/*
 *  synchtimer.h  -  timers which synchronize to time boundaries
 *  Program:  kalarm
 *  Copyright © 2004,2005 by David Jarvie <djarvie@kde.org>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#ifndef SYNCHTIMER_H
#define SYNCHTIMER_H

/* @file synchtimer.h - timers which synchronize to time boundaries */

#include <QObject>
#include <QList>
#include <QByteArray>
#include <QTime>
#include <QDate>
class QTimer;

/** SynchTimer is a virtual base class for application-wide timers synchronized
 *  to a time boundary.
 *
 *  @author David Jarvie <djarvie@kde.org>
 */
class SynchTimer : public QObject
{
        Q_OBJECT
    public:
        ~SynchTimer() override;

        struct Connection
        {
            Connection() { }
            Connection(QObject* r, const char* s) : receiver(r), slot(s) { }
            bool operator==(const Connection& c) const  { return receiver == c.receiver && slot == c.slot; }
            QObject*   receiver;
            QByteArray slot;
        };
    protected:
        SynchTimer();
        virtual void        start() = 0;
        void                connecT(QObject* receiver, const char* member);
        void                disconnecT(QObject* receiver, const char* member = nullptr);
        bool                hasConnections() const   { return !mConnections.isEmpty(); }

        QTimer*             mTimer;

    protected Q_SLOTS:
        virtual void        slotTimer() = 0;

    private Q_SLOTS:
        void                slotReceiverGone(QObject* r)  { disconnecT(r); }

    private:
        SynchTimer(const SynchTimer&);   // prohibit copying
        QList<Connection>   mConnections;  // list of current clients
};


/** MinuteTimer is an application-wide timer synchronized to the minute boundary.
 *
 *  @author David Jarvie <djarvie@kde.org>
 */
class MinuteTimer : public SynchTimer
{
        Q_OBJECT
    public:
        virtual ~MinuteTimer()  { mInstance = nullptr; }
        /** Connect to the timer signal.
         *  @param receiver Receiving object.
         *  @param member Slot to activate.
         */
        static void connect(QObject* receiver, const char* member)
                           { instance()->connecT(receiver, member); }
        /** Disconnect from the timer signal.
         *  @param receiver Receiving object.
         *  @param member Slot to disconnect. If null, all slots belonging to
         *                @p receiver will be disconnected.
         */
        static void disconnect(QObject* receiver, const char* member = nullptr)
                           { if (mInstance) mInstance->disconnecT(receiver, member); }

    protected:
        MinuteTimer() : SynchTimer() { }
        static MinuteTimer* instance();
        void        start() override    { slotTimer(); }

    protected Q_SLOTS:
        void        slotTimer() override;

    private:
        static MinuteTimer* mInstance;     // the one and only instance
};


/** DailyTimer is an application-wide timer synchronized to a specified time of day, local time.
 *
 *  Daily timers come in two flavors: fixed, which can only be accessed through static methods,
 *  and variable, whose time can be adjusted and which are accessed through non-static methods.
 *
 *  @author David Jarvie <djarvie@kde.org>
 */
class DailyTimer : public SynchTimer
{
        Q_OBJECT
    public:
        ~DailyTimer() override;
        /** Connect to the timer signal which triggers at the given fixed time of day.
         *  A new timer is created if necessary.
         *  @param timeOfDay Time at which the timer is to trigger.
         *  @param receiver Receiving object.
         *  @param member Slot to activate.
         */
        static void connect(const QTime& timeOfDay, QObject* receiver, const char* member)
                           { fixedInstance(timeOfDay)->connecT(receiver, member); }
        /** Disconnect from the timer signal which triggers at the given fixed time of day.
         *  If there are no remaining connections to that timer, it is destroyed.
         *  @param timeOfDay Time at which the timer triggers.
         *  @param receiver Receiving object.
         *  @param member Slot to disconnect. If null, all slots belonging to
         *                @p receiver will be disconnected.
         */
        static void disconnect(const QTime& timeOfDay, QObject* receiver, const char* member = nullptr);
        /** Change the time at which this variable timer triggers.
         *  @param newTimeOfDay New time at which the timer should trigger.
         *  @param triggerMissed If true, and if @p newTimeOfDay < @p oldTimeOfDay, and if the current
         *                       time is between @p newTimeOfDay and @p oldTimeOfDay, the timer will be
         *                       triggered immediately so as to avoid missing today's trigger.
         */
        void changeTime(const QTime& newTimeOfDay, bool triggerMissed = true);
        /** Return the current time of day at which this variable timer triggers. */
        QTime timeOfDay() const  { return mTime; }

    protected:
        /** Construct an instance.
         *  The constructor is protected to ensure that for variable timers, only derived classes
         *  can construct instances. This ensures that multiple timers are not created for the same
         *  use.
         */
        DailyTimer(const QTime&, bool fixed);
        /** Return the instance which triggers at the specified fixed time of day,
         *  optionally creating a new instance if necessary.
         *  @param timeOfDay Time at which the timer triggers.
         *  @param create    If true, create a new instance if none already exists
         *                   for @p timeOfDay.
         *  @return The instance for @p timeOfDay, or 0 if it does not exist.
         */
        static DailyTimer* fixedInstance(const QTime& timeOfDay, bool create = true);
        void start() override;

    protected Q_SLOTS:
        void slotTimer() override;

    private:
        static QList<DailyTimer*>  mFixedTimers;   // list of timers whose trigger time is fixed
        QTime  mTime;
        QDate  mLastDate;  // the date on which the timer was last triggered
        bool   mFixed;     // the time at which the timer triggers cannot be changed
};


/** MidnightTimer is an application-wide timer synchronized to midnight, local time.
 *
 *  @author David Jarvie <djarvie@kde.org>
 */
class MidnightTimer
{
    public:
        /** Connect to the timer signal.
         *  @param receiver Receiving object.
         *  @param member Slot to activate.
         */
        static void connect(QObject* receiver, const char* member)
                           { DailyTimer::connect(QTime(0,0), receiver, member); }
        /** Disconnect from the timer signal.
         *  @param receiver Receiving object.
         *  @param member Slot to disconnect. If null, all slots belonging to
         *                @p receiver will be disconnected.
         */
        static void disconnect(QObject* receiver, const char* member = nullptr)
                           { DailyTimer::disconnect(QTime(0,0), receiver, member); }

};

#endif // SYNCHTIMER_H

// vim: et sw=4:
