// SPDX-FileCopyrightText: 2017 - 2022 Uniontech Software Technology Co.,Ltd.
//
// SPDX-License-Identifier: LGPL-3.0-or-later

#include "ddynamicmetaobject.h"
#include "dplatformsettings.h"

#include <QDebug>
#include <QMetaProperty>
#include <QMetaMethod>

#define VALID_PROPERTIES "validProperties"
#define ALL_KEYS "allKeys"

DGUI_BEGIN_NAMESPACE

QHash<QObject*, DDynamicMetaObject*> DDynamicMetaObject::mapped;
/*
 * 将 base 对象的 metaobject 替换成 this，会跟随 base 对象一起销毁。
 * 通过覆盖 QObject 的 qt_metacall 虚函数，检测 base object 中自定义的属性列表
 * 将 settings 对应的 setting/setSetting 和 object 对象中的属性绑定到一起使用
 * 将 base 对象通过 property/setProperty 调用对属性的读写操作转为对 setting 的 setting/setSetting 调用
 */
DDynamicMetaObject::DDynamicMetaObject(QObject *base, DPlatformSettings *settings, bool global_settings)
    : m_base(base)
    , m_settings(settings)
    , m_isGlobalSettings(global_settings)
{
    if (mapped.value(base)) {
        qCritical() << "DDynamicMetaObject: Native settings are already initialized for object:" << base;
        std::abort();
    }

    mapped[base] = this;

    const QMetaObject *meta_object;

    if (qintptr ptr = qvariant_cast<qintptr>(m_base->property("_d_metaObject"))) {
        meta_object = reinterpret_cast<const QMetaObject*>(ptr);
    } else {
        meta_object = m_base->metaObject();
    }

    if (m_settings->initialized()) {
        init(meta_object);
    }
}

DDynamicMetaObject::~DDynamicMetaObject()
{
    if (!m_isGlobalSettings) {
        delete m_settings;
    } else if (m_settings->initialized()) {
        // 移除注册的callback
        m_settings->removeCallbackForHandle(this);
        m_settings->removeSignalCallback(this);
    }

    mapped.remove(m_base);

    if (m_metaObject) {
        free(m_metaObject);
    }
}

bool DDynamicMetaObject::isValid() const
{
    return m_settings->initialized();
}

void DDynamicMetaObject::init(const QMetaObject *metaObject)
{
    m_objectBuilder.addMetaObject(metaObject);
    m_firstProperty = metaObject->propertyOffset();
    m_propertyCount = m_objectBuilder.propertyCount();
    // 用于记录属性是否有效的属性, 属性类型为64位整数，最多可用于记录64个属性的状态
    m_flagPropertyIndex = metaObject->indexOfProperty(VALID_PROPERTIES);
    qint64 validProperties = 0;
    // 用于记录所有属性的key
    m_allKeysPropertyIndex = metaObject->indexOfProperty(ALL_KEYS);
    int allKeyPropertyType = 0;

    QMetaObjectBuilder &ob = m_objectBuilder;

#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
    ob.setFlags(ob.flags() | DynamicMetaObject);
#else
    ob.setFlags(ob.flags() | QMetaObjectBuilder::DynamicMetaObject);
#endif

    // 先删除所有的属性，等待重构
    while (ob.propertyCount() > 0) {
        ob.removeProperty(0);
    }

    QVector<int> propertySignalIndex;
    propertySignalIndex.reserve(m_propertyCount);

    // QMetaObjectBuilder对象中的属性、信号、方法均从0开始，但是m_base对象的QMetaObject则包含offset
    // 因此往QMetaObjectBuilder对象中添加属性时要将其对应的信号的index减去偏移量
    int signal_offset = metaObject->methodOffset();

    for (int i = 0; i < m_propertyCount; ++i) {
        int index = i + m_firstProperty;

        const QMetaProperty &mp = metaObject->property(index);

        if (mp.hasNotifySignal()) {
            propertySignalIndex << mp.notifySignalIndex();
        }

        // 跳过特殊属性
        if (index == m_flagPropertyIndex) {
            ob.addProperty(mp);
            continue;
        }

        if (index == m_allKeysPropertyIndex) {
            ob.addProperty(mp);
            allKeyPropertyType = mp.userType();
            continue;
        }

        if (m_settings->setting(mp.name()).isValid()) {
            validProperties |= (1 << i);
        }

        QMetaPropertyBuilder op;

        switch (mp.type()) {
        case QVariant::Type::ByteArray:
        case QVariant::Type::String:
        case QVariant::Type::Color:
        case QVariant::Type::Int:
        case QVariant::Type::Double:
        case QVariant::Type::Bool:
            op = ob.addProperty(mp);
            break;
        default:
            // 重设属性的类型，只支持Int double color string bytearray
            op = ob.addProperty(mp.name(), "QByteArray", mp.notifySignalIndex());
            break;
        }

        if (op.isWritable()) {
            // 声明支持属性reset
            op.setResettable(true);
        }

        // 重置属性对应的信号
        if (op.hasNotifySignal()) {
            op.setNotifySignal(ob.method(op.notifySignal().index() - signal_offset));
        }
    }

    {
        // 通过class info确定是否应该关联对象的信号
        int index = metaObject->indexOfClassInfo("SignalType");

        if (index >= 0) {
            const QByteArray signals_value(metaObject->classInfo(index).value());

            // 如果base对象声明为信号的生产者，则应该将其产生的信号转发到native settings
            if (signals_value == "producer") {
                // 创建一个槽用于接收所有信号
                m_relaySlotIndex = ob.addMethod("relaySlot(QByteArray,qint32,qint32)").index() + metaObject->methodOffset();
            }
        }
    }

    // 将属性状态设置给对象
    m_base->setProperty(VALID_PROPERTIES, validProperties);

    // 将所有属性名称设置给对象
    if (allKeyPropertyType == qMetaTypeId<QSet<QByteArray>>()) {
        QSet<QString> set(m_settings->settingKeys().begin(), m_settings->settingKeys().end());
        m_base->setProperty(ALL_KEYS, QVariant::fromValue(set));
    } else {
        m_base->setProperty(ALL_KEYS, QVariant::fromValue(m_settings->settingKeys()));
    }

    m_propertySignalIndex = metaObject->indexOfMethod(QMetaObject::normalizedSignature("propertyChanged(const QByteArray&, const QVariant&)"));
    // 监听native setting变化
    m_settings->registerCallback(reinterpret_cast<DPlatformSettings::PropertyChangeFunc>(onPropertyChanged), this);
    // 监听信号. 如果base对象声明了要转发其信号，则此对象不应该关心来自于native settings的信号
    // 即信号的生产者和消费者只能选其一
    if (!isRelaySignal()) {
        m_settings->registerSignalCallback(reinterpret_cast<DPlatformSettings::SignalFunc>(onSignal), this);
    }
    // 支持在base对象中直接使用property/setProperty读写native属性
    QObjectPrivate *op = QObjectPrivate::get(m_base);
    op->metaObject = this;
    m_metaObject = ob.toMetaObject();
    *static_cast<QMetaObject *>(this) = *m_metaObject;

    if (isRelaySignal()) {
        // 把 static_metacall 置为nullptr，迫使对base对象调用QMetaObject::invodeMethod时使用DDynamicMetaObject::metaCall
        d.static_metacall = nullptr;
        // 链接 base 对象的所有信号
        int first_method = methodOffset();
        int method_count = methodCount();

        for (int i = 0; i < method_count; ++i) {
            int index = i + first_method;

            // 排除属性对应的信号
            if (propertySignalIndex.contains(index)) {
                continue;
            }

            QMetaMethod method = this->method(index);

            if (method.methodType() != QMetaMethod::Signal) {
                continue;
            }

            QMetaObject::connect(m_base, index, m_base, m_relaySlotIndex, Qt::DirectConnection);
        }
    }
}

QByteArray DDynamicMetaObject::getSettingsProperty(QObject *base)
{
    const QMetaObject *meta_object;

    if (qintptr ptr = qvariant_cast<qintptr>(base->property("_d_metaObject"))) {
        meta_object = reinterpret_cast<const QMetaObject*>(ptr);
    } else {
        meta_object = base->metaObject();
    }

    QByteArray settings_property;

    {
        // 获取base对象是否指定了native settings的域
        // 默认情况下，native settings的值保存在窗口的_XSETTINGS_SETTINGS属性上
        // 指定域后，会将native settings的值保存到指定的窗口属性。
        // 将域的值转换成窗口属性时，会把 "/" 替换为 "_"，如域："/xxx/xxx" 转成窗口属性为："_xxx_xxx"
        // 且所有字母转换为大写
        settings_property = base->property("_d_domain").toByteArray();

        if (settings_property.isEmpty()) {
            int index = meta_object->indexOfClassInfo("Domain");

            if (index >= 0) {
                settings_property = QByteArray(meta_object->classInfo(index).value());
            }
        }

        if (!settings_property.isEmpty()) {
            settings_property = settings_property.toUpper();
            settings_property.replace('/', '_');
        }
    }

    return settings_property;
}

int DDynamicMetaObject::createProperty(const char *name, const char *)
{
    // 不处理空字符串
    if (strlen(name) == 0) {
        return -1;
    }

    // 不创建特殊属性(以'_'开头的属性认为是私有的，不自动关联到native Settings)
    if (QByteArrayLiteral(VALID_PROPERTIES) == name
            || QByteArrayLiteral(ALL_KEYS) == name
            || name[0] == '_') {
        return -1;
    }

    // 清理旧数据
    free(m_metaObject);

    // 添加新属性
    auto property = m_objectBuilder.addProperty(name, "QVariant");
    property.setReadable(true);
    property.setWritable(true);
    property.setResettable(true);
    m_metaObject = m_objectBuilder.toMetaObject();
    *static_cast<QMetaObject *>(this) = *m_metaObject;

    return m_firstProperty + property.index();
}

void DDynamicMetaObject::onPropertyChanged(const QByteArray &name, const QVariant &property, DDynamicMetaObject *handle)
{
    if (handle->m_propertySignalIndex >= 0) {
        handle->method(handle->m_propertySignalIndex).invoke(handle->m_base, Q_ARG(QByteArray, name), Q_ARG(QVariant, property));
    }

    // 重设对象的 ALL_KEYS 属性
    {
        const QVariant &old_property = handle->m_base->property(ALL_KEYS);

        if (old_property.canConvert<QSet<QByteArray>>()) {
            QSet<QByteArray> keys = qvariant_cast<QSet<QByteArray>>(old_property);
            int old_count = keys.count();

            if (property.isValid()) {
                keys << name;
            } else if (keys.contains(name)) {
                keys.remove(name);
            }

            // 数量无变化时说明值无变化
            if (old_count != keys.count()) {
                handle->m_base->setProperty(ALL_KEYS, QVariant::fromValue(keys));
            }
        } else {
            bool changed = false;
            QByteArrayList keys = qvariant_cast<QByteArrayList>(old_property);

            if (property.isValid()) {
                if (!keys.contains(name)) {
                    keys << name;
                    changed = true;
                }
            } else if (keys.contains(name)) {
                keys.removeOne(name);
                changed = true;
            }

            if (changed) {
                handle->m_base->setProperty(ALL_KEYS, QVariant::fromValue(keys));
            }
        }
    }

    // 不要直接调用自己的indexOfProperty函数，属性不存在时会导致调用createProperty函数
    int property_index = handle->m_objectBuilder.indexOfProperty(name.constData());

    if (Q_UNLIKELY(property_index < 0)) {
        return;
    }

    {
        bool ok = false;
        qint64 flags = handle->m_base->property(VALID_PROPERTIES).toLongLong(&ok);
        // 更新有效属性的标志位
        if (ok) {
            qint64 flag = (1 << property_index);
            flags = property.isValid() ? flags | flag : flags & ~flag;
            handle->m_base->setProperty(VALID_PROPERTIES, flags);
        }
    }

    const QMetaProperty &p = handle->property(handle->m_firstProperty + property_index);

    if (p.hasNotifySignal()) {
        // 通知属性改变
        p.notifySignal().invoke(handle->m_base);
    }
}

// 处理native settings发过来的信号
void DDynamicMetaObject::onSignal(const QByteArray &signal, qint32 data1, qint32 data2, DDynamicMetaObject *handle)
{
    // 根据不同的参数寻找对应的信号
    static QByteArrayList signal_suffixs {
        QByteArrayLiteral("()"),
        QByteArrayLiteral("(qint32)"),
        QByteArrayLiteral("(qint32,qint32)")
    };

    int signal_index = -1;

    for (const QByteArray &suffix : signal_suffixs) {
        signal_index = handle->indexOfMethod(signal + suffix);

        if (signal_index >= 0)
            break;
    }

    QMetaMethod signal_method = handle->method(signal_index);
    // 调用base对象对应的信号
    signal_method.invoke(handle->m_base, Qt::DirectConnection, Q_ARG(qint32, data1), Q_ARG(qint32, data2));
}

int DDynamicMetaObject::metaCall(QMetaObject::Call _c, int _id, void ** _a)
{
    enum CallFlag {
        ReadProperty = 1 << QMetaObject::ReadProperty,
        WriteProperty = 1 << QMetaObject::WriteProperty,
        ResetProperty = 1 << QMetaObject::ResetProperty,
        AllCall = ReadProperty | WriteProperty | ResetProperty
    };

    if (AllCall & (1 << _c)) {
        const QMetaProperty &p = property(_id);
        const int index = p.propertyIndex();
        // 对于本地属性，此处应该从m_settings中读写
        if (Q_LIKELY(index != m_flagPropertyIndex && index != m_allKeysPropertyIndex
                     && index >= m_firstProperty)) {
            switch (_c) {
            case QMetaObject::ReadProperty:
                *reinterpret_cast<QVariant*>(_a[1]) = m_settings->setting(p.name());
                _a[0] = reinterpret_cast<QVariant*>(_a[1])->data();
                break;
            case QMetaObject::WriteProperty:
                m_settings->setSetting(p.name(), *reinterpret_cast<QVariant*>(_a[1]));
                break;
            case QMetaObject::ResetProperty:
                m_settings->setSetting(p.name(), QVariant());
                break;
            default:
                break;
            }

            return -1;
        }
    }

    do {
        if (!isRelaySignal())
            break;

        if (Q_LIKELY(_c != QMetaObject::InvokeMetaMethod || _id != m_relaySlotIndex)) {
            break;
        }

        int signal = m_base->senderSignalIndex();
        QByteArray signal_name;
        qint32 data1 = 0, data2 = 0;

        // 不是通过信号触发的槽调用，可能是使用QMetaObject::invoke
        if (signal < 0) {
            signal_name = *reinterpret_cast<QByteArray*>(_a[1]);
            data1 = *reinterpret_cast<qint32*>(_a[2]);
            data2 = *reinterpret_cast<qint32*>(_a[3]);
        } else {
            const auto &signal_method = method(signal);
            signal_name = signal_method.name();

            // 0为return type, 因此参数值下标从1开始
            if (signal_method.parameterCount() > 0) {
#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
                QVariant arg(signal_method.parameterMetaType(0), _a[1]);
#else
                QVariant arg(signal_method.parameterType(0), _a[1]);
#endif
                // 获取参数1，获取参数2
                data1 = arg.toInt();
            }

            if (signal_method.parameterCount() > 1) {
#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
                QVariant arg(signal_method.parameterMetaType(1), _a[2]);
#else
                QVariant arg(signal_method.parameterType(1), _a[2]);
#endif
                data2 = arg.toInt();
            }
        }

        m_settings->emitSignal(signal_name, data1, data2);

        return -1;
    } while (false);

    return m_base->qt_metacall(_c, _id, _a);
}

bool DDynamicMetaObject::isRelaySignal() const
{
    return m_relaySlotIndex > 0;
}

DGUI_END_NAMESPACE
