/*
  logview.cpp

  This file is part of GammaRay, the Qt application inspection and manipulation tool.

  SPDX-FileCopyrightText: 2016 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
  Author: Giulio Camuffo <giulio.camuffo@kdab.com>

  SPDX-License-Identifier: GPL-2.0-or-later

  Contact KDAB at <info@kdab.com> for commercial licensing options.
*/

#include "logview.h"

#include <QMouseEvent>
#include <QScrollBar>
#include <QStaticText>
#include <QPainter>
#include <QScrollArea>
#include <QClipboard>
#include <QApplication>
#include <QtMath>

#include "ringbuffer.h"

namespace GammaRay {

class View : public QWidget
{
public:
    explicit View(QWidget *p)
        : QWidget(p)
        , m_lines(5000)
        , m_metrics(QFont())
        , m_lineHeight(m_metrics.height())
        , m_client(0)
    {
        resize(0, 0);
        setFocusPolicy(Qt::ClickFocus);
        setCursor(Qt::IBeamCursor);
    }

    QSize sizeHint() const override
    {
        return size();
    }

    void drawLine(QPainter &painter, const QRect &rect, const QStaticText &line)
    {
        painter.setPen(palette().color(QPalette::Text));
        painter.drawStaticText(0, rect.y(), line);
    }

    void drawLineSelected(QPainter &painter, const QRect &rect, const QStaticText &line)
    {
        painter.fillRect(rect, palette().highlight());
        painter.setPen(palette().color(QPalette::HighlightedText));
        painter.drawStaticText(0, rect.y(), line);
    }

    void drawLinePartialSelected(QPainter &painter, const QRect &rect, const QStaticText &line, int startSelectChar, int endSelectChar)
    {
        const QString &text = line.text();
        const int startX = m_metrics.horizontalAdvance(text.left(startSelectChar));
        const int endX = m_metrics.horizontalAdvance(text.left(endSelectChar));

        if (startSelectChar > 0) {
            painter.drawText(QRect(rect.x(), rect.y(), startX, rect.height()), Qt::TextDontClip, text.left(startSelectChar));
        }

        QRect selectRect(rect.x() + startX, rect.y(), endX - startX, rect.height());
        painter.fillRect(selectRect, palette().highlight());
        painter.setPen(palette().color(QPalette::HighlightedText));
        painter.drawText(selectRect, Qt::TextDontClip, text.mid(startSelectChar, endSelectChar - startSelectChar));

        if (endSelectChar < text.size()) {
            painter.setPen(palette().color(QPalette::Text));
            painter.drawText(QRect(rect.x() + endX, rect.y(), m_metrics.horizontalAdvance(text) - endX, rect.height()), text.mid(endSelectChar));
        }
    }

    void selectionBoundaries(QPoint &start, QPoint &end) const
    {
        bool startBeforeEnd = (m_selectionStart.y() < m_selectionEnd.y()) || (m_selectionStart.y() == m_selectionEnd.y() && m_selectionStart.x() < m_selectionEnd.x());
        start = startBeforeEnd ? m_selectionStart : m_selectionEnd;
        end = startBeforeEnd ? m_selectionEnd : m_selectionStart;
    }

    struct LineSelection
    {
        bool isNull() const
        {
            return start == end;
        }
        bool isFull() const
        {
            return start == 0 && end < 0;
        }

        int start;
        int end;
    };
    LineSelection lineSelection(int line) const
    {
        if (m_selectionStart == m_selectionEnd) {
            return { 0, 0 };
        }

        QPoint start, end;
        selectionBoundaries(start, end);

        if (start.y() < line && line < end.y()) {
            return { 0, ( int )m_lines.at(line).text.text().size() };
        }

        if (start.y() == line || end.y() == line) {
            int startChar = 0;
            int endChar = m_lines.at(line).text.text().size();
            if (start.y() == line)
                startChar = start.x();
            if (end.y() == line)
                endChar = end.x() + 1;
            return { startChar, endChar };
        }

        return { 0, 0 };
    }

    void paintEvent(QPaintEvent *event) override
    {
        if (m_lineHeight < 0) {
            return;
        }

        QPainter painter(this);

        QRectF drawRect = event->rect();
        int startingLine = lineAt(drawRect.y());
        int y = linePosAt(drawRect.y());

        for (int i = startingLine; i < m_lines.size(); ++i) {
            if (m_client && m_lines.at(i).pid != m_client) {
                continue;
            }
            const QStaticText &text = m_lines.at(i).text;

            QRect lineRect(QRect(0, y, text.size().width(), m_lineHeight));
            painter.fillRect(QRectF(0, y, drawRect.width(), m_lineHeight), i % 2 ? palette().base() : palette().alternateBase());

            LineSelection selection = lineSelection(i);
            if (selection.isNull()) {
                drawLine(painter, lineRect, text);
            } else if (selection.isFull()) {
                drawLineSelected(painter, lineRect, text);
            } else {
                drawLinePartialSelected(painter, lineRect, text, selection.start, selection.end);
            }

            y += m_lineHeight;
            if (y >= drawRect.bottom())
                break;
        }
    }

    inline int linesCount() const
    {
        return m_client ? m_linesCount.value(m_client) : m_lines.size();
    }

    inline int linePosAt(int y) const
    {
        int line = qMin(y / m_lineHeight, m_lines.size() - 1);
        return line * m_lineHeight;
    }

    inline int lineAt(int y) const
    {
        int line = qMin(y / m_lineHeight, m_lines.size() - 1);
        if (!m_client) {
            return line;
        }

        for (int i = 0, l = 0; i < m_lines.size(); ++i) {
            if (m_lines.at(i).pid == m_client) {
                if (l++ == line) {
                    return i;
                }
            }
        }
        return line;
    }
    inline QPoint charPosAt(const QPointF &p) const
    {
        int line = lineAt(p.y());
        int lineX = 0;

        const QString &text = m_lines.at(line).text.text();
        for (int x = 0, i = 0; i < text.size(); ++i) {
            const QChar &c = text.at(i);
            if (p.x() >= x) {
                lineX = i;
            }
            x += m_metrics.horizontalAdvance(c);
        }

        return { lineX, line };
    }

    void mousePressEvent(QMouseEvent *e) override
    {
        if (e->button() == Qt::LeftButton) {
            m_selectionStart = m_selectionEnd = charPosAt(e->pos());
            e->accept();
            update();
        }
    }

    void mouseMoveEvent(QMouseEvent *e) override
    {
        m_selectionEnd = charPosAt(e->pos());
        e->accept();
        update();
    }

    QString selectedText() const
    {
        if (m_selectionStart == m_selectionEnd) {
            return QString();
        }

        QPoint start, end;
        selectionBoundaries(start, end);
        QString string;
        for (int i = start.y(); i <= end.y(); ++i) {
            if (m_client && m_lines.at(i).pid != m_client) {
                continue;
            }
            const QStaticText &line = m_lines.at(i).text;
            LineSelection selection = lineSelection(i);
            string += line.text().mid(selection.start, selection.end - selection.start);
            string += QLatin1Char('\n');
        }
        return string;
    }

    void keyPressEvent(QKeyEvent *e) override
    {
        if (e->key() == Qt::Key_C && e->modifiers() == Qt::ControlModifier) {
            QApplication::clipboard()->setText(selectedText());
        }
    }

    void resetSelection()
    {
        m_selectionStart = m_selectionEnd = QPoint();
        update();
    }

    struct Line
    {
        quint64 pid = 0;
        QStaticText text;
        int *counter = nullptr;

        Line() = default;

        Line(quint64 p, const QStaticText &t, int *cnt)
            : pid(p)
            , text(t)
            , counter(cnt)
        {
            (*counter)++;
        }

        Line(const Line &l)
            : pid(l.pid)
            , text(l.text)
            , counter(l.counter)
        {
            (*counter)++;
        }

        ~Line()
        {
            (*counter)--;
        }

        Line &operator=(const Line &l)
        {
            (*counter)--;

            pid = l.pid;
            text = l.text;
            counter = l.counter;

            (*counter)++;
            return *this;
        }
    };
    RingBuffer<Line> m_lines;
    QHash<quint64, int> m_linesCount;
    QFontMetricsF m_metrics;
    int m_lineHeight;
    QPoint m_selectionStart;
    QPoint m_selectionEnd;
    quint64 m_client;
};


class Messages : public QScrollArea
{
public:
    explicit Messages(QWidget *parent)
        : QScrollArea(parent)
        , m_view(new View(this))
    {
        m_view->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
        setWidget(m_view);
        setWidgetResizable(true);
    }

    void logMessage(quint64 pid, qint64 time, const QByteArray &msg)
    {
        auto scrollbar = verticalScrollBar();
        bool scroll = scrollbar->value() >= scrollbar->maximum();

        add(pid, time, msg);

        if (scroll)
            scrollbar->setValue(scrollbar->maximum());
    }

    void reset() const
    {
        m_view->m_lines.clear();
        m_view->resize(0, 0);
    }

    void updateSize() const
    {
        QSizeF lineSize = m_view->m_lines.last().text.size();

        int w = m_view->width();
        int h = m_view->linesCount() * m_view->m_lineHeight;

        if (lineSize.width() > w) {
            w = lineSize.width();
        }
        m_view->resize(w, h);
        m_view->update();
    }

    void add(quint64 pid, qint64 time, const QByteArray &m)
    {
        m_view->m_lines.append(View::Line(pid, QStaticText(QString("[%1ms] %2").arg(QString::number(time / 1e6), QString(m))), &m_view->m_linesCount[pid]));

        if (m_view->m_client && pid != m_view->m_client) {
            return;
        }

        updateSize();
    }

    void setLoggingClient(quint64 pid)
    {
        m_view->m_client = pid;

        auto scrollbar = verticalScrollBar();
        qreal v = ( qreal )scrollbar->value() / ( qreal )scrollbar->maximum();

        m_view->resetSelection();
        updateSize();

        // keep the scrollbar at he same percentage
        scrollbar->setValue(v * ( qreal )scrollbar->maximum());
    }

    View *m_view;
};


class Timeline : public QScrollArea
{
public:
    class View : public QWidget
    {
    public:
        struct DataPoint
        {
            qint64 time;
            quint64 pid;
            QByteArray msg;
        };

        View()
            : m_data(5000)
        {
            resize(100, 100);
            setAttribute(Qt::WA_OpaquePaintEvent);
            setMouseTracking(true);
        }

        QSize sizeHint() const override
        {
            return size();
        }

        inline qint64 initialTime() const
        {
            return m_data.isEmpty() ? 0 : m_data.at(0).time;
        }

        void paintEvent(QPaintEvent *event) override
        {
            QPainter painter(this);
            QRectF drawRect = event->rect();
            const auto palette = this->palette();

            painter.fillRect(drawRect, palette.base());

            qreal l = 1;
            qreal step = l / m_zoom;
            while (step < 60) {
                l *= 10;
                step = l / m_zoom;
            }

            int substeps = 5;
            int mul = 2;
            while (step / substeps > 60) {
                substeps *= mul;
                mul = mul == 2 ? 5 : 2;
            }

            auto it = initialTime();
            auto rit = round(it, -1);

            // draw the grid lines
            qreal linesSpacing = step / substeps;
            int startLine = drawRect.left() / linesSpacing - (rit - it) / m_zoom; // round the starting position so that we have nice numbers'

            int s = startLine;
            // NOLINTNEXTLINE (clang-analyzer-security.FloatLoopCounter)
            for (qreal i = startLine * linesSpacing; i < drawRect.right(); i += linesSpacing, s++) {
                bool isStep = s % substeps == 0;
                painter.setPen(isStep ? palette.color(QPalette::Highlight) : palette.color(QPalette::Midlight));

                int y = 0;
                if (isStep) {
                    int stepN = s / substeps;
                    y = 15 * (stepN % 2 + 1);
                }

                painter.drawLine(i, y, i, drawRect.bottom());
            }

            // draw the text after having drawn all the lines, so we're sure they don't go over it
            s = startLine;
            painter.setPen(palette.color(QPalette::Highlight));
            // NOLINTNEXTLINE (clang-analyzer-security.FloatLoopCounter)
            for (qreal i = startLine * linesSpacing; i < drawRect.right(); i += step / substeps, s++) { // krazy:exclude=postfixop
                bool isStep = s % substeps == 0;
                if (isStep) {
                    painter.drawText(i - 100, ((s / substeps) % 2) * 15, 200, 200, Qt::AlignHCenter, QString("%1ms").arg(QString::number(qreal(it + i * m_zoom) / 1e6, 'g', 6)));
                }
            }

            // finally draw the event lines
            painter.setPen(palette.color(QPalette::Text));
            bool hasDrawn = false;
            for (int i = 0; i < m_data.size(); ++i) {
                const auto &point = m_data.at(i);
                if (m_client && point.pid != m_client) {
                    painter.setPen(palette.color(QPalette::Dark));
                } else {
                    painter.setPen(palette.color(QPalette::Text));
                }

                qreal offset = point.time - m_start;
                qreal x = offset / m_zoom;
                qreal y = qMax(qreal(40.), drawRect.y());
                if (!drawRect.contains(QPoint(x, y))) {
                    if (hasDrawn)
                        break;
                    else
                        continue;
                }
                hasDrawn = true;

                painter.drawLine(x, y, x, drawRect.bottom());
            }
        }

        void mouseMoveEvent(QMouseEvent *e) override
        {
            const QPointF &pos = e->position();
            for (int i = 0; i < m_data.size(); ++i) {
                qreal timex = (m_data.at(i).time - m_start) / m_zoom;
                if (fabs(pos.x() - timex) < 2) {
                    setToolTip(m_data.at(i).msg);
                    return;
                }
            }
        }

        static qint64 round(qint64 time, int direction)
        {
            qint64 v = time % 200;
            return time + direction * v;
        }

        void updateSize()
        {
            if (m_data.size() == 0)
                return;

            m_start = round(m_data.at(0).time, -1);
            m_timespan = round(m_data.last().time, 1) - m_start;
            resize(m_timespan / m_zoom, height());
        }

        RingBuffer<DataPoint> m_data;
        qreal m_zoom = 100000;
        qint64 m_start = 0;
        qint64 m_timespan = 0;
        quint64 m_client = 0;
    };

    explicit Timeline(QWidget *parent)
        : QScrollArea(parent)
    {
        m_view.setSizePolicy(QSizePolicy::MinimumExpanding, QSizePolicy::Fixed);
        setWidget(&m_view);
        setWidgetResizable(true);
        m_view.installEventFilter(this);
    }

    void logMessage(quint64 pid, qint64 time, const QByteArray &msg)
    {
        m_view.m_data.append({ time, pid, msg });
        m_view.updateSize();
    }

    void setLoggingClient(quint64 pid)
    {
        m_view.m_client = pid;
        m_view.update();
    }

    bool eventFilter(QObject *o, QEvent *e) override
    {
        if (o == &m_view && e->type() == QEvent::Wheel) {
            QWheelEvent *we = static_cast<QWheelEvent *>(e);

            qreal pos = we->position().x() * m_view.m_zoom;
            auto sb = horizontalScrollBar();
            int sbvalue = horizontalScrollBar()->value();

            m_view.m_zoom += (1. - qPow(5. / 4., qreal(we->angleDelta().y()) / 150.)) * m_view.m_zoom;
            if (m_view.m_zoom < 10) {
                m_view.m_zoom = 10;
            }

            m_view.updateSize();

            // keep the point under the mouse still, if possible
            pos = pos / m_view.m_zoom;
            sb->setValue(sbvalue + (0.5 + pos - we->position().x()));
        }
        return QScrollArea::eventFilter(o, e);
    }

    View m_view;
};

LogView::LogView(QWidget *p)
    : QTabWidget(p)
    , m_messages(new Messages(this))
    , m_timeline(new Timeline(this))
{
    setTabPosition(QTabWidget::West);
    addTab(m_messages, tr("Messages"));
    addTab(m_timeline, tr("Timeline"));
}

QSize LogView::sizeHint() const
{
    return { 200, 200 };
}

void LogView::logMessage(quint64 pid, qint64 time, const QByteArray &msg)
{
    m_messages->logMessage(pid, time, msg);
    m_timeline->logMessage(pid, time, msg);
}

void LogView::setLoggingClient(quint64 pid)
{
    m_messages->setLoggingClient(pid);
    m_timeline->setLoggingClient(pid);
}

void LogView::reset()
{
    m_messages->reset();
}

}