/*
 * Copyright (C) 2010 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:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY GOOGLE INC. ``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 GOOGLE INC. 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/html/parser/HTMLFormattingElementList.h"

#ifndef NDEBUG
#include <stdio.h>
#endif

namespace blink {

// Biblically, Noah's Ark only had room for two of each animal, but in the
// Book of Hixie (aka
// http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#list-of-active-formatting-elements),
// Noah's Ark of Formatting Elements can fit three of each element.
static const size_t kNoahsArkCapacity = 3;

HTMLFormattingElementList::HTMLFormattingElementList() {}

HTMLFormattingElementList::~HTMLFormattingElementList() {}

Element* HTMLFormattingElementList::closestElementInScopeWithName(
    const AtomicString& targetName) {
  for (unsigned i = 1; i <= m_entries.size(); ++i) {
    const Entry& entry = m_entries[m_entries.size() - i];
    if (entry.isMarker())
      return nullptr;
    if (entry.stackItem()->matchesHTMLTag(targetName))
      return entry.element();
  }
  return nullptr;
}

bool HTMLFormattingElementList::contains(Element* element) {
  return !!find(element);
}

HTMLFormattingElementList::Entry* HTMLFormattingElementList::find(
    Element* element) {
  size_t index = m_entries.reverseFind(element);
  if (index != kNotFound) {
    // This is somewhat of a hack, and is why this method can't be const.
    return &m_entries[index];
  }
  return nullptr;
}

HTMLFormattingElementList::Bookmark HTMLFormattingElementList::bookmarkFor(
    Element* element) {
  size_t index = m_entries.reverseFind(element);
  ASSERT(index != kNotFound);
  return Bookmark(&at(index));
}

void HTMLFormattingElementList::swapTo(Element* oldElement,
                                       HTMLStackItem* newItem,
                                       const Bookmark& bookmark) {
  ASSERT(contains(oldElement));
  ASSERT(!contains(newItem->element()));
  if (!bookmark.hasBeenMoved()) {
    ASSERT(bookmark.mark()->element() == oldElement);
    bookmark.mark()->replaceElement(newItem);
    return;
  }
  size_t index = bookmark.mark() - first();
  ASSERT_WITH_SECURITY_IMPLICATION(index < size());
  m_entries.insert(index + 1, newItem);
  remove(oldElement);
}

void HTMLFormattingElementList::append(HTMLStackItem* item) {
  ensureNoahsArkCondition(item);
  m_entries.append(item);
}

void HTMLFormattingElementList::remove(Element* element) {
  size_t index = m_entries.reverseFind(element);
  if (index != kNotFound)
    m_entries.remove(index);
}

void HTMLFormattingElementList::appendMarker() {
  m_entries.append(Entry::MarkerEntry);
}

void HTMLFormattingElementList::clearToLastMarker() {
  // http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#clear-the-list-of-active-formatting-elements-up-to-the-last-marker
  while (m_entries.size()) {
    bool shouldStop = m_entries.last().isMarker();
    m_entries.removeLast();
    if (shouldStop)
      break;
  }
}

void HTMLFormattingElementList::tryToEnsureNoahsArkConditionQuickly(
    HTMLStackItem* newItem,
    HeapVector<Member<HTMLStackItem>>& remainingCandidates) {
  ASSERT(remainingCandidates.isEmpty());

  if (m_entries.size() < kNoahsArkCapacity)
    return;

  // Use a vector with inline capacity to avoid a malloc in the common case of a
  // quickly ensuring the condition.
  HeapVector<Member<HTMLStackItem>, 10> candidates;

  size_t newItemAttributeCount = newItem->attributes().size();

  for (size_t i = m_entries.size(); i;) {
    --i;
    Entry& entry = m_entries[i];
    if (entry.isMarker())
      break;

    // Quickly reject obviously non-matching candidates.
    HTMLStackItem* candidate = entry.stackItem();
    if (newItem->localName() != candidate->localName() ||
        newItem->namespaceURI() != candidate->namespaceURI())
      continue;
    if (candidate->attributes().size() != newItemAttributeCount)
      continue;

    candidates.append(candidate);
  }

  // There's room for the new element in the ark. There's no need to copy out
  // the remainingCandidates.
  if (candidates.size() < kNoahsArkCapacity)
    return;

  remainingCandidates.appendVector(candidates);
}

void HTMLFormattingElementList::ensureNoahsArkCondition(
    HTMLStackItem* newItem) {
  HeapVector<Member<HTMLStackItem>> candidates;
  tryToEnsureNoahsArkConditionQuickly(newItem, candidates);
  if (candidates.isEmpty())
    return;

  // We pre-allocate and re-use this second vector to save one malloc per
  // attribute that we verify.
  HeapVector<Member<HTMLStackItem>> remainingCandidates;
  remainingCandidates.reserveInitialCapacity(candidates.size());

  const Vector<Attribute>& attributes = newItem->attributes();
  for (size_t i = 0; i < attributes.size(); ++i) {
    const Attribute& attribute = attributes[i];

    for (size_t j = 0; j < candidates.size(); ++j) {
      HTMLStackItem* candidate = candidates[j];

      // These properties should already have been checked by
      // tryToEnsureNoahsArkConditionQuickly.
      ASSERT(newItem->attributes().size() == candidate->attributes().size());
      ASSERT(newItem->localName() == candidate->localName() &&
             newItem->namespaceURI() == candidate->namespaceURI());

      Attribute* candidateAttribute =
          candidate->getAttributeItem(attribute.name());
      if (candidateAttribute &&
          candidateAttribute->value() == attribute.value())
        remainingCandidates.append(candidate);
    }

    if (remainingCandidates.size() < kNoahsArkCapacity)
      return;

    candidates.swap(remainingCandidates);
    remainingCandidates.shrink(0);
  }

  // Inductively, we shouldn't spin this loop very many times. It's possible,
  // however, that we wil spin the loop more than once because of how the
  // formatting element list gets permuted.
  for (size_t i = kNoahsArkCapacity - 1; i < candidates.size(); ++i)
    remove(candidates[i]->element());
}

#ifndef NDEBUG

void HTMLFormattingElementList::show() {
  for (unsigned i = 1; i <= m_entries.size(); ++i) {
    const Entry& entry = m_entries[m_entries.size() - i];
    if (entry.isMarker())
      LOG(INFO) << "marker";
    else
      LOG(INFO) << *entry.element();
  }
}

#endif

}  // namespace blink