// This program requires libusb. I used version 0.10.
//
// Compilation on Linux:
//
// gcc -g -o trance-vibrator trance-vibrator.c -lusb
//
// Compilation on MacOS X: first use fink to install libusb, then
//
// gcc -I/sw/include -L/sw/lib -g -o trance-vibrator trance-vibrator.c -lusb
//
// On Linux, you must run this program as a user that has write access
// to the appropriate file in /proc/bus/usb. Typically that means you
// must either be root or chown or chmod the appropriate file.
//
// The only message that the vibrator understands (apparently) is one
// that sets the speed of vibration. The possible speeds are 0-255.
//
// This program simply reads speeds from standard input (in plain ASCII,
// separated by whitespace), and sets the vibrator speed. For example,
// to turn the vibration off:
//
// echo 0 | trance-vibrator
//
// or perhaps
//
// echo 0 | sudo trance-vibrator
//
// To turn on maximum vibration speed:
//
// echo 255 | trance-vibrator
//
// To run full speed for one second, then half speed for one second,
// then stop:
//
// ( echo 255; sleep 1; echo 128; sleep 1; echo 0 ) | trance-vibrator

#include <stdio.h>
#include <usb.h>
#include <errno.h>
#include <string.h>

int
main(int argc, char** argv)
{
    struct usb_bus* bus = 0;
    struct usb_device* dev = 0;
    struct usb_dev_handle* h;

    usb_init();
    usb_find_busses();
    usb_find_devices();

    for (bus = usb_get_busses(); bus != 0; bus = bus->next) {
	for (dev = bus->devices; dev != 0; dev = dev->next) {
	    if (dev->descriptor.idVendor == 0x0b49
		&& dev->descriptor.idProduct == 0x064f
	    )
		goto done;
	}
    }

done:
    if (dev == 0) {
	fprintf(stderr, "error: no trance vibrator found\n");
	return 1;
    }

    h = usb_open(dev);
    if (h == 0) {
	fprintf(stderr, "error: could not open device\n");
	return 1;
    }

#if 0
    // This stuff doesn't seem to be necessary...

    if (usb_set_configuration(h, 1) < 0) {
	fprintf(stderr, "error: could not set configuration\n");
	return 1;
    }

    if (usb_claim_interface(h, 0) < 0) {
	fprintf(stderr, "error: could not claim interface\n");
	return 1;
    }

    if (usb_set_altinterface(h, 0) < 0) {
	fprintf(stderr, "error: could not set altinterface\n");
	return 1;
    }
#endif

    while (1) {
	int i;
	int speed;

	scanf("%d", &speed);
	if (feof(stdin))
	    break;

	// The vibrator is flaky, so try the request a few times...
	for (i = 0; i < 3; ++i) {
	    if (usb_control_msg(h,
		USB_ENDPOINT_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
		1, speed, 0, 0, 0, 0) < 0)
	    {
		fprintf(stderr,
		    "warning: error sending control request: %s\n",
		    strerror(errno));
	    }
	    else break;
	}
    }

    return 0;
}