/*
 * barrier -- mouse and keyboard sharing utility
 * Copyright (C) 2012-2016 Symless Ltd.
 * Copyright (C) 2004 Chris Schoeneman
 *
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file LICENSE that should have accompanied this file.
 *
 * This package 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, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include "common/IInterface.h"
#include "common/basic_types.h"

class Event;
class EventQueueTimer;

//! Event queue buffer interface
/*!
An event queue buffer provides a queue of events for an IEventQueue.
*/
class IEventQueueBuffer : public IInterface {
public:
    enum Type {
        kNone,        //!< No event is available
        kSystem,    //!< Event is a system event
        kUser        //!< Event is a user event
    };

    //! @name manipulators
    //@{

    //! Initialize
    /*!
    Useful for platform-specific initialisation from a specific thread.
    */
    virtual    void        init() = 0;

    //! Block waiting for an event
    /*!
    Wait for an event in the event queue buffer for up to \p timeout
    seconds.
    */
    virtual void        waitForEvent(double timeout) = 0;

    //! Get the next event
    /*!
    Get the next event from the buffer.  Return kNone if no event is
    available.  If a system event is next, return kSystem and fill in
    event.  The event data in a system event can point to a static
    buffer (because Event::deleteData() will not attempt to delete
    data in a kSystem event).  Otherwise, return kUser and fill in
    \p dataID with the value passed to \c addEvent().
    */
    virtual Type        getEvent(Event& event, UInt32& dataID) = 0;

    //! Post an event
    /*!
    Add the given event to the end of the queue buffer.  This is a user
    event and \c getEvent() must be able to identify it as such and
    return \p dataID.  This method must cause \c waitForEvent() to
    return at some future time if it's blocked waiting on an event.
    */
    virtual bool        addEvent(UInt32 dataID) = 0;

    //@}
    //! @name accessors
    //@{

    //! Check if event queue buffer is empty
    /*!
    Return true iff the event queue buffer  is empty.
    */
    virtual bool        isEmpty() const = 0;

    //! Create a timer object
    /*!
    Create and return a timer object.  The object is opaque and is
    used only by the buffer but it must be a valid object (i.e.
    not NULL).
    */
    virtual EventQueueTimer*
                        newTimer(double duration, bool oneShot) const = 0;

    //! Destroy a timer object
    /*!
    Destroy a timer object previously returned by \c newTimer().
    */
    virtual void        deleteTimer(EventQueueTimer*) const = 0;

    //@}
};
