/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "core/dom/ChildListMutationScope.h"

#include "core/dom/MutationObserverInterestGroup.h"
#include "core/dom/MutationRecord.h"
#include "core/dom/StaticNodeList.h"
#include "wtf/HashMap.h"
#include "wtf/StdLibExtras.h"

namespace blink {

// The accumulator map is used to make sure that there is only one mutation
// accumulator for a given node even if there are multiple
// ChildListMutationScopes on the stack. The map is always empty when there are
// no ChildListMutationScopes on the stack.
typedef HeapHashMap<Member<Node>, Member<ChildListMutationAccumulator>>
    AccumulatorMap;

static AccumulatorMap& accumulatorMap() {
  DEFINE_STATIC_LOCAL(AccumulatorMap, map, (new AccumulatorMap));
  return map;
}

ChildListMutationAccumulator::ChildListMutationAccumulator(
    Node* target,
    MutationObserverInterestGroup* observers)
    : m_target(target),
      m_lastAdded(nullptr),
      m_observers(observers),
      m_mutationScopes(0) {}

void ChildListMutationAccumulator::leaveMutationScope() {
  DCHECK_GT(m_mutationScopes, 0u);
  if (!--m_mutationScopes) {
    if (!isEmpty())
      enqueueMutationRecord();
    accumulatorMap().remove(m_target.get());
  }
}

ChildListMutationAccumulator* ChildListMutationAccumulator::getOrCreate(
    Node& target) {
  AccumulatorMap::AddResult result = accumulatorMap().add(&target, nullptr);
  ChildListMutationAccumulator* accumulator;
  if (!result.isNewEntry) {
    accumulator = result.storedValue->value;
  } else {
    accumulator = new ChildListMutationAccumulator(
        &target,
        MutationObserverInterestGroup::createForChildListMutation(target));
    result.storedValue->value = accumulator;
  }
  return accumulator;
}

inline bool ChildListMutationAccumulator::isAddedNodeInOrder(Node* child) {
  return isEmpty() || (m_lastAdded == child->previousSibling() &&
                       m_nextSibling == child->nextSibling());
}

void ChildListMutationAccumulator::childAdded(Node* child) {
  DCHECK(hasObservers());

  if (!isAddedNodeInOrder(child))
    enqueueMutationRecord();

  if (isEmpty()) {
    m_previousSibling = child->previousSibling();
    m_nextSibling = child->nextSibling();
  }

  m_lastAdded = child;
  m_addedNodes.append(child);
}

inline bool ChildListMutationAccumulator::isRemovedNodeInOrder(Node* child) {
  return isEmpty() || m_nextSibling == child;
}

void ChildListMutationAccumulator::willRemoveChild(Node* child) {
  DCHECK(hasObservers());

  if (!m_addedNodes.isEmpty() || !isRemovedNodeInOrder(child))
    enqueueMutationRecord();

  if (isEmpty()) {
    m_previousSibling = child->previousSibling();
    m_nextSibling = child->nextSibling();
    m_lastAdded = child->previousSibling();
  } else {
    m_nextSibling = child->nextSibling();
  }

  m_removedNodes.append(child);
}

void ChildListMutationAccumulator::enqueueMutationRecord() {
  DCHECK(hasObservers());
  DCHECK(!isEmpty());

  StaticNodeList* addedNodes = StaticNodeList::adopt(m_addedNodes);
  StaticNodeList* removedNodes = StaticNodeList::adopt(m_removedNodes);
  MutationRecord* record = MutationRecord::createChildList(
      m_target, addedNodes, removedNodes, m_previousSibling.release(),
      m_nextSibling.release());
  m_observers->enqueueMutationRecord(record);
  m_lastAdded = nullptr;
  DCHECK(isEmpty());
}

bool ChildListMutationAccumulator::isEmpty() {
  bool result = m_removedNodes.isEmpty() && m_addedNodes.isEmpty();
#if DCHECK_IS_ON()
  if (result) {
    DCHECK(!m_previousSibling);
    DCHECK(!m_nextSibling);
    DCHECK(!m_lastAdded);
  }
#endif
  return result;
}

DEFINE_TRACE(ChildListMutationAccumulator) {
  visitor->trace(m_target);
  visitor->trace(m_removedNodes);
  visitor->trace(m_addedNodes);
  visitor->trace(m_previousSibling);
  visitor->trace(m_nextSibling);
  visitor->trace(m_lastAdded);
  visitor->trace(m_observers);
}

}  // namespace blink