/*
 * In this module we implement the function that locates a USB device
 * by matchspec structure: looking for specific VID/PID, possibly qualified
 * by strings and/or index.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <usb.h>
#include "find_dev.h"
#include "prelim_init.h"

static void
get_string(usb_dev_handle *usbh, int index, char *buf, size_t buflen)
{
	int rc;

	rc = usb_get_string_simple(usbh, index, buf, buflen);
	if (rc <= 0) {
		fprintf(stderr, "error: USB string retrieval failed\n");
		exit(1);
	}
}

static int
is_match(struct usb_device *dev, const struct usbdev_matchspec *match)
{
	struct usb_device_descriptor *desc = &dev->descriptor;
	usb_dev_handle *usbh;
	char strbuf[1024];

	if (desc->idVendor != match->usb_vid)
		return 0;
	if (desc->idProduct != match->usb_pid)
		return 0;
	if (match->manuf_string || match->product_string || match->serial) {
		usbh = usb_open(dev);
		if (!usbh) {
			fprintf(stderr, "error: usb_open() failed\n");
			exit(1);
		}
		if (match->manuf_string) {
			get_string(usbh, desc->iManufacturer,
				   strbuf, sizeof strbuf);
			if (strncmp(match->manuf_string,
				    strbuf, sizeof strbuf)) {
				usb_close(usbh);
				return 0;
			}
		}
		if (match->product_string) {
			get_string(usbh, desc->iProduct, strbuf, sizeof strbuf);
			if (strncmp(match->product_string,
				    strbuf, sizeof strbuf)) {
				usb_close(usbh);
				return 0;
			}
		}
		if (match->serial) {
			get_string(usbh, desc->iSerialNumber,
				   strbuf, sizeof strbuf);
			if (strncmp(match->serial, strbuf, sizeof strbuf)) {
				usb_close(usbh);
				return 0;
			}
		}
		usb_close(usbh);
	}
	return 1;
}

struct usb_device *
find_usbdev_by_matchspec(const struct usbdev_matchspec *match)
{
	struct usb_bus *bus;
	struct usb_device *dev;
	unsigned index = match->index;

	libusb_prelim_init();
	for (bus = usb_get_busses(); bus; bus = bus->next) {
		for (dev = bus->devices; dev; dev = dev->next) {
			if (is_match(dev, match)) {
				if (!index)
					return dev;
				index--;
			}
		}
	}
	return 0;
}