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// This file was copied from qtbase/qtbase/src/platformsupport/input/evdevmouse
// and stripped of its Q prefix and Qt namespace.
// QEvdevMouseHandler is a private part of Qt, and vboxmouse relies on its
// handleMouseEvent signal which is probably an implementation detail, so
// copying it is better than trying to use it directly.

#include "evdevmousehandler.h"

#include <QSocketNotifier>
#include <QStringList>
#include <QPoint>
#include <QGuiApplication>
#include <QScreen>

#include <qplatformdefs.h>
#include <qpa/qwindowsysteminterface.h>

#include <errno.h>

#include <linux/kd.h>
#include <linux/input.h>

#include <qdebug.h>

//#define QT_QPA_MOUSE_HANDLER_DEBUG

EvdevMouseHandler *EvdevMouseHandler::create(const QString &device, const QString &specification)
{
#ifdef QT_QPA_MOUSE_HANDLER_DEBUG
    qWarning() << "Try to create mouse handler for" << device << specification;
#endif

    bool compression = true;
    int jitterLimit = 0;
    int grab = 0;
    float scale = 1;

    QStringList args = specification.split(QLatin1Char(':'));
    foreach (const QString &arg, args) {
        if (arg == QLatin1String("nocompress"))
            compression = false;
        else if (arg.startsWith(QLatin1String("dejitter=")))
            jitterLimit = arg.mid(9).toInt();
        else if (arg.startsWith(QLatin1String("grab=")))
            grab = arg.mid(5).toInt();
        else if (arg.startsWith(QLatin1String("scale=")))
            scale = arg.mid(6).toFloat();
    }

    int fd;
    fd = open(device.toLocal8Bit().constData(), O_RDONLY | O_NDELAY, 0);
    if (fd >= 0) {
        ::ioctl(fd, EVIOCGRAB, grab);
        return new EvdevMouseHandler(device, fd, compression, jitterLimit, scale);
    } else {
        qWarning("Cannot open mouse input device '%s': %s", qPrintable(device), strerror(errno));
        return 0;
    }
}

EvdevMouseHandler::EvdevMouseHandler(const QString &device, int fd, bool compression, int jitterLimit, float scale)
    : m_device(device), m_fd(fd), m_notify(0), m_x(0), m_y(0), m_prevx(0), m_prevy(0),
      m_compression(compression), m_buttons(0), m_prevInvalid(true), m_scale(scale)
{
    setObjectName(QLatin1String("Evdev Mouse Handler"));

    m_jitterLimitSquared = jitterLimit * jitterLimit;

    // socket notifier for events on the mouse device
    QSocketNotifier *notifier;
    notifier = new QSocketNotifier(m_fd, QSocketNotifier::Read, this);
    connect(notifier, SIGNAL(activated(int)), this, SLOT(readMouseData()));
}

EvdevMouseHandler::~EvdevMouseHandler()
{
    if (m_fd >= 0)
        close(m_fd);
}

Qt::MouseButtons EvdevMouseHandler::buttons() const
{
    return m_buttons;
}

void EvdevMouseHandler::sendMouseEvent()
{
    int x = m_x - m_prevx;
    int y = m_y - m_prevy;
    if (m_prevInvalid) {
        x = y = 0;
        m_prevInvalid = false;
    }

    emit handleMouseEvent(x * m_scale, y * m_scale, m_buttons);

    m_prevx = m_x;
    m_prevy = m_y;
}

void EvdevMouseHandler::readMouseData()
{
    struct ::input_event buffer[32];
    int n = 0;
    bool posChanged = false, btnChanged = false;
    bool pendingMouseEvent = false;
    int eventCompressCount = 0;
    forever {
        int result = QT_READ(m_fd, reinterpret_cast<char *>(buffer) + n, sizeof(buffer) - n);

        if (result == 0) {
            qWarning("Got EOF from the input device.");
            return;
        } else if (result < 0) {
            if (errno != EINTR && errno != EAGAIN) {
                qWarning("Could not read from input device: %s", strerror(errno));
                return;
            }
        } else {
            n += result;
            if (n % sizeof(buffer[0]) == 0)
                break;
        }
    }

    n /= sizeof(buffer[0]);

    for (int i = 0; i < n; ++i) {
        struct ::input_event *data = &buffer[i];
        //qDebug() << ">>" << hex << data->type << data->code << dec << data->value;
        if (data->type == EV_ABS) {
            // Touchpads: store the absolute position for now, will calculate a relative one later.
            if (data->code == ABS_X && m_x != data->value) {
                m_x = data->value;
                posChanged = true;
            } else if (data->code == ABS_Y && m_y != data->value) {
                m_y = data->value;
                posChanged = true;
            }
        } else if (data->type == EV_REL) {
            if (data->code == REL_X) {
                m_x += data->value;
                posChanged = true;
            } else if (data->code == REL_Y) {
                m_y += data->value;
                posChanged = true;
            } else if (data->code == ABS_WHEEL) { // vertical scroll
                // data->value: 1 == up, -1 == down
                const int delta = 120 * data->value;
                emit handleWheelEvent(delta, Qt::Vertical);
            } else if (data->code == ABS_THROTTLE) { // horizontal scroll
                // data->value: 1 == right, -1 == left
                const int delta = 120 * -data->value;
                emit handleWheelEvent(delta, Qt::Horizontal);
            }
        } else if (data->type == EV_KEY && data->code == BTN_TOUCH) {
            // We care about touchpads only, not touchscreens -> don't map to button press.
            // Need to invalidate prevx/y however to get proper relative pos.
            m_prevInvalid = true;
        } else if (data->type == EV_KEY && data->code >= BTN_LEFT && data->code <= BTN_JOYSTICK) {
            Qt::MouseButton button = Qt::NoButton;
            // BTN_LEFT == 0x110 in kernel's input.h
            // The range of possible mouse buttons ends just before BTN_JOYSTICK, value 0x120.
            switch (data->code) {
            case 0x110: button = Qt::LeftButton; break;    // BTN_LEFT
            case 0x111: button = Qt::RightButton; break;
            case 0x112: button = Qt::MiddleButton; break;
            case 0x113: button = Qt::ExtraButton1; break;  // AKA Qt::BackButton
            case 0x114: button = Qt::ExtraButton2; break;  // AKA Qt::ForwardButton
            case 0x115: button = Qt::ExtraButton3; break;  // AKA Qt::TaskButton
            case 0x116: button = Qt::ExtraButton4; break;
            case 0x117: button = Qt::ExtraButton5; break;
            case 0x118: button = Qt::ExtraButton6; break;
            case 0x119: button = Qt::ExtraButton7; break;
            case 0x11a: button = Qt::ExtraButton8; break;
            case 0x11b: button = Qt::ExtraButton9; break;
            case 0x11c: button = Qt::ExtraButton10; break;
            case 0x11d: button = Qt::ExtraButton11; break;
            case 0x11e: button = Qt::ExtraButton12; break;
            case 0x11f: button = Qt::ExtraButton13; break;
            }
            if (data->value)
                m_buttons |= button;
            else
                m_buttons &= ~button;
            btnChanged = true;
        } else if (data->type == EV_SYN && data->code == SYN_REPORT) {
            if (btnChanged) {
                btnChanged = posChanged = false;
                sendMouseEvent();
                pendingMouseEvent = false;
            } else if (posChanged) {
                posChanged = false;
                if (m_compression) {
                    pendingMouseEvent = true;
                    eventCompressCount++;
                } else {
                    sendMouseEvent();
                }
            }
        } else if (data->type == EV_MSC && data->code == MSC_SCAN) {
            // kernel encountered an unmapped key - just ignore it
            continue;
        }
    }
    if (m_compression && pendingMouseEvent) {
        int distanceSquared = (m_x - m_prevx)*(m_x - m_prevx) + (m_y - m_prevy)*(m_y - m_prevy);
        if (distanceSquared > m_jitterLimitSquared)
            sendMouseEvent();
    }
}