/*
 * $snafu: gpscap.c,v 2.0 2003/10/06 19:13:52 marc Exp $
 *
 * Public Domain, 2001, Marco S Hyman <marc@snafu.org>
 */

#include <sys/types.h>

#include <stdio.h>
#include <stdlib.h>

#include "gpslib.h"

/*
 * Garmin GPS protocol capability application protocol
 *
 * gps -> host:	protocol array
 *
 * The array contains tag/value pairs.   The only tag/values this program
 * cares about is A{protocol indicator} and D{data type indicator}.  The
 * D{data type indicator} relate to the immediately preceeding A{protocol
 * indicator}.   The protocols A100, A200, A201, A300, and A301 are
 * processed.  All others are ignored.
 */
static void
gps_cap_parse(gps_handle gps, const u_char *data, int datalen)
{
	int ix;
	int tag;
	int val;
	int proto = 0;
	int dix = 0;

	gps_printf(gps, 3, "%s:\n", __func__);
	if (data[0] == p_cap) {
		for (ix = 1; ix + 2 < datalen; ix += 3) {
			tag = data[ix];
			val = data[ix + 1] + (data[ix + 2] << 8);
			gps_printf(gps, 3, "%s %c%03d", tag == 'A' ? "\n" : "",
				   tag, val);
			switch (tag) {
			case 'A':
				proto = val;
				dix = 0;
				break;
			case 'D':
				switch (proto) {
				default:
					break;
				case 100:
					gps_set_wpt_type(gps, val);
					break;
				case 200:
					if (dix == 0)
						gps_set_rte_hdr_type(gps, val);
					else
						gps_set_rte_wpt_type(gps, val);
					break;
				case 201:
					switch (dix) {
					case 0:
						gps_set_rte_hdr_type(gps, val);
						break;
					case 1:
						gps_set_rte_wpt_type(gps, val);
						break;
					case 2:
						gps_set_rte_lnk_type(gps, val);
						break;
					}
					break;
				case 300:
					if (dix == 0)
						gps_set_trk_type(gps, val);
					break;
				case 301:
					if (dix == 0)
						gps_set_trk_hdr_type(gps, val);
					else
						gps_set_trk_type(gps, val);
					break;
				}
				dix++;
				break;
			default:
				break;
			}
		}
		gps_printf(gps, 3, "\n");
	} else
		gps_printf(gps, 2, "%s: unknown packet type %d\n",
			   __func__, data[0]);
}

/*
 * See if the gps unit will send the supported protocol array.
 * Garmin says that some products will send this immediatly
 * following the product data protocol.  We'll wait about
 * 5 seconds for the data.  If it is not found assume it is
 * not supported.
 *
 * procedure returns -1 on error, otherwise 0.
 */

#define RCV_TO	5

int
gps_protocol_cap(gps_handle gps)
{
	int retries = 5;
	u_char *data = malloc(GPS_FRAME_MAX);
	int datalen;

	/* Start with a set of default capabilities.   These will be
	   overridden if the device sends up a capability packet. */

	gps_set_wpt_type(gps, D100);
	gps_set_rte_hdr_type(gps, D200);
	gps_set_rte_wpt_type(gps, D100);
	gps_set_trk_type(gps, D300);

	if (! data) {
		gps_printf(gps, 0, "%s: no memory\n", __func__);
		return -1;
	}
	gps_printf(gps, 3, "%s: recv\n", __func__);
	while (retries--) {
		datalen = GPS_FRAME_MAX;
		switch (gps_recv(gps, RCV_TO, data, &datalen)) {
		case -1:
			gps_send_nak(gps, *data);
			gps_printf(gps, 3, "%s: retry\n", __func__);
			break;
		case 0:
			goto done;
		case 1:
			gps_cap_parse(gps, data, datalen);
			gps_send_ack(gps, *data);
			free(data);
			gps_printf(gps, 3, "%s: rcvd\n", __func__);
			return 0;
		}
	}
done:
	free(data);
	return -1;
}