/*
 * 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, 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 * Copyright (C) 2008 Nikolas Zimmermann <zimmermann@kde.org>
 *
 * 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 "core/dom/ScriptLoader.h"

#include "HTMLNames.h"
#include "SVGNames.h"
#include "bindings/v8/ScriptController.h"
#include "bindings/v8/ScriptSourceCode.h"
#include "core/dom/Document.h"
#include "core/dom/Event.h"
#include "core/dom/IgnoreDestructiveWriteCountIncrementer.h"
#include "core/dom/ScriptLoaderClient.h"
#include "core/dom/ScriptRunner.h"
#include "core/dom/ScriptableDocumentParser.h"
#include "core/dom/Text.h"
#include "core/html/HTMLScriptElement.h"
#include "core/html/parser/HTMLParserIdioms.h"
#include "core/loader/cache/CachedResourceLoader.h"
#include "core/loader/cache/CachedResourceRequest.h"
#include "core/loader/cache/CachedScript.h"
#include "core/page/ContentSecurityPolicy.h"
#include "core/page/Frame.h"
#include "core/platform/MIMETypeRegistry.h"
#include "core/svg/SVGScriptElement.h"
#include "weborigin/SecurityOrigin.h"
#include "wtf/StdLibExtras.h"
#include "wtf/text/StringBuilder.h"
#include "wtf/text/StringHash.h"
#include "wtf/text/TextPosition.h"

namespace WebCore {

ScriptLoader::ScriptLoader(Element* element, bool parserInserted, bool alreadyStarted)
    : m_element(element)
    , m_cachedScript(0)
    , m_startLineNumber(WTF::OrdinalNumber::beforeFirst())
    , m_parserInserted(parserInserted)
    , m_isExternalScript(false)
    , m_alreadyStarted(alreadyStarted)
    , m_haveFiredLoad(false)
    , m_willBeParserExecuted(false)
    , m_readyToBeParserExecuted(false)
    , m_willExecuteWhenDocumentFinishedParsing(false)
    , m_forceAsync(!parserInserted)
    , m_willExecuteInOrder(false)
{
    ASSERT(m_element);
    if (parserInserted && element->document()->scriptableDocumentParser() && !element->document()->isInDocumentWrite())
        m_startLineNumber = element->document()->scriptableDocumentParser()->lineNumber();
}

ScriptLoader::~ScriptLoader()
{
    stopLoadRequest();
}

void ScriptLoader::insertedInto(ContainerNode* insertionPoint)
{
    if (insertionPoint->inDocument() && !m_parserInserted)
        prepareScript(); // FIXME: Provide a real starting line number here.
}

void ScriptLoader::childrenChanged()
{
    if (!m_parserInserted && m_element->inDocument())
        prepareScript(); // FIXME: Provide a real starting line number here.
}

void ScriptLoader::handleSourceAttribute(const String& sourceUrl)
{
    if (ignoresLoadRequest() || sourceUrl.isEmpty())
        return;

    prepareScript(); // FIXME: Provide a real starting line number here.
}

void ScriptLoader::handleAsyncAttribute()
{
    m_forceAsync = false;
}

// Helper function
static bool isLegacySupportedJavaScriptLanguage(const String& language)
{
    // Mozilla 1.8 accepts javascript1.0 - javascript1.7, but WinIE 7 accepts only javascript1.1 - javascript1.3.
    // Mozilla 1.8 and WinIE 7 both accept javascript and livescript.
    // WinIE 7 accepts ecmascript and jscript, but Mozilla 1.8 doesn't.
    // Neither Mozilla 1.8 nor WinIE 7 accept leading or trailing whitespace.
    // We want to accept all the values that either of these browsers accept, but not other values.

    // FIXME: This function is not HTML5 compliant. These belong in the MIME registry as "text/javascript<version>" entries.
    typedef HashSet<String, CaseFoldingHash> LanguageSet;
    DEFINE_STATIC_LOCAL(LanguageSet, languages, ());
    if (languages.isEmpty()) {
        languages.add("javascript");
        languages.add("javascript");
        languages.add("javascript1.0");
        languages.add("javascript1.1");
        languages.add("javascript1.2");
        languages.add("javascript1.3");
        languages.add("javascript1.4");
        languages.add("javascript1.5");
        languages.add("javascript1.6");
        languages.add("javascript1.7");
        languages.add("livescript");
        languages.add("ecmascript");
        languages.add("jscript");
    }

    return languages.contains(language);
}

void ScriptLoader::dispatchErrorEvent()
{
    m_element->dispatchEvent(Event::create(eventNames().errorEvent, false, false));
}

void ScriptLoader::dispatchLoadEvent()
{
    if (ScriptLoaderClient* client = this->client())
        client->dispatchLoadEvent();
    setHaveFiredLoadEvent(true);
}

bool ScriptLoader::isScriptTypeSupported(LegacyTypeSupport supportLegacyTypes) const
{
    // FIXME: isLegacySupportedJavaScriptLanguage() is not valid HTML5. It is used here to maintain backwards compatibility with existing layout tests. The specific violations are:
    // - Allowing type=javascript. type= should only support MIME types, such as text/javascript.
    // - Allowing a different set of languages for language= and type=. language= supports Javascript 1.1 and 1.4-1.6, but type= does not.

    String type = client()->typeAttributeValue();
    String language = client()->languageAttributeValue();
    if (type.isEmpty() && language.isEmpty())
        return true; // Assume text/javascript.
    if (type.isEmpty()) {
        type = "text/" + language.lower();
        if (MIMETypeRegistry::isSupportedJavaScriptMIMEType(type) || isLegacySupportedJavaScriptLanguage(language))
            return true;
    } else if (MIMETypeRegistry::isSupportedJavaScriptMIMEType(type.stripWhiteSpace().lower()) || (supportLegacyTypes == AllowLegacyTypeInTypeAttribute && isLegacySupportedJavaScriptLanguage(type))) {
        return true;
    }

    return false;
}

// http://dev.w3.org/html5/spec/Overview.html#prepare-a-script
bool ScriptLoader::prepareScript(const TextPosition& scriptStartPosition, LegacyTypeSupport supportLegacyTypes)
{
    if (m_alreadyStarted)
        return false;

    ScriptLoaderClient* client = this->client();

    bool wasParserInserted;
    if (m_parserInserted) {
        wasParserInserted = true;
        m_parserInserted = false;
    } else {
        wasParserInserted = false;
    }

    if (wasParserInserted && !client->asyncAttributeValue())
        m_forceAsync = true;

    // FIXME: HTML5 spec says we should check that all children are either comments or empty text nodes.
    if (!client->hasSourceAttribute() && !m_element->firstChild())
        return false;

    if (!m_element->inDocument())
        return false;

    if (!isScriptTypeSupported(supportLegacyTypes))
        return false;

    if (wasParserInserted) {
        m_parserInserted = true;
        m_forceAsync = false;
    }

    m_alreadyStarted = true;

    // FIXME: If script is parser inserted, verify it's still in the original document.
    Document* document = m_element->document();

    // FIXME: Eventually we'd like to evaluate scripts which are inserted into a
    // viewless document but this'll do for now.
    // See http://bugs.webkit.org/show_bug.cgi?id=5727
    if (!document->frame())
        return false;

    if (!document->frame()->script()->canExecuteScripts(AboutToExecuteScript))
        return false;

    if (!isScriptForEventSupported())
        return false;

    if (!client->charsetAttributeValue().isEmpty())
        m_characterEncoding = client->charsetAttributeValue();
    else
        m_characterEncoding = document->charset();

    if (client->hasSourceAttribute()) {
        if (!requestScript(client->sourceAttributeValue()))
            return false;
    }

    if (client->hasSourceAttribute() && client->deferAttributeValue() && m_parserInserted && !client->asyncAttributeValue()) {
        m_willExecuteWhenDocumentFinishedParsing = true;
        m_willBeParserExecuted = true;
    } else if (client->hasSourceAttribute() && m_parserInserted && !client->asyncAttributeValue()) {
        m_willBeParserExecuted = true;
    } else if (!client->hasSourceAttribute() && m_parserInserted && !document->haveStylesheetsAndImportsLoaded()) {
        m_willBeParserExecuted = true;
        m_readyToBeParserExecuted = true;
    } else if (client->hasSourceAttribute() && !client->asyncAttributeValue() && !m_forceAsync) {
        m_willExecuteInOrder = true;
        document->scriptRunner()->queueScriptForExecution(this, m_cachedScript, ScriptRunner::IN_ORDER_EXECUTION);
        m_cachedScript->addClient(this);
    } else if (client->hasSourceAttribute()) {
        document->scriptRunner()->queueScriptForExecution(this, m_cachedScript, ScriptRunner::ASYNC_EXECUTION);
        m_cachedScript->addClient(this);
    } else {
        // Reset line numbering for nested writes.
        TextPosition position = document->isInDocumentWrite() ? TextPosition() : scriptStartPosition;
        KURL scriptURL = (!document->isInDocumentWrite() && m_parserInserted) ? document->url() : KURL();
        executeScript(ScriptSourceCode(scriptContent(), scriptURL, position));
    }

    return true;
}

bool ScriptLoader::requestScript(const String& sourceUrl)
{
    ASSERT(m_element);

    RefPtr<Document> originalDocument = m_element->document();
    if (!m_element->dispatchBeforeLoadEvent(sourceUrl))
        return false;
    if (!m_element->inDocument() || m_element->document() != originalDocument)
        return false;

    ASSERT(!m_cachedScript);
    if (!stripLeadingAndTrailingHTMLSpaces(sourceUrl).isEmpty()) {
        CachedResourceRequest request(ResourceRequest(m_element->document()->completeURL(sourceUrl)), m_element->localName());

        String crossOriginMode = m_element->fastGetAttribute(HTMLNames::crossoriginAttr);
        if (!crossOriginMode.isNull()) {
            StoredCredentials allowCredentials = equalIgnoringCase(crossOriginMode, "use-credentials") ? AllowStoredCredentials : DoNotAllowStoredCredentials;
            request.setPotentiallyCrossOriginEnabled(m_element->document()->securityOrigin(), allowCredentials);
        }
        request.setCharset(scriptCharset());

        bool isValidScriptNonce = m_element->document()->contentSecurityPolicy()->allowScriptNonce(m_element->fastGetAttribute(HTMLNames::nonceAttr));
        if (isValidScriptNonce)
            request.setContentSecurityCheck(DoNotCheckContentSecurityPolicy);

        m_cachedScript = m_element->document()->cachedResourceLoader()->requestScript(request);
        m_isExternalScript = true;
    }

    if (m_cachedScript) {
        return true;
    }

    dispatchErrorEvent();
    return false;
}

bool isHTMLScriptLoader(Element* element)
{
    return element->hasTagName(HTMLNames::scriptTag);
}

bool isSVGScriptLoader(Element* element)
{
    return element->hasTagName(SVGNames::scriptTag);
}

void ScriptLoader::executeScript(const ScriptSourceCode& sourceCode)
{
    ASSERT(m_alreadyStarted);

    if (sourceCode.isEmpty())
        return;

    RefPtr<Document> document = m_element->document();
    Frame* frame = document->frame();

    bool shouldBypassMainWorldContentSecurityPolicy = (frame && frame->script()->shouldBypassMainWorldContentSecurityPolicy()) || document->contentSecurityPolicy()->allowScriptNonce(m_element->fastGetAttribute(HTMLNames::nonceAttr));

    if (!m_isExternalScript && (!shouldBypassMainWorldContentSecurityPolicy && !document->contentSecurityPolicy()->allowInlineScript(document->url(), m_startLineNumber)))
        return;

    if (m_isExternalScript && m_cachedScript && !m_cachedScript->mimeTypeAllowedByNosniff()) {
        document->addConsoleMessage(SecurityMessageSource, ErrorMessageLevel, "Refused to execute script from '" + m_cachedScript->url().elidedString() + "' because its MIME type ('" + m_cachedScript->mimeType() + "') is not executable, and strict MIME type checking is enabled.");
        return;
    }

    if (frame) {
        IgnoreDestructiveWriteCountIncrementer ignoreDesctructiveWriteCountIncrementer(m_isExternalScript ? document.get() : 0);

        if (isHTMLScriptLoader(m_element))
            document->pushCurrentScript(toHTMLScriptElement(m_element));

        // Create a script from the script element node, using the script
        // block's source and the script block's type.
        // Note: This is where the script is compiled and actually executed.
        frame->script()->executeScriptInMainWorld(sourceCode);

        if (isHTMLScriptLoader(m_element)) {
            ASSERT(document->currentScript() == m_element);
            document->popCurrentScript();
        }
    }
}

void ScriptLoader::stopLoadRequest()
{
    if (m_cachedScript) {
        if (!m_willBeParserExecuted)
            m_cachedScript->removeClient(this);
        m_cachedScript = 0;
    }
}

void ScriptLoader::execute(CachedScript* cachedScript)
{
    ASSERT(!m_willBeParserExecuted);
    ASSERT(cachedScript);
    if (cachedScript->errorOccurred()) {
        dispatchErrorEvent();
    } else if (!cachedScript->wasCanceled()) {
        executeScript(ScriptSourceCode(cachedScript));
        dispatchLoadEvent();
    }
    cachedScript->removeClient(this);
}

void ScriptLoader::notifyFinished(CachedResource* resource)
{
    ASSERT(!m_willBeParserExecuted);

    // CachedResource possibly invokes this notifyFinished() more than
    // once because ScriptLoader doesn't unsubscribe itself from
    // CachedResource here and does it in execute() instead.
    // We use m_cachedScript to check if this function is already called.
    ASSERT_UNUSED(resource, resource == m_cachedScript);
    if (!m_cachedScript)
        return;
    if (!m_element->document()->cachedResourceLoader()->canAccess(m_cachedScript.get())) {
        dispatchErrorEvent();
        return;
    }

    if (m_willExecuteInOrder)
        m_element->document()->scriptRunner()->notifyScriptReady(this, ScriptRunner::IN_ORDER_EXECUTION);
    else
        m_element->document()->scriptRunner()->notifyScriptReady(this, ScriptRunner::ASYNC_EXECUTION);

    m_cachedScript = 0;
}

bool ScriptLoader::ignoresLoadRequest() const
{
    return m_alreadyStarted || m_isExternalScript || m_parserInserted || !element() || !element()->inDocument();
}

bool ScriptLoader::isScriptForEventSupported() const
{
    String eventAttribute = client()->eventAttributeValue();
    String forAttribute = client()->forAttributeValue();
    if (!eventAttribute.isEmpty() && !forAttribute.isEmpty()) {
        forAttribute = forAttribute.stripWhiteSpace();
        if (!equalIgnoringCase(forAttribute, "window"))
            return false;

        eventAttribute = eventAttribute.stripWhiteSpace();
        if (!equalIgnoringCase(eventAttribute, "onload") && !equalIgnoringCase(eventAttribute, "onload()"))
            return false;
    }
    return true;
}

String ScriptLoader::scriptContent() const
{
    return m_element->textFromChildren();
}

ScriptLoaderClient* ScriptLoader::client() const
{
    if (isHTMLScriptLoader(m_element))
        return toHTMLScriptElement(m_element);

    if (isSVGScriptLoader(m_element))
        return toSVGScriptElement(m_element);

    ASSERT_NOT_REACHED();
    return 0;
}

ScriptLoader* toScriptLoaderIfPossible(Element* element)
{
    if (isHTMLScriptLoader(element))
        return toHTMLScriptElement(element)->loader();

    if (isSVGScriptLoader(element))
        return toSVGScriptElement(element)->loader();

    return 0;
}

}