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

#include <qtest.h>

#include <QtCore/qmath.h>
#include <QtCore/QElapsedTimer>
#include <QtWidgets/QWidget>

#include "benchmarktests.h"

class BenchWidget : public QWidget
{
public:
    BenchWidget(Benchmark *benchmark);

    void paintEvent(QPaintEvent *event) override;

    bool done() const { return m_done; }
    qreal result() const { return m_result; }

public:
    QElapsedTimer timer;

    Benchmark *m_benchmark;

    bool m_done;
    qreal m_result;

    uint m_total;
    uint m_iteration;

    QList<uint> iterationTimes;
};

void BenchWidget::paintEvent(QPaintEvent *)
{
    if (m_done)
        return;

    QPainter p(this);

    m_benchmark->begin(&p, 100);

    PaintingRectAdjuster adjuster;
    adjuster.setNewBenchmark(m_benchmark);
    adjuster.reset(rect());

    for (int i = 0; i < 100; ++i)
        m_benchmark->draw(&p, adjuster.newPaintingRect(), i);

    m_benchmark->end(&p);

    ++m_iteration;

    uint currentElapsed = timer.isValid() ? timer.elapsed() : 0;
    timer.restart();

    m_total += currentElapsed;

    // warm up for at most 5 iterations or half a second
    if (m_iteration >= 5 || m_total >= 500) {
        iterationTimes << currentElapsed;

        if (iterationTimes.size() >= 5) {
            qreal mean = 0;
            qreal stddev = 0;
            uint min = INT_MAX;

            for (int i = 0; i < iterationTimes.size(); ++i) {
                mean += iterationTimes.at(i);
                min = qMin(min, iterationTimes.at(i));
            }

            mean /= qreal(iterationTimes.size());

            for (int i = 0; i < iterationTimes.size(); ++i) {
                qreal delta = iterationTimes.at(i) - mean;
                stddev += delta * delta;
            }

            stddev = qSqrt(stddev / iterationTimes.size());

            stddev = 100 * stddev / mean;
            // do 50 iterations, break earlier if we spend more than 5 seconds or have a low std deviation after 2 seconds
            if (iterationTimes.size() >= 50 || m_total >= 5000 || (m_total >= 2000 && stddev < 4)) {
                m_result = min;
                m_done = true;
                return;
            }
        }
    }
}

BenchWidget::BenchWidget(Benchmark *benchmark)
    : m_benchmark(benchmark)
    , m_done(false)
    , m_result(0)
    , m_total(0)
    , m_iteration(0)
{
    setWindowTitle(benchmark->name());
    resize(640, 480);
}

class tst_QtBench : public QObject
{
    Q_OBJECT

    QList<Benchmark *> benchmarks;

private slots:
    void qtBench();
    void qtBench_data();

    void cleanupTestCase() { qDeleteAll(benchmarks); }
};

QString makeString(int length)
{
    const char chars[] = "abcd efgh ijkl mnop qrst uvwx yz!$. ABCD 1234";
    const int len = int(strlen(chars));

    QString ret;
    for (int j = 0; j < length; j++) {
        ret += QChar(chars[(j * 97) % len]);
    }

    return ret;
}

void tst_QtBench::qtBench_data()
{
    QTest::addColumn<void *>("benchmark");

    QString shortString = makeString(5);
    QString middleString = makeString(50);
    QString longString = makeString(35) + "\n"
                         + makeString(45) + "\n"
                         + makeString(75);
    QString superLongString = "Lorem ipsum dolor sit am\n"
                              "et, consectetur adipisci\n"
                              "ng elit. Integer mi leo,\n"
                              "interdum ut congue at, p\n"
                              "ulvinar et tellus. Quisq\n"
                              "ue pretium eleifend laci\n"
                              "nia. Ut semper gravida l\n"
                              "ectus in commodo. Vestib\n"
                              "ulum pharetra arcu in en\n"
                              "im ultrices hendrerit. P\n"
                              "ellentesque habitant mor\n"
                              "bi tristique senectus et\n"
                              "netus et malesuada fames\n"
                              "ac turpis egestas. Ut er\n"
                              "os sem, feugiat in eleme\n"
                              "ntum in, porta sit amet \n"
                              "neque. Fusce mi tellus, \n"
                              "congue non dapibus eget,\n"
                              "pharetra quis quam. Duis\n"
                              "dui massa, pulvinar ac s\n"
                              "odales pharetra, dictum \n"
                              "in enim. Phasellus a nis\n"
                              "i erat, sed pellentesque\n"
                              "mi. Curabitur sed.";

    benchmarks << (new DrawText(shortString, DrawText::PainterMode));
    benchmarks << (new DrawText(middleString, DrawText::PainterMode));
    benchmarks << (new DrawText(longString, DrawText::PainterMode));
    benchmarks << (new DrawText(superLongString, DrawText::PainterMode));

    benchmarks << (new DrawText(shortString, DrawText::PainterQPointMode));
    benchmarks << (new DrawText(middleString, DrawText::PainterQPointMode));
    benchmarks << (new DrawText(longString, DrawText::PainterQPointMode));
    benchmarks << (new DrawText(superLongString, DrawText::PainterQPointMode));

    benchmarks << (new DrawText(shortString, DrawText::PixmapMode));
    benchmarks << (new DrawText(middleString, DrawText::PixmapMode));
    benchmarks << (new DrawText(longString, DrawText::PixmapMode));
    benchmarks << (new DrawText(superLongString, DrawText::PixmapMode));

    benchmarks << (new DrawText(shortString, DrawText::StaticTextMode));
    benchmarks << (new DrawText(middleString, DrawText::StaticTextMode));
    benchmarks << (new DrawText(longString, DrawText::StaticTextMode));
    benchmarks << (new DrawText(superLongString, DrawText::StaticTextMode));

    benchmarks << (new DrawText(shortString, DrawText::StaticTextWithMaximumSizeMode));
    benchmarks << (new DrawText(middleString, DrawText::StaticTextWithMaximumSizeMode));
    benchmarks << (new DrawText(longString, DrawText::StaticTextWithMaximumSizeMode));
    benchmarks << (new DrawText(superLongString, DrawText::StaticTextWithMaximumSizeMode));

    benchmarks << (new DrawText(shortString, DrawText::StaticTextBackendOptimizations));
    benchmarks << (new DrawText(middleString, DrawText::StaticTextBackendOptimizations));
    benchmarks << (new DrawText(longString, DrawText::StaticTextBackendOptimizations));
    benchmarks << (new DrawText(superLongString, DrawText::StaticTextBackendOptimizations));

    for (Benchmark *benchmark : std::as_const(benchmarks))
        QTest::newRow(qPrintable(benchmark->name())) << reinterpret_cast<void *>(benchmark);
}

void tst_QtBench::qtBench()
{
    QFETCH(void *, benchmark);

    BenchWidget widget(reinterpret_cast<Benchmark *>(benchmark));
    widget.show();
    QVERIFY(QTest::qWaitForWindowExposed(&widget));

    while (!widget.done()) {
        widget.update();
        QApplication::processEvents();
    }

    QTest::setBenchmarkResult(widget.result(), QTest::WalltimeMilliseconds);
}

QTEST_MAIN(tst_QtBench)
#include "tst_qtbench.moc"
