Copy the KDE 3.5 branch to branches/trinity for new KDE 3.5 features.

BUG:215923


git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/kdepim@1054174 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

1 files changed, 1428 insertions, 0 deletions

diff --git a/libkcal/recurrencerule.cpp b/libkcal/recurrencerule.cpp
new file mode 100644
index 000000000..ef6f9ccd9
--- /dev/null
+++ b/libkcal/recurrencerule.cpp
@@ -0,0 +1,1428 @@
+/*
+    This file is part of libkcal.
+
+    Copyright (c) 2005 Reinhold Kainhofer <reinhold@kainhofe.com>
+
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 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
+    Library General Public License for more details.
+
+    You should have received a copy of the GNU Library General Public License
+    along with this library; see the file COPYING.LIB.  If not, write to
+    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+    Boston, MA 02110-1301, USA.
+*/
+
+#include "recurrencerule.h"
+
+#include <kdebug.h>
+#include <kglobal.h>
+#include <qdatetime.h>
+#include <qstringlist.h>
+
+#include <limits.h>
+#include <math.h>
+
+using namespace KCal;
+
+
+// FIXME: If Qt is ever changed so that QDateTime:::addSecs takes into account
+//        DST shifts, we need to use our own addSecs method, too, since we
+//        need to caalculate things in UTC!
+/** Workaround for broken QDateTime::secsTo (at least in Qt 3.3). While
+   QDateTime::secsTo does take time zones into account, QDateTime::addSecs
+   does not, so we have a problem:
+      QDateTime d1(QDate(2005, 10, 30), QTime(1, 30, 0) );
+      QDateTime d2(QDate(2005, 10, 30), QTime(3, 30, 0) );
+
+      kdDebug(5800) << "d1=" << d1 << ", d2=" << d2 << endl;
+      kdDebug(5800) << "d1.secsTo(d2)=" << d1.secsTo(d2) << endl;
+      kdDebug(5800) << "d1.addSecs(d1.secsTo(d2))=" << d1.addSecs(d1.secsTo(d2)) << endl;
+   This code generates the following output:
+      libkcal: d1=Son Okt 30 01:30:00 2005, d2=Son Okt 30 03:30:00 2005
+      libkcal: d1.secsTo(d2)=10800
+      libkcal: d1.addSecs(d1.secsTo(d2))=Son Okt 30 04:30:00 2005
+   Notice that secsTo counts the hour between 2:00 and 3:00 twice, while
+   adddSecs doesn't and so has one additional hour. This basically makes it
+   impossible to use QDateTime for *any* calculations, in local time zone as
+   well as in UTC. Since we don't want to use
+   time zones anyway, but do all secondsly/minutely/hourly calculations in UTC,
+   we simply use our own secsTo, which ignores all time zone shifts. */
+long long ownSecsTo( const QDateTime &dt1, const QDateTime &dt2 )
+{
+  long long res = static_cast<long long>( dt1.date().daysTo( dt2.date() ) ) * 24*3600;
+  res += dt1.time().secsTo( dt2.time() );
+  return res;
+}
+
+
+
+/**************************************************************************
+ *                               DateHelper                               *
+ **************************************************************************/
+
+
+class DateHelper {
+  public:
+#ifndef NDEBUG
+    static QString dayName( short day );
+#endif
+    static QDate getNthWeek( int year, int weeknumber, short weekstart = 1 );
+    static int weekNumbersInYear( int year, short weekstart = 1 );
+    static int getWeekNumber( const QDate &date, short weekstart, int *year = 0 );
+    static int getWeekNumberNeg( const QDate &date, short weekstart, int *year = 0 );
+};
+
+
+#ifndef NDEBUG
+QString DateHelper::dayName( short day )
+{
+  switch ( day ) {
+    case 1: return "MO"; break;
+    case 2: return "TU"; break;
+    case 3: return "WE"; break;
+    case 4: return "TH"; break;
+    case 5: return "FR"; break;
+    case 6: return "SA"; break;
+    case 7: return "SU"; break;
+    default: return "??";
+  }
+}
+#endif
+
+
+QDate DateHelper::getNthWeek( int year, int weeknumber, short weekstart )
+{
+  if ( weeknumber == 0 ) return QDate();
+  // Adjust this to the first day of week #1 of the year and add 7*weekno days.
+  QDate dt( year, 1, 4 ); // Week #1 is the week that contains Jan 4
+  int adjust = -(7 + dt.dayOfWeek() - weekstart) % 7;
+  if ( weeknumber > 0 ) {
+    dt = dt.addDays( 7 * (weeknumber-1) + adjust );
+  } else if ( weeknumber < 0 ) {
+    dt = dt.addYears( 1 );
+    dt = dt.addDays( 7 * weeknumber + adjust );
+  }
+  return dt;
+}
+
+
+int DateHelper::getWeekNumber( const QDate &date, short weekstart, int *year )
+{
+// kdDebug(5800) << "Getting week number for " << date << " with weekstart="<<weekstart<<endl;
+  if ( year ) *year = date.year();
+  QDate dt( date.year(), 1, 4 ); // <= definitely in week #1
+  dt = dt.addDays( -(7 + dt.dayOfWeek() - weekstart) % 7 ); // begin of week #1
+  QDate dtn( date.year()+1, 1, 4 ); // <= definitely first week of next year
+  dtn = dtn.addDays( -(7 + dtn.dayOfWeek() - weekstart) % 7 );
+
+  int daysto = dt.daysTo( date );
+  int dayston = dtn.daysTo( date );
+  if ( daysto < 0 ) {
+    if ( year ) *year = date.year()-1;
+    dt = QDate( date.year()-1, 1, 4 );
+    dt = dt.addDays( -(7 + dt.dayOfWeek() - weekstart) % 7 ); // begin of week #1
+    daysto = dt.daysTo( date );
+  } else if ( dayston >= 0 ) {
+    // in first week of next year;
+    if ( year ) *year = date.year() + 1;
+    dt = dtn;
+    daysto = dayston;
+  }
+  return daysto / 7 + 1;
+}
+
+int DateHelper::weekNumbersInYear( int year, short weekstart )
+{
+  QDate dt( year, 1, weekstart );
+  QDate dt1( year + 1, 1, weekstart );
+  return dt.daysTo( dt1 ) / 7;
+}
+
+// Week number from the end of the year
+int DateHelper::getWeekNumberNeg( const QDate &date, short weekstart, int *year )
+{
+  int weekpos = getWeekNumber( date, weekstart, year );
+  return weekNumbersInYear( *year, weekstart ) - weekpos - 1;
+}
+
+
+
+
+
+/**************************************************************************
+ *                       RecurrenceRule::Constraint                       *
+ **************************************************************************/
+
+
+RecurrenceRule::Constraint::Constraint( int wkst )
+{
+  weekstart = wkst;
+  clear();
+}
+
+RecurrenceRule::Constraint::Constraint( const QDateTime &preDate, PeriodType type, int wkst )
+{
+  weekstart = wkst;
+  readDateTime( preDate, type );
+}
+
+void RecurrenceRule::Constraint::clear()
+{
+  year = 0;
+  month = 0;
+  day = 0;
+  hour = -1;
+  minute = -1;
+  second = -1;
+  weekday = 0;
+  weekdaynr = 0;
+  weeknumber = 0;
+  yearday = 0;
+}
+
+bool RecurrenceRule::Constraint::matches( const QDate &dt, RecurrenceRule::PeriodType type ) const
+{
+  // If the event recurs in week 53 or 1, the day might not belong to the same
+  // year as the week it is in. E.g. Jan 1, 2005 is in week 53 of year 2004.
+  // So we can't simply check the year in that case!
+  if ( weeknumber == 0 ) {
+    if ( year > 0 && year != dt.year() ) return false;
+  } else {
+    int y;
+    if ( weeknumber > 0 &&
+         weeknumber != DateHelper::getWeekNumber( dt, weekstart, &y ) ) return false;
+    if ( weeknumber < 0 &&
+         weeknumber != DateHelper::getWeekNumberNeg( dt, weekstart, &y ) ) return false;
+    if ( year > 0 && year != y ) return false;
+  }
+
+  if ( month > 0 && month != dt.month() ) return false;
+  if ( day > 0 && day != dt.day() ) return false;
+  if ( day < 0 && dt.day() != (dt.daysInMonth() + day + 1 ) ) return false;
+  if ( weekday > 0 ) {
+    if ( weekday != dt.dayOfWeek() ) return false;
+    if ( weekdaynr != 0 ) {
+      // If it's a yearly recurrence and a month is given, the position is
+      // still in the month, not in the year.
+      bool inMonth = (type == rMonthly) || ( type == rYearly && month > 0 );
+      // Monthly
+      if ( weekdaynr > 0 && inMonth &&
+           weekdaynr != (dt.day() - 1)/7 + 1 ) return false;
+      if ( weekdaynr < 0 && inMonth &&
+           weekdaynr != -((dt.daysInMonth() - dt.day() )/7 + 1 ) )
+        return false;
+      // Yearly
+      if ( weekdaynr > 0 && !inMonth &&
+           weekdaynr != (dt.dayOfYear() - 1)/7 + 1 ) return false;
+      if ( weekdaynr < 0 && !inMonth &&
+           weekdaynr != -((dt.daysInYear() - dt.dayOfYear() )/7 + 1 ) )
+        return false;
+    }
+  }
+  if ( yearday > 0 && yearday != dt.dayOfYear() ) return false;
+  if ( yearday < 0 && yearday != dt.daysInYear() - dt.dayOfYear() + 1 )
+    return false;
+  return true;
+}
+
+bool RecurrenceRule::Constraint::matches( const QDateTime &dt, RecurrenceRule::PeriodType type ) const
+{
+  if ( !matches( dt.date(), type ) ) return false;
+  if ( hour >= 0 && hour != dt.time().hour() ) return false;
+  if ( minute >= 0 && minute != dt.time().minute() ) return false;
+  if ( second >= 0 && second != dt.time().second() ) return false;
+  return true;
+}
+
+bool RecurrenceRule::Constraint::isConsistent( PeriodType /*period*/) const
+{
+  // TODO: Check for consistency, e.g. byyearday=3 and bymonth=10
+  return true;
+}
+
+QDateTime RecurrenceRule::Constraint::intervalDateTime( RecurrenceRule::PeriodType type ) const
+{
+  QDateTime dt;
+  dt.setTime( QTime( 0, 0, 0 ) );
+  dt.setDate( QDate( year, (month>0)?month:1, (day>0)?day:1 ) );
+  if ( day < 0 )
+    dt = dt.addDays( dt.date().daysInMonth() + day );
+  switch ( type ) {
+    case rSecondly:
+      dt.setTime( QTime( hour, minute, second ) ); break;
+    case rMinutely:
+      dt.setTime( QTime( hour, minute, 1 ) ); break;
+    case rHourly:
+      dt.setTime( QTime( hour, 1, 1 ) ); break;
+    case rDaily:
+      break;
+    case rWeekly:
+      dt = DateHelper::getNthWeek( year, weeknumber, weekstart ); break;
+    case rMonthly:
+      dt.setDate( QDate( year, month, 1 ) ); break;
+    case rYearly:
+      dt.setDate( QDate( year, 1, 1 ) ); break;
+    default:
+      break;
+  }
+  return dt;
+}
+
+
+//           Y  M  D | H  Mn S | WD #WD | WN | YD
+// required:
+//           x       | x  x  x |        |    |
+// 0) Trivial: Exact date given, maybe other restrictions
+//           x  x  x | x  x  x |        |    |
+// 1) Easy case: no weekly restrictions -> at most a loop through possible dates
+//           x  +  + | x  x  x |  -  -  |  - |  -
+// 2) Year day is given -> date known
+//           x       | x  x  x |        |    |  +
+// 3) week number is given -> loop through all days of that week. Further
+//    restrictions will be applied in the end, when we check all dates for
+//    consistency with the constraints
+//           x       | x  x  x |        |  + | (-)
+// 4) week day is specified ->
+//           x       | x  x  x |  x  ?  | (-)| (-)
+// 5) All possiblecases have already been treated, so this must be an error!
+
+DateTimeList RecurrenceRule::Constraint::dateTimes( RecurrenceRule::PeriodType type ) const
+{
+// kdDebug(5800) << "              RecurrenceRule::Constraint::dateTimes: " << endl;
+  DateTimeList result;
+  bool done = false;
+  // TODO_Recurrence: Handle floating
+  QTime tm( hour, minute, second );
+  if ( !isConsistent( type ) ) return result;
+
+  if ( !done && day > 0 && month > 0 ) {
+    QDateTime dt( QDate( year, month, day ), tm );
+    if ( dt.isValid() ) result.append( dt );
+    done = true;
+  }
+  if ( !done && day < 0 && month > 0 ) {
+    QDateTime dt( QDate( year, month, 1 ), tm );
+    dt = dt.addDays( dt.date().daysInMonth() + day );
+    if ( dt.isValid() ) result.append( dt );
+    done = true;
+  }
+
+
+  if ( !done && weekday == 0 && weeknumber == 0 && yearday == 0 ) {
+    // Easy case: date is given, not restrictions by week or yearday
+    uint mstart = (month>0) ? month : 1;
+    uint mend = (month <= 0) ? 12 : month;
+    for ( uint m = mstart; m <= mend; ++m ) {
+      uint dstart, dend;
+      if ( day > 0 ) {
+        dstart = dend = day;
+      } else if ( day < 0 ) {
+        QDate date( year, month, 1 );
+        dstart = dend = date.daysInMonth() + day + 1;
+      } else {
+        QDate date( year, month, 1 );
+        dstart = 1;
+        dend = date.daysInMonth();
+      }
+      for ( uint d = dstart; d <= dend; ++d ) {
+        QDateTime dt( QDate( year, m, d ), tm );
+        if ( dt.isValid() ) result.append( dt );
+      }
+    }
+    done = true;
+  }
+
+  // Else: At least one of the week / yearday restrictions was given...
+  // If we have a yearday (and of course a year), we know the exact date
+  if ( !done && yearday != 0 ) {
+    // yearday < 0 means from end of year, so we'll need Jan 1 of the next year
+    QDate d( year + ((yearday>0)?0:1), 1, 1 );
+    d = d.addDays( yearday - ((yearday>0)?1:0) );
+    result.append( QDateTime( d, tm ) );
+    done = true;
+  }
+
+  // Else: If we have a weeknumber, we have at most 7 possible dates, loop through them
+  if ( !done && weeknumber != 0 ) {
+    QDate wst( DateHelper::getNthWeek( year, weeknumber, weekstart ) );
+    if ( weekday != 0 ) {
+      wst = wst.addDays( (7 + weekday - weekstart ) % 7 );
+      result.append( QDateTime( wst, tm ) );
+    } else {
+      for ( int i = 0; i < 7; ++i ) {
+        result.append( QDateTime( wst, tm ) );
+        wst = wst.addDays( 1 );
+      }
+    }
+    done = true;
+  }
+
+  // weekday is given
+  if ( !done && weekday != 0 ) {
+    QDate dt( year, 1, 1 );
+    // If type == yearly and month is given, pos is still in month not year!
+    // TODO_Recurrence: Correct handling of n-th  BYDAY...
+    int maxloop = 53;
+    bool inMonth = ( type == rMonthly) || ( type == rYearly && month > 0 );
+    if ( inMonth && month > 0 ) {
+      dt = QDate( year, month, 1 );
+      maxloop = 5;
+    }
+    if ( weekdaynr < 0 ) {
+      // From end of period (month, year) => relative to begin of next period
+      if ( inMonth )
+        dt = dt.addMonths( 1 );
+      else
+        dt = dt.addYears( 1 );
+    }
+    int adj = ( 7 + weekday - dt.dayOfWeek() ) % 7;
+    dt = dt.addDays( adj ); // correct first weekday of the period
+
+    if ( weekdaynr > 0 ) {
+      dt = dt.addDays( ( weekdaynr - 1 ) * 7 );
+      result.append( QDateTime( dt, tm ) );
+    } else if ( weekdaynr < 0 ) {
+      dt = dt.addDays( weekdaynr * 7 );
+      result.append( QDateTime( dt, tm ) );
+    } else {
+      // loop through all possible weeks, non-matching will be filtered later
+      for ( int i = 0; i < maxloop; ++i ) {
+        result.append( QDateTime( dt, tm ) );
+        dt = dt.addDays( 7 );
+      }
+    }
+  } // weekday != 0
+
+
+  // Only use those times that really match all other constraints, too
+  DateTimeList valid;
+  DateTimeList::Iterator it;
+  for ( it = result.begin(); it != result.end(); ++it ) {
+    if ( matches( *it, type ) ) valid.append( *it );
+  }
+  // Don't sort it here, would be unnecessary work. The results from all
+  // constraints will be merged to one big list of the interval. Sort that one!
+  return valid;
+}
+
+
+bool RecurrenceRule::Constraint::increase( RecurrenceRule::PeriodType type, int freq )
+{
+  // convert the first day of the interval to QDateTime
+  // Sub-daily types need to be converted to UTC to correctly handle DST shifts
+  QDateTime dt( intervalDateTime( type ) );
+
+  // Now add the intervals
+  switch ( type ) {
+    case rSecondly:
+      dt = dt.addSecs( freq ); break;
+    case rMinutely:
+      dt = dt.addSecs( 60*freq ); break;
+    case rHourly:
+      dt = dt.addSecs( 3600 * freq ); break;
+    case rDaily:
+      dt = dt.addDays( freq ); break;
+    case rWeekly:
+      dt = dt.addDays( 7*freq ); break;
+    case rMonthly:
+      dt = dt.addMonths( freq ); break;
+    case rYearly:
+      dt = dt.addYears( freq ); break;
+    default:
+      break;
+  }
+  // Convert back from QDateTime to the Constraint class
+  readDateTime( dt, type );
+
+  return true;
+}
+
+bool RecurrenceRule::Constraint::readDateTime( const QDateTime &preDate, PeriodType type )
+{
+  clear();
+  switch ( type ) {
+    // Really fall through! Only weekly needs to be treated differentely!
+    case rSecondly:
+      second = preDate.time().second();
+    case rMinutely:
+      minute = preDate.time().minute();
+    case rHourly:
+      hour = preDate.time().hour();
+    case rDaily:
+      day = preDate.date().day();
+    case rMonthly:
+      month = preDate.date().month();
+    case rYearly:
+      year = preDate.date().year();
+      break;
+
+    case rWeekly:
+      // Determine start day of the current week, calculate the week number from that
+      weeknumber = DateHelper::getWeekNumber( preDate.date(), weekstart, &year );
+      break;
+    default:
+      break;
+  }
+  return true;
+}
+
+
+RecurrenceRule::RecurrenceRule( )
+: mPeriod( rNone ), mFrequency( 0 ), mIsReadOnly( false ),
+  mFloating( false ),
+  mWeekStart(1)
+{
+}
+
+RecurrenceRule::RecurrenceRule( const RecurrenceRule &r )
+{
+  mRRule = r.mRRule;
+  mPeriod = r.mPeriod;
+  mDateStart = r.mDateStart;
+  mDuration = r.mDuration;
+  mDateEnd = r.mDateEnd;
+  mFrequency = r.mFrequency;
+
+  mIsReadOnly = r.mIsReadOnly;
+  mFloating = r.mFloating;
+
+  mBySeconds = r.mBySeconds;
+  mByMinutes = r.mByMinutes;
+  mByHours = r.mByHours;
+  mByDays = r.mByDays;
+  mByMonthDays = r.mByMonthDays;
+  mByYearDays = r.mByYearDays;
+  mByWeekNumbers = r.mByWeekNumbers;
+  mByMonths = r.mByMonths;
+  mBySetPos = r.mBySetPos;
+  mWeekStart = r.mWeekStart;
+
+  setDirty();
+}
+
+RecurrenceRule::~RecurrenceRule()
+{
+}
+
+bool RecurrenceRule::operator==( const RecurrenceRule& r ) const
+{
+  if ( mPeriod != r.mPeriod ) return false;
+  if ( mDateStart != r.mDateStart ) return false;
+  if ( mDuration != r.mDuration ) return false;
+  if ( mDateEnd != r.mDateEnd ) return false;
+  if ( mFrequency != r.mFrequency ) return false;
+
+  if ( mIsReadOnly != r.mIsReadOnly ) return false;
+  if ( mFloating != r.mFloating ) return false;
+
+  if ( mBySeconds != r.mBySeconds ) return false;
+  if ( mByMinutes != r.mByMinutes ) return false;
+  if ( mByHours != r.mByHours ) return false;
+  if ( mByDays != r.mByDays ) return false;
+  if ( mByMonthDays != r.mByMonthDays ) return false;
+  if ( mByYearDays != r.mByYearDays ) return false;
+  if ( mByWeekNumbers != r.mByWeekNumbers ) return false;
+  if ( mByMonths != r.mByMonths ) return false;
+  if ( mBySetPos != r.mBySetPos ) return false;
+  if ( mWeekStart != r.mWeekStart ) return false;
+
+  return true;
+}
+
+void RecurrenceRule::addObserver( Observer *observer )
+{
+  if ( !mObservers.contains( observer ) )
+    mObservers.append( observer );
+}
+
+void RecurrenceRule::removeObserver( Observer *observer )
+{
+  if ( mObservers.contains( observer ) )
+    mObservers.remove( observer );
+}
+
+
+
+void RecurrenceRule::setRecurrenceType( PeriodType period )
+{
+  if ( isReadOnly() ) return;
+  mPeriod = period;
+  setDirty();
+}
+
+QDateTime RecurrenceRule::endDt( bool *result ) const
+{
+  if ( result ) *result = false;
+  if ( mPeriod == rNone ) return QDateTime();
+  if ( mDuration < 0 ) return QDateTime();
+  if ( mDuration == 0 ) {
+    if ( result ) *result = true;
+    return mDateEnd;
+  }
+  // N occurrences. Check if we have a full cache. If so, return the cached end date.
+  if ( ! mCached ) {
+    // If not enough occurrences can be found (i.e. inconsistent constraints)
+    if ( !buildCache() ) return QDateTime();
+  }
+  if ( result ) *result = true;
+  return mCachedDateEnd;
+}
+
+void RecurrenceRule::setEndDt( const QDateTime &dateTime )
+{
+  if ( isReadOnly() ) return;
+  mDateEnd = dateTime;
+  mDuration = 0; // set to 0 because there is an end date/time
+  setDirty();
+}
+
+void RecurrenceRule::setDuration(int duration)
+{
+  if ( isReadOnly() ) return;
+  mDuration = duration;
+  setDirty();
+}
+
+void RecurrenceRule::setFloats( bool floats )
+{
+  if ( isReadOnly() ) return;
+  mFloating = floats;
+  setDirty();
+}
+
+void RecurrenceRule::clear()
+{
+  if ( isReadOnly() ) return;
+  mPeriod = rNone;
+  mBySeconds.clear();
+  mByMinutes.clear();
+  mByHours.clear();
+  mByDays.clear();
+  mByMonthDays.clear();
+  mByYearDays.clear();
+  mByWeekNumbers.clear();
+  mByMonths.clear();
+  mBySetPos.clear();
+  mWeekStart = 1;
+
+  setDirty();
+}
+
+void RecurrenceRule::setDirty()
+{
+  mConstraints.clear();
+  buildConstraints();
+  mDirty = true;
+  mCached = false;
+  mCachedDates.clear();
+  for ( QValueList<Observer*>::ConstIterator it = mObservers.begin();
+        it != mObservers.end(); ++it ) {
+    if ( (*it) ) (*it)->recurrenceChanged( this );
+  }
+}
+
+void RecurrenceRule::setStartDt( const QDateTime &start )
+{
+  if ( isReadOnly() ) return;
+  mDateStart = start;
+  setDirty();
+}
+
+void RecurrenceRule::setFrequency(int freq)
+{
+  if ( isReadOnly() || freq <= 0 ) return;
+  mFrequency = freq;
+  setDirty();
+}
+
+void RecurrenceRule::setBySeconds( const QValueList<int> bySeconds )
+{
+  if ( isReadOnly() ) return;
+  mBySeconds = bySeconds;
+  setDirty();
+}
+
+void RecurrenceRule::setByMinutes( const QValueList<int> byMinutes )
+{
+  if ( isReadOnly() ) return;
+  mByMinutes = byMinutes;
+  setDirty();
+}
+
+void RecurrenceRule::setByHours( const QValueList<int> byHours )
+{
+  if ( isReadOnly() ) return;
+  mByHours = byHours;
+  setDirty();
+}
+
+
+void RecurrenceRule::setByDays( const QValueList<WDayPos> byDays )
+{
+  if ( isReadOnly() ) return;
+  mByDays = byDays;
+  setDirty();
+}
+
+void RecurrenceRule::setByMonthDays( const QValueList<int> byMonthDays )
+{
+  if ( isReadOnly() ) return;
+  mByMonthDays = byMonthDays;
+  setDirty();
+}
+
+void RecurrenceRule::setByYearDays( const QValueList<int> byYearDays )
+{
+  if ( isReadOnly() ) return;
+  mByYearDays = byYearDays;
+  setDirty();
+}
+
+void RecurrenceRule::setByWeekNumbers( const QValueList<int> byWeekNumbers )
+{
+  if ( isReadOnly() ) return;
+  mByWeekNumbers = byWeekNumbers;
+  setDirty();
+}
+
+void RecurrenceRule::setByMonths( const QValueList<int> byMonths )
+{
+  if ( isReadOnly() ) return;
+  mByMonths = byMonths;
+  setDirty();
+}
+
+void RecurrenceRule::setBySetPos( const QValueList<int> bySetPos )
+{
+  if ( isReadOnly() ) return;
+  mBySetPos = bySetPos;
+  setDirty();
+}
+
+void RecurrenceRule::setWeekStart( short weekStart )
+{
+  if ( isReadOnly() ) return;
+  mWeekStart = weekStart;
+  setDirty();
+}
+
+
+
+// Taken from recurrence.cpp
+// int RecurrenceRule::maxIterations() const
+// {
+//   /* Find the maximum number of iterations which may be needed to reach the
+//    * next actual occurrence of a monthly or yearly recurrence.
+//    * More than one iteration may be needed if, for example, it's the 29th February,
+//    * the 31st day of the month or the 5th Monday, and the month being checked is
+//    * February or a 30-day month.
+//    * The following recurrences may never occur:
+//    * - For rMonthlyDay: if the frequency is a whole number of years.
+//    * - For rMonthlyPos: if the frequency is an even whole number of years.
+//    * - For rYearlyDay, rYearlyMonth: if the frequeny is a multiple of 4 years.
+//    * - For rYearlyPos: if the frequency is an even number of years.
+//    * The maximum number of iterations needed, assuming that it does actually occur,
+//    * was found empirically.
+//    */
+//   switch (recurs) {
+//     case rMonthlyDay:
+//       return (rFreq % 12) ? 6 : 8;
+//
+//     case rMonthlyPos:
+//       if (rFreq % 12 == 0) {
+//         // Some of these frequencies may never occur
+//         return (rFreq % 84 == 0) ? 364         // frequency = multiple of 7 years
+//              : (rFreq % 48 == 0) ? 7           // frequency = multiple of 4 years
+//              : (rFreq % 24 == 0) ? 14 : 28;    // frequency = multiple of 2 or 1 year
+//       }
+//       // All other frequencies will occur sometime
+//       if (rFreq > 120)
+//         return 364;    // frequencies of > 10 years will hit the date limit first
+//       switch (rFreq) {
+//         case 23:   return 50;
+//         case 46:   return 38;
+//         case 56:   return 138;
+//         case 66:   return 36;
+//         case 89:   return 54;
+//         case 112:  return 253;
+//         default:   return 25;       // most frequencies will need < 25 iterations
+//       }
+//
+//     case rYearlyMonth:
+//     case rYearlyDay:
+//       return 8;          // only 29th Feb or day 366 will need more than one iteration
+//
+//     case rYearlyPos:
+//       if (rFreq % 7 == 0)
+//         return 364;    // frequencies of a multiple of 7 years will hit the date limit first
+//       if (rFreq % 2 == 0) {
+//         // Some of these frequencies may never occur
+//         return (rFreq % 4 == 0) ? 7 : 14;    // frequency = even number of years
+//       }
+//       return 28;
+//   }
+//   return 1;
+// }
+
+void RecurrenceRule::buildConstraints()
+{
+  mConstraints.clear();
+  Constraint con;
+  if ( mWeekStart > 0 ) con.weekstart = mWeekStart;
+  mConstraints.append( con );
+
+  Constraint::List tmp;
+  Constraint::List::const_iterator it;
+  QValueList<int>::const_iterator intit;
+
+  #define intConstraint( list, element ) \
+  if ( !list.isEmpty() ) { \
+    for ( it = mConstraints.constBegin(); it != mConstraints.constEnd(); ++it ) { \
+      for ( intit = list.constBegin(); intit != list.constEnd(); ++intit ) { \
+        con = (*it); \
+        con.element = (*intit); \
+        tmp.append( con ); \
+      } \
+    } \
+    mConstraints = tmp; \
+    tmp.clear(); \
+  }
+
+  intConstraint( mBySeconds, second );
+  intConstraint( mByMinutes, minute );
+  intConstraint( mByHours, hour );
+  intConstraint( mByMonthDays, day );
+  intConstraint( mByMonths, month );
+  intConstraint( mByYearDays, yearday );
+  intConstraint( mByWeekNumbers, weeknumber );
+  #undef intConstraint
+
+  if ( !mByDays.isEmpty() ) {
+    for ( it = mConstraints.constBegin(); it != mConstraints.constEnd(); ++it ) {
+      QValueList<WDayPos>::const_iterator dayit;
+      for ( dayit = mByDays.constBegin(); dayit != mByDays.constEnd(); ++dayit ) {
+        con = (*it);
+        con.weekday = (*dayit).day();
+        con.weekdaynr = (*dayit).pos();
+        tmp.append( con );
+      }
+    }
+    mConstraints = tmp;
+    tmp.clear();
+  }
+
+  #define fixConstraint( element, value ) \
+  { \
+    tmp.clear(); \
+    for ( it = mConstraints.constBegin(); it != mConstraints.constEnd(); ++it ) { \
+      con = (*it); con.element = value; tmp.append( con ); \
+    } \
+    mConstraints = tmp; \
+  }
+  // Now determine missing values from DTSTART. This can speed up things,
+  // because we have more restrictions and save some loops.
+
+  // TODO: Does RFC 2445 intend to restrict the weekday in all cases of weekly?
+  if ( mPeriod == rWeekly && mByDays.isEmpty() ) {
+    fixConstraint( weekday, mDateStart.date().dayOfWeek() );
+  }
+
+  // Really fall through in the cases, because all smaller time intervals are
+  // constrained from dtstart
+  switch ( mPeriod ) {
+    case rYearly:
+      if ( mByDays.isEmpty() && mByWeekNumbers.isEmpty() && mByYearDays.isEmpty() && mByMonths.isEmpty() ) {
+        fixConstraint( month, mDateStart.date().month() );
+      }
+    case rMonthly:
+      if ( mByDays.isEmpty() && mByWeekNumbers.isEmpty() && mByYearDays.isEmpty() && mByMonthDays.isEmpty() ) {
+        fixConstraint( day, mDateStart.date().day() );
+      }
+
+    case rWeekly:
+    case rDaily:
+      if ( mByHours.isEmpty() ) {
+        fixConstraint( hour, mDateStart.time().hour() );
+      }
+    case rHourly:
+      if ( mByMinutes.isEmpty() ) {
+        fixConstraint( minute, mDateStart.time().minute() );
+      }
+    case rMinutely:
+      if ( mBySeconds.isEmpty() ) {
+        fixConstraint( second, mDateStart.time().second() );
+      }
+    case rSecondly:
+    default:
+      break;
+  }
+  #undef fixConstraint
+
+  Constraint::List::Iterator conit = mConstraints.begin();
+  while ( conit != mConstraints.end() ) {
+    if ( (*conit).isConsistent( mPeriod ) ) {
+      ++conit;
+    } else {
+      conit = mConstraints.remove( conit );
+    }
+  }
+}
+
+bool RecurrenceRule::buildCache() const
+{
+kdDebug(5800) << "         RecurrenceRule::buildCache: " << endl;
+  // Build the list of all occurrences of this event (we need that to determine
+  // the end date!)
+  Constraint interval( getNextValidDateInterval( startDt(), recurrenceType() ) );
+  QDateTime next;
+
+  DateTimeList dts = datesForInterval( interval, recurrenceType() );
+  DateTimeList::Iterator it = dts.begin();
+  // Only use dates after the event has started (start date is only included
+  // if it matches)
+  while ( it != dts.end() ) {
+    if ( (*it) < startDt() ) it =  dts.remove( it );
+    else ++it;
+  }
+//  dts.prepend( startDt() ); // the start date is always the first occurrence
+
+
+  int loopnr = 0;
+  int dtnr = dts.count();
+  // some validity checks to avoid infinite loops (i.e. if we have
+  // done this loop already 10000 times and found no occurrence, bail out )
+  while ( loopnr < 10000 && dtnr < mDuration ) {
+    interval.increase( recurrenceType(), frequency() );
+    // The returned date list is already sorted!
+    dts += datesForInterval( interval, recurrenceType() );
+    dtnr = dts.count();
+    ++loopnr;
+  }
+  if ( int(dts.count()) > mDuration ) {
+    // we have picked up more occurrences than necessary, remove them
+    it = dts.at( mDuration );
+    while ( it != dts.end() ) it = dts.remove( it );
+  }
+  mCached = true;
+  mCachedDates = dts;
+
+kdDebug(5800) << "    Finished Building Cache, cache has " << dts.count() << " entries:" << endl;
+// it = dts.begin();
+// while ( it != dts.end() ) {
+//   kdDebug(5800) << "            -=> " << (*it) << endl;
+//   ++it;
+// }
+  if ( int(dts.count()) == mDuration ) {
+    mCachedDateEnd = dts.last();
+    return true;
+  } else {
+    mCachedDateEnd = QDateTime();
+    return false;
+  }
+}
+
+bool RecurrenceRule::dateMatchesRules( const QDateTime &qdt ) const
+{
+  bool match = false;
+  for ( Constraint::List::ConstIterator it = mConstraints.begin();
+        it!=mConstraints.end(); ++it ) {
+    match = match || ( (*it).matches( qdt, recurrenceType() ) );
+  }
+  return match;
+}
+
+bool RecurrenceRule::recursOn( const QDate &qd ) const
+{
+//  kdDebug(5800) << "         RecurrenceRule::recursOn: " << qd << endl;
+  if ( qd < startDt().date() ) return false;
+  // Start date is only included if it really matches
+//   if ( qd == startDt().date() ) return true;
+  if ( mDuration >= 0 && qd > endDt().date() ) return false;
+
+  // The date must be in an appropriate interval (getNextValidDateInterval),
+  // Plus it must match at least one of the constraints
+  bool match = false;
+  for ( Constraint::List::ConstIterator it = mConstraints.begin();
+        it!=mConstraints.end(); ++it ) {
+    match = match  || ( (*it).matches( qd, recurrenceType() ) );
+  }
+  if ( !match ) return false;
+  QDateTime tmp( qd, QTime( 0, 0, 0 ) );
+  Constraint interval( getNextValidDateInterval( tmp, recurrenceType() ) );
+  // Constraint::matches is quite efficient, so first check if it can occur at
+  // all before we calculate all actual dates.
+  if ( !interval.matches( qd, recurrenceType() ) ) return false;
+  // We really need to obtain the list of dates in this interval, since
+  // otherwise BYSETPOS will not work (i.e. the date will match the interval,
+  // but BYSETPOS selects only one of these matching dates!
+  DateTimeList times = datesForInterval( interval, recurrenceType() );
+  DateTimeList::ConstIterator it = times.begin();
+  while ( ( it != times.end() ) && ( (*it).date() < qd ) )
+    ++it;
+  if ( it != times.end() ) {
+    // If we are beyond the end...
+    if ( mDuration >= 0 && (*it) > endDt() )
+      return false;
+    if ( (*it).date() == qd )
+      return true;
+  }
+  return false;
+}
+
+
+bool RecurrenceRule::recursAt( const QDateTime &qd ) const
+{
+// kdDebug(5800) << "         RecurrenceRule::recursAt: " << qd << endl;
+  if ( doesFloat() ) return recursOn( qd.date() );
+  if ( qd < startDt() ) return false;
+  // Start date is only included if it really matches
+//   if ( qd == startDt() ) return true;
+  if ( mDuration >= 0 && qd > endDt() ) return false;
+
+  // The date must be in an appropriate interval (getNextValidDateInterval),
+  // Plus it must match at least one of the constraints
+  bool match = dateMatchesRules( qd );
+  if ( !match ) return false;
+  // if it recurs every interval, speed things up...
+//   if ( mFrequency == 1 && mBySetPos.isEmpty() && mByDays.isEmpty() ) return true;
+  Constraint interval( getNextValidDateInterval( qd, recurrenceType() ) );
+  // TODO_Recurrence: Does this work with BySetPos???
+  if ( interval.matches( qd, recurrenceType() ) ) return true;
+
+  return false;
+}
+
+
+TimeList RecurrenceRule::recurTimesOn( const QDate &date ) const
+{
+// kdDebug(5800) << "         RecurrenceRule::recurTimesOn: " << date << endl;
+  TimeList lst;
+  if ( !recursOn( date ) ) return lst;
+
+  if ( doesFloat() ) return lst;
+
+  QDateTime dt( date, QTime( 0, 0, 0 ) );
+  bool valid = dt.isValid() && ( dt.date() == date );
+  while ( valid ) {
+    // TODO: Add a flag so that the date is never increased!
+    dt = getNextDate( dt );
+    valid = dt.isValid() && ( dt.date() == date );
+    if ( valid ) lst.append( dt.time() );
+  }
+  return lst;
+}
+
+/** Returns the number of recurrences up to and including the date/time specified. */
+int RecurrenceRule::durationTo( const QDateTime &dt ) const
+{
+// kdDebug(5800) << "         RecurrenceRule::durationTo: " << dt << endl;
+  // Easy cases: either before start, or after all recurrences and we know
+  // their number
+  if ( dt < startDt() ) return 0;
+  // Start date is only included if it really matches
+//   if ( dt == startDt() ) return 1;
+  if ( mDuration > 0 && dt >= endDt() ) return mDuration;
+
+  QDateTime next( startDt() );
+  int found = 0;
+  while ( next.isValid() && next <= dt ) {
+    ++found;
+    next = getNextDate( next );
+  }
+  return found;
+}
+
+
+QDateTime RecurrenceRule::getPreviousDate( const QDateTime& afterDate ) const
+{
+// kdDebug(5800) << "         RecurrenceRule::getPreviousDate: " << afterDate << endl;
+  // Beyond end of recurrence
+  if ( afterDate < startDt() )
+    return QDateTime();
+
+  // If we have a cache (duration given), use that
+  QDateTime prev;
+  if ( mDuration > 0 ) {
+    if ( !mCached ) buildCache();
+    DateTimeList::ConstIterator it = mCachedDates.begin();
+    while ( it != mCachedDates.end() && (*it) < afterDate ) {
+      prev = *it;
+      ++it;
+    }
+    if ( prev.isValid() && prev < afterDate ) return prev;
+    else return QDateTime();
+  }
+
+// kdDebug(5800) << "    getNext date after " << preDate << endl;
+  prev = afterDate;
+  if ( mDuration >= 0 && endDt().isValid() && afterDate > endDt() )
+    prev = endDt().addSecs( 1 );
+
+  Constraint interval( getPreviousValidDateInterval( prev, recurrenceType() ) );
+// kdDebug(5800) << "Previous Valid Date Interval for date " << prev << ": " << endl;
+// interval.dump();
+  DateTimeList dts = datesForInterval( interval, recurrenceType() );
+  DateTimeList::Iterator dtit = dts.end();
+  if ( dtit != dts.begin() ) {
+    do {
+      --dtit;
+    } while ( dtit != dts.begin() && (*dtit) >= prev );
+    if ( (*dtit) < prev ) {
+      if ( (*dtit) >= startDt() ) return (*dtit);
+      else return QDateTime();
+    }
+  }
+
+  // Previous interval. As soon as we find an occurrence, we're done.
+  while ( interval.intervalDateTime( recurrenceType() ) > startDt() ) {
+    interval.increase( recurrenceType(), -frequency() );
+// kdDebug(5800) << "Decreased interval: " << endl;
+// interval.dump();
+    // The returned date list is sorted
+    DateTimeList dts = datesForInterval( interval, recurrenceType() );
+    // The list is sorted, so take the last one.
+    if ( dts.count() > 0 ) {
+      prev = dts.last();
+      if ( prev.isValid() && prev >= startDt() ) return prev;
+      else return QDateTime();
+    }
+  }
+  return QDateTime();
+}
+
+
+QDateTime RecurrenceRule::getNextDate( const QDateTime &preDate ) const
+{
+// kdDebug(5800) << "         RecurrenceRule::getNextDate: " << preDate << endl;
+  // Beyond end of recurrence
+  if ( mDuration >= 0 && endDt().isValid() && preDate >= endDt() )
+    return QDateTime();
+
+  // Start date is only included if it really matches
+  QDateTime adjustedPreDate;
+  if ( preDate < startDt() )
+    adjustedPreDate = startDt().addSecs( -1 );
+  else
+    adjustedPreDate = preDate;
+
+  if ( mDuration > 0 ) {
+    if ( !mCached ) buildCache();
+    DateTimeList::ConstIterator it = mCachedDates.begin();
+    while ( it != mCachedDates.end() && (*it) <= adjustedPreDate ) ++it;
+    if ( it != mCachedDates.end() ) {
+//  kdDebug(5800) << "    getNext date after " << adjustedPreDate << ", cached date: " << *it << endl;
+      return (*it);
+    }
+  }
+
+// kdDebug(5800) << "    getNext date after " << adjustedPreDate << endl;
+  Constraint interval( getNextValidDateInterval( adjustedPreDate, recurrenceType() ) );
+  DateTimeList dts = datesForInterval( interval, recurrenceType() );
+  DateTimeList::Iterator dtit = dts.begin();
+  while ( dtit != dts.end() && (*dtit) <= adjustedPreDate ) ++dtit;
+  if ( dtit != dts.end() ) {
+    if ( mDuration >= 0 && (*dtit) > endDt() ) return QDateTime();
+    else return (*dtit);
+  }
+
+  // Increase the interval. The first occurrence that we find is the result (if
+  // if's before the end date).
+    // TODO: some validity checks to avoid infinite loops for contradictory constraints
+  int loopnr = 0;
+  while ( loopnr < 10000 ) {
+    interval.increase( recurrenceType(), frequency() );
+    DateTimeList dts = datesForInterval( interval, recurrenceType() );
+    if ( dts.count() > 0 ) {
+      QDateTime ret( dts.first() );
+      if ( mDuration >= 0 && ret > endDt() ) return QDateTime();
+      else return ret;
+    }
+    ++loopnr;
+  }
+  return QDateTime();
+}
+
+RecurrenceRule::Constraint RecurrenceRule::getPreviousValidDateInterval( const QDateTime &preDate, PeriodType type ) const
+{
+// kdDebug(5800) << "       (o) getPreviousValidDateInterval after " << preDate << ", type=" << type << endl;
+  long periods = 0;
+  QDateTime nextValid = startDt();
+  QDateTime start = startDt();
+  int modifier = 1;
+  QDateTime toDate( preDate );
+  // for super-daily recurrences, don't care about the time part
+
+  // Find the #intervals since the dtstart and round to the next multiple of
+  // the frequency
+      // FIXME: All sub-daily periods need to convert to UTC, do the calculations
+      //        in UTC, then convert back to the local time zone. Otherwise,
+      //        recurrences across DST changes will be determined wrongly
+  switch ( type ) {
+    // Really fall through for sub-daily, since the calculations only differ
+    // by the factor 60 and 60*60! Same for weekly and daily (factor 7)
+    case rHourly:   modifier *= 60;
+    case rMinutely: modifier *= 60;
+    case rSecondly:
+        periods = ownSecsTo( start, toDate ) / modifier;
+        // round it down to the next lower multiple of frequency():
+        periods = ( periods / frequency() ) * frequency();
+        nextValid = start.addSecs( modifier * periods );
+        break;
+
+    case rWeekly:
+        toDate = toDate.addDays( -(7 + toDate.date().dayOfWeek() - mWeekStart) % 7 );
+        start = start.addDays( -(7 + start.date().dayOfWeek() - mWeekStart) % 7 );
+        modifier *= 7;
+    case rDaily:
+        periods = start.daysTo( toDate ) / modifier;
+        // round it down to the next lower multiple of frequency():
+        periods = ( periods / frequency() ) * frequency();
+        nextValid = start.addDays( modifier * periods );
+        break;
+
+    case rMonthly: {
+        periods = 12*( toDate.date().year() - start.date().year() ) +
+             ( toDate.date().month() - start.date().month() );
+        // round it down to the next lower multiple of frequency():
+        periods = ( periods / frequency() ) * frequency();
+        // set the day to the first day of the month, so we don't have problems
+        // with non-existent days like Feb 30 or April 31
+        start.setDate( QDate( start.date().year(), start.date().month(), 1 ) );
+        nextValid.setDate( start.date().addMonths( periods ) );
+        break; }
+    case rYearly:
+        periods = ( toDate.date().year() - start.date().year() );
+        // round it down to the next lower multiple of frequency():
+        periods = ( periods / frequency() ) * frequency();
+        nextValid.setDate( start.date().addYears( periods ) );
+        break;
+    default:
+        break;
+  }
+// kdDebug(5800) << "    ~~~> date in previous interval is: : " << nextValid << endl;
+
+  return Constraint( nextValid, type, mWeekStart );
+}
+
+RecurrenceRule::Constraint RecurrenceRule::getNextValidDateInterval( const QDateTime &preDate, PeriodType type ) const
+{
+  // TODO: Simplify this!
+  kdDebug(5800) << "       (o) getNextValidDateInterval after " << preDate << ", type=" << type << endl;
+  long periods = 0;
+  QDateTime start = startDt();
+  QDateTime nextValid( start );
+  int modifier = 1;
+  QDateTime toDate( preDate );
+  // for super-daily recurrences, don't care about the time part
+
+  // Find the #intervals since the dtstart and round to the next multiple of
+  // the frequency
+      // FIXME: All sub-daily periods need to convert to UTC, do the calculations
+      //        in UTC, then convert back to the local time zone. Otherwise,
+      //        recurrences across DST changes will be determined wrongly
+  switch ( type ) {
+    // Really fall through for sub-daily, since the calculations only differ
+    // by the factor 60 and 60*60! Same for weekly and daily (factor 7)
+    case rHourly:   modifier *= 60;
+    case rMinutely: modifier *= 60;
+    case rSecondly:
+        periods = ownSecsTo( start, toDate ) / modifier;
+        periods = QMAX( 0, periods);
+        if ( periods > 0 )
+          periods += ( frequency() - 1 - ( (periods - 1) % frequency() ) );
+        nextValid = start.addSecs( modifier * periods );
+        break;
+
+    case rWeekly:
+        // correct both start date and current date to start of week
+        toDate = toDate.addDays( -(7 + toDate.date().dayOfWeek() - mWeekStart) % 7 );
+        start = start.addDays( -(7 + start.date().dayOfWeek() - mWeekStart) % 7 );
+        modifier *= 7;
+    case rDaily:
+        periods = start.daysTo( toDate ) / modifier;
+        periods = QMAX( 0, periods);
+        if ( periods > 0 )
+          periods += (frequency() - 1 - ( (periods - 1) % frequency() ) );
+        nextValid = start.addDays( modifier * periods );
+        break;
+
+    case rMonthly: {
+        periods = 12*( toDate.date().year() - start.date().year() ) +
+             ( toDate.date().month() - start.date().month() );
+        periods = QMAX( 0, periods);
+        if ( periods > 0 )
+          periods += (frequency() - 1 - ( (periods - 1) % frequency() ) );
+        // set the day to the first day of the month, so we don't have problems
+        // with non-existent days like Feb 30 or April 31
+        start.setDate( QDate( start.date().year(), start.date().month(), 1 ) );
+        nextValid.setDate( start.date().addMonths( periods ) );
+        break; }
+    case rYearly:
+        periods = ( toDate.date().year() - start.date().year() );
+        periods = QMAX( 0, periods);
+        if ( periods > 0 )
+          periods += ( frequency() - 1 - ( (periods - 1) % frequency() ) );
+        nextValid.setDate( start.date().addYears( periods ) );
+        break;
+    default:
+        break;
+  }
+// kdDebug(5800) << "    ~~~> date in next interval is: : " << nextValid << endl;
+
+  return Constraint( nextValid, type, mWeekStart );
+}
+
+bool RecurrenceRule::mergeIntervalConstraint( Constraint *merged,
+          const Constraint &conit, const Constraint &interval ) const
+{
+  Constraint result( interval );
+
+#define mergeConstraint( name, cmparison ) \
+  if ( conit.name cmparison ) { \
+    if ( !(result.name cmparison) || result.name == conit.name ) { \
+      result.name = conit.name; \
+    } else return false;\
+  }
+
+  mergeConstraint( year, > 0 );
+  mergeConstraint( month, > 0 );
+  mergeConstraint( day, != 0 );
+  mergeConstraint( hour, >= 0 );
+  mergeConstraint( minute, >= 0 );
+  mergeConstraint( second, >= 0 );
+
+  mergeConstraint( weekday, != 0 );
+  mergeConstraint( weekdaynr, != 0 );
+  mergeConstraint( weeknumber, != 0 );
+  mergeConstraint( yearday, != 0 );
+
+  #undef mergeConstraint
+  if ( merged ) *merged = result;
+  return true;
+}
+
+
+DateTimeList RecurrenceRule::datesForInterval( const Constraint &interval, PeriodType type ) const
+{
+  /* -) Loop through constraints,
+     -) merge interval with each constraint
+     -) if merged constraint is not consistent => ignore that constraint
+     -) if complete => add that one date to the date list
+     -) Loop through all missing fields => For each add the resulting
+  */
+// kdDebug(5800) << "         RecurrenceRule::datesForInterval: " << endl;
+// interval.dump();
+  DateTimeList lst;
+  Constraint::List::ConstIterator conit = mConstraints.begin();
+  for ( ; conit != mConstraints.end(); ++conit ) {
+    Constraint merged;
+    bool mergeok = mergeIntervalConstraint( &merged, *conit, interval );
+    // If the information is incomplete, we can't use this constraint
+    if ( merged.year <= 0 || merged.hour < 0 || merged.minute < 0 || merged.second < 0 )
+      mergeok = false;
+    if ( mergeok ) {
+// kdDebug(5800) << "      -) merged constraint: " << endl;
+// merged.dump();
+      // We have a valid constraint, so get all datetimes that match it andd
+      // append it to all date/times of this interval
+      DateTimeList lstnew = merged.dateTimes( type );
+      lst += lstnew;
+    }
+  }
+  // Sort it so we can apply the BySetPos. Also some logic relies on this being sorted
+  qSortUnique( lst );
+
+
+/*if ( lst.isEmpty() ) {
+  kdDebug(5800) << "         No Dates in Interval " << endl;
+} else {
+  kdDebug(5800) << "         Dates: " << endl;
+  for ( DateTimeList::Iterator it = lst.begin(); it != lst.end(); ++it ) {
+    kdDebug(5800)<< "              -) " << (*it).toString() << endl;
+  }
+  kdDebug(5800) << "       ---------------------" << endl;
+}*/
+  if ( !mBySetPos.isEmpty() ) {
+    DateTimeList tmplst = lst;
+    lst.clear();
+    QValueList<int>::ConstIterator it;
+    for ( it = mBySetPos.begin(); it != mBySetPos.end(); ++it ) {
+      int pos = *it;
+      if ( pos > 0 ) --pos;
+      if ( pos < 0 ) pos += tmplst.count();
+      if ( pos >= 0 && uint(pos) < tmplst.count() ) {
+        lst.append( tmplst[pos] );
+      }
+    }
+    qSortUnique( lst );
+  }
+
+  return lst;
+}
+
+
+void RecurrenceRule::dump() const
+{
+#ifndef NDEBUG
+  kdDebug(5800) << "RecurrenceRule::dump():" << endl;
+  if ( !mRRule.isEmpty() )
+    kdDebug(5800) << "   RRULE=" << mRRule << endl;
+  kdDebug(5800) << "   Read-Only: " << isReadOnly() <<
+                   ", dirty: " << mDirty << endl;
+
+  kdDebug(5800) << "   Period type: " << recurrenceType() << ", frequency: " << frequency() << endl;
+  kdDebug(5800) << "   #occurrences: " << duration() << endl;
+  kdDebug(5800) << "   start date: " << startDt() <<", end date: " << endDt() << endl;
+
+
+#define dumpByIntList(list,label) \
+  if ( !list.isEmpty() ) {\
+    QStringList lst;\
+    for ( QValueList<int>::ConstIterator it = list.begin();\
+          it != list.end(); ++it ) {\
+      lst.append( QString::number( *it ) );\
+    }\
+    kdDebug(5800) << "   " << label << lst.join(", ") << endl;\
+  }
+  dumpByIntList( mBySeconds,    "BySeconds:  " );
+  dumpByIntList( mByMinutes,    "ByMinutes:  " );
+  dumpByIntList( mByHours,      "ByHours:    " );
+  if ( !mByDays.isEmpty() ) {
+    QStringList lst;
+    for ( QValueList<WDayPos>::ConstIterator it = mByDays.begin();
+          it != mByDays.end(); ++it ) {
+      lst.append( ( ((*it).pos()!=0) ? QString::number( (*it).pos() ) : "" ) +
+                   DateHelper::dayName( (*it).day() ) );
+    }
+    kdDebug(5800) << "   ByDays:     " << lst.join(", ") << endl;
+  }
+  dumpByIntList( mByMonthDays,  "ByMonthDays:" );
+  dumpByIntList( mByYearDays,   "ByYearDays: " );
+  dumpByIntList( mByWeekNumbers,"ByWeekNr:   " );
+  dumpByIntList( mByMonths,     "ByMonths:   " );
+  dumpByIntList( mBySetPos,     "BySetPos:   " );
+  #undef dumpByIntList
+
+  kdDebug(5800) << "   Week start: " << DateHelper::dayName( mWeekStart ) << endl;
+
+  kdDebug(5800) << "   Constraints:" << endl;
+  // dump constraints
+  for ( Constraint::List::ConstIterator it = mConstraints.begin();
+        it!=mConstraints.end(); ++it ) {
+    (*it).dump();
+  }
+#endif
+}
+
+void RecurrenceRule::Constraint::dump() const
+{
+  kdDebug(5800) << "     ~> Y="<<year<<", M="<<month<<", D="<<day<<", H="<<hour<<", m="<<minute<<", S="<<second<<", wd="<<weekday<<",#wd="<<weekdaynr<<", #w="<<weeknumber<<", yd="<<yearday<<endl;
+}