/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2001 Dirk Mueller (mueller@kde.org)
 *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
 * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All
 * rights reserved.
 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
 * (http://www.torchmobile.com/)
 * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
 * Copyright (C) 2013 Google 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.
 */

#include "core/dom/TreeScopeStyleSheetCollection.h"

#include "core/css/CSSStyleSheet.h"
#include "core/css/StyleRuleImport.h"
#include "core/css/StyleSheetContents.h"
#include "core/css/invalidation/StyleSheetInvalidationAnalysis.h"
#include "core/css/resolver/StyleResolver.h"
#include "core/dom/Element.h"
#include "core/dom/StyleEngine.h"
#include "core/html/HTMLLinkElement.h"
#include "core/html/HTMLStyleElement.h"

namespace blink {

TreeScopeStyleSheetCollection::TreeScopeStyleSheetCollection(
    TreeScope& treeScope)
    : m_treeScope(treeScope), m_hadActiveLoadingStylesheet(false) {}

void TreeScopeStyleSheetCollection::addStyleSheetCandidateNode(Node& node) {
  if (!node.isConnected())
    return;

  m_styleSheetCandidateNodes.add(&node);
}

TreeScopeStyleSheetCollection::StyleResolverUpdateType
TreeScopeStyleSheetCollection::compareStyleSheets(
    const HeapVector<Member<CSSStyleSheet>>& oldStyleSheets,
    const HeapVector<Member<CSSStyleSheet>>& newStylesheets,
    HeapVector<Member<StyleSheetContents>>& addedSheets) {
  unsigned newStyleSheetCount = newStylesheets.size();
  unsigned oldStyleSheetCount = oldStyleSheets.size();
  DCHECK_GE(newStyleSheetCount, oldStyleSheetCount);

  if (!newStyleSheetCount)
    return Reconstruct;

  unsigned newIndex = 0;
  for (unsigned oldIndex = 0; oldIndex < oldStyleSheetCount; ++oldIndex) {
    while (oldStyleSheets[oldIndex] != newStylesheets[newIndex]) {
      addedSheets.append(newStylesheets[newIndex]->contents());
      if (++newIndex == newStyleSheetCount)
        return Reconstruct;
    }
    if (++newIndex == newStyleSheetCount)
      return Reconstruct;
  }
  bool hasInsertions = !addedSheets.isEmpty();
  while (newIndex < newStyleSheetCount) {
    addedSheets.append(newStylesheets[newIndex]->contents());
    ++newIndex;
  }
  // If all new sheets were added at the end of the list we can just add them to
  // existing StyleResolver.  If there were insertions we need to re-add all the
  // stylesheets so rules are ordered correctly.
  return hasInsertions ? Reset : Additive;
}

bool TreeScopeStyleSheetCollection::activeLoadingStyleSheetLoaded(
    const HeapVector<Member<CSSStyleSheet>>& newStyleSheets) {
  // StyleSheets of <style> elements that @import stylesheets are active but
  // loading. We need to trigger a full recalc when such loads are done.
  bool hasActiveLoadingStylesheet = false;
  for (const auto& sheet : newStyleSheets) {
    if (sheet->isLoading())
      hasActiveLoadingStylesheet = true;
  }
  if (m_hadActiveLoadingStylesheet && !hasActiveLoadingStylesheet) {
    m_hadActiveLoadingStylesheet = false;
    return true;
  }
  m_hadActiveLoadingStylesheet = hasActiveLoadingStylesheet;
  return false;
}

static bool findFontFaceRulesFromStyleSheetContents(
    const HeapVector<Member<StyleSheetContents>>& sheets,
    HeapVector<Member<const StyleRuleFontFace>>& fontFaceRules) {
  bool hasFontFaceRule = false;

  for (const auto& sheet : sheets) {
    DCHECK(sheet);
    if (sheet->hasFontFaceRule()) {
      // FIXME: We don't need this for styles in shadow tree.
      sheet->findFontFaceRules(fontFaceRules);
      hasFontFaceRule = true;
    }
  }
  return hasFontFaceRule;
}

void TreeScopeStyleSheetCollection::analyzeStyleSheetChange(
    StyleResolverUpdateMode updateMode,
    const HeapVector<Member<CSSStyleSheet>>& newActiveAuthorStyleSheets,
    StyleSheetChange& change) {
  if (activeLoadingStyleSheetLoaded(newActiveAuthorStyleSheets))
    return;

  if (updateMode != AnalyzedStyleUpdate)
    return;

  // Find out which stylesheets are new.
  HeapVector<Member<StyleSheetContents>> addedSheets;
  if (m_activeAuthorStyleSheets.size() <= newActiveAuthorStyleSheets.size()) {
    change.styleResolverUpdateType = compareStyleSheets(
        m_activeAuthorStyleSheets, newActiveAuthorStyleSheets, addedSheets);
  } else {
    StyleResolverUpdateType updateType = compareStyleSheets(
        newActiveAuthorStyleSheets, m_activeAuthorStyleSheets, addedSheets);
    if (updateType != Additive) {
      change.styleResolverUpdateType = updateType;
    } else {
      change.styleResolverUpdateType = Reset;
      // If @font-face is removed, needs full style recalc.
      if (findFontFaceRulesFromStyleSheetContents(addedSheets,
                                                  change.fontFaceRulesToRemove))
        return;
    }
  }

  // FIXME: If styleResolverUpdateType is Reconstruct, we should return early
  // here since we need to recalc the whole document. It's wrong to use
  // StyleSheetInvalidationAnalysis since it only looks at the addedSheets.

  // No point in doing the analysis work if we're just going to recalc the whole
  // document anyways.  This needs to be done after the compareStyleSheets calls
  // above to ensure we don't throw away the StyleResolver if we don't need to.
  if (document().hasPendingForcedStyleRecalc())
    return;

  // If we are already parsing the body and so may have significant amount of
  // elements, put some effort into trying to avoid style recalcs.
  if (!document().body() || document().hasNodesWithPlaceholderStyle())
    return;
  StyleSheetInvalidationAnalysis invalidationAnalysis(*m_treeScope,
                                                      addedSheets);
  if (invalidationAnalysis.dirtiesAllStyle())
    return;
  invalidationAnalysis.invalidateStyle();
  change.requiresFullStyleRecalc = false;
  return;
}

void TreeScopeStyleSheetCollection::clearMediaQueryRuleSetStyleSheets() {
  for (const auto& sheet : m_activeAuthorStyleSheets) {
    StyleSheetContents* contents = sheet->contents();
    if (contents->hasMediaQueries())
      contents->clearRuleSet();
  }
}

DEFINE_TRACE(TreeScopeStyleSheetCollection) {
  visitor->trace(m_treeScope);
  visitor->trace(m_styleSheetCandidateNodes);
  StyleSheetCollection::trace(visitor);
}

}  // namespace blink