/*!
  \internal
  \since 4.5

  Adds the given \a object to the front of this context's scope chain.

  If \a object is not an object, this function does nothing.
*/
void QScriptContext::pushScope(const QScriptValue &object)
{
    activationObject(); //ensure the creation of the normal scope for native context
    if (!object.isObject())
        return;
    else if (object.engine() != engine()) {
        qWarning("QScriptContext::pushScope() failed: "
                 "cannot push an object created in "
                 "a different engine");
        return;
    }
    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);
    QScript::APIShim shim(engine);
    JSC::JSObject *jscObject = JSC::asObject(engine->scriptValueToJSCValue(object));
    if (jscObject == engine->originalGlobalObjectProxy)
        jscObject = engine->originalGlobalObject();
    JSC::ScopeChainNode *scope = frame->scopeChain();
    Q_ASSERT(scope != 0);
    if (!scope->object) {
        // pushing to an "empty" chain
        if (!jscObject->isGlobalObject()) {
            qWarning("QScriptContext::pushScope() failed: initial object in scope chain has to be the Global Object");
            return;
        }
        scope->object = jscObject;
    }
    else
        frame->setScopeChain(scope->push(jscObject));
}
QScriptValue QScriptContext::activationObject() const
{
    JSC::CallFrame *frame = const_cast<JSC::ExecState*>(QScriptEnginePrivate::frameForContext(this));
    QScript::APIShim shim(QScript::scriptEngineFromExec(frame));
    JSC::JSObject *result = 0;

    uint flags = QScriptEnginePrivate::contextFlags(frame);
    if ((flags & QScriptEnginePrivate::NativeContext) && !(flags & QScriptEnginePrivate::HasScopeContext)) {
        //For native functions, lazily create it if needed
        QScript::QScriptActivationObject *scope = new (frame) QScript::QScriptActivationObject(frame);
        frame->setScopeChain(frame->scopeChain()->copy()->push(scope));
        result = scope;
        QScriptEnginePrivate::setContextFlags(frame, flags | QScriptEnginePrivate::HasScopeContext);
    } else {
        // look in scope chain
        JSC::ScopeChainNode *node = frame->scopeChain();
        JSC::ScopeChainIterator it(node);
        for (it = node->begin(); it != node->end(); ++it) {
            if ((*it) && (*it)->isVariableObject()) {
                result = *it;
                break;
            }
        }
    }
    if (!result) {
        if (!parentContext())
            return engine()->globalObject();

        qWarning("QScriptContext::activationObject:  could not get activation object for frame");
        return QScriptValue();
        /*JSC::CodeBlock *codeBlock = frame->codeBlock();
        if (!codeBlock) {
            // non-Qt native function 
            Q_ASSERT(true); //### this should in theorry not happen
            result = new (frame)QScript::QScriptActivationObject(frame);
        } else {
            // ### this is wrong
            JSC::FunctionBodyNode *body = static_cast<JSC::FunctionBodyNode*>(codeBlock->ownerNode());
            result = new (frame)JSC::JSActivation(frame, body);
        }*/
    }

    if (result && result->inherits(&QScript::QScriptActivationObject::info)
        && (static_cast<QScript::QScriptActivationObject*>(result)->delegate() != 0)) {
        // Return the object that property access is being delegated to
        result = static_cast<QScript::QScriptActivationObject*>(result)->delegate();
    }

    return QScript::scriptEngineFromExec(frame)->scriptValueFromJSCValue(result);
}
/*!
  \internal
  \since 4.5

  Removes the front object from this context's scope chain, and
  returns the removed object.

  If the scope chain is already empty, this function returns an
  invalid QScriptValue.
*/
QScriptValue QScriptContext::popScope()
{
    activationObject(); //ensure the creation of the normal scope for native context
    JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    JSC::ScopeChainNode *scope = frame->scopeChain();
    Q_ASSERT(scope != 0);
    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);
    QScript::APIShim shim(engine);
    QScriptValue result = engine->scriptValueFromJSCValue(scope->object);
    if (!scope->next) {
        // We cannot have a null scope chain, so just zap the object pointer.
        scope->object = 0;
    } else {
        frame->setScopeChain(scope->pop());
    }
    return result;
}
/*
Returns the scope chain entry at \a index.  If index is less than 0, returns
entries starting at the end.  For example, scopeChainValue(context, -1) will return
the value last in the scope chain.
*/
QScriptValue QScriptDeclarativeClass::scopeChainValue(QScriptContext *context, int index)
{
    context->activationObject(); //ensure the creation of the normal scope for native context
    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(context);
    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);
    QScript::APIShim shim(engine);

    JSC::ScopeChainNode *node = frame->scopeChain();
    JSC::ScopeChainIterator it(node);

    if (index < 0) {
        int count = 0;
        for (it = node->begin(); it != node->end(); ++it) 
            ++count;

        index = qAbs(index);
        if (index > count)
            return QScriptValue();
        else
            index = count - index;
    }

    for (it = node->begin(); it != node->end(); ++it) {

        if (index == 0) {

            JSC::JSObject *object = *it;
            if (!object) return QScriptValue();

            if (object->inherits(&QScript::QScriptActivationObject::info)
                    && (static_cast<QScript::QScriptActivationObject*>(object)->delegate() != 0)) {
                // Return the object that property access is being delegated to
                object = static_cast<QScript::QScriptActivationObject*>(object)->delegate();
            }
            return engine->scriptValueFromJSCValue(object);

        } else {
            --index;
        }

    }

    return QScriptValue();
}
/*!
  \internal
  \since 4.5

  Returns the scope chain of this QScriptContext.
*/
QScriptValueList QScriptContext::scopeChain() const
{
    activationObject(); //ensure the creation of the normal scope for native context
    const JSC::CallFrame *frame = QScriptEnginePrivate::frameForContext(this);
    QScriptEnginePrivate *engine = QScript::scriptEngineFromExec(frame);
    QScript::APIShim shim(engine);
    QScriptValueList result;
    JSC::ScopeChainNode *node = frame->scopeChain();
    JSC::ScopeChainIterator it(node);
    for (it = node->begin(); it != node->end(); ++it) {
        JSC::JSObject *object = *it;
        if (!object)
            continue;
        if (object->inherits(&QScript::QScriptActivationObject::info)
            && (static_cast<QScript::QScriptActivationObject*>(object)->delegate() != 0)) {
            // Return the object that property access is being delegated to
            object = static_cast<QScript::QScriptActivationObject*>(object)->delegate();
        }
        result.append(engine->scriptValueFromJSCValue(object));
    }
    return result;
}