/*
  Copyright (C) 2004-2005 SKYRIX Software AG
 
  This file is part of SOPE.
 
  SOPE 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, or (at your option) any
  later version.
 
  SOPE 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 SOPE; see the file COPYING. If not, write to the
  Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

#import <NGExtensions/NSCalendarDate+misc.h>

#import "iCalRecurrenceCalculator.h"

@interface iCalYearlyRecurrenceCalculator : iCalRecurrenceCalculator
@end

#import <NGExtensions/NGCalendarDateRange.h>
#import "iCalRecurrenceRule.h"
#import "NSCalendarDate+ICal.h"

@interface iCalRecurrenceCalculator (PrivateAPI)
- (NSCalendarDate *) lastInstanceStartDate;
@end

@implementation iCalYearlyRecurrenceCalculator

- (NSArray *)
 recurrenceRangesWithinCalendarDateRange: (NGCalendarDateRange *) _r
{
  NSMutableArray *ranges;
  NSCalendarDate *firStart, *rStart, *rEnd, *until;
  unsigned i, count, interval;
  int diff;
 
  firStart = [firstRange startDate];
  rStart = [_r startDate];
  rEnd = [_r endDate];
  interval = [rrule repeatInterval];
  until = [self lastInstanceStartDate];
 
  if (until)
    {
      if ([until compare: rStart] == NSOrderedAscending)
	return nil;
      if ([until compare: rEnd] == NSOrderedDescending)
	rEnd = until;
    }
 
  diff = [firStart yearsBetweenDate: rStart];
  if ((diff != 0) && [rStart compare: firStart] == NSOrderedAscending)
    diff = -diff;

  count = [rStart yearsBetweenDate: rEnd] + 1;
  ranges = [NSMutableArray arrayWithCapacity: count];
  for (i = 0 ; i < count; i++)
    {
      int test;

      test = diff + i;
      if ((test >= 0) && (test % interval) == 0)
	{
	  NSCalendarDate *start, *end;
	  NGCalendarDateRange *r;
 
	  start = [firStart dateByAddingYears: diff + i
			    months: 0
			    days: 0];
	  [start setTimeZone: [firStart timeZone]];
	  end = [start addTimeInterval: [firstRange duration]];
	  r = [NGCalendarDateRange calendarDateRangeWithStartDate: start
				   endDate: end];
	  if ([_r containsDateRange: r])
	    [ranges addObject: r];
	}
    }
  return ranges;
}

- (NSCalendarDate *) lastInstanceStartDate
{
  if ([rrule repeatCount] > 0)
    {
      NSCalendarDate *until;
      unsigned years, interval;
 
      interval = [rrule repeatInterval];
      years = [rrule repeatCount] * interval;
      until = [[firstRange startDate] dateByAddingYears: years
				      months: 0
				      days: 0];
      return until;
    }
  return [super lastInstanceStartDate];
}

@end /* iCalYearlyRecurrenceCalculator */