/*

 * Copyright (C) 2008 Apple Inc. All Rights Reserved.

 * Copyright (C) 2009 Torch Mobile, Inc. http://www.torchmobile.com/

 * 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 APPLE 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 APPLE 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 "config.h"

#include "HTMLPreloadScanner.h"

#include "CSSHelper.h"

#include "DocLoader.h"

#include "Document.h"

#include "HTMLTreeBuilder.h"

#include "HTMLLinkElement.h"

#include "HTMLNames.h"

namespace WebCore {

using namespace HTMLNames;

namespace {

class PreloadTask {

public:

    PreloadTask(const HTMLToken& token)

        : m_tagName(token.name().data(), token.name().size())

        , m_linkIsStyleSheet(false)

    {

        processAttributes(token.attributes());

    }

    void processAttributes(const HTMLToken::AttributeList& attributes)

    {

        if (m_tagName != scriptTag && m_tagName != imgTag && m_tagName != linkTag)

            return;

        for (HTMLToken::AttributeList::const_iterator iter = attributes.begin();

             iter != attributes.end(); ++iter) {

            AtomicString attributeName(iter->m_name.data(), iter->m_name.size());

            String attributeValue(iter->m_value.data(), iter->m_value.size());

            if (attributeName == charsetAttr)

                m_charset = attributeValue;

            if (m_tagName == scriptTag || m_tagName == imgTag) {

                if (attributeName == srcAttr)

                    setUrlToLoad(attributeValue);

            } else if (m_tagName == linkTag) {

                if (attributeName == hrefAttr)

                    setUrlToLoad(attributeValue);

                else if (attributeName == relAttr)

                    m_linkIsStyleSheet = relAttributeIsStyleSheet(attributeValue);

            }

        }

    }

    bool relAttributeIsStyleSheet(const String& attributeValue)

    {

        ASSERT(m_tagName == linkTag);

        HTMLLinkElement::RelAttribute rel;

        HTMLLinkElement::tokenizeRelAttribute(attributeValue, rel);

        return rel.m_isStyleSheet && !rel.m_isAlternate && !rel.m_isIcon && !rel.m_isDNSPrefetch;

    }

    void setUrlToLoad(const String& attributeValue)

    {

        // We only respect the first src/href, per HTML5:

        // http://www.whatwg.org/specs/web-apps/current-work/multipage/tokenization.html#attribute-name-state

        if (!m_urlToLoad.isEmpty())

            return;

        m_urlToLoad = deprecatedParseURL(attributeValue);

    }

    void preload(Document* document, bool scanningBody)

    {

        if (m_urlToLoad.isEmpty())

            return;

        DocLoader* docLoader = document->docLoader();

        if (m_tagName == scriptTag)

            docLoader->preload(CachedResource::Script, m_urlToLoad, m_charset, scanningBody);

        else if (m_tagName == imgTag) 

            docLoader->preload(CachedResource::ImageResource, m_urlToLoad, String(), scanningBody);

        else if (m_tagName == linkTag && m_linkIsStyleSheet) 

            docLoader->preload(CachedResource::CSSStyleSheet, m_urlToLoad, m_charset, scanningBody);

    }

    const AtomicString& tagName() const { return m_tagName; }

private:

    AtomicString m_tagName;

    String m_urlToLoad;

    String m_charset;

    bool m_linkIsStyleSheet;

};

} // namespace

HTMLPreloadScanner::HTMLPreloadScanner(Document* document)

    : m_document(document)

    , m_cssScanner(document)

    , m_bodySeen(false)

    , m_inStyle(false)

{

}

void HTMLPreloadScanner::appendToEnd(const SegmentedString& source)

{

    m_source.append(source);

}

void HTMLPreloadScanner::scan()

{

    // FIXME: We should save and re-use these tokens in HTMLDocumentParser if

    // the pending script doesn't end up calling document.write.

    while (m_tokenizer.nextToken(m_source, m_token)) {

        processToken();

        m_token.clear();

    }

}

void HTMLPreloadScanner::processToken()

{

    if (m_inStyle) {

        if (m_token.type() == HTMLToken::Character)

            m_cssScanner.scan(m_token, scanningBody());

        else if (m_token.type() == HTMLToken::EndTag) {

            m_inStyle = false;

            m_cssScanner.reset();

        }

    }

    if (m_token.type() != HTMLToken::StartTag)

        return;

    PreloadTask task(m_token);

    m_tokenizer.setState(HTMLTreeBuilder::adjustedLexerState(m_tokenizer.state(), task.tagName(), m_document->frame()));

    if (task.tagName() == scriptTag) {

        // The tree builder handles scriptTag separately from the other tokenizer

        // state adjustments, so we need to handle it separately too.

        ASSERT(m_tokenizer.state() == HTMLTokenizer::DataState);

        m_tokenizer.setState(HTMLTokenizer::ScriptDataState);

    }

    if (task.tagName() == bodyTag)

        m_bodySeen = true;

    if (task.tagName() == styleTag)

        m_inStyle = true;

    task.preload(m_document, scanningBody());

}

bool HTMLPreloadScanner::scanningBody() const

{

    return m_document->body() || m_bodySeen;

}

}