTimeInMillis(); 
  
          adjustCalendarForTime(initial, target); 
          
          target.set(Calendar.MILLISECOND, 0);
         
         Time result = createTime(target);
         
         target.setTimeInMillis(time);
 
         return result;
     }
     
     public static Date createDate(Calendar initial, Calendar target) {
         if (target == null) {
             return createDate(initial);
         }
 
         long time = target.getTimeInMillis(); 
         
         target = adjustCalendarForDate(initial, target);
                  
         Date result = normalizeDate(target, true);
                
         target.setTimeInMillis(time);
 
         return result;
     }
     
     /**
      * Creates normalized SQL Time Object based on
      * the target Calendar.
      * @param target Calendar 
      * 
      * @return Time
      */
     public static Time createTime(Calendar target) {  
     	return new Time(target.getTimeInMillis());
     }
     
   /**
   * Creates normalized SQL Date Object based on
   * the target Calendar
   * @param target Calendar 
   *  
   * @return Date
   */ 
     public static Date createDate(Calendar target) {		        
         return new java.sql.Date(target.getTime().getTime());
     }
     
     
     /**
      * Creates normalized SQL Timestamp Object based on
      * the target Calendar
      * @param target Calendar 
      *  
      * @return Timestamp
      */ 
     public static Timestamp createTimestamp(Calendar target) {
         return new Timestamp(target.getTime().getTime());
     }
     
     private static Date normalizeDate(Calendar target, boolean isDate) {
          if (isDate) {
             target.set(Calendar.HOUR_OF_DAY, 0);
             target.set(Calendar.MINUTE, 0);
             target.set(Calendar.SECOND, 0);
             target.set(Calendar.MILLISECOND, 0);
         }
         return createDate(target);
     } 
     
 	private static void adjustCalendarForTime(Calendar initial,
 			Calendar target) {
 		assert initial != null;
 
         if (initial.getTimeZone().hasSameRules(target.getTimeZone())) {
 			 target.setTime(initial.getTime());
 			 return;
         }
          
         target.clear();
         for (int i = 0; i <= Calendar.MILLISECOND; i++) {
             target.set(i, initial.get(i));
         }     		
 	}
    
 	private static Calendar adjustCalendarForDate(Calendar initial,
 			Calendar target) {
 		assert initial != null;
 
 		if (initial.getTimeZone().hasSameRules(target.getTimeZone())) {	
 			target.setTime(initial.getTime());
 			return target;
 		}
 		
 		Calendar ntarget = new GregorianCalendar(target.getTimeZone());
 		ntarget.setTimeInMillis(initial.getTimeInMillis()); 	
 
         return ntarget;
 	}
 	
 	private static Calendar adjustCalendarForTimeStamp(Calendar initial,
 			Calendar target) {
 		assert initial != null;
 
 		if (initial.getTimeZone().hasSameRules(target.getTimeZone())) {	
 			target.setTime(initial.getTime());
 			return target;
 		}
 		
 		TimeZone targetTimeZone = target.getTimeZone();
 		    Calendar ret = new GregorianCalendar(targetTimeZone);
 		    ret.setTimeInMillis(initial.getTimeInMillis() +
 		    		targetTimeZone.getOffset(initial.getTimeInMillis()) -
 		            initial.getTimeZone().getOffset(initial.getTimeInMillis()));
 		    ret.getTime();
 		    return ret;
 		    
 //		    Calendar ret = new GregorianCalendar(targetTimeZone);
 //		    ret.setTimeInMillis(initial.getTimeInMillis() +
 //		    		targetTimeZone.getOffset(initial.getTimeInMillis()) -
 //		            TimeZone.getDefault().getOffset(initial.getTimeInMillis()));
 		
 	}	
 }