/*
    Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
    Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
    Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
    Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
    Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple 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.

    This class provides all functionality needed for loading images, style sheets and html
    pages from the web. It has a memory cache for these objects.
*/

#include "config.h"
#include "CachedScript.h"

#include "CachedResourceClient.h"
#include "CachedResourceClientWalker.h"
#include "HTTPHeaderNames.h"
#include "HTTPParsers.h"
#include "MIMETypeRegistry.h"
#include "MemoryCache.h"
#include "RuntimeApplicationChecks.h"
#include "SharedBuffer.h"
#include "TextResourceDecoder.h"
#include <wtf/Vector.h>

namespace WebCore {

CachedScript::CachedScript(const ResourceRequest& resourceRequest, const String& charset, SessionID sessionID)
    : CachedResource(resourceRequest, Script, sessionID)
    , m_decoder(TextResourceDecoder::create(ASCIILiteral("application/javascript"), charset))
{
    // It's javascript we want.
    // But some websites think their scripts are <some wrong mimetype here>
    // and refuse to serve them if we only accept application/x-javascript.
    setAccept("*/*");
}

CachedScript::~CachedScript()
{
}

void CachedScript::setEncoding(const String& chs)
{
    m_decoder->setEncoding(chs, TextResourceDecoder::EncodingFromHTTPHeader);
}

String CachedScript::encoding() const
{
    return m_decoder->encoding().name();
}

String CachedScript::mimeType() const
{
    return extractMIMETypeFromMediaType(m_response.httpHeaderField(HTTPHeaderName::ContentType)).convertToASCIILowercase();
}

StringView CachedScript::script()
{
    if (!m_data)
        return { };

    if (m_decodingState == NeverDecoded
        && TextEncoding(encoding()).isByteBasedEncoding()
        && m_data->size()
        && charactersAreAllASCII(reinterpret_cast<const LChar*>(m_data->data()), m_data->size())) {

        m_decodingState = DataAndDecodedStringHaveSameBytes;

        // If the encoded and decoded data are the same, there is no decoded data cost!
        setDecodedSize(0);
        m_decodedDataDeletionTimer.stop();

        m_scriptHash = StringHasher::computeHashAndMaskTop8Bits(reinterpret_cast<const LChar*>(m_data->data()), m_data->size());
    }

    if (m_decodingState == DataAndDecodedStringHaveSameBytes)
        return { reinterpret_cast<const LChar*>(m_data->data()), m_data->size() };

    if (!m_script) {
        m_script = m_decoder->decodeAndFlush(m_data->data(), encodedSize());
        m_scriptHash = m_script.impl()->hash();
        m_decodingState = DataAndDecodedStringHaveDifferentBytes;
        setDecodedSize(m_script.sizeInBytes());
    }

    m_decodedDataDeletionTimer.restart();
    return m_script;
}

unsigned CachedScript::scriptHash()
{
    if (m_decodingState == NeverDecoded)
        script();
    return m_scriptHash;
}

void CachedScript::finishLoading(SharedBuffer* data)
{
    m_data = data;
    setEncodedSize(data ? data->size() : 0);
    CachedResource::finishLoading(data);
}

void CachedScript::destroyDecodedData()
{
    m_script = String();
    setDecodedSize(0);
}

#if ENABLE(NOSNIFF)
bool CachedScript::mimeTypeAllowedByNosniff() const
{
    return parseContentTypeOptionsHeader(m_response.httpHeaderField(HTTPHeaderName::XContentTypeOptions)) != ContentTypeOptionsNosniff || MIMETypeRegistry::isSupportedJavaScriptMIMEType(mimeType());
}
#endif

bool CachedScript::shouldIgnoreHTTPStatusCodeErrors() const
{
    // This is a workaround for <rdar://problem/13916291>
    // REGRESSION (r119759): Adobe Flash Player "smaller" installer relies on the incorrect firing
    // of a load event and needs an app-specific hack for compatibility.
    // The installer in question tries to load .js file that doesn't exist, causing the server to
    // return a 404 response. Normally, this would trigger an error event to be dispatched, but the
    // installer expects a load event instead so we work around it here.
    if (applicationIsSolidStateNetworksDownloader())
        return true;

    return CachedResource::shouldIgnoreHTTPStatusCodeErrors();
}

} // namespace WebCore