// This is the support for QString.
//
// Copyright (c) 2021 Riverbank Computing Limited <info@riverbankcomputing.com>
// 
// This file is part of PyQt5.
// 
// This file may be used under the terms of the GNU General Public License
// version 3.0 as published by the Free Software Foundation and appearing in
// the file LICENSE included in the packaging of this file.  Please review the
// following information to ensure the GNU General Public License version 3.0
// requirements will be met: http://www.gnu.org/copyleft/gpl.html.
// 
// If you do not wish to use this file under the terms of the GPL version 3.0
// then you may purchase a commercial license.  For more information contact
// info@riverbankcomputing.com.
// 
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.


#include <Python.h>
#include <string.h>

#include <QString>
#include <QVector>

#include "qpycore_api.h"

#include "sipAPIQtCore.h"


// Work out if we should enable PEP 393 support.  This is complicated by the
// broken LLVM that XCode v4 installs.
#if PY_VERSION_HEX >= 0x03030000
#if defined(Q_OS_MAC)
#if !defined(__llvm__) || defined(__clang__)
// Python v3.3 or later on a Mac using either g++ or Clang, but not LLVM.
#define PYQT_PEP_393
#endif
#else
// Python v3.3 or later on a non-Mac.
#define PYQT_PEP_393
#endif
#endif


// Convert a QString to a Python Unicode object.
PyObject *qpycore_PyObject_FromQString(const QString &qstr)
{
    PyObject *obj;

#if defined(PYQT_PEP_393)
    // We have to work out exactly which kind to use.  We assume ASCII while we
    // are checking so that we only go through the string once in the most
    // common case.  Note that we can't use PyUnicode_FromKindAndData() because
    // it doesn't handle surrogates in UCS2 strings.
    int qt_len = qstr.length();
    int kind;
    void *data;

    if ((obj = sipUnicodeNew(qt_len, 0x007f, &kind, &data)) == NULL)
        return NULL;

    const QChar *qch = qstr.constData();

    for (int qt_i = 0; qt_i < qt_len; ++qt_i)
    {
        ushort uch = qch->unicode();

        if (uch > 0x007f)
        {
            // This is useless.
            Py_DECREF(obj);

            // Work out what kind we really need and what the Python length
            // should be.
            uint maxchar = 0x00ff;

            int py_len = qt_len;

            while (qt_i < qt_len)
            {
                uch = qch->unicode();

                if (uch > 0x00ff)
                {
                    if (maxchar == 0x00ff)
                        maxchar = 0x00ffff;

                    // See if this is a surrogate pair.  Note that we cannot
                    // trust that the QString is terminated by a null QChar.
                    if (qch->isHighSurrogate() && qt_i + 1 < qt_len && (qch + 1)->isLowSurrogate())
                    {
                        maxchar = 0x10ffff;
                        --py_len;
                        ++qch;
                        ++qt_i;
                    }
                }

                ++qch;
                ++qt_i;
            }

            // Create the correctly sized object.
            if ((obj = sipUnicodeNew(py_len, maxchar, &kind, &data)) == NULL)
                return NULL;

            qch = qstr.constData();

            int qt_i2 = 0;

            for (int py_i = 0; py_i < py_len; ++py_i)
            {
                uint py_ch;

                if (qch->isHighSurrogate() && qt_i2 + 1 < qt_len && (qch + 1)->isLowSurrogate())
                {
                    py_ch = QChar::surrogateToUcs4(*qch, *(qch + 1));
                    ++qt_i2;
                    ++qch;
                }
                else
                {
                    py_ch = qch->unicode();
                }

                ++qt_i2;
                ++qch;

                sipUnicodeWrite(kind, data, py_i, py_ch);
            }

            break;
        }

        ++qch;

        sipUnicodeWrite(kind, data, qt_i, uch);
    }
#elif defined(Py_UNICODE_WIDE)
    QVector<uint> ucs4 = qstr.toUcs4();

    if ((obj = PyUnicode_FromUnicode(NULL, ucs4.size())) == NULL)
        return NULL;

    memcpy(PyUnicode_AS_UNICODE(obj), ucs4.constData(),
            ucs4.size() * sizeof (Py_UNICODE));
#else
    if ((obj = PyUnicode_FromUnicode(NULL, qstr.length())) == NULL)
        return NULL;

    memcpy(PyUnicode_AS_UNICODE(obj), qstr.utf16(),
            qstr.length() * sizeof (Py_UNICODE));
#endif

    return obj;
}


// Convert a Python string object to a QString.
QString qpycore_PyObject_AsQString(PyObject *obj)
{
#if PY_MAJOR_VERSION < 3
    if (PyString_Check(obj))
    {
        const char *obj_s = PyString_AsString(obj);

        if (!obj_s)
            return QString();

        return QString::fromUtf8(obj_s);
    }
#endif

#if defined(PYQT_PEP_393)
    int char_size;
    Py_ssize_t len;
    void *data = sipUnicodeData(obj, &char_size, &len);

    if (char_size == 1)
        return QString::fromLatin1(reinterpret_cast<char *>(data), len);

    if (char_size == 2)
        // The (QChar *) cast should be safe.
        return QString(reinterpret_cast<QChar *>(data), len);

    if (char_size == 4)
        return QString::fromUcs4(reinterpret_cast<uint *>(data), len);

    return QString();
#elif defined(Py_UNICODE_WIDE)
    return QString::fromUcs4((const uint *)PyUnicode_AS_UNICODE(obj),
            PyUnicode_GET_SIZE(obj));
#else
    return QString::fromUtf16((const ushort *)PyUnicode_AS_UNICODE(obj),
            PyUnicode_GET_SIZE(obj));
#endif
}
