/*
    SPDX-License-Identifier: GPL-2.0-or-later
    SPDX-FileCopyrightText: 2009 Alexander Rieder <alexanderrieder@gmail.com>
    SPDX-FileCopyrightText: 2019 Alexander Semke <alexander.semke@web.de>
*/

#include "session.h"
using namespace Cantor;

#include <map>

#include "backend.h"
#include "textresult.h"

#include <QTimer>
#include <QQueue>
#include <QDebug>
#include <KMessageBox>
#include <KLocalizedString>

class Cantor::SessionPrivate
{
  public:
    SessionPrivate() { }

    Backend* backend{nullptr};
    Session::Status status{Session::Disable};
    bool typesettingEnabled{false};
    int expressionCount{0};
    QList<Cantor::Expression*> expressionQueue;
    DefaultVariableModel* variableModel{nullptr};
    QList<GraphicPackage> usableGraphicPackages;
    QList<GraphicPackage> enabledGraphicPackages;
    QList<QString> ignorableGraphicPackageIds;
    bool needUpdate{false};
};

Session::Session(Backend* backend ) : QObject(backend), d(new SessionPrivate)
{
    d->backend = backend;

#ifdef WITH_EPS
    if (Cantor::LatexRenderer::isLatexAvailable())
        d->typesettingEnabled = Settings::self()->typesetDefault();
#endif
}

Session::Session(Backend* backend, DefaultVariableModel* model) : QObject(backend), d(new SessionPrivate)
{
    d->backend = backend;
    d->variableModel = model;

#ifdef WITH_EPS
    if (Cantor::LatexRenderer::isLatexAvailable())
        d->typesettingEnabled = Settings::self()->typesetDefault();
#endif
}

Session::~Session()
{
    delete d;
}

void Cantor::Session::testGraphicsPackages(QList<GraphicPackage> packages)
{
    std::map<QString, bool> handlingStatus;

    QEventLoop loop;
    for (GraphicPackage& package : packages)
    {
        if (GraphicPackage::findById(package, d->usableGraphicPackages) != -1)
            continue;

        handlingStatus[package.id()] = false;
        Expression* expr = package.isAvailable(this);

        connect(expr, &Expression::expressionFinished, [this, expr, &package, &loop, &handlingStatus](Expression::Status status) {
            if (status == Expression::Status::Done) {
                if (expr->result() != nullptr
                    && expr->result()->type() == TextResult::Type
                    && expr->result()->data().toString() == QLatin1String("1")) {
                    this->d->usableGraphicPackages.push_back(package);
                }
            } else {
                qDebug() << "test presence command for" << package.id() << "finished because of" << (status == Expression::Error ? "error" : "interrupt");
                if (status == Expression::Error && expr)
                    qDebug() << "error message:" << expr->errorMessage();
            }

            handlingStatus[package.id()] = true;

            bool allExpersionsFinished = true;
            for (auto& iter : handlingStatus)
            {
                if (iter.second == false)
                {
                    allExpersionsFinished = false;
                    break;
                }
            }

            if (allExpersionsFinished)
                loop.exit();
        });
    }
    // If handlingStatus size is empty (it means, that no connections have been done), then we will stay in the 'loop' event loop forever
    if (handlingStatus.size() != 0)
        loop.exec();
}

void Session::logout()
{
    if (d->status == Session::Running)
        interrupt();

    if (d->variableModel)
    {
        d->variableModel->clearVariables();
        d->variableModel->clearFunctions();
    }

    d->expressionCount = 0;
    changeStatus(Status::Disable);

    // Clean graphic package state
    d->enabledGraphicPackages.clear();
    d->ignorableGraphicPackageIds.clear();
    d->usableGraphicPackages.clear();
}

QList<Expression*>& Cantor::Session::expressionQueue() const
{
    return d->expressionQueue;
}

void Session::enqueueExpression(Expression* expr)
{
    d->expressionQueue.append(expr);

    //run the newly added expression immediately if it's the only one in the queue
    if (d->expressionQueue.size() == 1)
    {
        changeStatus(Cantor::Session::Running);
        runFirstExpression();
    }
    else
        expr->setStatus(Cantor::Expression::Queued);
}

void Session::runFirstExpression()
{

}

void Session::finishFirstExpression(bool setDoneAfterUpdate)
{
    if (!d->expressionQueue.isEmpty())
    {
        auto first = d->expressionQueue.takeFirst();
        d->needUpdate |= !first->isInternal() && !first->isHelpRequest();
    }

    if (d->expressionQueue.isEmpty())
        if (d->variableModel && d->needUpdate)
        {
            d->variableModel->update();
            d->needUpdate = false;

            // Some variable models could update internal lists without running expressions
            // or don't need to be updated at all like for Maxima being in Lisp-mode.
            // So, if after update queue still empty, set status to Done
            // setDoneAfterUpdate used for compatibility with some backends, like R - TODO: check why this is requried
            if (setDoneAfterUpdate && d->expressionQueue.isEmpty())
                changeStatus(Done);
            else if (d->expressionQueue.isEmpty())
                changeStatus(Done);
        }
        else
            changeStatus(Done);
    else
        runFirstExpression();
}

void Session::currentExpressionStatusChanged(Cantor::Expression::Status status)
{
    auto* expression = expressionQueue().first();
    qDebug() << "expression status changed: command = " << expression->command() << ", status = " << status;

    switch (status)
    {
    case Cantor::Expression::Done:
    case Cantor::Expression::Error:
        qDebug()<<"################################## EXPRESSION END ###############################################";
        disconnect(expression, &Cantor::Expression::statusChanged, this, &Session::currentExpressionStatusChanged);
        finishFirstExpression();
        break;
    default:
        break;
    }
}

Backend* Session::backend()
{
    return d->backend;
}

Cantor::Session::Status Session::status()
{
    return d->status;
}

void Session::changeStatus(Session::Status newStatus)
{
    d->status = newStatus;
    emit statusChanged(newStatus);
}

void Session::setTypesettingEnabled(bool enable)
{
    d->typesettingEnabled = enable;
}

bool Session::isTypesettingEnabled()
{
    return d->typesettingEnabled;
}

void Session::setWorksheetPath(const QString&) { }

CompletionObject* Session::completionFor(const QString&, int)
{
    //Return nullptr per default, so Backends not offering tab completions don't have
    //to reimplement this. This method should only be called on backends with
    //the Completion Capability flag

    return nullptr;
}

SyntaxHelpObject* Session::syntaxHelpFor(const QString&)
{
    //Return nullptr per default, so Backends not offering tab completions don't have
    //to reimplement this. This method should only be called on backends with
    //the SyntaxHelp Capability flag
    return nullptr;
}

QSyntaxHighlighter* Session::syntaxHighlighter(QObject*)
{
    return nullptr;
}

DefaultVariableModel* Session::variableModel() const
{
    //By default, there is variableModel in session, used by syntax higlighter for variable analyzing
    //The model store only variable names by default.
    //In backends with VariableManagement Capability flag, this model also used for Cantor variable doc panel
    return d->variableModel;
}

QAbstractItemModel* Session::variableDataModel() const
{
    return variableModel();
}

void Session::updateVariables()
{
    if (d->variableModel)
    {
        d->variableModel->update();
        d->needUpdate = false;
    }
}

void Cantor::Session::setVariableModel(Cantor::DefaultVariableModel* model)
{
    d->variableModel = model;
}

int Session::nextExpressionId()
{
    return d->expressionCount++;
}

QString Session::locateCantorFile(const QString& partialPath, QStandardPaths::LocateOptions options)
{
    QString file = QStandardPaths::locate(QStandardPaths::AppDataLocation, partialPath, options);

    if (file.isEmpty())
        file = QStandardPaths::locate(QStandardPaths::GenericDataLocation, QLatin1String("cantor/") + partialPath, options);

    return file;
}

QStringList Session::locateAllCantorFiles(const QString& partialPath, QStandardPaths::LocateOptions options)
{
    QStringList files = QStandardPaths::locateAll(QStandardPaths::AppDataLocation, partialPath, options);

    if (files.isEmpty())
        files = QStandardPaths::locateAll(QStandardPaths::GenericDataLocation, QLatin1String("cantor/") + partialPath, options);

    return files;
}

void Cantor::Session::reportSessionCrash(const QString& additionalInfo)
{
    // Reporting about crashing backend in session without backend has not sense
    if (d->backend == nullptr)
        return;

    if (additionalInfo.isEmpty())
        KMessageBox::error(nullptr, i18n("%1 process has died unexpectedly. All calculation results are lost.", d->backend->name()), i18n("Error - Cantor"));
    else
        KMessageBox::error(nullptr, i18n("%1 process has died unexpectedly with message \"%2\". All calculation results are lost.", d->backend->name(), additionalInfo), i18n("Error - Cantor"));
    logout();
}

QList<Cantor::GraphicPackage> Cantor::Session::usableGraphicPackages()
{
    return d->usableGraphicPackages;
}

const QList<Cantor::GraphicPackage>& Cantor::Session::enabledGraphicPackages() const
{
    return d->enabledGraphicPackages;
}

QString Cantor::Session::graphicPackageErrorMessage(QString packageId) const
{
    Q_UNUSED(packageId);
    return QString();
}

void Cantor::Session::updateEnabledGraphicPackages(const QList<Cantor::GraphicPackage>& newEnabledPackages, const QString& additionalInfo)
{
    if (newEnabledPackages.isEmpty())
    {
        if (!d->enabledGraphicPackages.isEmpty())
        {
            for (const GraphicPackage& package : d->enabledGraphicPackages)
                evaluateExpression(package.disableSupportCommand(), Cantor::Expression::DeleteOnFinish, true);
        }
        d->enabledGraphicPackages.clear();
    }
    else
    {
        QList<GraphicPackage> packagesExceptIgnored;
        for (const GraphicPackage& package : newEnabledPackages)
            if (d->ignorableGraphicPackageIds.contains(package.id()) == false)
                packagesExceptIgnored.append(package);

        testGraphicsPackages(packagesExceptIgnored);

        QList<GraphicPackage> unavailablePackages;
        QList<GraphicPackage> willEnabledPackages;

        for (const GraphicPackage& package : packagesExceptIgnored)
        {
            if (GraphicPackage::findById(package, usableGraphicPackages()) != -1)
                willEnabledPackages.append(package);
            else
                unavailablePackages.append(package);
        }

        for (const GraphicPackage& package : d->enabledGraphicPackages)
            if (GraphicPackage::findById(package, willEnabledPackages) == -1)
                evaluateExpression(package.disableSupportCommand(), Cantor::Expression::DeleteOnFinish, true);

        for (const GraphicPackage& newPackage : willEnabledPackages)
            if (GraphicPackage::findById(newPackage, d->enabledGraphicPackages) == -1)
                evaluateExpression(newPackage.enableSupportCommand(additionalInfo), Cantor::Expression::DeleteOnFinish, true);

        d->enabledGraphicPackages = willEnabledPackages;

        for (const Cantor::GraphicPackage& notEnabledPackage : unavailablePackages)
        {
            if (d->ignorableGraphicPackageIds.contains(notEnabledPackage.id()) == false)
            {
                KMessageBox::information(nullptr, i18n(
                    "You choose support for %1 graphic package, but the support can't be "\
                    "activated due to the missing requirements, so integration for this package will be disabled. %2",
                    notEnabledPackage.name(), graphicPackageErrorMessage(notEnabledPackage.id())), i18n("Cantor")
                );

                d->ignorableGraphicPackageIds.append(notEnabledPackage.id());
            }
        }
    }
}
