// g++ nobump.c -std=c++14 -lXi -lXext -lX11
// SPDX-License-Identifier: GPL-3.0-or-later
// Copyright © 2019 Jeff Epler
#include <X11/extensions/XInput2.h>
#include <X11/extensions/dpms.h>
#include <X11/X.h>
#include <cstring>
#include <cstdio>
#include <unistd.h>

// Customize this to match your mouse (device string shown by 'xinput list')
const char *device_name = "Logitech USB-PS/2 Optical Mouse";
const char *property = "Device Enabled";

int32_t int_from_buffer(unsigned char *buffer) {
    int32_t result;
    memcpy(&result, buffer, sizeof(result));
    return result;
}

unsigned char *buffer_from_int(unsigned char *buffer, int32_t data) {
    memcpy(buffer, &data, sizeof(data));
    return buffer;
}

int find_deviceid_by_name(Display *display, const char *name) {
    auto ndevices = int{};
    auto info = XIQueryDevice(display, XIAllDevices, &ndevices);
    auto result = -1;
    for(auto i = info; i != info+ndevices; i++) {
        if(strcmp(i->name, name) == 0) { result = i->deviceid; break; }
    }
    XIFreeDeviceInfo(info);
    return result;
}

int main() {
    auto display = XOpenDisplay(nullptr);
    auto deviceid = find_deviceid_by_name(display, device_name);
    auto property_atom = XInternAtom(display, property, true);

    Atom type_atom;
    int format;
    unsigned char *data = {};
    unsigned long num_items, bytes_after;
    auto status = XIGetProperty( display, deviceid, property_atom,
        0, 1, false, 0, &type_atom, &format, &num_items, &bytes_after, 
        &data);

    auto old_state = -1;
    while(1) {
        CARD16 power;
        BOOL enable;
        auto status = DPMSInfo(display, &power, &enable);

        auto new_state = !(enable && power != DPMSModeOn);
        if(new_state != old_state) {
            buffer_from_int(data, new_state);
            XIChangeProperty(display, deviceid, property_atom, type_atom,
                format, XIPropModeReplace, data, num_items);
        }
        old_state = new_state;
        sleep(1);
    }

}