/*

 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)

 *           (C) 1999 Antti Koivisto (koivisto@kde.org)

 *           (C) 2001 Dirk Mueller (mueller@kde.org)

 * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.

 * Copyright (C) 2009 Rob Buis (rwlbuis@gmail.com)

 *

 * 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 "config.h"

#include "HTMLLinkElement.h"

#include "Attribute.h"

#include "CSSHelper.h"

#include "CachedCSSStyleSheet.h"

#include "DocLoader.h"

#include "Document.h"

#include "Frame.h"

#include "FrameLoader.h"

#include "FrameLoaderClient.h"

#include "FrameTree.h"

#include "HTMLNames.h"

#include "MediaList.h"

#include "MediaQueryEvaluator.h"

#include "Page.h"

#include "ResourceHandle.h"

#include "ScriptEventListener.h"

#include "Settings.h"

#include <wtf/StdLibExtras.h>

namespace WebCore {

using namespace HTMLNames;

inline HTMLLinkElement::HTMLLinkElement(const QualifiedName& tagName, Document* document, bool createdByParser)

    : HTMLElement(tagName, document)

    , m_disabledState(Unset)

    , m_loading(false)

    , m_createdByParser(createdByParser)

    , m_shouldProcessAfterAttach(false)

{

    ASSERT(hasTagName(linkTag));

}

PassRefPtr<HTMLLinkElement> HTMLLinkElement::create(const QualifiedName& tagName, Document* document, bool createdByParser)

{

    return adoptRef(new HTMLLinkElement(tagName, document, createdByParser));

}

HTMLLinkElement::~HTMLLinkElement()

{

    if (m_cachedSheet) {

        m_cachedSheet->removeClient(this);

        if (m_loading && !isDisabled() && !isAlternate())

            document()->removePendingSheet();

    }

}

void HTMLLinkElement::setDisabledState(bool _disabled)

{

    DisabledState oldDisabledState = m_disabledState;

    m_disabledState = _disabled ? Disabled : EnabledViaScript;

    if (oldDisabledState != m_disabledState) {

        // If we change the disabled state while the sheet is still loading, then we have to

        // perform three checks:

        if (isLoading()) {

            // Check #1: If the sheet becomes disabled while it was loading, and if it was either

            // a main sheet or a sheet that was previously enabled via script, then we need

            // to remove it from the list of pending sheets.

            if (m_disabledState == Disabled && (!m_relAttribute.m_isAlternate || oldDisabledState == EnabledViaScript))

                document()->removePendingSheet();

            // Check #2: An alternate sheet becomes enabled while it is still loading.

            if (m_relAttribute.m_isAlternate && m_disabledState == EnabledViaScript)

                document()->addPendingSheet();

            // Check #3: A main sheet becomes enabled while it was still loading and

            // after it was disabled via script.  It takes really terrible code to make this

            // happen (a double toggle for no reason essentially).  This happens on

            // virtualplastic.net, which manages to do about 12 enable/disables on only 3

            // sheets. :)

            if (!m_relAttribute.m_isAlternate && m_disabledState == EnabledViaScript && oldDisabledState == Disabled)

                document()->addPendingSheet();

            // If the sheet is already loading just bail.

            return;

        }

        // Load the sheet, since it's never been loaded before.

        if (!m_sheet && m_disabledState == EnabledViaScript)

            process();

        else

            document()->updateStyleSelector(); // Update the style selector.

    }

}

StyleSheet* HTMLLinkElement::sheet() const

{

    return m_sheet.get();

}

void HTMLLinkElement::parseMappedAttribute(Attribute* attr)

{

    if (attr->name() == relAttr) {

        tokenizeRelAttribute(attr->value(), m_relAttribute);

        process();

    } else if (attr->name() == hrefAttr) {

        m_url = document()->completeURL(deprecatedParseURL(attr->value()));

        process();

    } else if (attr->name() == typeAttr) {

        m_type = attr->value();

        process();

    } else if (attr->name() == mediaAttr) {

        m_media = attr->value().string().lower();

        process();

    } else if (attr->name() == disabledAttr)

        setDisabledState(!attr->isNull());

    else if (attr->name() == onbeforeloadAttr)

        setAttributeEventListener(eventNames().beforeloadEvent, createAttributeEventListener(this, attr));

    else {

        if (attr->name() == titleAttr && m_sheet)

            m_sheet->setTitle(attr->value());

        HTMLElement::parseMappedAttribute(attr);

    }

}

void HTMLLinkElement::tokenizeRelAttribute(const AtomicString& rel, RelAttribute& relAttribute)

{

    relAttribute.m_isStyleSheet = false;

    relAttribute.m_isIcon = false;

    relAttribute.m_isAlternate = false;

    relAttribute.m_isDNSPrefetch = false;

#if ENABLE(LINK_PREFETCH)

    relAttribute.m_isLinkPrefetch = false;

#endif

    if (equalIgnoringCase(rel, "stylesheet"))

        relAttribute.m_isStyleSheet = true;

    else if (equalIgnoringCase(rel, "icon") || equalIgnoringCase(rel, "shortcut icon"))

        relAttribute.m_isIcon = true;

    else if (equalIgnoringCase(rel, "dns-prefetch"))

        relAttribute.m_isDNSPrefetch = true;

#if ENABLE(LINK_PREFETCH)

    else if (equalIgnoringCase(rel, "prefetch"))

        relAttribute.m_isLinkPrefetch = true;

#endif

    else if (equalIgnoringCase(rel, "alternate stylesheet") || equalIgnoringCase(rel, "stylesheet alternate")) {

        relAttribute.m_isStyleSheet = true;

        relAttribute.m_isAlternate = true;

    } else {

        // Tokenize the rel attribute and set bits based on specific keywords that we find.

        String relString = rel.string();

        relString.replace('\n', ' ');

        Vector<String> list;

        relString.split(' ', list);

        Vector<String>::const_iterator end = list.end();

        for (Vector<String>::const_iterator it = list.begin(); it != end; ++it) {

            if (equalIgnoringCase(*it, "stylesheet"))

                relAttribute.m_isStyleSheet = true;

            else if (equalIgnoringCase(*it, "alternate"))

                relAttribute.m_isAlternate = true;

            else if (equalIgnoringCase(*it, "icon"))

                relAttribute.m_isIcon = true;

        }

    }

}

void HTMLLinkElement::process()

{

    if (!inDocument())

        return;

    String type = m_type.lower();

    // IE extension: location of small icon for locationbar / bookmarks

    // We'll record this URL per document, even if we later only use it in top level frames

    if (m_relAttribute.m_isIcon && m_url.isValid() && !m_url.isEmpty())

        document()->setIconURL(m_url.string(), type);

    if (m_relAttribute.m_isDNSPrefetch && document()->isDNSPrefetchEnabled() && m_url.isValid() && !m_url.isEmpty())

        ResourceHandle::prepareForURL(m_url);

#if ENABLE(LINK_PREFETCH)

    if (m_relAttribute.m_isLinkPrefetch && m_url.isValid())

        document()->docLoader()->requestLinkPrefetch(m_url);

#endif

    bool acceptIfTypeContainsTextCSS = document()->page() && document()->page()->settings() && document()->page()->settings()->treatsAnyTextCSSLinkAsStylesheet();

    // Stylesheet

    // This was buggy and would incorrectly match <link rel="alternate">, which has a different specified meaning. -dwh

    if (m_disabledState != Disabled && (m_relAttribute.m_isStyleSheet || (acceptIfTypeContainsTextCSS && type.contains("text/css"))) && document()->frame() && m_url.isValid()) {

        // also, don't load style sheets for standalone documents

        String charset = getAttribute(charsetAttr);

        if (charset.isEmpty() && document()->frame())

            charset = document()->frame()->loader()->writer()->encoding();

        if (m_cachedSheet) {

            if (m_loading)

                document()->removePendingSheet();

            m_cachedSheet->removeClient(this);

            m_cachedSheet = 0;

        }

        if (!dispatchBeforeLoadEvent(m_url))

            return;

        m_loading = true;

        // Add ourselves as a pending sheet, but only if we aren't an alternate 

        // stylesheet.  Alternate stylesheets don't hold up render tree construction.

        if (!isAlternate())

            document()->addPendingSheet();

        m_cachedSheet = document()->docLoader()->requestCSSStyleSheet(m_url, charset);

        if (m_cachedSheet)

            m_cachedSheet->addClient(this);

        else {

            // The request may have been denied if (for example) the stylesheet is local and the document is remote.

            m_loading = false;

            if (!isAlternate())

                document()->removePendingSheet();

        }

    } else if (m_sheet) {

        // we no longer contain a stylesheet, e.g. perhaps rel or type was changed

        m_sheet = 0;

        document()->updateStyleSelector();

    }

}

void HTMLLinkElement::processCallback(Node* node)

{

    ASSERT_ARG(node, node && node->hasTagName(linkTag));

    static_cast<HTMLLinkElement*>(node)->process();

}

void HTMLLinkElement::insertedIntoDocument()

{

    HTMLElement::insertedIntoDocument();

    document()->addStyleSheetCandidateNode(this, m_createdByParser);

    // Since processing a stylesheet link causes a beforeload event

    // to fire, it is possible for JavaScript to remove the element in the midst

    // of it being inserted into the DOM, which can lead to assertion failures

    // and crashes. Avoid this by postponing the beforeload/load until after

    // attach.

    m_shouldProcessAfterAttach = true;

}

void HTMLLinkElement::removedFromDocument()

{

    HTMLElement::removedFromDocument();

    document()->removeStyleSheetCandidateNode(this);

    // FIXME: It's terrible to do a synchronous update of the style selector just because a <style> or <link> element got removed.

    if (document()->renderer())

        document()->updateStyleSelector();

    m_shouldProcessAfterAttach = false;

}

void HTMLLinkElement::attach()

{

    if (m_shouldProcessAfterAttach) {

        m_shouldProcessAfterAttach = false;

        queuePostAttachCallback(&HTMLLinkElement::processCallback, this);

    }

    HTMLElement::attach();

}

void HTMLLinkElement::finishParsingChildren()

{

    m_createdByParser = false;

    HTMLElement::finishParsingChildren();

}

void HTMLLinkElement::setCSSStyleSheet(const String& href, const KURL& baseURL, const String& charset, const CachedCSSStyleSheet* sheet)

{

    m_sheet = CSSStyleSheet::create(this, href, baseURL, charset);

    bool strictParsing = !document()->inCompatMode();

    bool enforceMIMEType = strictParsing;

    bool crossOriginCSS = false;

    bool validMIMEType = false;

    bool needsSiteSpecificQuirks = document()->page() && document()->page()->settings()->needsSiteSpecificQuirks();

    // Check to see if we should enforce the MIME type of the CSS resource in strict mode.

    // Running in iWeb 2 is one example of where we don't want to - <rdar://problem/6099748>

    if (enforceMIMEType && document()->page() && !document()->page()->settings()->enforceCSSMIMETypeInStrictMode())

        enforceMIMEType = false;

#if defined(BUILDING_ON_TIGER) || defined(BUILDING_ON_LEOPARD)

    if (enforceMIMEType && needsSiteSpecificQuirks) {

        // Covers both http and https, with or without "www."

        if (baseURL.string().contains("mcafee.com/japan/", false))

            enforceMIMEType = false;

    }

#endif

    String sheetText = sheet->sheetText(enforceMIMEType, &validMIMEType);

    m_sheet->parseString(sheetText, strictParsing);

    // If we're loading a stylesheet cross-origin, and the MIME type is not

    // standard, require the CSS to at least start with a syntactically

    // valid CSS rule.

    // This prevents an attacker playing games by injecting CSS strings into

    // HTML, XML, JSON, etc. etc.

    if (!document()->securityOrigin()->canRequest(baseURL))

        crossOriginCSS = true;

    if (crossOriginCSS && !validMIMEType && !m_sheet->hasSyntacticallyValidCSSHeader())

        m_sheet = CSSStyleSheet::create(this, href, baseURL, charset);

    if (strictParsing && needsSiteSpecificQuirks) {

        // Work around <https://bugs.webkit.org/show_bug.cgi?id=28350>.

        DEFINE_STATIC_LOCAL(const String, slashKHTMLFixesDotCss, ("/KHTMLFixes.css"));

        DEFINE_STATIC_LOCAL(const String, mediaWikiKHTMLFixesStyleSheet, ("/* KHTML fix stylesheet */\n/* work around the horizontal scrollbars */\n#column-content { margin-left: 0; }\n\n"));

        // There are two variants of KHTMLFixes.css. One is equal to mediaWikiKHTMLFixesStyleSheet,

        // while the other lacks the second trailing newline.

        if (baseURL.string().endsWith(slashKHTMLFixesDotCss) && !sheetText.isNull() && mediaWikiKHTMLFixesStyleSheet.startsWith(sheetText)

                && sheetText.length() >= mediaWikiKHTMLFixesStyleSheet.length() - 1) {

            ASSERT(m_sheet->length() == 1);

            ExceptionCode ec;

            m_sheet->deleteRule(0, ec);

        }

    }

    m_sheet->setTitle(title());

    RefPtr<MediaList> media = MediaList::createAllowingDescriptionSyntax(m_media);

    m_sheet->setMedia(media.get());

    m_loading = false;

    m_sheet->checkLoaded();

}

bool HTMLLinkElement::isLoading() const

{

    if (m_loading)

        return true;

    if (!m_sheet)

        return false;

    return static_cast<CSSStyleSheet *>(m_sheet.get())->isLoading();

}

bool HTMLLinkElement::sheetLoaded()

{

    if (!isLoading() && !isDisabled() && !isAlternate()) {

        document()->removePendingSheet();

        return true;

    }

    return false;

}

bool HTMLLinkElement::isURLAttribute(Attribute *attr) const

{

    return attr->name() == hrefAttr;

}

KURL HTMLLinkElement::href() const

{

    return document()->completeURL(getAttribute(hrefAttr));

}

String HTMLLinkElement::rel() const

{

    return getAttribute(relAttr);

}

String HTMLLinkElement::target() const

{

    return getAttribute(targetAttr);

}

String HTMLLinkElement::type() const

{

    return getAttribute(typeAttr);

}

void HTMLLinkElement::addSubresourceAttributeURLs(ListHashSet<KURL>& urls) const

{

    HTMLElement::addSubresourceAttributeURLs(urls);

    // Favicons are handled by a special case in LegacyWebArchive::create()

    if (m_relAttribute.m_isIcon)

        return;

    if (!m_relAttribute.m_isStyleSheet)

        return;

    // Append the URL of this link element.

    addSubresourceURL(urls, href());

    // Walk the URLs linked by the linked-to stylesheet.

    if (StyleSheet* styleSheet = const_cast<HTMLLinkElement*>(this)->sheet())

        styleSheet->addSubresourceStyleURLs(urls);

}

}