/*
    Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)

    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.
*/

#ifndef qscriptvalue_p_h
#define qscriptvalue_p_h

#include "qscriptconverter_p.h"
#include "qscriptengine_p.h"
#include "qscriptvalue.h"
#include <JavaScriptCore/JavaScript.h>
#include <JavaScriptCore/JSRetainPtr.h>
#include <QtCore/qmath.h>
#include <QtCore/qnumeric.h>
#include <QtCore/qshareddata.h>
#include <QtCore/qvarlengtharray.h>

class QScriptEngine;
class QScriptValue;

/*
  \internal
  \class QScriptValuePrivate

  Implementation of QScriptValue.
  The implementation is based on a state machine. The states names are included in
  QScriptValuePrivate::State. Each method should check for the current state and then perform a
  correct action.

  State:
    Invalid -> QSVP is invalid, no assumptions should be made about class members (apart from m_value).
    CString -> QSVP is created from QString or const char* and no JSC engine has been associated yet.
        Current value is kept in m_string,
    CNumber -> QSVP is created from int, uint, double... and no JSC engine has been bind yet. Current
        value is kept in m_number
    CBool -> QSVP is created from bool and no JSC engine has been associated yet. Current value is kept
        in m_number
    CSpecial -> QSVP is Undefined or Null, but a JSC engine hasn't been associated yet, current value
        is kept in m_number (cast of QScriptValue::SpecialValue)
    JSValue -> QSVP is associated with engine, but there is no information about real type, the state
        have really short live cycle. Normally it is created as a function call result.
    JSPrimitive -> QSVP is associated with engine, and it is sure that it isn't a JavaScript object.
    JSObject -> QSVP is associated with engine, and it is sure that it is a JavaScript object.

  Each state keep all necessary information to invoke all methods, if not it should be changed to
  a proper state. Changed state shouldn't be reverted.
*/

class QScriptValuePrivate : public QSharedData {
public:
    inline static QScriptValuePrivate* get(const QScriptValue& q);
    inline static QScriptValue get(const QScriptValuePrivate* d);
    inline static QScriptValue get(QScriptValuePrivate* d);

    inline ~QScriptValuePrivate();

    inline QScriptValuePrivate();
    inline QScriptValuePrivate(const QString& string);
    inline QScriptValuePrivate(bool value);
    inline QScriptValuePrivate(int number);
    inline QScriptValuePrivate(uint number);
    inline QScriptValuePrivate(qsreal number);
    inline QScriptValuePrivate(QScriptValue::SpecialValue value);

    inline QScriptValuePrivate(const QScriptEnginePrivate* engine, bool value);
    inline QScriptValuePrivate(const QScriptEnginePrivate* engine, int value);
    inline QScriptValuePrivate(const QScriptEnginePrivate* engine, uint value);
    inline QScriptValuePrivate(const QScriptEnginePrivate* engine, qsreal value);
    inline QScriptValuePrivate(const QScriptEnginePrivate* engine, const QString& value);
    inline QScriptValuePrivate(const QScriptEnginePrivate* engine, QScriptValue::SpecialValue value);

    inline QScriptValuePrivate(const QScriptEnginePrivate* engine, JSValueRef value);
    inline QScriptValuePrivate(const QScriptEnginePrivate* engine, JSValueRef value, JSObjectRef object);

    inline bool isValid() const;
    inline bool isBool();
    inline bool isNumber();
    inline bool isNull();
    inline bool isString();
    inline bool isUndefined();
    inline bool isError();
    inline bool isObject();
    inline bool isFunction();

    inline QString toString() const;
    inline qsreal toNumber() const;
    inline bool toBool() const;
    inline qsreal toInteger() const;
    inline qint32 toInt32() const;
    inline quint32 toUInt32() const;
    inline quint16 toUInt16() const;
    inline QScriptValuePrivate* toObject(QScriptEnginePrivate* engine);
    inline QScriptValuePrivate* toObject();

    inline bool equals(QScriptValuePrivate* other);
    inline bool strictlyEquals(const QScriptValuePrivate* other) const;
    inline bool assignEngine(QScriptEnginePrivate* engine);

    inline QScriptValuePrivate* call(const QScriptValuePrivate* , const QScriptValueList& args);

    inline JSGlobalContextRef context() const;
    inline JSValueRef value() const;
    inline JSObjectRef object() const;
    inline QScriptEnginePrivate* engine() const;

private:
    // Please, update class documentation when you change the enum.
    enum State {
        Invalid = 0,
        CString = 0x1000,
        CNumber,
        CBool,
        CSpecial,
        JSValue = 0x2000, // JS values are equal or higher then this value.
        JSPrimitive,
        JSObject
    } m_state;
    QScriptEnginePtr m_engine;
    QString m_string;
    qsreal m_number;
    JSValueRef m_value;
    JSObjectRef m_object;

    inline void setValue(JSValueRef);

    inline bool inherits(const char*);
    inline State refinedJSValue();

    inline bool isJSBased() const;
    inline bool isNumberBased() const;
    inline bool isStringBased() const;
};

QScriptValuePrivate* QScriptValuePrivate::get(const QScriptValue& q) { return q.d_ptr.data(); }

QScriptValue QScriptValuePrivate::get(const QScriptValuePrivate* d)
{
    return QScriptValue(const_cast<QScriptValuePrivate*>(d));
}

QScriptValue QScriptValuePrivate::get(QScriptValuePrivate* d)
{
    return QScriptValue(d);
}

QScriptValuePrivate::~QScriptValuePrivate()
{
    if (m_value)
        JSValueUnprotect(context(), m_value);
}

QScriptValuePrivate::QScriptValuePrivate()
    : m_state(Invalid)
    , m_value(0)
{
}

QScriptValuePrivate::QScriptValuePrivate(const QString& string)
    : m_state(CString)
    , m_string(string)
    , m_value(0)
{
}

QScriptValuePrivate::QScriptValuePrivate(bool value)
    : m_state(CBool)
    , m_number(value)
    , m_value(0)
{
}

QScriptValuePrivate::QScriptValuePrivate(int number)
    : m_state(CNumber)
    , m_number(number)
    , m_value(0)
{
}

QScriptValuePrivate::QScriptValuePrivate(uint number)
    : m_state(CNumber)
    , m_number(number)
    , m_value(0)
{
}

QScriptValuePrivate::QScriptValuePrivate(qsreal number)
    : m_state(CNumber)
    , m_number(number)
    , m_value(0)
{
}

QScriptValuePrivate::QScriptValuePrivate(QScriptValue::SpecialValue value)
    : m_state(CSpecial)
    , m_number(value)
    , m_value(0)
{
}

QScriptValuePrivate::QScriptValuePrivate(const QScriptEnginePrivate* engine, bool value)
    : m_state(JSPrimitive)
    , m_engine(const_cast<QScriptEnginePrivate*>(engine))
    , m_value(engine->makeJSValue(value))
{
    Q_ASSERT(engine);
    JSValueProtect(context(), m_value);
}

QScriptValuePrivate::QScriptValuePrivate(const QScriptEnginePrivate* engine, int value)
    : m_state(JSPrimitive)
    , m_engine(const_cast<QScriptEnginePrivate*>(engine))
    , m_value(m_engine->makeJSValue(value))
{
    Q_ASSERT(engine);
    JSValueProtect(context(), m_value);
}

QScriptValuePrivate::QScriptValuePrivate(const QScriptEnginePrivate* engine, uint value)
    : m_state(JSPrimitive)
    , m_engine(const_cast<QScriptEnginePrivate*>(engine))
    , m_value(m_engine->makeJSValue(value))
{
    Q_ASSERT(engine);
    JSValueProtect(context(), m_value);
}

QScriptValuePrivate::QScriptValuePrivate(const QScriptEnginePrivate* engine, qsreal value)
    : m_state(JSPrimitive)
    , m_engine(const_cast<QScriptEnginePrivate*>(engine))
    , m_value(m_engine->makeJSValue(value))
{
    Q_ASSERT(engine);
    JSValueProtect(context(), m_value);
}

QScriptValuePrivate::QScriptValuePrivate(const QScriptEnginePrivate* engine, const QString& value)
    : m_state(JSPrimitive)
    , m_engine(const_cast<QScriptEnginePrivate*>(engine))
    , m_value(m_engine->makeJSValue(value))
{
    Q_ASSERT(engine);
    JSValueProtect(context(), m_value);
}

QScriptValuePrivate::QScriptValuePrivate(const QScriptEnginePrivate* engine, QScriptValue::SpecialValue value)
    : m_state(JSPrimitive)
    , m_engine(const_cast<QScriptEnginePrivate*>(engine))
    , m_value(m_engine->makeJSValue(value))
{
    Q_ASSERT(engine);
    JSValueProtect(context(), m_value);
}

QScriptValuePrivate::QScriptValuePrivate(const QScriptEnginePrivate* engine, JSValueRef value)
    : m_state(JSValue)
    , m_engine(const_cast<QScriptEnginePrivate*>(engine))
    , m_value(value)
{
    Q_ASSERT(engine);
    Q_ASSERT(value);
    JSValueProtect(context(), m_value);
}

QScriptValuePrivate::QScriptValuePrivate(const QScriptEnginePrivate* engine, JSValueRef value, JSObjectRef object)
    : m_state(JSObject)
    , m_engine(const_cast<QScriptEnginePrivate*>(engine))
    , m_value(value)
    , m_object(object)
{
    Q_ASSERT(engine);
    Q_ASSERT(value);
    Q_ASSERT(object);
    JSValueProtect(context(), m_value);
}

bool QScriptValuePrivate::isValid() const { return m_state != Invalid; }

bool QScriptValuePrivate::isBool()
{
    switch (m_state) {
    case CBool:
        return true;
    case JSValue:
        if (refinedJSValue() != JSPrimitive)
            return false;
        // Fall-through.
    case JSPrimitive:
        return JSValueIsBoolean(context(), value());
    default:
        return false;
    }
}

bool QScriptValuePrivate::isNumber()
{
    switch (m_state) {
    case CNumber:
        return true;
    case JSValue:
        if (refinedJSValue() != JSPrimitive)
            return false;
        // Fall-through.
    case JSPrimitive:
        return JSValueIsNumber(context(), value());
    default:
        return false;
    }
}

bool QScriptValuePrivate::isNull()
{
    switch (m_state) {
    case CSpecial:
        return m_number == static_cast<int>(QScriptValue::NullValue);
    case JSValue:
        if (refinedJSValue() != JSPrimitive)
            return false;
        // Fall-through.
    case JSPrimitive:
        return JSValueIsNull(context(), value());
    default:
        return false;
    }
}

bool QScriptValuePrivate::isString()
{
    switch (m_state) {
    case CString:
        return true;
    case JSValue:
        if (refinedJSValue() != JSPrimitive)
            return false;
        // Fall-through.
    case JSPrimitive:
        return JSValueIsString(context(), value());
    default:
        return false;
    }
}

bool QScriptValuePrivate::isUndefined()
{
    switch (m_state) {
    case CSpecial:
        return m_number == static_cast<int>(QScriptValue::UndefinedValue);
    case JSValue:
        if (refinedJSValue() != JSPrimitive)
            return false;
        // Fall-through.
    case JSPrimitive:
        return JSValueIsUndefined(context(), value());
    default:
        return false;
    }
}

bool QScriptValuePrivate::isError()
{
    switch (m_state) {
    case JSValue:
        if (refinedJSValue() != JSObject)
            return false;
        // Fall-through.
    case JSObject:
        return inherits("Error");
    default:
        return false;
    }
}

bool QScriptValuePrivate::isObject()
{
    switch (m_state) {
    case JSValue:
        return refinedJSValue() == JSObject;
    case JSObject:
        return true;

    default:
        return false;
    }
}

bool QScriptValuePrivate::isFunction()
{
    switch (m_state) {
    case JSValue:
        if (refinedJSValue() != JSObject)
            return false;
        // Fall-through.
    case JSObject:
        return JSObjectIsFunction(context(), object());
    default:
        return false;
    }
}

QString QScriptValuePrivate::toString() const
{
    switch (m_state) {
    case Invalid:
        return QString();
    case CBool:
        return m_number ? QString::fromLatin1("true") : QString::fromLatin1("false");
    case CString:
        return m_string;
    case CNumber:
        return QScriptConverter::toString(m_number);
    case CSpecial:
        return m_number == QScriptValue::NullValue ? QString::fromLatin1("null") : QString::fromLatin1("undefined");
    case JSValue:
    case JSPrimitive:
    case JSObject:
        JSRetainPtr<JSStringRef> ptr(Adopt, JSValueToStringCopy(context(), value(), /* exception */ 0));
        return QScriptConverter::toString(ptr.get());
    }

    Q_ASSERT_X(false, "toString()", "Not all states are included in the previous switch statement.");
    return QString(); // Avoid compiler warning.
}

qsreal QScriptValuePrivate::toNumber() const
{
    switch (m_state) {
    case JSValue:
    case JSPrimitive:
    case JSObject:
        return JSValueToNumber(context(), value(), /* exception */ 0);
    case CNumber:
        return m_number;
    case CBool:
        return m_number ? 1 : 0;
    case Invalid:
        return 0;
    case CSpecial:
        return m_number == QScriptValue::NullValue ? 0 : qQNaN();
    case CString:
        bool ok;
        qsreal result = m_string.toDouble(&ok);
        if (ok)
            return result;
        result = m_string.toInt(&ok, 0); // Try other bases.
        if (ok)
            return result;
        if (m_string == "Infinity" || m_string == "-Infinity")
            return qInf();
        return m_string.length() ? qQNaN() : 0;
    }

    Q_ASSERT_X(false, "toNumber()", "Not all states are included in the previous switch statement.");
    return 0; // Avoid compiler warning.
}

bool QScriptValuePrivate::toBool() const
{
    switch (m_state) {
    case JSValue:
    case JSPrimitive:
        return JSValueToBoolean(context(), value());
    case JSObject:
        return true;
    case CNumber:
        return !(qIsNaN(m_number) || !m_number);
    case CBool:
        return m_number;
    case Invalid:
    case CSpecial:
        return false;
    case CString:
        return m_string.length();
    }

    Q_ASSERT_X(false, "toBool()", "Not all states are included in the previous switch statement.");
    return false; // Avoid compiler warning.
}

qsreal QScriptValuePrivate::toInteger() const
{
    qsreal result = toNumber();
    if (qIsNaN(result))
        return 0;
    if (qIsInf(result))
        return result;
    return (result > 0) ? qFloor(result) : -1 * qFloor(-result);
}

qint32 QScriptValuePrivate::toInt32() const
{
    qsreal result = toInteger();
    // Orginaly it should look like that (result == 0 || qIsInf(result) || qIsNaN(result)), but
    // some of these operation are invoked in toInteger subcall.
    if (qIsInf(result))
        return 0;
    return result;
}

quint32 QScriptValuePrivate::toUInt32() const
{
    qsreal result = toInteger();
    // Orginaly it should look like that (result == 0 || qIsInf(result) || qIsNaN(result)), but
    // some of these operation are invoked in toInteger subcall.
    if (qIsInf(result))
        return 0;
    return result;
}

quint16 QScriptValuePrivate::toUInt16() const
{
    return toInt32();
}

/*!
  Creates a copy of this value and converts it to an object. If this value is an object
  then pointer to this value will be returned.
  \attention it should not happen but if this value is bounded to a different engine that the given, the first
  one will be used.
  \internal
  */
QScriptValuePrivate* QScriptValuePrivate::toObject(QScriptEnginePrivate* engine)
{
    switch (m_state) {
    case Invalid:
    case CSpecial:
        return new QScriptValuePrivate;
    case CString:
        {
            // Exception can't occur here.
            JSObjectRef object = JSValueToObject(engine->context(), engine->makeJSValue(m_string), /* exception */ 0);
            Q_ASSERT(object);
            return new QScriptValuePrivate(engine, object, object);
        }
    case CNumber:
        {
            // Exception can't occur here.
            JSObjectRef object = JSValueToObject(engine->context(), engine->makeJSValue(m_number), /* exception */ 0);
            Q_ASSERT(object);
            return new QScriptValuePrivate(engine, object, object);
        }
    case CBool:
        {
            // Exception can't occure here.
            JSObjectRef object = JSValueToObject(engine->context(), engine->makeJSValue(static_cast<bool>(m_number)), /* exception */ 0);
            Q_ASSERT(object);
            return new QScriptValuePrivate(engine, object, object);
        }
    case JSValue:
        if (refinedJSValue() != JSPrimitive)
            break;
        // Fall-through.
    case JSPrimitive:
        {
            if (engine != this->engine())
                qWarning("QScriptEngine::toObject: cannot convert value created in a different engine");
            JSObjectRef object = JSValueToObject(context(), value(), /* exception */ 0);
            if (object)
                return new QScriptValuePrivate(m_engine.constData(), object);
        }
        return new QScriptValuePrivate;
    case JSObject:
        break;
    }

    if (engine != this->engine())
        qWarning("QScriptEngine::toObject: cannot convert value created in a different engine");
    Q_ASSERT(m_state == JSObject);
    return this;
}

/*!
  This method is created only for QScriptValue::toObject() purpose which is obsolete.
  \internal
 */
QScriptValuePrivate* QScriptValuePrivate::toObject()
{
    if (isJSBased())
        return toObject(m_engine.data());

    // Without an engine there is not much we can do.
    return new QScriptValuePrivate;
}

bool QScriptValuePrivate::equals(QScriptValuePrivate* other)
{
    if (!isValid() || !other->isValid())
        return false;

    if ((m_state == other->m_state) && !isJSBased()) {
        if (isNumberBased())
            return m_number == other->m_number;
        return m_string == other->m_string;
    }

    if (isJSBased() && !other->isJSBased()) {
        if (!other->assignEngine(engine())) {
            qWarning("equals(): Cannot compare to a value created in a different engine");
            return false;
        }
    } else if (!isJSBased() && other->isJSBased()) {
        if (!other->assignEngine(other->engine())) {
            qWarning("equals(): Cannot compare to a value created in a different engine");
            return false;
        }
    }

    return JSValueIsEqual(context(), value(), other->value(), /* exception */ 0);
}

bool QScriptValuePrivate::strictlyEquals(const QScriptValuePrivate* other) const
{
    if (m_state != other->m_state)
        return false;
    if (isJSBased()) {
        if (other->engine() != engine()) {
            qWarning("strictlyEquals(): Cannot compare to a value created in a different engine");
            return false;
        }
        return JSValueIsStrictEqual(context(), value(), other->value());
    }
    if (isStringBased())
        return m_string == other->m_string;
    if (isNumberBased())
        return m_number == other->m_number;

    return false; // Invalid state.
}

/*!
  Tries to assign \a engine to this value. Returns true on success; otherwise returns false.
*/
bool QScriptValuePrivate::assignEngine(QScriptEnginePrivate* engine)
{
    JSValueRef value;
    switch (m_state) {
    case CBool:
        value = engine->makeJSValue(static_cast<bool>(m_number));
        break;
    case CString:
        value = engine->makeJSValue(m_string);
        break;
    case CNumber:
        value = engine->makeJSValue(m_number);
        break;
    case CSpecial:
        value = engine->makeJSValue(static_cast<QScriptValue::SpecialValue>(m_number));
        break;
    default:
        if (!isJSBased())
            Q_ASSERT_X(!isJSBased(), "assignEngine()", "Not all states are included in the previous switch statement.");
        else
            qWarning("JSValue can't be rassigned to an another engine.");
        return false;
    }
    m_engine = engine;
    m_state = JSPrimitive;
    setValue(value);
    return true;
}

QScriptValuePrivate* QScriptValuePrivate::call(const QScriptValuePrivate*, const QScriptValueList& args)
{
    switch (m_state) {
    case JSValue:
        if (refinedJSValue() != JSObject)
            return new QScriptValuePrivate;
        // Fall-through.
    case JSObject:
        {
            // Convert all arguments and bind to the engine.
            int argc = args.size();
            QVarLengthArray<JSValueRef, 8> argv(argc);
            QScriptValueList::const_iterator i = args.constBegin();
            for (int j = 0; i != args.constEnd(); j++, i++) {
                QScriptValuePrivate* value = QScriptValuePrivate::get(*i);
                if (!value->assignEngine(engine())) {
                    qWarning("QScriptValue::call() failed: cannot call function with values created in a different engine");
                    return new QScriptValuePrivate;
                }
                argv[j] = value->value();
            }

            // Make the call
            JSValueRef exception = 0;
            JSValueRef result = JSObjectCallAsFunction(context(), object(), /* thisObject */ 0, argc, argv.constData(), &exception);
            if (!result && exception)
                return new QScriptValuePrivate(engine(), exception);
            if (result && !exception)
                return new QScriptValuePrivate(engine(), result);
        }
        // this QSV is not a function <-- !result && !exception. Fall-through.
    default:
        return new QScriptValuePrivate;
    }
}

QScriptEnginePrivate* QScriptValuePrivate::engine() const
{
    // As long as m_engine is an autoinitializated pointer we can safely return it without
    // checking current state.
    return m_engine.data();
}

JSGlobalContextRef QScriptValuePrivate::context() const
{
    Q_ASSERT(isJSBased());
    return m_engine->context();
}

JSValueRef QScriptValuePrivate::value() const
{
    Q_ASSERT(isJSBased());
    return m_value;
}

JSObjectRef QScriptValuePrivate::object() const
{
    Q_ASSERT(m_state == JSObject);
    return m_object;
}

void QScriptValuePrivate::setValue(JSValueRef value)
{
    if (m_value)
        JSValueUnprotect(context(), m_value);
    if (value)
        JSValueProtect(context(), value);
    m_value = value;
}

/*!
  \internal
  Returns true if QSV is created from constructor with the given \a name, it has to be a
  built-in type.
*/
bool QScriptValuePrivate::inherits(const char* name)
{
    Q_ASSERT(isJSBased());
    JSObjectRef globalObject = JSContextGetGlobalObject(context());
    JSStringRef errorAttrName = QScriptConverter::toString(name);
    JSValueRef error = JSObjectGetProperty(context(), globalObject, errorAttrName, /* exception */ 0);
    JSStringRelease(errorAttrName);
    return JSValueIsInstanceOfConstructor(context(), value(), JSValueToObject(context(), error, /* exception */ 0), /* exception */ 0);
}

/*!
  \internal
  Refines the state of this QScriptValuePrivate. Returns the new state.
*/
QScriptValuePrivate::State QScriptValuePrivate::refinedJSValue()
{
    Q_ASSERT(m_state == JSValue);
    if (!JSValueIsObject(context(), value())) {
        m_state = JSPrimitive;
    } else {
        m_state = JSObject;
        // We are sure that value is an JSObject, so we can const_cast safely without
        // calling JSC C API (JSValueToObject(context(), value(), /* exceptions */ 0)).
        m_object = const_cast<JSObjectRef>(m_value);
    }
    return m_state;
}

/*!
  \internal
  Returns true if QSV have an engine associated.
*/
bool QScriptValuePrivate::isJSBased() const { return m_state >= JSValue; }

/*!
  \internal
  Returns true if current value of QSV is placed in m_number.
*/
bool QScriptValuePrivate::isNumberBased() const { return !isJSBased() && !isStringBased() && m_state != Invalid; }

/*!
  \internal
  Returns true if current value of QSV is placed in m_string.
*/
bool QScriptValuePrivate::isStringBased() const { return m_state == CString; }

#endif // qscriptvalue_p_h