// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial

#include <Python.h> // Include before Qt headers due to 'slots' macro definition

#include "designercustomwidgets.h"

#include <QtCore/QCoreApplication>
#include <QtCore/QDebug>
#include <QtCore/QDir>
#include <QtCore/QFile>
#include <QtCore/QFileInfoList>
#include <QtCore/QLoggingCategory>
#include <QtCore/QOperatingSystemVersion>
#include <QtCore/QTextStream>
#include <QtCore/QVariant>

#include <string_view>

using namespace Qt::StringLiterals;

Q_LOGGING_CATEGORY(lcPySidePlugin, "qt.pysideplugin")

static const char pathVar[] = "PYSIDE_DESIGNER_PLUGINS";
static const char pythonPathVar[] = "PYTHONPATH";

// Find the static instance of 'QPyDesignerCustomWidgetCollection'
// registered as a dynamic property of QCoreApplication.
static QDesignerCustomWidgetCollectionInterface *findPyDesignerCustomWidgetCollection()
{
    static const char propertyName[] =  "__qt_PySideCustomWidgetCollection";
    if (auto *coreApp = QCoreApplication::instance()) {
        const QVariant value = coreApp->property(propertyName);
        if (value.isValid() && value.canConvert<void *>())
            return reinterpret_cast<QDesignerCustomWidgetCollectionInterface *>(value.value<void *>());
    }
    return nullptr;
}

static QString pyStringToQString(PyObject *s)
{
    // PyUnicode_AsUTF8() is not available in the Limited API
    if (PyObject *bytesStr = PyUnicode_AsEncodedString(s, "utf8", nullptr))
        return QString::fromUtf8(PyBytes_AsString(bytesStr));
    return {};
}

// Return str() of a Python object
static QString pyStr(PyObject *o)
{
    PyObject *pstr = PyObject_Str(o);
    return pstr != nullptr ? pyStringToQString(pstr) : QString();
}

static QString pyErrorMessage()
{
    QString result = QLatin1String("<error information not available>");
    PyObject *ptype = {};
    PyObject *pvalue = {};
    PyObject *ptraceback = {};
    PyErr_Fetch(&ptype, &pvalue, &ptraceback);
    if (pvalue != nullptr)
        result = pyStr(pvalue);
    PyErr_Restore(ptype, pvalue, ptraceback);
    return result;
}


#ifdef Py_LIMITED_API
// Provide PyRun_String() for limited API (see libshiboken/pep384impl.cpp)
// Flags are ignored in these simple helpers.
PyObject *PyRun_String(const char *str, int start, PyObject *globals, PyObject *locals)
{
    PyObject *code = Py_CompileString(str, "pyscript", start);
    PyObject *ret = nullptr;

    if (code != nullptr) {
        ret = PyEval_EvalCode(code, globals, locals);
    }
    Py_XDECREF(code);
    return ret;
}
#endif // Py_LIMITED_API

static bool runPyScript(const char *script, QString *errorMessage)
{
    PyObject *main = PyImport_AddModule("__main__");
    if (main == nullptr) {
        *errorMessage = QLatin1String("Internal error: Cannot retrieve __main__");
        return false;
    }
    PyObject *globalDictionary = PyModule_GetDict(main);
    PyObject *localDictionary = PyDict_New();
    // Note: Limited API only has PyRun_String()
    PyObject *result = PyRun_String(script, Py_file_input, globalDictionary, localDictionary);
    const bool ok = result != nullptr;
    Py_DECREF(localDictionary);
    Py_XDECREF(result);
    if (!ok) {
        *errorMessage = pyErrorMessage();
        PyErr_Clear();
    }
    return ok;
}

static bool runPyScriptFile(const QString &fileName, QString *errorMessage)
{
    QFile file(fileName);
    if (!file.open(QIODevice::ReadOnly| QIODevice::Text)) {
        QTextStream(errorMessage) << "Cannot open "
            << QDir::toNativeSeparators(fileName) << " for reading: "
            << file.errorString();
        return false;
    }

    const QByteArray script = file.readAll();
    file.close();
    const bool ok = runPyScript(script.constData(), errorMessage);
    if (!ok && !errorMessage->isEmpty()) {
        errorMessage->prepend(QLatin1String("Error running ") + fileName
                              + QLatin1String(": "));
    }
    return ok;
}

static void initVirtualEnvironment()
{
    static const char virtualEnvVar[] = "VIRTUAL_ENV";
    // As of Python 3.8/Windows, Python is no longer able to run stand-alone in
    // a virtualenv due to missing libraries. Add the path to the modules
    // instead. macOS seems to be showing the same issues.

    const auto os = QOperatingSystemVersion::currentType();

    bool ok;
    int majorVersion = qEnvironmentVariableIntValue("PY_MAJOR_VERSION", &ok);
    int minorVersion = qEnvironmentVariableIntValue("PY_MINOR_VERSION", &ok);
    if (!ok) {
        majorVersion = PY_MAJOR_VERSION;
        minorVersion = PY_MINOR_VERSION;
    }

    if (!qEnvironmentVariableIsSet(virtualEnvVar)
        || (os != QOperatingSystemVersion::MacOS && os != QOperatingSystemVersion::Windows)
        || (majorVersion == 3 && minorVersion < 8)) {
        return;
    }

    const QByteArray virtualEnvPath = qgetenv(virtualEnvVar);
    QByteArray pythonPath = qgetenv(pythonPathVar);
    if (!pythonPath.isEmpty())
        pythonPath.append(QDir::listSeparator().toLatin1());

    switch (os) {
    case QOperatingSystemVersion::Windows:
        pythonPath.append(virtualEnvPath + R"(\Lib\site-packages)");
        break;
    case QOperatingSystemVersion::MacOS:
        pythonPath.append(virtualEnvPath + "/lib/python"_ba +
                          QByteArray::number(majorVersion) + '.'
                          + QByteArray::number(minorVersion)
                          + "/site-packages"_ba);
        break;
    default:
        break;
    }

    qputenv(pythonPathVar, pythonPath);
}

static void initPython()
{
    // Py_SetProgramName() is considered harmful, it can break virtualenv.
    initVirtualEnvironment();

    Py_Initialize();
    qAddPostRoutine(Py_Finalize);
}

static bool withinQtDesigner = false;

PyDesignerCustomWidgets::PyDesignerCustomWidgets(QObject *parent) : QObject(parent)
{
    qCDebug(lcPySidePlugin, "%s", __FUNCTION__);

    withinQtDesigner = QCoreApplication::applicationName() == u"Designer"
                       && QCoreApplication::organizationName() == u"QtProject";

    if (!qEnvironmentVariableIsSet(pathVar)) {
        if (withinQtDesigner) {
            qCWarning(lcPySidePlugin, "Environment variable %s is not set, bailing out.",
                      pathVar);
        }
        return;
    }

    QStringList pythonFiles;
    const QString pathStr = qEnvironmentVariable(pathVar);
    const QChar listSeparator = QDir::listSeparator();
    const auto paths = pathStr.split(listSeparator);
    const QStringList oldPythonPaths =
        qEnvironmentVariable(pythonPathVar).split(listSeparator, Qt::SkipEmptyParts);
    QStringList pythonPaths = oldPythonPaths;
    // Scan for register*.py in the path
    for (const auto &p : paths) {
        QDir dir(p);
        if (dir.exists()) {
            const QFileInfoList matches =
                dir.entryInfoList({u"register*.py"_s}, QDir::Files,
                                  QDir::Name);
            for (const auto &fi : matches)
                pythonFiles.append(fi.absoluteFilePath());
            if (!matches.isEmpty()) {
                const QString dir =
                    QDir::toNativeSeparators(matches.constFirst().absolutePath());
                if (!oldPythonPaths.contains(dir))
                    pythonPaths.append(dir);
            }
        } else {
            qCWarning(lcPySidePlugin, "Directory '%s' as specified in %s does not exist.",
                      qPrintable(p), pathVar);
        }
    }
    if (pythonFiles.isEmpty()) {
        qCWarning(lcPySidePlugin, "No python files found in '%s'.", qPrintable(pathStr));
        return;
    }

    // Make modules available by adding them to the path
    if (pythonPaths != oldPythonPaths) {
        const QByteArray value = pythonPaths.join(listSeparator).toLocal8Bit();
        qCDebug(lcPySidePlugin) << "setting" << pythonPathVar << value;
        qputenv(pythonPathVar, value);
    }

    // Might be initialized already, for example, when loaded from QUiLoader.
    if (Py_IsInitialized() == 0)
        initPython();

    // Run all register*py files
    QString errorMessage;
    for (const auto &pythonFile : std::as_const(pythonFiles)) {
        qCDebug(lcPySidePlugin) << "running" << pythonFile;
        if (!runPyScriptFile(pythonFile, &errorMessage))
            qCWarning(lcPySidePlugin, "%s", qPrintable(errorMessage));
    }
}

PyDesignerCustomWidgets::~PyDesignerCustomWidgets()
{
    qCDebug(lcPySidePlugin, "%s", __FUNCTION__);
}

QList<QDesignerCustomWidgetInterface *> PyDesignerCustomWidgets::customWidgets() const
{
    if (auto *collection = findPyDesignerCustomWidgetCollection())
        return collection->customWidgets();
    if (withinQtDesigner)
        qCWarning(lcPySidePlugin, "No instance of QPyDesignerCustomWidgetCollection was found.");
    return {};
}
