/*
 * Copyright (C) 2010. Adam Barth. 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. 
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") 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 APPLE AND ITS 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 APPLE OR ITS 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 "DocumentWriter.h"

#include "DOMImplementation.h"
#include "DOMWindow.h"
#include "Frame.h"
#include "FrameLoader.h"
#include "FrameLoaderClient.h"
#include "FrameView.h"
#include "PlaceholderDocument.h"
#include "PluginDocument.h"
#include "SecurityOrigin.h"
#include "SegmentedString.h"
#include "Settings.h"
#include "TextResourceDecoder.h"
#include "Tokenizer.h"

namespace WebCore {

static inline bool canReferToParentFrameEncoding(const Frame* frame, const Frame* parentFrame) 
{
    return parentFrame && parentFrame->document()->securityOrigin()->canAccess(frame->document()->securityOrigin());
}
    
DocumentWriter::DocumentWriter(Frame* frame)
    : m_frame(frame)
    , m_receivedData(false)
    , m_encodingWasChosenByUser(false)
{
}

void DocumentWriter::replaceDocument(const String& html)
{
    m_frame->loader()->stopAllLoaders();
    begin(m_frame->loader()->url(), true, m_frame->document()->securityOrigin());
    addData(html);
    end();
}

void DocumentWriter::clear()
{
    m_decoder = 0;
    m_receivedData = false;
    if (!m_encodingWasChosenByUser)
        m_encoding = String();
}

void DocumentWriter::begin()
{
    begin(KURL());
}

PassRefPtr<Document> DocumentWriter::createDocument()
{
    if (!m_frame->loader()->isDisplayingInitialEmptyDocument() && m_frame->loader()->client()->shouldUsePluginDocument(m_mimeType))
        return PluginDocument::create(m_frame);
    if (!m_frame->loader()->client()->hasHTMLView())
        return PlaceholderDocument::create(m_frame);
    return DOMImplementation::createDocument(m_mimeType, m_frame, m_frame->inViewSourceMode());
}

void DocumentWriter::begin(const KURL& url, bool dispatch, SecurityOrigin* origin)
{
    // We need to take a reference to the security origin because |clear|
    // might destroy the document that owns it.
    RefPtr<SecurityOrigin> forcedSecurityOrigin = origin;

    // Create a new document before clearing the frame, because it may need to
    // inherit an aliased security context.
    RefPtr<Document> document = createDocument();

    bool resetScripting = !(m_frame->loader()->isDisplayingInitialEmptyDocument() && m_frame->document()->securityOrigin()->isSecureTransitionTo(url));
    m_frame->loader()->clear(resetScripting, resetScripting);
    if (resetScripting)
        m_frame->script()->updatePlatformScriptObjects();

    m_frame->loader()->setURL(url);
    document->setURL(url);
    m_frame->setDocument(document);

    if (m_decoder)
        document->setDecoder(m_decoder.get());
    if (forcedSecurityOrigin)
        document->setSecurityOrigin(forcedSecurityOrigin.get());

    m_frame->domWindow()->setURL(document->url());
    m_frame->domWindow()->setSecurityOrigin(document->securityOrigin());

    m_frame->loader()->didBeginDocument(dispatch);

    document->implicitOpen();

    if (m_frame->view() && m_frame->loader()->client()->hasHTMLView())
        m_frame->view()->setContentsSize(IntSize());
}

void DocumentWriter::addData(const char* str, int len, bool flush)
{
    if (len == 0 && !flush)
        return;

    if (len == -1)
        len = strlen(str);

    Tokenizer* tokenizer = m_frame->document()->tokenizer();
    if (tokenizer && tokenizer->wantsRawData()) {
        if (len > 0)
            tokenizer->writeRawData(str, len);
        return;
    }
    
    if (!m_decoder) {
        if (Settings* settings = m_frame->settings()) {
            m_decoder = TextResourceDecoder::create(m_mimeType,
                settings->defaultTextEncodingName(),
                settings->usesEncodingDetector());
            Frame* parentFrame = m_frame->tree()->parent();
            // Set the hint encoding to the parent frame encoding only if
            // the parent and the current frames share the security origin.
            // We impose this condition because somebody can make a child frame 
            // containing a carefully crafted html/javascript in one encoding
            // that can be mistaken for hintEncoding (or related encoding) by
            // an auto detector. When interpreted in the latter, it could be
            // an attack vector.
            // FIXME: This might be too cautious for non-7bit-encodings and
            // we may consider relaxing this later after testing.
            if (canReferToParentFrameEncoding(m_frame, parentFrame))
                m_decoder->setHintEncoding(parentFrame->document()->decoder());
        } else
            m_decoder = TextResourceDecoder::create(m_mimeType, String());
        Frame* parentFrame = m_frame->tree()->parent();
        if (m_encoding.isEmpty()) {
            if (canReferToParentFrameEncoding(m_frame, parentFrame))
                m_decoder->setEncoding(parentFrame->document()->inputEncoding(), TextResourceDecoder::EncodingFromParentFrame);
        } else {
            m_decoder->setEncoding(m_encoding,
                m_encodingWasChosenByUser ? TextResourceDecoder::UserChosenEncoding : TextResourceDecoder::EncodingFromHTTPHeader);
        }
        m_frame->document()->setDecoder(m_decoder.get());
    }

    String decoded = m_decoder->decode(str, len);
    if (flush)
        decoded += m_decoder->flush();
    if (decoded.isEmpty())
        return;

    if (!m_receivedData) {
        m_receivedData = true;
        if (m_decoder->encoding().usesVisualOrdering())
            m_frame->document()->setVisuallyOrdered();
        m_frame->document()->recalcStyle(Node::Force);
    }

    if (tokenizer) {
        ASSERT(!tokenizer->wantsRawData());
        tokenizer->write(decoded, true);
    }
}

void DocumentWriter::addData(const String& str)
{
    if (str.isNull())
        return;

    if (!m_receivedData) {
        m_receivedData = true;
        m_frame->document()->setParseMode(Document::Strict);
    }

    if (Tokenizer* tokenizer = m_frame->document()->tokenizer())
        tokenizer->write(str, true);
}

void DocumentWriter::end()
{
    m_frame->loader()->didEndDocument();
    endIfNotLoadingMainResource();
}

void DocumentWriter::endIfNotLoadingMainResource()
{
    if (m_frame->loader()->isLoadingMainResource() || !m_frame->page() || !m_frame->document())
        return;

    // http://bugs.webkit.org/show_bug.cgi?id=10854
    // The frame's last ref may be removed and it can be deleted by checkCompleted(), 
    // so we'll add a protective refcount
    RefPtr<Frame> protector(m_frame);

    // make sure nothing's left in there
    addData(0, 0, true);
    m_frame->document()->finishParsing();
}

String DocumentWriter::encoding() const
{
    if (m_encodingWasChosenByUser && !m_encoding.isEmpty())
        return m_encoding;
    if (m_decoder && m_decoder->encoding().isValid())
        return m_decoder->encoding().name();
    Settings* settings = m_frame->settings();
    return settings ? settings->defaultTextEncodingName() : String();
}

void DocumentWriter::setEncoding(const String& name, bool userChosen)
{
    m_frame->loader()->willSetEncoding();
    m_encoding = name;
    m_encodingWasChosenByUser = userChosen;
}

void DocumentWriter::setDecoder(TextResourceDecoder* decoder)
{
    m_decoder = decoder;
}

String DocumentWriter::deprecatedFrameEncoding() const
{
    return m_frame->loader()->url().isEmpty() ? m_encoding : encoding();
}

} // namespace WebCore