kde-playground/kdepimlibs/kcalcore/recurrence.cpp

/*
  This file is part of kcalcore library.

  Copyright (c) 1998 Preston Brown <pbrown@kde.org>
  Copyright (c) 2001 Cornelius Schumacher <schumacher@kde.org>
  Copyright (c) 2002,2006 David Jarvie <software@astrojar.org.uk>
  Copyright (C) 2005 Reinhold Kainhofer <kainhofer@kde.org>

  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 "recurrence.h"

#include <KDebug>

#include <QtCore/QBitArray>
#include <QtCore/QTime>

using namespace KCalCore;

//@cond PRIVATE
class KCalCore::Recurrence::Private
{
public:
    Private()
        : mCachedType(rMax),
          mAllDay(false),
          mRecurReadOnly(false)
    {
    }

    Private(const Private &p)
        : mRDateTimes(p.mRDateTimes),
          mRDates(p.mRDates),
          mExDateTimes(p.mExDateTimes),
          mExDates(p.mExDates),
          mStartDateTime(p.mStartDateTime),
          mCachedType(p.mCachedType),
          mAllDay(p.mAllDay),
          mRecurReadOnly(p.mRecurReadOnly)
    {
    }

    bool operator==(const Private &p) const;

    RecurrenceRule::List mExRules;
    RecurrenceRule::List mRRules;
    DateTimeList mRDateTimes;
    DateList mRDates;
    DateTimeList mExDateTimes;
    DateList mExDates;
    KDateTime mStartDateTime;    // date/time of first recurrence
    QList<RecurrenceObserver*> mObservers;

    // Cache the type of the recurrence with the old system (e.g. MonthlyPos)
    mutable ushort mCachedType;

    bool mAllDay;                // the recurrence has no time, just a date
    bool mRecurReadOnly;
};

bool Recurrence::Private::operator==(const Recurrence::Private &p) const
{
    if ((mStartDateTime != p.mStartDateTime &&
            (mStartDateTime.isValid() || p.mStartDateTime.isValid())) ||
            mAllDay != p.mAllDay ||
            mRecurReadOnly != p.mRecurReadOnly ||
            mExDates != p.mExDates ||
            mExDateTimes != p.mExDateTimes ||
            mRDates != p.mRDates ||
            mRDateTimes != p.mRDateTimes) {
        return false;
    }

// Compare the rrules, exrules! Assume they have the same order... This only
// matters if we have more than one rule (which shouldn't be the default anyway)
    int i;
    int end = mRRules.count();
    if (end != p.mRRules.count()) {
        return false;
    }
    for (i = 0;  i < end;  ++i) {
        if (*mRRules[i] != *p.mRRules[i]) {
            return false;
        }
    }
    end = mExRules.count();
    if (end != p.mExRules.count()) {
        return false;
    }
    for (i = 0;  i < end;  ++i) {
        if (*mExRules[i] != *p.mExRules[i]) {
            return false;
        }
    }
    return true;
}
//@endcond

Recurrence::Recurrence()
    : d(new KCalCore::Recurrence::Private())
{
}

Recurrence::Recurrence(const Recurrence &r)
    : RecurrenceRule::RuleObserver(),
      d(new KCalCore::Recurrence::Private(*r.d))
{
    int i, end;
    for (i = 0, end = r.d->mRRules.count();  i < end;  ++i) {
        RecurrenceRule *rule = new RecurrenceRule(*r.d->mRRules[i]);
        d->mRRules.append(rule);
        rule->addObserver(this);
    }
    for (i = 0, end = r.d->mExRules.count();  i < end;  ++i) {
        RecurrenceRule *rule = new RecurrenceRule(*r.d->mExRules[i]);
        d->mExRules.append(rule);
        rule->addObserver(this);
    }
}

Recurrence::~Recurrence()
{
    qDeleteAll(d->mExRules);
    qDeleteAll(d->mRRules);
    delete d;
}

bool Recurrence::operator==(const Recurrence &recurrence) const
{
    return *d == *recurrence.d;
}

Recurrence &Recurrence::operator=(const Recurrence &recurrence)
{
    // check for self assignment
    if (&recurrence == this) {
        return *this;
    }

    *d = *recurrence.d;
    return *this;
}

void Recurrence::addObserver(RecurrenceObserver *observer)
{
    if (!d->mObservers.contains(observer)) {
        d->mObservers.append(observer);
    }
}

void Recurrence::removeObserver(RecurrenceObserver *observer)
{
    if (d->mObservers.contains(observer)) {
        d->mObservers.removeAll(observer);
    }
}

KDateTime Recurrence::startDateTime() const
{
    return d->mStartDateTime;
}

bool Recurrence::allDay() const
{
    return d->mAllDay;
}

void Recurrence::setAllDay(bool allDay)
{
    if (d->mRecurReadOnly || allDay == d->mAllDay) {
        return;
    }

    d->mAllDay = allDay;
    for (int i = 0, end = d->mRRules.count();  i < end;  ++i) {
        d->mRRules[i]->setAllDay(allDay);
    }
    for (int i = 0, end = d->mExRules.count();  i < end;  ++i) {
        d->mExRules[i]->setAllDay(allDay);
    }
    updated();
}

RecurrenceRule *Recurrence::defaultRRule(bool create) const
{
    if (d->mRRules.isEmpty()) {
        if (!create || d->mRecurReadOnly) {
            return 0;
        }
        RecurrenceRule *rrule = new RecurrenceRule();
        rrule->setStartDt(startDateTime());
        const_cast<KCalCore::Recurrence*>(this)->addRRule(rrule);
        return rrule;
    } else {
        return d->mRRules[0];
    }
}

RecurrenceRule *Recurrence::defaultRRuleConst() const
{
    return d->mRRules.isEmpty() ? 0 : d->mRRules[0];
}

void Recurrence::updated()
{
    // recurrenceType() re-calculates the type if it's rMax
    d->mCachedType = rMax;
    for (int i = 0, end = d->mObservers.count();  i < end;  ++i) {
        if (d->mObservers[i]) {
            d->mObservers[i]->recurrenceUpdated(this);
        }
    }
}

bool Recurrence::recurs() const
{
    return !d->mRRules.isEmpty() || !d->mRDates.isEmpty() || !d->mRDateTimes.isEmpty();
}

ushort Recurrence::recurrenceType() const
{
    if (d->mCachedType == rMax) {
        d->mCachedType = recurrenceType(defaultRRuleConst());
    }
    return d->mCachedType;
}

ushort Recurrence::recurrenceType(const RecurrenceRule *rrule)
{
    if (!rrule) {
        return rNone;
    }
    RecurrenceRule::PeriodType type = rrule->recurrenceType();

    // BYSETPOS, BYWEEKNUMBER and BYSECOND were not supported in old versions
    if (!rrule->bySetPos().isEmpty() ||
            !rrule->bySeconds().isEmpty() ||
            !rrule->byWeekNumbers().isEmpty()) {
        return rOther;
    }

    // It wasn't possible to set BYMINUTES, BYHOUR etc. by the old code. So if
    // it's set, it's none of the old types
    if (!rrule->byMinutes().isEmpty() || !rrule->byHours().isEmpty()) {
        return rOther;
    }

    // Possible combinations were:
    // BYDAY: with WEEKLY, MONTHLY, YEARLY
    // BYMONTHDAY: with MONTHLY, YEARLY
    // BYMONTH: with YEARLY
    // BYYEARDAY: with YEARLY
    if ((!rrule->byYearDays().isEmpty() && type != RecurrenceRule::rYearly) ||
            (!rrule->byMonths().isEmpty() && type != RecurrenceRule::rYearly)) {
        return rOther;
    }
    if (!rrule->byDays().isEmpty()) {
        if (type != RecurrenceRule::rYearly &&
                type != RecurrenceRule::rMonthly &&
                type != RecurrenceRule::rWeekly) {
            return rOther;
        }
    }

    switch (type) {
    case RecurrenceRule::rNone:
        return rNone;
    case RecurrenceRule::rMinutely:
        return rMinutely;
    case RecurrenceRule::rHourly:
        return rHourly;
    case RecurrenceRule::rDaily:
        return rDaily;
    case RecurrenceRule::rWeekly:
        return rWeekly;
    case RecurrenceRule::rMonthly:
    {
        if (rrule->byDays().isEmpty()) {
            return rMonthlyDay;
        } else if (rrule->byMonthDays().isEmpty()) {
            return rMonthlyPos;
        } else {
            return rOther; // both position and date specified
        }
    }
    case RecurrenceRule::rYearly:
    {
        // Possible combinations:
        //   rYearlyMonth: [BYMONTH &] BYMONTHDAY
        //   rYearlyDay: BYYEARDAY
        //   rYearlyPos: [BYMONTH &] BYDAY
        if (!rrule->byDays().isEmpty()) {
            // can only by rYearlyPos
            if (rrule->byMonthDays().isEmpty() && rrule->byYearDays().isEmpty()) {
                return rYearlyPos;
            } else {
                return rOther;
            }
        } else if (!rrule->byYearDays().isEmpty()) {
            // Can only be rYearlyDay
            if (rrule->byMonths().isEmpty() && rrule->byMonthDays().isEmpty()) {
                return rYearlyDay;
            } else {
                return rOther;
            }
        } else {
            return rYearlyMonth;
        }
        break;
    }
    default:
        return rOther;
    }
    return rOther;
}

bool Recurrence::recursOn(const QDate &qd, const KDateTime::Spec &timeSpec) const
{
    // Don't waste time if date is before the start of the recurrence
    if (KDateTime(qd, QTime(23, 59, 59), timeSpec) < d->mStartDateTime) {
        return false;
    }

    // First handle dates. Exrules override
    if (d->mExDates.containsSorted(qd)) {
        return false;
    }

    int i, end;
    TimeList tms;
    // For all-day events a matching exrule excludes the whole day
    // since exclusions take precedence over inclusions, we know it can't occur on that day.
    if (allDay()) {
        for (i = 0, end = d->mExRules.count();  i < end;  ++i) {
            if (d->mExRules[i]->recursOn(qd, timeSpec)) {
                return false;
            }
        }
    }

    if (d->mRDates.containsSorted(qd)) {
        return true;
    }

    // Check if it might recur today at all.
    bool recurs = (startDate() == qd);
    for (i = 0, end = d->mRDateTimes.count();  i < end && !recurs;  ++i) {
        recurs = (d->mRDateTimes[i].toTimeSpec(timeSpec).date() == qd);
    }
    for (i = 0, end = d->mRRules.count();  i < end && !recurs;  ++i) {
        recurs = d->mRRules[i]->recursOn(qd, timeSpec);
    }
    // If the event wouldn't recur at all, simply return false, don't check ex*
    if (!recurs) {
        return false;
    }

    // Check if there are any times for this day excluded, either by exdate or exrule:
    bool exon = false;
    for (i = 0, end = d->mExDateTimes.count();  i < end && !exon;  ++i) {
        exon = (d->mExDateTimes[i].toTimeSpec(timeSpec).date() == qd);
    }
    if (!allDay()) {       // we have already checked all-day times above
        for (i = 0, end = d->mExRules.count();  i < end && !exon;  ++i) {
            exon = d->mExRules[i]->recursOn(qd, timeSpec);
        }
    }

    if (!exon) {
        // Simple case, nothing on that day excluded, return the value from before
        return recurs;
    } else {
        // Harder part: I don't think there is any way other than to calculate the
        // whole list of items for that day.
//TODO: consider whether it would be more efficient to call
//      Rule::recurTimesOn() instead of Rule::recursOn() from the start
        TimeList timesForDay(recurTimesOn(qd, timeSpec));
        return !timesForDay.isEmpty();
    }
}

bool Recurrence::recursAt(const KDateTime &dt) const
{
    // Convert to recurrence's time zone for date comparisons, and for more efficient time comparisons
    KDateTime dtrecur = dt.toTimeSpec(d->mStartDateTime.timeSpec());

    // if it's excluded anyway, don't bother to check if it recurs at all.
    if (d->mExDateTimes.containsSorted(dtrecur) ||
            d->mExDates.containsSorted(dtrecur.date())) {
        return false;
    }
    int i, end;
    for (i = 0, end = d->mExRules.count();  i < end;  ++i) {
        if (d->mExRules[i]->recursAt(dtrecur)) {
            return false;
        }
    }

    // Check explicit recurrences, then rrules.
    if (startDateTime() == dtrecur || d->mRDateTimes.containsSorted(dtrecur)) {
        return true;
    }
    for (i = 0, end = d->mRRules.count();  i < end;  ++i) {
        if (d->mRRules[i]->recursAt(dtrecur)) {
            return true;
        }
    }

    return false;
}

/** Calculates the cumulative end of the whole recurrence (rdates and rrules).
    If any rrule is infinite, or the recurrence doesn't have any rrules or
    rdates, an invalid date is returned. */
KDateTime Recurrence::endDateTime() const
{
    DateTimeList dts;
    dts << startDateTime();
    if (!d->mRDates.isEmpty()) {
        dts << KDateTime(d->mRDates.last(), QTime(0, 0, 0), d->mStartDateTime.timeSpec());
    }
    if (!d->mRDateTimes.isEmpty()) {
        dts << d->mRDateTimes.last();
    }
    for (int i = 0, end = d->mRRules.count();  i < end;  ++i) {
        KDateTime rl(d->mRRules[i]->endDt());
        // if any of the rules is infinite, the whole recurrence is
        if (!rl.isValid()) {
            return KDateTime();
        }
        dts << rl;
    }
    dts.sortUnique();
    return dts.isEmpty() ? KDateTime() : dts.last();
}

/** Calculates the cumulative end of the whole recurrence (rdates and rrules).
    If any rrule is infinite, or the recurrence doesn't have any rrules or
    rdates, an invalid date is returned. */
QDate Recurrence::endDate() const
{
    KDateTime end(endDateTime());
    return end.isValid() ? end.date() : QDate();
}

void Recurrence::setEndDate(const QDate &date)
{
    KDateTime dt(date, d->mStartDateTime.time(), d->mStartDateTime.timeSpec());
    if (allDay()) {
        dt.setTime(QTime(23, 59, 59));
    }
    setEndDateTime(dt);
}

void Recurrence::setEndDateTime(const KDateTime &dateTime)
{
    if (d->mRecurReadOnly) {
        return;
    }
    RecurrenceRule *rrule = defaultRRule(true);
    if (!rrule) {
        return;
    }
    rrule->setEndDt(dateTime);
    updated();
}

int Recurrence::duration() const
{
    RecurrenceRule *rrule = defaultRRuleConst();
    return rrule ? rrule->duration() : 0;
}

int Recurrence::durationTo(const KDateTime &datetime) const
{
    // Emulate old behavior: This is just an interface to the first rule!
    RecurrenceRule *rrule = defaultRRuleConst();
    return rrule ? rrule->durationTo(datetime) : 0;
}

int Recurrence::durationTo(const QDate &date) const
{
    return durationTo(KDateTime(date, QTime(23, 59, 59), d->mStartDateTime.timeSpec()));
}

void Recurrence::setDuration(int duration)
{
    if (d->mRecurReadOnly) {
        return;
    }

    RecurrenceRule *rrule = defaultRRule(true);
    if (!rrule) {
        return;
    }
    rrule->setDuration(duration);
    updated();
}

void Recurrence::shiftTimes(const KDateTime::Spec &oldSpec, const KDateTime::Spec &newSpec)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mStartDateTime = d->mStartDateTime.toTimeSpec(oldSpec);
    d->mStartDateTime.setTimeSpec(newSpec);

    int i, end;
    for (i = 0, end = d->mRDateTimes.count();  i < end;  ++i) {
        d->mRDateTimes[i] = d->mRDateTimes[i].toTimeSpec(oldSpec);
        d->mRDateTimes[i].setTimeSpec(newSpec);
    }
    for (i = 0, end = d->mExDateTimes.count();  i < end;  ++i) {
        d->mExDateTimes[i] = d->mExDateTimes[i].toTimeSpec(oldSpec);
        d->mExDateTimes[i].setTimeSpec(newSpec);
    }
    for (i = 0, end = d->mRRules.count();  i < end;  ++i) {
        d->mRRules[i]->shiftTimes(oldSpec, newSpec);
    }
    for (i = 0, end = d->mExRules.count();  i < end;  ++i) {
        d->mExRules[i]->shiftTimes(oldSpec, newSpec);
    }
}

void Recurrence::unsetRecurs()
{
    if (d->mRecurReadOnly) {
        return;
    }
    qDeleteAll(d->mRRules);
    d->mRRules.clear();
    updated();
}

void Recurrence::clear()
{
    if (d->mRecurReadOnly) {
        return;
    }
    qDeleteAll(d->mRRules);
    d->mRRules.clear();
    qDeleteAll(d->mExRules);
    d->mExRules.clear();
    d->mRDates.clear();
    d->mRDateTimes.clear();
    d->mExDates.clear();
    d->mExDateTimes.clear();
    d->mCachedType = rMax;
    updated();
}

void Recurrence::setRecurReadOnly(bool readOnly)
{
    d->mRecurReadOnly = readOnly;
}

bool Recurrence::recurReadOnly() const
{
    return d->mRecurReadOnly;
}

QDate Recurrence::startDate() const
{
    return d->mStartDateTime.date();
}

void Recurrence::setStartDateTime(const KDateTime &start)
{
    if (d->mRecurReadOnly) {
        return;
    }
    d->mStartDateTime = start;
    setAllDay(start.isDateOnly());     // set all RRULEs and EXRULEs

    int i, end;
    for (i = 0, end = d->mRRules.count();  i < end;  ++i) {
        d->mRRules[i]->setStartDt(start);
    }
    for (i = 0, end = d->mExRules.count();  i < end;  ++i) {
        d->mExRules[i]->setStartDt(start);
    }
    updated();
}

int Recurrence::frequency() const
{
    RecurrenceRule *rrule = defaultRRuleConst();
    return rrule ? rrule->frequency() : 0;
}

// Emulate the old behaviour. Make this methods just an interface to the
// first rrule
void Recurrence::setFrequency(int freq)
{
    if (d->mRecurReadOnly || freq <= 0) {
        return;
    }

    RecurrenceRule *rrule = defaultRRule(true);
    if (rrule) {
        rrule->setFrequency(freq);
    }
    updated();
}

// WEEKLY

int Recurrence::weekStart() const
{
    RecurrenceRule *rrule = defaultRRuleConst();
    return rrule ? rrule->weekStart() : 1;
}

// Emulate the old behavior
QBitArray Recurrence::days() const
{
    QBitArray days(7);
    days.fill(0);
    RecurrenceRule *rrule = defaultRRuleConst();
    if (rrule) {
        QList<RecurrenceRule::WDayPos> bydays = rrule->byDays();
        for (int i = 0; i < bydays.size(); ++i) {
            if (bydays.at(i).pos() == 0) {
                days.setBit(bydays.at(i).day() - 1);
            }
        }
    }
    return days;
}

// MONTHLY

// Emulate the old behavior
QList<int> Recurrence::monthDays() const
{
    RecurrenceRule *rrule = defaultRRuleConst();
    if (rrule) {
        return rrule->byMonthDays();
    } else {
        return QList<int>();
    }
}

// Emulate the old behavior
QList<RecurrenceRule::WDayPos> Recurrence::monthPositions() const
{
    RecurrenceRule *rrule = defaultRRuleConst();
    return rrule ? rrule->byDays() : QList<RecurrenceRule::WDayPos>();
}

// YEARLY

QList<int> Recurrence::yearDays() const
{
    RecurrenceRule *rrule = defaultRRuleConst();
    return rrule ? rrule->byYearDays() : QList<int>();
}

QList<int> Recurrence::yearDates() const
{
    return monthDays();
}

QList<int> Recurrence::yearMonths() const
{
    RecurrenceRule *rrule = defaultRRuleConst();
    return rrule ? rrule->byMonths() : QList<int>();
}

QList<RecurrenceRule::WDayPos> Recurrence::yearPositions() const
{
    return monthPositions();
}

RecurrenceRule *Recurrence::setNewRecurrenceType(RecurrenceRule::PeriodType type, int freq)
{
    if (d->mRecurReadOnly || freq <= 0) {
        return 0;
    }

    qDeleteAll(d->mRRules);
    d->mRRules.clear();
    updated();
    RecurrenceRule *rrule = defaultRRule(true);
    if (!rrule) {
        return 0;
    }
    rrule->setRecurrenceType(type);
    rrule->setFrequency(freq);
    rrule->setDuration(-1);
    return rrule;
}

void Recurrence::setMinutely(int _rFreq)
{
    if (setNewRecurrenceType(RecurrenceRule::rMinutely, _rFreq)) {
        updated();
    }
}

void Recurrence::setHourly(int _rFreq)
{
    if (setNewRecurrenceType(RecurrenceRule::rHourly, _rFreq)) {
        updated();
    }
}

void Recurrence::setDaily(int _rFreq)
{
    if (setNewRecurrenceType(RecurrenceRule::rDaily, _rFreq)) {
        updated();
    }
}

void Recurrence::setWeekly(int freq, int weekStart)
{
    RecurrenceRule *rrule = setNewRecurrenceType(RecurrenceRule::rWeekly, freq);
    if (!rrule) {
        return;
    }
    rrule->setWeekStart(weekStart);
    updated();
}

void Recurrence::setWeekly(int freq, const QBitArray &days, int weekStart)
{
    setWeekly(freq, weekStart);
    addMonthlyPos(0, days);
}

void Recurrence::addWeeklyDays(const QBitArray &days)
{
    addMonthlyPos(0, days);
}

void Recurrence::setMonthly(int freq)
{
    if (setNewRecurrenceType(RecurrenceRule::rMonthly, freq)) {
        updated();
    }
}

void Recurrence::addMonthlyPos(short pos, const QBitArray &days)
{
    // Allow 53 for yearly!
    if (d->mRecurReadOnly || pos > 53 || pos < -53) {
        return;
    }

    RecurrenceRule *rrule = defaultRRule(false);
    if (!rrule) {
        return;
    }
    bool changed = false;
    QList<RecurrenceRule::WDayPos> positions = rrule->byDays();

    for (int i = 0; i < 7; ++i) {
        if (days.testBit(i)) {
            RecurrenceRule::WDayPos p(pos, i + 1);
            if (!positions.contains(p)) {
                changed = true;
                positions.append(p);
            }
        }
    }
    if (changed) {
        rrule->setByDays(positions);
        updated();
    }
}

void Recurrence::addMonthlyPos(short pos, ushort day)
{
    // Allow 53 for yearly!
    if (d->mRecurReadOnly || pos > 53 || pos < -53) {
        return;
    }

    RecurrenceRule *rrule = defaultRRule(false);
    if (!rrule) {
        return;
    }
    QList<RecurrenceRule::WDayPos> positions = rrule->byDays();

    RecurrenceRule::WDayPos p(pos, day);
    if (!positions.contains(p)) {
        positions.append(p);
        rrule->setByDays(positions);
        updated();
    }
}

void Recurrence::addMonthlyDate(short day)
{
    if (d->mRecurReadOnly || day > 31 || day < -31) {
        return;
    }

    RecurrenceRule *rrule = defaultRRule(true);
    if (!rrule) {
        return;
    }

    QList<int> monthDays = rrule->byMonthDays();
    if (!monthDays.contains(day)) {
        monthDays.append(day);
        rrule->setByMonthDays(monthDays);
        updated();
    }
}

void Recurrence::setYearly(int freq)
{
    if (setNewRecurrenceType(RecurrenceRule::rYearly, freq)) {
        updated();
    }
}

// Daynumber within year
void Recurrence::addYearlyDay(int day)
{
    RecurrenceRule *rrule = defaultRRule(false);   // It must already exist!
    if (!rrule) {
        return;
    }

    QList<int> days = rrule->byYearDays();
    if (!days.contains(day)) {
        days << day;
        rrule->setByYearDays(days);
        updated();
    }
}

// day part of date within year
void Recurrence::addYearlyDate(int day)
{
    addMonthlyDate(day);
}

// day part of date within year, given as position (n-th weekday)
void Recurrence::addYearlyPos(short pos, const QBitArray &days)
{
    addMonthlyPos(pos, days);
}

// month part of date within year
void Recurrence::addYearlyMonth(short month)
{
    if (d->mRecurReadOnly || month < 1 || month > 12) {
        return;
    }

    RecurrenceRule *rrule = defaultRRule(false);
    if (!rrule) {
        return;
    }

    QList<int> months = rrule->byMonths();
    if (!months.contains(month)) {
        months << month;
        rrule->setByMonths(months);
        updated();
    }
}

TimeList Recurrence::recurTimesOn(const QDate &date, const KDateTime::Spec &timeSpec) const
{
// kDebug() << "recurTimesOn(" << date << ")";
    int i, end;
    TimeList times;

    // The whole day is excepted
    if (d->mExDates.containsSorted(date)) {
        return times;
    }

    // EXRULE takes precedence over RDATE entries, so for all-day events,
    // a matching excule also excludes the whole day automatically
    if (allDay()) {
        for (i = 0, end = d->mExRules.count();  i < end;  ++i) {
            if (d->mExRules[i]->recursOn(date, timeSpec)) {
                return times;
            }
        }
    }

    KDateTime dt = startDateTime().toTimeSpec(timeSpec);
    if (dt.date() == date) {
        times << dt.time();
    }

    bool foundDate = false;
    for (i = 0, end = d->mRDateTimes.count();  i < end;  ++i) {
        dt = d->mRDateTimes[i].toTimeSpec(timeSpec);
        if (dt.date() == date) {
            times << dt.time();
            foundDate = true;
        } else if (foundDate) {
            break; // <= Assume that the rdatetime list is sorted
        }
    }
    for (i = 0, end = d->mRRules.count();  i < end;  ++i) {
        times += d->mRRules[i]->recurTimesOn(date, timeSpec);
    }
    times.sortUnique();

    foundDate = false;
    TimeList extimes;
    for (i = 0, end = d->mExDateTimes.count();  i < end;  ++i) {
        dt = d->mExDateTimes[i].toTimeSpec(timeSpec);
        if (dt.date() == date) {
            extimes << dt.time();
            foundDate = true;
        } else if (foundDate) {
            break;
        }
    }
    if (!allDay()) {       // we have already checked all-day times above
        for (i = 0, end = d->mExRules.count();  i < end;  ++i) {
            extimes += d->mExRules[i]->recurTimesOn(date, timeSpec);
        }
    }
    extimes.sortUnique();

    int st = 0;
    for (i = 0, end = extimes.count();  i < end;  ++i) {
        int j = times.removeSorted(extimes[i], st);
        if (j >= 0) {
            st = j;
        }
    }
    return times;
}

DateTimeList Recurrence::timesInInterval(const KDateTime &start, const KDateTime &end) const
{
    int i, count;
    DateTimeList times;
    for (i = 0, count = d->mRRules.count();  i < count;  ++i) {
        times += d->mRRules[i]->timesInInterval(start, end);
    }

    // add rdatetimes that fit in the interval
    for (i = 0, count = d->mRDateTimes.count();  i < count;  ++i) {
        if (d->mRDateTimes[i] >= start && d->mRDateTimes[i] <= end) {
            times += d->mRDateTimes[i];
        }
    }

    // add rdates that fit in the interval
    KDateTime kdt(d->mStartDateTime);
    for (i = 0, count = d->mRDates.count();  i < count;  ++i) {
        kdt.setDate(d->mRDates[i]);
        if (kdt >= start && kdt <= end) {
            times += kdt;
        }
    }

    // Recurrence::timesInInterval(...) doesn't explicitly add mStartDateTime to the list
    // of times to be returned. It calls mRRules[i]->timesInInterval(...) which include
    // mStartDateTime.
    // So, If we have rdates/rdatetimes but don't have any rrule we must explicitly
    // add mStartDateTime to the list, otherwise we won't see the first occurrence.
    if ((!d->mRDates.isEmpty() || !d->mRDateTimes.isEmpty()) &&
            d->mRRules.isEmpty() &&
            start <= d->mStartDateTime &&
            end >= d->mStartDateTime) {
        times += d->mStartDateTime;
    }

    times.sortUnique();

    // Remove excluded times
    int idt = 0;
    int enddt = times.count();
    for (i = 0, count = d->mExDates.count();  i < count && idt < enddt;  ++i) {
        while (idt < enddt && times[idt].date() < d->mExDates[i]) {
            ++idt;
        }
        while (idt < enddt && times[idt].date() == d->mExDates[i]) {
            times.removeAt(idt);
            --enddt;
        }
    }
    DateTimeList extimes;
    for (i = 0, count = d->mExRules.count();  i < count;  ++i) {
        extimes += d->mExRules[i]->timesInInterval(start, end);
    }
    extimes += d->mExDateTimes;
    extimes.sortUnique();

    int st = 0;
    for (i = 0, count = extimes.count();  i < count;  ++i) {
        int j = times.removeSorted(extimes[i], st);
        if (j >= 0) {
            st = j;
        }
    }

    return times;
}

KDateTime Recurrence::getNextDateTime(const KDateTime &preDateTime) const
{
    KDateTime nextDT = preDateTime;
    // prevent infinite loops, e.g. when an exrule extinguishes an rrule (e.g.
    // the exrule is identical to the rrule). If an occurrence is found, break
    // out of the loop by returning that KDateTime
// TODO_Recurrence: Is a loop counter of 1000 really okay? I mean for secondly
// recurrence, an exdate might exclude more than 1000 intervals!
    int loop = 0;
    while (loop < 1000) {
        // Outline of the algo:
        //   1) Find the next date/time after preDateTime when the event could recur
        //     1.0) Add the start date if it's after preDateTime
        //     1.1) Use the next occurrence from the explicit RDATE lists
        //     1.2) Add the next recurrence for each of the RRULEs
        //   2) Take the earliest recurrence of these = KDateTime nextDT
        //   3) If that date/time is not excluded, either explicitly by an EXDATE or
        //      by an EXRULE, return nextDT as the next date/time of the recurrence
        //   4) If it's excluded, start all at 1), but starting at nextDT (instead
        //      of preDateTime). Loop at most 1000 times.
        ++loop;
        // First, get the next recurrence from the RDate lists
        DateTimeList dates;
        if (nextDT < startDateTime()) {
            dates << startDateTime();
        }

        int end;
        // Assume that the rdatetime list is sorted
        int i = d->mRDateTimes.findGT(nextDT);
        if (i >= 0) {
            dates << d->mRDateTimes[i];
        }

        KDateTime kdt(startDateTime());
        for (i = 0, end = d->mRDates.count();  i < end;  ++i) {
            kdt.setDate(d->mRDates[i]);
            if (kdt > nextDT) {
                dates << kdt;
                break;
            }
        }

        // Add the next occurrences from all RRULEs.
        for (i = 0, end = d->mRRules.count();  i < end;  ++i) {
            KDateTime dt = d->mRRules[i]->getNextDate(nextDT);
            if (dt.isValid()) {
                dates << dt;
            }
        }

        // Take the first of these (all others can't be used later on)
        dates.sortUnique();
        if (dates.isEmpty()) {
            return KDateTime();
        }
        nextDT = dates.first();

        // Check if that date/time is excluded explicitly or by an exrule:
        if (!d->mExDates.containsSorted(nextDT.date()) &&
                !d->mExDateTimes.containsSorted(nextDT)) {
            bool allowed = true;
            for (i = 0, end = d->mExRules.count();  i < end;  ++i) {
                allowed = allowed && !(d->mExRules[i]->recursAt(nextDT));
            }
            if (allowed) {
                return nextDT;
            }
        }
    }

    // Couldn't find a valid occurrences in 1000 loops, something is wrong!
    return KDateTime();
}

KDateTime Recurrence::getPreviousDateTime(const KDateTime &afterDateTime) const
{
    KDateTime prevDT = afterDateTime;
    // prevent infinite loops, e.g. when an exrule extinguishes an rrule (e.g.
    // the exrule is identical to the rrule). If an occurrence is found, break
    // out of the loop by returning that KDateTime
    int loop = 0;
    while (loop < 1000) {
        // Outline of the algo:
        //   1) Find the next date/time after preDateTime when the event could recur
        //     1.1) Use the next occurrence from the explicit RDATE lists
        //     1.2) Add the next recurrence for each of the RRULEs
        //   2) Take the earliest recurrence of these = KDateTime nextDT
        //   3) If that date/time is not excluded, either explicitly by an EXDATE or
        //      by an EXRULE, return nextDT as the next date/time of the recurrence
        //   4) If it's excluded, start all at 1), but starting at nextDT (instead
        //      of preDateTime). Loop at most 1000 times.
        ++loop;
        // First, get the next recurrence from the RDate lists
        DateTimeList dates;
        if (prevDT > startDateTime()) {
            dates << startDateTime();
        }

        int i = d->mRDateTimes.findLT(prevDT);
        if (i >= 0) {
            dates << d->mRDateTimes[i];
        }

        KDateTime kdt(startDateTime());
        for (i = d->mRDates.count();  --i >= 0;) {
            kdt.setDate(d->mRDates[i]);
            if (kdt < prevDT) {
                dates << kdt;
                break;
            }
        }

        // Add the previous occurrences from all RRULEs.
        int end;
        for (i = 0, end = d->mRRules.count();  i < end;  ++i) {
            KDateTime dt = d->mRRules[i]->getPreviousDate(prevDT);
            if (dt.isValid()) {
                dates << dt;
            }
        }

        // Take the last of these (all others can't be used later on)
        dates.sortUnique();
        if (dates.isEmpty()) {
            return KDateTime();
        }
        prevDT = dates.last();

        // Check if that date/time is excluded explicitly or by an exrule:
        if (!d->mExDates.containsSorted(prevDT.date()) &&
                !d->mExDateTimes.containsSorted(prevDT)) {
            bool allowed = true;
            for (i = 0, end = d->mExRules.count();  i < end;  ++i) {
                allowed = allowed && !(d->mExRules[i]->recursAt(prevDT));
            }
            if (allowed) {
                return prevDT;
            }
        }
    }

    // Couldn't find a valid occurrences in 1000 loops, something is wrong!
    return KDateTime();
}

/***************************** PROTECTED FUNCTIONS ***************************/

RecurrenceRule::List Recurrence::rRules() const
{
    return d->mRRules;
}

void Recurrence::addRRule(RecurrenceRule *rrule)
{
    if (d->mRecurReadOnly || !rrule) {
        return;
    }

    rrule->setAllDay(d->mAllDay);
    d->mRRules.append(rrule);
    rrule->addObserver(this);
    updated();
}

void Recurrence::removeRRule(RecurrenceRule *rrule)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mRRules.removeAll(rrule);
    rrule->removeObserver(this);
    updated();
}

void Recurrence::deleteRRule(RecurrenceRule *rrule)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mRRules.removeAll(rrule);
    delete rrule;
    updated();
}

RecurrenceRule::List Recurrence::exRules() const
{
    return d->mExRules;
}

void Recurrence::addExRule(RecurrenceRule *exrule)
{
    if (d->mRecurReadOnly || !exrule) {
        return;
    }

    exrule->setAllDay(d->mAllDay);
    d->mExRules.append(exrule);
    exrule->addObserver(this);
    updated();
}

void Recurrence::removeExRule(RecurrenceRule *exrule)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mExRules.removeAll(exrule);
    exrule->removeObserver(this);
    updated();
}

void Recurrence::deleteExRule(RecurrenceRule *exrule)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mExRules.removeAll(exrule);
    delete exrule;
    updated();
}

DateTimeList Recurrence::rDateTimes() const
{
    return d->mRDateTimes;
}

void Recurrence::setRDateTimes(const DateTimeList &rdates)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mRDateTimes = rdates;
    d->mRDateTimes.sortUnique();
    updated();
}

void Recurrence::addRDateTime(const KDateTime &rdate)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mRDateTimes.insertSorted(rdate);
    updated();
}

DateList Recurrence::rDates() const
{
    return d->mRDates;
}

void Recurrence::setRDates(const DateList &rdates)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mRDates = rdates;
    d->mRDates.sortUnique();
    updated();
}

void Recurrence::addRDate(const QDate &rdate)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mRDates.insertSorted(rdate);
    updated();
}

DateTimeList Recurrence::exDateTimes() const
{
    return d->mExDateTimes;
}

void Recurrence::setExDateTimes(const DateTimeList &exdates)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mExDateTimes = exdates;
    d->mExDateTimes.sortUnique();
}

void Recurrence::addExDateTime(const KDateTime &exdate)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mExDateTimes.insertSorted(exdate);
    updated();
}

DateList Recurrence::exDates() const
{
    return d->mExDates;
}

void Recurrence::setExDates(const DateList &exdates)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mExDates = exdates;
    d->mExDates.sortUnique();
    updated();
}

void Recurrence::addExDate(const QDate &exdate)
{
    if (d->mRecurReadOnly) {
        return;
    }

    d->mExDates.insertSorted(exdate);
    updated();
}

void Recurrence::recurrenceChanged(RecurrenceRule *)
{
    updated();
}

// %%%%%%%%%%%%%%%%%% end:Recurrencerule %%%%%%%%%%%%%%%%%%

void Recurrence::dump() const
{
    kDebug();

    int i;
    int count = d->mRRules.count();
    kDebug() << "  -)" << count << "RRULEs:";
    for (i = 0;  i < count;  ++i) {
        kDebug() << "    -) RecurrenceRule: ";
        d->mRRules[i]->dump();
    }
    count = d->mExRules.count();
    kDebug() << "  -)" << count << "EXRULEs:";
    for (i = 0;  i < count;  ++i) {
        kDebug() << "    -) ExceptionRule :";
        d->mExRules[i]->dump();
    }

    count = d->mRDates.count();
    kDebug() << endl << "  -)" << count << "Recurrence Dates:";
    for (i = 0;  i < count;  ++i) {
        kDebug() << "    " << d->mRDates[i];
    }
    count = d->mRDateTimes.count();
    kDebug() << endl << "  -)" << count << "Recurrence Date/Times:";
    for (i = 0;  i < count;  ++i) {
        kDebug() << "    " << d->mRDateTimes[i].dateTime();
    }
    count = d->mExDates.count();
    kDebug() << endl << "  -)" << count << "Exceptions Dates:";
    for (i = 0;  i < count;  ++i) {
        kDebug() << "    " << d->mExDates[i];
    }
    count = d->mExDateTimes.count();
    kDebug() << endl << "  -)" << count << "Exception Date/Times:";
    for (i = 0;  i < count;  ++i) {
        kDebug() << "    " << d->mExDateTimes[i].dateTime();
    }
}

Recurrence::RecurrenceObserver::~RecurrenceObserver()
{
}

KCALCORE_EXPORT QDataStream& KCalCore::operator<<(QDataStream &out, KCalCore::Recurrence *r)
{
    if (!r)
        return out;

    out << r->d->mRDateTimes << r->d->mExDateTimes
        << r->d->mRDates << r->d->mStartDateTime << r->d->mCachedType
        << r->d->mAllDay << r->d->mRecurReadOnly << r->d->mExDates
        << r->d->mExRules.count() << r->d->mRRules.count();

    foreach(RecurrenceRule *rule, r->d->mExRules) {
        out << rule;
    }

    foreach(RecurrenceRule *rule, r->d->mRRules) {
        out << rule;
    }

    return out;
}


KCALCORE_EXPORT QDataStream& KCalCore::operator>>(QDataStream &in, KCalCore::Recurrence *r)
{
    if (!r)
        return in;

    int rruleCount, exruleCount;

    in >> r->d->mRDateTimes >> r->d->mExDateTimes
       >> r->d->mRDates >> r->d->mStartDateTime >> r->d->mCachedType
       >> r->d->mAllDay >> r->d->mRecurReadOnly >> r->d->mExDates
       >> exruleCount >> rruleCount;

    r->d->mExRules.clear();
    r->d->mRRules.clear();

    for (int i=0; i<exruleCount; ++i) {
        RecurrenceRule *rule = new RecurrenceRule();
        rule->addObserver(r);
        in >> rule;
        r->d->mExRules.append(rule);
    }

    for (int i=0; i<rruleCount; ++i) {
        RecurrenceRule *rule = new RecurrenceRule();
        rule->addObserver(r);
        in >> rule;
        r->d->mRRules.append(rule);
    }

    return in;
}