/* -*- 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 MOZILLA_DOMSVGLENGTH_H__

#define MOZILLA_DOMSVGLENGTH_H__

#include "DOMSVGLengthList.h"

#include "nsCycleCollectionParticipant.h"

#include "nsDebug.h"

#include "nsTArray.h"

#include "SVGLength.h"

#include "mozilla/Attributes.h"

#include "nsWrapperCache.h"

class nsSVGElement;

// We make DOMSVGLength a pseudo-interface to allow us to QI to it in order to

// check that the objects that scripts pass to DOMSVGLengthList methods are our

// *native* length objects.

//

// {A8468350-7F7B-4976-9A7E-3765A1DADF9A}

#define MOZILLA_DOMSVGLENGTH_IID \

  { 0xA8468350, 0x7F7B, 0x4976, { 0x9A, 0x7E, 0x37, 0x65, 0xA1, 0xDA, 0xDF, 0x9A } }

#define MOZ_SVG_LIST_INDEX_BIT_COUNT 22 // supports > 4 million list items

namespace mozilla {

class ErrorResult;

/**

 * Class DOMSVGLength

 *

 * This class creates the DOM objects that wrap internal SVGLength objects that

 * are in an SVGLengthList. It is also used to create the objects returned by

 * SVGSVGElement.createSVGLength().

 *

 * For the DOM wrapper classes for non-list SVGLength, see nsSVGLength2.h.

 *

 * See the architecture comment in DOMSVGAnimatedLengthList.h.

 *

 * This class is strongly intertwined with DOMSVGAnimatedLengthList and

 * DOMSVGLengthList. We are a friend of DOMSVGLengthList, and are responsible

 * for nulling out our DOMSVGLengthList's pointer to us when we die, making it

 * a real weak pointer.

 *

 * When objects of this type are in a DOMSVGLengthList they belong to an

 * attribute. While they belong to an attribute, the objects' values come from

 * their corresponding internal SVGLength objects in the internal SVGLengthList

 * objects for the attribute. Getting and setting values of a DOMSVGLength

 * requires reading and writing to its internal SVGLength. However, if the

 * DOMSVGLength is detached from its DOMSVGLengthList then it first makes a

 * copy of its internal SVGLength's value and unit so that it doesn't appear to

 * "lose" its value from script's perspective on being removed from the list.

 * This means that these DOM tearoffs have space to store these values, even

 * though they're not used in the common case.

 *

 * Objects of this type are also used to reflect the baseVal and animVal of

 * a single, non-list SVGLength attribute. Getting and settings values of the

 * DOMSVGLength in this case requires reading and writing to the corresponding

 * nsSVGLength2 object.

 *

 * This class also stores its current list index, attribute enum, and whether

 * it belongs to a baseVal or animVal list. This is so that objects of this

 * type can find their corresponding internal SVGLength.

 *

 * To use these classes for <length> attributes as well as <list-of-length>

 * attributes, we would need to take a bit from mListIndex and use that to

 * indicate whether the object belongs to a list or non-list attribute, then

 * if-else as appropriate. The bug for doing that work is:

 * https://bugzilla.mozilla.org/show_bug.cgi?id=571734

 */

class DOMSVGLength final : public nsISupports,

                           public nsWrapperCache

{

  friend class AutoChangeLengthNotifier;

  /**

   * Ctor for creating the object returned by nsSVGLength2::ToDOMBaseVal/ToDOMAnimVal

   */

  DOMSVGLength(nsSVGLength2* aVal, nsSVGElement* aSVGElement, bool aAnimVal);

  ~DOMSVGLength();

public:

  NS_DECLARE_STATIC_IID_ACCESSOR(MOZILLA_DOMSVGLENGTH_IID)

  NS_DECL_CYCLE_COLLECTING_ISUPPORTS

  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMSVGLength)

  /**

   * Generic ctor for DOMSVGLength objects that are created for an attribute.

   */

  DOMSVGLength(DOMSVGLengthList *aList,

               uint8_t aAttrEnum,

               uint32_t aListIndex,

               bool aIsAnimValItem);

  /**

   * Ctor for creating the objects returned by SVGSVGElement.createSVGLength(),

   * which do not initially belong to an attribute.

   */

  DOMSVGLength();

  static already_AddRefed<DOMSVGLength> GetTearOff(nsSVGLength2* aVal,

                                                   nsSVGElement* aSVGElement,

                                                   bool aAnimVal);

  /**

   * Create an unowned copy of a length that is owned or is reflecting a single

   * attribute. The caller is responsible for the first AddRef().

   */

  DOMSVGLength* Copy();

  bool IsInList() const {

    return !!mList;

  }

  /**

   * In future, if this class is used for non-list lengths, this will be

   * different to IsInList().

   */

  bool HasOwner() const {

    return !!mList;

  }

  /**

   * Returns whether this length object is reflecting a single SVG element

   * attribute.  This includes the baseVal or animVal of SVGRectElement.x, for

   * example, but not an item in an SVGLengthList, such as those in the

   * baseVal or animVal of SVGTextElement.x.

   */

  bool IsReflectingAttribute() const {

    return mVal;

  }

  /**

   * This method is called to notify this DOM object that it is being inserted

   * into a list, and give it the information it needs as a result.

   *

   * This object MUST NOT already belong to a list when this method is called.

   * That's not to say that script can't move these DOM objects between

   * lists - it can - it's just that the logic to handle that (and send out

   * the necessary notifications) is located elsewhere (in DOMSVGLengthList).)

   */

  void InsertingIntoList(DOMSVGLengthList *aList,

                         uint8_t aAttrEnum,

                         uint32_t aListIndex,

                         bool aIsAnimValItem);

  static uint32_t MaxListIndex() {

    return (1U << MOZ_SVG_LIST_INDEX_BIT_COUNT) - 1;

  }

  /// This method is called to notify this object that its list index changed.

  void UpdateListIndex(uint32_t aListIndex) {

    mListIndex = aListIndex;

  }

  /**

   * This method is called to notify this DOM object that it is about to be

   * removed from its current DOM list so that it can first make a copy of its

   * internal counterpart's values. (If it didn't do this, then it would

   * "lose" its value on being removed.)

   */

  void RemovingFromList();

  SVGLength ToSVGLength();

  // WebIDL

  uint16_t UnitType();

  float GetValue(ErrorResult& aRv);

  void SetValue(float aValue, ErrorResult& aRv);

  float ValueInSpecifiedUnits();

  void SetValueInSpecifiedUnits(float aValue, ErrorResult& aRv);

  void GetValueAsString(nsAString& aValue);

  void SetValueAsString(const nsAString& aValue, ErrorResult& aRv);

  void NewValueSpecifiedUnits(uint16_t aUnit, float aValue,

                              ErrorResult& aRv);

  void ConvertToSpecifiedUnits(uint16_t aUnit, ErrorResult& aRv);

  nsISupports* GetParentObject() const {

    auto svgElement = mList ? Element() : mSVGElement.get();

    return svgElement;

  }

  JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;

private:

  nsSVGElement* Element() const {

    return mList->Element();

  }

  uint8_t AttrEnum() const {

    return mAttrEnum;

  }

  /**

   * Get the axis that this length lies along. This method must only be called

   * when this object is associated with an element (HasOwner() returns true).

   */

  uint8_t Axis() const {

    return mList->Axis();

  }

  /**

   * Get a reference to the internal SVGLength list item that this DOM wrapper

   * object currently wraps.

   *

   * To simplify the code we just have this one method for obtaining both

   * baseVal and animVal internal items. This means that animVal items don't

   * get const protection, but then our setter methods guard against changing

   * animVal items.

   */

  SVGLength& InternalItem();

#ifdef DEBUG

  bool IndexIsValid();

#endif

  /**

   * Clears soon-to-be-invalid weak references in external objects that were

   * set up during the creation of this object. This should be called during

   * destruction and during cycle collection.

   */

  void CleanupWeakRefs();

  RefPtr<DOMSVGLengthList> mList;

  // Bounds for the following are checked in the ctor, so be sure to update

  // that if you change the capacity of any of the following.

  uint32_t mListIndex:MOZ_SVG_LIST_INDEX_BIT_COUNT;

  uint32_t mAttrEnum:4; // supports up to 16 attributes

  uint32_t mIsAnimValItem:1;

  // The following members are only used when we're not in a list:

  uint32_t mUnit:5; // can handle 31 units (the 10 SVG 1.1 units + rem, vw, vh, wm, calc + future additions)

  float mValue;

  // The following members are only used when we have an nsSVGLength2

  nsSVGLength2* mVal; // kept alive because it belongs to mSVGElement

  RefPtr<nsSVGElement> mSVGElement;

};

NS_DEFINE_STATIC_IID_ACCESSOR(DOMSVGLength, MOZILLA_DOMSVGLENGTH_IID)

} // namespace mozilla

#undef MOZ_SVG_LIST_INDEX_BIT_COUNT

#endif // MOZILLA_DOMSVGLENGTH_H__