/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef NS_SMILINSTANCETIME_H_

#define NS_SMILINSTANCETIME_H_

#include "nsSMILTimeValue.h"

class nsSMILInterval;

class nsSMILTimeContainer;

class nsSMILTimeValueSpec;

//----------------------------------------------------------------------

// nsSMILInstanceTime

//

// An instant in document simple time that may be used in creating a new

// interval.

//

// For an overview of how this class is related to other SMIL time classes see

// the documentation in nsSMILTimeValue.h

//

// These objects are owned by an nsSMILTimedElement but MAY also be referenced

// by:

//

// a) nsSMILIntervals that belong to the same nsSMILTimedElement and which refer

//    to the nsSMILInstanceTimes which form the interval endpoints; and/or

// b) nsSMILIntervals that belong to other nsSMILTimedElements but which need to

//    update dependent instance times when they change or are deleted.

//    E.g. for begin='a.begin', 'a' needs to inform dependent

//    nsSMILInstanceTimes if its begin time changes. This notification is

//    performed by the nsSMILInterval.

class nsSMILInstanceTime final

{

public:

  // Instance time source. Times generated by events, syncbase relationships,

  // and DOM calls behave differently in some circumstances such as when a timed

  // element is reset.

  enum nsSMILInstanceTimeSource {

    // No particularly significant source, e.g. offset time, 'indefinite'

    SOURCE_NONE,

    // Generated by a DOM call such as beginElement

    SOURCE_DOM,

    // Generated by a syncbase relationship

    SOURCE_SYNCBASE,

    // Generated by an event

    SOURCE_EVENT

  };

  explicit nsSMILInstanceTime(const nsSMILTimeValue& aTime,

                              nsSMILInstanceTimeSource aSource = SOURCE_NONE,

                              nsSMILTimeValueSpec* aCreator = nullptr,

                              nsSMILInterval* aBaseInterval = nullptr);

  void Unlink();

  void HandleChangedInterval(const nsSMILTimeContainer* aSrcContainer,

                             bool aBeginObjectChanged,

                             bool aEndObjectChanged);

  void HandleDeletedInterval();

  void HandleFilteredInterval();

  const nsSMILTimeValue& Time() const { return mTime; }

  const nsSMILTimeValueSpec* GetCreator() const { return mCreator; }

  bool IsDynamic() const { return !!(mFlags & kDynamic); }

  bool IsFixedTime() const { return !(mFlags & kMayUpdate); }

  bool FromDOM() const { return !!(mFlags & kFromDOM); }

  bool ShouldPreserve() const;

  void   UnmarkShouldPreserve();

  void AddRefFixedEndpoint();

  void ReleaseFixedEndpoint();

  void DependentUpdate(const nsSMILTimeValue& aNewTime)

  {

    MOZ_ASSERT(!IsFixedTime(),

               "Updating an instance time that is not expected to be updated");

    mTime = aNewTime;

  }

  bool IsDependent() const { return !!mBaseInterval; }

  bool IsDependentOn(const nsSMILInstanceTime& aOther) const;

  const nsSMILInterval* GetBaseInterval() const { return mBaseInterval; }

  const nsSMILInstanceTime* GetBaseTime() const;

  bool SameTimeAndBase(const nsSMILInstanceTime& aOther) const

  {

    return mTime == aOther.mTime && GetBaseTime() == aOther.GetBaseTime();

  }

  // Get and set a serial number which may be used by a containing class to

  // control the sort order of otherwise similar instance times.

  uint32_t Serial() const { return mSerial; }

  void SetSerial(uint32_t aIndex) { mSerial = aIndex; }

  NS_INLINE_DECL_REFCOUNTING(nsSMILInstanceTime)

private:

  // Private destructor, to discourage deletion outside of Release():

  ~nsSMILInstanceTime();

  void SetBaseInterval(nsSMILInterval* aBaseInterval);

  nsSMILTimeValue mTime;

  // Internal flags used to represent the behaviour of different instance times

  enum {

    // Indicates that this instance time was generated by an event or a DOM

    // call. Such instance times require special handling when (i) the owning

    // element is reset, (ii) when they are to be added as a new end instance

    // times (as per SMIL's event sensitivity contraints), and (iii) when

    // a backwards seek is performed and the timing model is reconstructed.

    kDynamic = 1,

    // Indicates that this instance time is referred to by an

    // nsSMILTimeValueSpec and as such may be updated. Such instance time should

    // not be filtered out by the nsSMILTimedElement even if they appear to be

    // in the past as they may be updated to a future time.

    kMayUpdate = 2,

    // Indicates that this instance time was generated from the DOM as opposed

    // to an nsSMILTimeValueSpec. When a 'begin' or 'end' attribute is set or

    // reset we should clear all the instance times that have been generated by

    // that attribute (and hence an nsSMILTimeValueSpec), but not those from the

    // DOM.

    kFromDOM = 4,

    // Indicates that this instance time was used as the endpoint of an interval

    // that has been filtered or removed. However, since it is a dynamic time it

    // should be preserved and not filtered.

    kWasDynamicEndpoint = 8

  };

  uint8_t       mFlags;   // Combination of kDynamic, kMayUpdate, etc.

  mutable bool  mVisited; // Cycle tracking

  // Additional reference count to determine if this instance time is currently

  // used as a fixed endpoint in any intervals. Instance times that are used in

  // this way should not be removed when the owning nsSMILTimedElement removes

  // instance times in response to a restart or in an attempt to free up memory

  // by filtering out old instance times.

  //

  // Instance times are only shared in a few cases, namely:

  // a) early ends,

  // b) zero-duration intervals,

  // c) momentarily whilst establishing new intervals and updating the current

  //    interval, and

  // d) trimmed intervals

  // Hence the limited range of a uint16_t should be more than adequate.

  uint16_t      mFixedEndpointRefCnt;

  uint32_t      mSerial; // A serial number used by the containing class to

                         // specify the sort order for instance times with the

                         // same mTime.

  nsSMILTimeValueSpec* mCreator; // The nsSMILTimeValueSpec object that created

                                 // us. (currently only needed for syncbase

                                 // instance times.)

  nsSMILInterval* mBaseInterval; // Interval from which this time is derived

                                 // (only used for syncbase instance times)

};

#endif // NS_SMILINSTANCETIME_H_