/*
 * Copyright 2011 Benjamin Tissoires <benjamin....@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/input.h>
#include <linux/hidraw.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>

#define USB_VENDOR_ID_LOGITECH                        (__u32)0x046d
#define USB_DEVICE_ID_UNIFYING_RECEIVER                (__s16)0xc52b
#define USB_DEVICE_ID_UNIFYING_RECEIVER_2        (__s16)0xc532

int main(int argc, char **argv)
{
        int fd;
        int res;
        struct hidraw_devinfo info;
        char magic_sequence[] = {0x10, 0xFF, 0x80, 0xB2, 0x01, 0x00, 0x00};

        if (argc == 1) {
                errno = EINVAL;
                perror("No hidraw device given");
                return 1;
        }

        /* Open the Device with non-blocking reads. */
        fd = open(argv[1], O_RDWR|O_NONBLOCK);

        if (fd < 0) {
                perror("Unable to open device");
                return 1;
        }

        /* Get Raw Info */
        res = ioctl(fd, HIDIOCGRAWINFO, &info);
        if (res < 0) {
                perror("error while getting info from device");
                return 1;
        } else {
                if (info.bustype != BUS_USB ||
                    info.vendor != USB_VENDOR_ID_LOGITECH ||
                    (info.product != USB_DEVICE_ID_UNIFYING_RECEIVER &&
                     info.product != USB_DEVICE_ID_UNIFYING_RECEIVER_2)) {
                        errno = EPERM;
                        perror("The given device is not a Logitech "
                                "Unifying Receiver");
                        return 1;
                }
        }

        /* Send the magic sequence to the Device */
        res = write(fd, magic_sequence, sizeof(magic_sequence));
        if (res < 0) {
                printf("Error: %d\n", errno);
                perror("write");
                return 1;
        } else if (res == sizeof(magic_sequence)) {
                printf("The receiver is ready to pair a new device.\n"
                "Switch your device on to pair it.\n");
        } else {
                errno = ENOMEM;
                printf("write: %d were written instead of %ld.\n", res,
                        sizeof(magic_sequence));
                perror("write");
                return 1;
        }
        close(fd);
        return 0;
}