/*
 * Copyright (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
 * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 *
 * 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.
 *
 */

#ifndef LayoutCounter_h
#define LayoutCounter_h

#include "core/layout/LayoutText.h"
#include "core/style/CounterContent.h"

namespace blink {

class CounterNode;

// LayoutCounter is used to represent the text of a counter.
// See http://www.w3.org/TR/CSS21/generate.html#counters
//
// Counters are always generated content ("content: counter(a)") thus this
// LayoutObject is always anonymous.
//
// CounterNodes is where the logic for knowing the value of a counter is.
// LayoutCounter makes sure the CounterNodes tree is consistent with the
// style. It then just queries CounterNodes for their values.
//
// CounterNodes are rare so they are stored in a map instead of growing
// LayoutObject. counterMaps() (in LayoutCounter.cpp) keeps the association
// between LayoutObject and CounterNodes. To avoid unneeded hash-lookups in the
// common case where there is no CounterNode, LayoutObject also keeps track of
// whether it has at least one CounterNode in the hasCounterNodeMap bit.
//
// Keeping the map up-to-date is the reason why LayoutObjects need to call into
// LayoutCounter during their lifetime (see the static functions below).
class LayoutCounter final : public LayoutText {
public:
    LayoutCounter(Document*, const CounterContent&);
    ~LayoutCounter() override;

    // These functions are static so that any LayoutObject can call them.
    // The reason is that any LayoutObject in the tree can have a CounterNode
    // without a LayoutCounter (e.g. by specifying 'counter-increment' without
    // a "content: counter(a)" directive)).
    static void destroyCounterNodes(LayoutObject&);
    static void destroyCounterNode(LayoutObject&, const AtomicString& identifier);
    static void layoutObjectSubtreeAttached(LayoutObject*);
    static void layoutObjectSubtreeWillBeDetached(LayoutObject*);
    static void layoutObjectStyleChanged(LayoutObject&, const ComputedStyle* oldStyle, const ComputedStyle& newStyle);

    void updateCounter();

    const char* name() const override { return "LayoutCounter"; }

protected:
    void willBeDestroyed() override;

private:
    bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectCounter || LayoutText::isOfType(type); }
    PassRefPtr<StringImpl> originalText() const override;

    // Removes the reference to the CounterNode associated with this layoutObject.
    // This is used to cause a counter display update when the CounterNode tree changes.
    void invalidate();

    CounterContent m_counter;
    CounterNode* m_counterNode;
    LayoutCounter* m_nextForSameCounter;
    friend class CounterNode;
};

DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutCounter, isCounter());

} // namespace blink

#ifndef NDEBUG
// Outside the WebCore namespace for ease of invocation from gdb.
void showCounterLayoutTree(const blink::LayoutObject*, const char* counterName = nullptr);
#endif

#endif // LayoutCounter_h