/*
 * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple 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
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "core/dom/DocumentOrderedMap.h"

#include "core/HTMLNames.h"
#include "core/dom/Element.h"
#include "core/dom/ElementTraversal.h"
#include "core/dom/TreeScope.h"
#include "core/html/HTMLMapElement.h"
#include "core/html/HTMLSlotElement.h"

namespace blink {

using namespace HTMLNames;

DocumentOrderedMap* DocumentOrderedMap::create() {
  return new DocumentOrderedMap;
}

DocumentOrderedMap::DocumentOrderedMap() {}

#if DCHECK_IS_ON()
static int s_removeScopeLevel = 0;

DocumentOrderedMap::RemoveScope::RemoveScope() {
  s_removeScopeLevel++;
}

DocumentOrderedMap::RemoveScope::~RemoveScope() {
  DCHECK(s_removeScopeLevel);
  s_removeScopeLevel--;
}
#endif

inline bool keyMatchesId(const AtomicString& key, const Element& element) {
  return element.getIdAttribute() == key;
}

inline bool keyMatchesMapName(const AtomicString& key, const Element& element) {
  return isHTMLMapElement(element) &&
         toHTMLMapElement(element).getName() == key;
}

inline bool keyMatchesSlotName(const AtomicString& key,
                               const Element& element) {
  return isHTMLSlotElement(element) && toHTMLSlotElement(element).name() == key;
}

inline bool keyMatchesLowercasedMapName(const AtomicString& key,
                                        const Element& element) {
  return isHTMLMapElement(element) &&
         toHTMLMapElement(element).getName().lower() == key;
}

void DocumentOrderedMap::add(const AtomicString& key, Element* element) {
  DCHECK(key);
  DCHECK(element);

  Map::AddResult addResult = m_map.add(key, new MapEntry(element));
  if (addResult.isNewEntry)
    return;

  Member<MapEntry>& entry = addResult.storedValue->value;
  DCHECK(entry->count);
  entry->element = nullptr;
  entry->count++;
  entry->orderedList.clear();
}

void DocumentOrderedMap::remove(const AtomicString& key, Element* element) {
  DCHECK(key);
  DCHECK(element);

  Map::iterator it = m_map.find(key);
  if (it == m_map.end())
    return;

  Member<MapEntry>& entry = it->value;
  DCHECK(entry->count);
  if (entry->count == 1) {
    DCHECK(!entry->element || entry->element == element);
    m_map.remove(it);
  } else {
    if (entry->element == element) {
      DCHECK(entry->orderedList.isEmpty() ||
             entry->orderedList.front() == element);
      entry->element =
          entry->orderedList.size() > 1 ? entry->orderedList[1] : nullptr;
    }
    entry->count--;
    entry->orderedList.clear();
  }
}

template <bool keyMatches(const AtomicString&, const Element&)>
inline Element* DocumentOrderedMap::get(const AtomicString& key,
                                        const TreeScope* scope) const {
  DCHECK(key);
  DCHECK(scope);

  MapEntry* entry = m_map.get(key);
  if (!entry)
    return 0;

  DCHECK(entry->count);
  if (entry->element)
    return entry->element;

  // Iterate to find the node that matches. Nothing will match iff an element
  // with children having duplicate IDs is being removed -- the tree traversal
  // will be over an updated tree not having that subtree. In all other cases,
  // a match is expected.
  for (Element& element : ElementTraversal::startsAfter(scope->rootNode())) {
    if (!keyMatches(key, element))
      continue;
    entry->element = &element;
    return &element;
  }
// As get()/getElementById() can legitimately be called while handling element
// removals, allow failure iff we're in the scope of node removals.
#if DCHECK_IS_ON()
  DCHECK(s_removeScopeLevel);
#endif
  return 0;
}

Element* DocumentOrderedMap::getElementById(const AtomicString& key,
                                            const TreeScope* scope) const {
  return get<keyMatchesId>(key, scope);
}

const HeapVector<Member<Element>>& DocumentOrderedMap::getAllElementsById(
    const AtomicString& key,
    const TreeScope* scope) const {
  DCHECK(key);
  DCHECK(scope);
  DEFINE_STATIC_LOCAL(HeapVector<Member<Element>>, emptyVector,
                      (new HeapVector<Member<Element>>));

  Map::iterator it = m_map.find(key);
  if (it == m_map.end())
    return emptyVector;

  Member<MapEntry>& entry = it->value;
  DCHECK(entry->count);

  if (entry->orderedList.isEmpty()) {
    entry->orderedList.reserveCapacity(entry->count);
    for (Element* element =
             entry->element ? entry->element.get()
                            : ElementTraversal::firstWithin(scope->rootNode());
         entry->orderedList.size() < entry->count;
         element = ElementTraversal::next(*element)) {
      DCHECK(element);
      if (!keyMatchesId(key, *element))
        continue;
      entry->orderedList.uncheckedAppend(element);
    }
    if (!entry->element)
      entry->element = entry->orderedList.front();
  }

  return entry->orderedList;
}

Element* DocumentOrderedMap::getElementByMapName(const AtomicString& key,
                                                 const TreeScope* scope) const {
  return get<keyMatchesMapName>(key, scope);
}

// TODO(hayato): Template get<> by return type.
HTMLSlotElement* DocumentOrderedMap::getSlotByName(
    const AtomicString& key,
    const TreeScope* scope) const {
  if (Element* slot = get<keyMatchesSlotName>(key, scope)) {
    DCHECK(isHTMLSlotElement(slot));
    return toHTMLSlotElement(slot);
  }
  return nullptr;
}

Element* DocumentOrderedMap::getElementByLowercasedMapName(
    const AtomicString& key,
    const TreeScope* scope) const {
  return get<keyMatchesLowercasedMapName>(key, scope);
}

DEFINE_TRACE(DocumentOrderedMap) {
  visitor->trace(m_map);
}

DEFINE_TRACE(DocumentOrderedMap::MapEntry) {
  visitor->trace(element);
  visitor->trace(orderedList);
}

}  // namespace blink