/*
    SPDX-FileCopyrightText: 2007 Barış Metin <baris@pardus.org.tr>
    SPDX-FileCopyrightText: 2006 David Faure <faure@kde.org>
    SPDX-FileCopyrightText: 2007 Richard Moore <rich@kde.org>
    SPDX-FileCopyrightText: 2010 Matteo Agostinelli <agostinelli@gmail.com>
    SPDX-FileCopyrightText: 2021 Alexander Lohnau <alexander.lohnau@gmx.de>

    SPDX-License-Identifier: LGPL-2.0-only
*/

#include "calculatorrunner.h"

#ifdef ENABLE_QALCULATE
#include "qalculate_engine.h"
#else
#include <QClipboard>
#include <QGuiApplication>
#include <QJSEngine>
#endif

#include <QDebug>
#include <QIcon>
#include <QRegularExpression>

#include <KLocalizedString>
#include <krunner/querymatch.h>

K_PLUGIN_CLASS_WITH_JSON(CalculatorRunner, "plasma-runner-calculator.json")

CalculatorRunner::CalculatorRunner(QObject *parent, const KPluginMetaData &metaData, const QVariantList &args)
    : Plasma::AbstractRunner(parent, metaData, args)
{
#ifdef ENABLE_QALCULATE
    m_engine = new QalculateEngine;
#endif

    setObjectName(QStringLiteral("Calculator"));

    QString description = i18n(
        "Calculates the value of :q: when :q: is made up of numbers and "
        "mathematical symbols such as +, -, /, *, ! and ^.");
    addSyntax(Plasma::RunnerSyntax(QStringLiteral(":q:"), description));
    addSyntax(Plasma::RunnerSyntax(QStringLiteral("=:q:"), description));
    addSyntax(Plasma::RunnerSyntax(QStringLiteral(":q:="), description));

    m_actions = {new QAction(QIcon::fromTheme(QStringLiteral("edit-copy")), i18n("Copy to Clipboard"), this)};
    setMinLetterCount(2);
}

CalculatorRunner::~CalculatorRunner()
{
#ifdef ENABLE_QALCULATE
    delete m_engine;
#endif
}

#ifndef ENABLE_QALCULATE
void CalculatorRunner::powSubstitutions(QString &cmd)
{
    if (cmd.contains(QLatin1String("e+"), Qt::CaseInsensitive)) {
        cmd.replace(QLatin1String("e+"), QLatin1String("*10^"), Qt::CaseInsensitive);
    }

    if (cmd.contains(QLatin1String("e-"), Qt::CaseInsensitive)) {
        cmd.replace(QLatin1String("e-"), QLatin1String("*10^-"), Qt::CaseInsensitive);
    }

    // the below code is scary mainly because we have to honor priority
    // honor decimal numbers and parenthesis.
    while (cmd.contains(QLatin1Char('^'))) {
        int where = cmd.indexOf(QLatin1Char('^'));
        cmd.replace(where, 1, QLatin1Char(','));
        int preIndex = where - 1;
        int postIndex = where + 1;
        int count = 0;

        QChar decimalSymbol = QLocale().decimalPoint();
        // avoid out of range on weird commands
        preIndex = qMax(0, preIndex);
        postIndex = qMin(postIndex, cmd.length() - 1);

        // go backwards looking for the beginning of the number or expression
        while (preIndex != 0) {
            QChar current = cmd.at(preIndex);
            QChar next = cmd.at(preIndex - 1);
            // qDebug() << "index " << preIndex << " char " << current;
            if (current == QLatin1Char(')')) {
                count++;
            } else if (current == QLatin1Char('(')) {
                count--;
            } else {
                if (((next <= QLatin1Char('9')) && (next >= QLatin1Char('0'))) || next == decimalSymbol) {
                    preIndex--;
                    continue;
                }
            }
            if (count == 0) {
                // check for functions
                if (!((next <= QLatin1Char('z')) && (next >= QLatin1Char('a')))) {
                    break;
                }
            }
            preIndex--;
        }

        // go forwards looking for the end of the number or expression
        count = 0;
        while (postIndex != cmd.size() - 1) {
            QChar current = cmd.at(postIndex);
            QChar next = cmd.at(postIndex + 1);

            // check for functions
            if ((count == 0) && (current <= QLatin1Char('z')) && (current >= QLatin1Char('a'))) {
                postIndex++;
                continue;
            }

            if (current == QLatin1Char('(')) {
                count++;
            } else if (current == QLatin1Char(')')) {
                count--;
            } else {
                if (((next <= QLatin1Char('9')) && (next >= QLatin1Char('0'))) || next == decimalSymbol) {
                    postIndex++;
                    continue;
                }
            }
            if (count == 0) {
                break;
            }
            postIndex++;
        }

        preIndex = qMax(0, preIndex);
        postIndex = qMin(postIndex, cmd.length());

        cmd.insert(preIndex, QLatin1String("pow("));
        // +1 +4 == next position to the last number after we add 4 new characters pow(
        cmd.insert(postIndex + 1 + 4, QLatin1Char(')'));
        // qDebug() << "from" << preIndex << " to " << postIndex << " got: " << cmd;
    }
}

void CalculatorRunner::hexSubstitutions(QString &cmd)
{
    if (cmd.contains(QLatin1String("0x"))) {
        // Append +0 so that the calculator can serve also as a hex converter
        cmd.append(QLatin1String("+0"));
        bool ok;
        int pos = 0;
        QString hex;

        while (cmd.contains(QLatin1String("0x"))) {
            hex.clear();
            pos = cmd.indexOf(QLatin1String("0x"), pos);

            for (int q = 0; q < cmd.size(); q++) { // find end of hex number
                QChar current = cmd[pos + q + 2];
                if (((current <= QLatin1Char('9')) && (current >= QLatin1Char('0'))) || ((current <= QLatin1Char('F')) && (current >= QLatin1Char('A')))
                    || ((current <= QLatin1Char('f')) && (current >= QLatin1Char('a')))) { // Check if valid hex sign
                    hex[q] = current;
                } else {
                    break;
                }
            }
            cmd = cmd.replace(pos, 2 + hex.length(), QString::number(hex.toInt(&ok, 16))); // replace hex with decimal
        }
    }
}
#endif

void CalculatorRunner::userFriendlySubstitutions(QString &cmd)
{
    if (QLocale().decimalPoint() != QLatin1Char('.')) {
        cmd.replace(QLocale().decimalPoint(), QLatin1Char('.'), Qt::CaseInsensitive);
    } else if (!cmd.contains(QLatin1Char('[')) && !cmd.contains(QLatin1Char(']'))) {
        // If we are sure that the user does not want to use vectors we can replace this char
        // Especially when switching between locales that use a different decimal separator
        // this ensures that the results are valid, see BUG: 406388
        cmd.replace(QLatin1Char(','), QLatin1Char('.'), Qt::CaseInsensitive);
    }

    // the following substitutions are not needed with libqalculate
#ifndef ENABLE_QALCULATE
    hexSubstitutions(cmd);
    powSubstitutions(cmd);

    QRegularExpression re(QStringLiteral("(\\d+)and(\\d+)"));
    cmd.replace(re, QStringLiteral("\\1&\\2"));

    re.setPattern(QStringLiteral("(\\d+)or(\\d+)"));
    cmd.replace(re, QStringLiteral("\\1|\\2"));

    re.setPattern(QStringLiteral("(\\d+)xor(\\d+)"));
    cmd.replace(re, QStringLiteral("\\1^\\2"));
#endif
}

void CalculatorRunner::match(Plasma::RunnerContext &context)
{
    const QString term = context.query();
    QString cmd = term;

    // no meanless space between friendly guys: helps simplify code
    cmd = cmd.trimmed().remove(QLatin1Char(' '));

    if (cmd.length() < 2) {
        return;
    }

    if (cmd.toLower() == QLatin1String("universe") || cmd.toLower() == QLatin1String("life")) {
        Plasma::QueryMatch match(this);
        match.setType(Plasma::QueryMatch::InformationalMatch);
        match.setIconName(QStringLiteral("accessories-calculator"));
        match.setText(QStringLiteral("42"));
        match.setData(QStringLiteral("42"));
        match.setId(term);
        context.addMatch(match);
        return;
    }

    bool toHex = cmd.startsWith(QLatin1String("hex="));
    bool startsWithEquals = !toHex && cmd[0] == QLatin1Char('=');
    const static QRegularExpression hexRegex(QStringLiteral("0x[0-9a-f]+"), QRegularExpression::CaseInsensitiveOption);
    const bool parseHex = cmd.contains(hexRegex);
    if (!parseHex) {
        userFriendlyMultiplication(cmd);
    }

    if (toHex || startsWithEquals) {
        cmd.remove(0, cmd.indexOf(QLatin1Char('=')) + 1);
    } else if (cmd.endsWith(QLatin1Char('='))) {
        cmd.chop(1);
    } else if (!parseHex) {
        bool foundDigit = false;
        for (int i = 0; i < cmd.length(); ++i) {
            QChar c = cmd.at(i);
            if (c.isLetter() && c != QLatin1Char('!')) {
                // not just numbers and symbols, so we return
                return;
            }
            if (c.isDigit()) {
                foundDigit = true;
            }
        }
        if (!foundDigit) {
            return;
        }
    }

    if (cmd.isEmpty()) {
        return;
    }

    userFriendlySubstitutions(cmd);
#ifndef ENABLE_QALCULATE
    // needed for accessing math functions like sin(),....
    cmd.replace(QRegularExpression(QStringLiteral("([a-zA-Z]+)")), QStringLiteral("Math.\\1"));
#endif

    bool isApproximate = false;
    QString result = calculate(cmd, &isApproximate);
    if (!result.isEmpty() && (result != cmd || toHex)) {
        if (toHex) {
            result = QLatin1String("0x") + QString::number(result.toInt(), 16).toUpper();
        }

        Plasma::QueryMatch match(this);
        match.setType(Plasma::QueryMatch::InformationalMatch);
        match.setIconName(QStringLiteral("accessories-calculator"));
        match.setText(result);
        if (isApproximate) {
            match.setSubtext(i18nc("The result of the calculation is only an approximation", "Approximation"));
        }
        match.setData(result);
        match.setId(term);
        match.setActions(m_actions);
        context.addMatch(match);
    }
}

QString CalculatorRunner::calculate(const QString &term, bool *isApproximate)
{
#ifdef ENABLE_QALCULATE
    QString result;

    try {
        result = m_engine->evaluate(term, isApproximate);
    } catch (std::exception &e) {
        qDebug() << "qalculate error: " << e.what();
    }

    return result.replace(QLatin1Char('.'), QLocale().decimalPoint(), Qt::CaseInsensitive);
#else
    Q_UNUSED(isApproximate);
    // qDebug() << "calculating" << term;
    QJSEngine eng;
    QJSValue result = eng.evaluate(QStringLiteral("var result = %1; result").arg(term));

    if (result.isError()) {
        return QString();
    }

    const QString resultString = result.toString();
    if (resultString.isEmpty()) {
        return QString();
    }

    if (!resultString.contains(QLatin1Char('.'))) {
        return resultString;
    }

    // ECMAScript has issues with the last digit in simple rational computations
    // This script rounds off the last digit; see bug 167986
    QString roundedResultString = eng.evaluate(QStringLiteral("var exponent = 14-(1+Math.floor(Math.log(Math.abs(result))/Math.log(10)));\
                                                var order=Math.pow(10,exponent);\
                                                (order > 0? Math.round(result*order)/order : 0)"))
                                      .toString();

    roundedResultString.replace(QLatin1Char('.'), QLocale().decimalPoint(), Qt::CaseInsensitive);

    return roundedResultString;
#endif
}

void CalculatorRunner::run(const Plasma::RunnerContext &context, const Plasma::QueryMatch &match)
{
    Q_UNUSED(context)
    if (match.selectedAction()) {
#ifdef ENABLE_QALCULATE
        m_engine->copyToClipboard();
#else
        QGuiApplication::clipboard()->setText(match.text());
#endif
    }
}

QMimeData *CalculatorRunner::mimeDataForMatch(const Plasma::QueryMatch &match)
{
    QMimeData *result = new QMimeData();
    result->setText(match.text());
    return result;
}

void CalculatorRunner::userFriendlyMultiplication(QString &cmd)
{
    // convert multiplication sign to *
    cmd.replace(QChar(U'\u00D7'), QChar('*'));

    for (int i = 0; i < cmd.length(); ++i) {
        if (i == 0 || i == cmd.length() - 1) {
            continue;
        }
        const QChar prev = cmd.at(i - 1);
        const QChar current = cmd.at(i);
        const QChar next = cmd.at(i + 1);
        if (current == QLatin1Char('x')) {
            if (prev.isDigit() && (next.isDigit() || next == QLatin1Char(',') || next == QLatin1Char('.'))) {
                cmd[i] = '*';
            }
        }
    }
}

#include "calculatorrunner.moc"