// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#if 0
// keep existing syncqt header working after the move of the class
// into qstringconverter_base
#pragma qt_class(QStringConverter)
#pragma qt_class(QStringConverterBase)
#endif

#ifndef QSTRINGCONVERTER_H
#define QSTRINGCONVERTER_H

#include <QtCore/qstringconverter_base.h>
#include <QtCore/qstring.h>
#include <QtCore/qstringbuilder.h>

QT_BEGIN_NAMESPACE

class QStringEncoder : public QStringConverter
{
protected:
    constexpr explicit QStringEncoder(const Interface *i) noexcept
        : QStringConverter(i)
    {}
public:
    constexpr QStringEncoder() noexcept
        : QStringConverter()
    {}
    constexpr explicit QStringEncoder(Encoding encoding, Flags flags = Flag::Default)
        : QStringConverter(encoding, flags)
    {}
    explicit QStringEncoder(const char *name, Flags flags = Flag::Default)
        : QStringConverter(name, flags)
    {}

#if defined(Q_QDOC)
    QByteArray operator()(const QString &in);
    QByteArray operator()(QStringView in);
    QByteArray encode(const QString &in);
    QByteArray encode(QStringView in);
#else
    template<typename T>
    struct DecodedData
    {
        QStringEncoder *encoder;
        T data;
        operator QByteArray() const { return encoder->encodeAsByteArray(data); }
    };
    Q_WEAK_OVERLOAD
    DecodedData<const QString &> operator()(const QString &str)
    { return DecodedData<const QString &>{this, str}; }
    DecodedData<QStringView> operator()(QStringView in)
    { return DecodedData<QStringView>{this, in}; }
    Q_WEAK_OVERLOAD
    DecodedData<const QString &> encode(const QString &str)
    { return DecodedData<const QString &>{this, str}; }
    DecodedData<QStringView> encode(QStringView in)
    { return DecodedData<QStringView>{this, in}; }
#endif

    qsizetype requiredSpace(qsizetype inputLength) const
    { return iface ? iface->fromUtf16Len(inputLength) : 0; }
    char *appendToBuffer(char *out, QStringView in)
    {
        if (!iface) {
            state.invalidChars = 1;
            return out;
        }
        return iface->fromUtf16(out, in, &state);
    }
private:
    QByteArray encodeAsByteArray(QStringView in)
    {
        if (!iface) {
            // ensure that hasError returns true
            state.invalidChars = 1;
            return {};
        }
        QByteArray result(iface->fromUtf16Len(in.size()), Qt::Uninitialized);
        char *out = result.data();
        out = iface->fromUtf16(out, in, &state);
        result.truncate(out - result.constData());
        return result;
    }

};

class QStringDecoder : public QStringConverter
{
protected:
    constexpr explicit QStringDecoder(const Interface *i) noexcept
        : QStringConverter(i)
    {}
public:
    constexpr explicit QStringDecoder(Encoding encoding, Flags flags = Flag::Default)
        : QStringConverter(encoding, flags)
    {}
    constexpr QStringDecoder() noexcept
        : QStringConverter()
    {}
    explicit QStringDecoder(const char *name, Flags f = Flag::Default)
        : QStringConverter(name, f)
    {}

#if defined(Q_QDOC)
    QString operator()(const QByteArray &ba);
    QString operator()(QByteArrayView ba);
    QString decode(const QByteArray &ba);
    QString decode(QByteArrayView ba);
#else
    template<typename T>
    struct EncodedData
    {
        QStringDecoder *decoder;
        T data;
        operator QString() const { return decoder->decodeAsString(data); }
    };
    Q_WEAK_OVERLOAD
    EncodedData<const QByteArray &> operator()(const QByteArray &ba)
    { return EncodedData<const QByteArray &>{this, ba}; }
    EncodedData<QByteArrayView> operator()(QByteArrayView ba)
    { return EncodedData<QByteArrayView>{this, ba}; }
    Q_WEAK_OVERLOAD
    EncodedData<const QByteArray &> decode(const QByteArray &ba)
    { return EncodedData<const QByteArray &>{this, ba}; }
    EncodedData<QByteArrayView> decode(QByteArrayView ba)
    { return EncodedData<QByteArrayView>{this, ba}; }
#endif

    qsizetype requiredSpace(qsizetype inputLength) const
    { return iface ? iface->toUtf16Len(inputLength) : 0; }
    QChar *appendToBuffer(QChar *out, QByteArrayView ba)
    {
        if (!iface) {
            state.invalidChars = 1;
            return out;
        }
        return iface->toUtf16(out, ba, &state);
    }

    Q_CORE_EXPORT static QStringDecoder decoderForHtml(QByteArrayView data);

private:
    QString decodeAsString(QByteArrayView in)
    {
        if (!iface) {
            // ensure that hasError returns true
            state.invalidChars = 1;
            return {};
        }
        QString result(iface->toUtf16Len(in.size()), Qt::Uninitialized);
        const QChar *out = iface->toUtf16(result.data(), in, &state);
        result.truncate(out - result.constData());
        return result;
    }
};


#if defined(QT_USE_FAST_OPERATOR_PLUS) || defined(QT_USE_QSTRINGBUILDER)
template <typename T>
struct QConcatenable<QStringDecoder::EncodedData<T>>
        : private QAbstractConcatenable
{
    typedef QChar type;
    typedef QString ConvertTo;
    enum { ExactSize = false };
    static qsizetype size(const QStringDecoder::EncodedData<T> &s) { return s.decoder->requiredSpace(s.data.size()); }
    static inline void appendTo(const QStringDecoder::EncodedData<T> &s, QChar *&out)
    {
        out = s.decoder->appendToBuffer(out, s.data);
    }
};

template <typename T>
struct QConcatenable<QStringEncoder::DecodedData<T>>
        : private QAbstractConcatenable
{
    typedef char type;
    typedef QByteArray ConvertTo;
    enum { ExactSize = false };
    static qsizetype size(const QStringEncoder::DecodedData<T> &s) { return s.encoder->requiredSpace(s.data.size()); }
    static inline void appendTo(const QStringEncoder::DecodedData<T> &s, char *&out)
    {
        out = s.encoder->appendToBuffer(out, s.data);
    }
};

template <typename T>
QString &operator+=(QString &a, const QStringDecoder::EncodedData<T> &b)
{
    qsizetype len = a.size() + QConcatenable<QStringDecoder::EncodedData<T>>::size(b);
    a.reserve(len);
    QChar *it = a.data() + a.size();
    QConcatenable<QStringDecoder::EncodedData<T>>::appendTo(b, it);
    a.resize(qsizetype(it - a.constData())); //may be smaller than len
    return a;
}

template <typename T>
QByteArray &operator+=(QByteArray &a, const QStringEncoder::DecodedData<T> &b)
{
    qsizetype len = a.size() + QConcatenable<QStringEncoder::DecodedData<T>>::size(b);
    a.reserve(len);
    char *it = a.data() + a.size();
    QConcatenable<QStringEncoder::DecodedData<T>>::appendTo(b, it);
    a.resize(qsizetype(it - a.constData())); //may be smaller than len
    return a;
}
#endif

QT_END_NAMESPACE

#endif
