/**

 * @file bmc.c

 * @note Copyright (C) 2011 Richard Cochran <richardcochran@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 2 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, write to the Free Software Foundation, Inc.,

 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

 */

#include <string.h>

#include "bmc.h"

#include "ds.h"

int dscmp2(struct dataset *a, struct dataset *b)

{

	int diff;

	unsigned int A = a->stepsRemoved, B = b->stepsRemoved;

	if (A + 1 < B)

		return A_BETTER;

	if (B + 1 < A)

		return B_BETTER;

	/*

	 * We ignore the "error-1" conditions mentioned in the

	 * standard, since there is nothing we can do about it anyway.

	 */

	if (A < B) {

		diff = memcmp(&b->receiver, &b->sender, sizeof(b->receiver));

		if (diff < 0)

			return A_BETTER;

		if (diff > 0)

			return A_BETTER_TOPO;

		/* error-1 */

		return 0;

	}

	if (A > B) {

		diff = memcmp(&a->receiver, &a->sender, sizeof(a->receiver));

		if (diff < 0)

			return B_BETTER;

		if (diff > 0)

			return B_BETTER_TOPO;

		/* error-1 */

		return 0;

	}

	diff = memcmp(&a->sender, &b->sender, sizeof(a->sender));

	if (diff < 0)

		return A_BETTER_TOPO;

	if (diff > 0)

		return B_BETTER_TOPO;

	if (a->receiver.portNumber < b->receiver.portNumber)

		return A_BETTER_TOPO;

	if (a->receiver.portNumber > b->receiver.portNumber)

		return B_BETTER_TOPO;

	/*

	 * If we got this far, it means "error-2" has occured.

	 */

	return 0;

}

int dscmp(struct dataset *a, struct dataset *b)

{

	int diff;

	if (a == b)

		return 0;

	if (a && !b)

		return A_BETTER;

	if (b && !a)

		return B_BETTER;

	diff = memcmp(&a->identity, &b->identity, sizeof(a->identity));

	if (!diff)

		return dscmp2(a, b);

	if (a->priority1 < b->priority1)

		return A_BETTER;

	if (a->priority1 > b->priority1)

		return B_BETTER;

	if (a->quality.clockClass < b->quality.clockClass)

		return A_BETTER;

	if (a->quality.clockClass > b->quality.clockClass)

		return B_BETTER;

	if (a->quality.clockAccuracy < b->quality.clockAccuracy)

		return A_BETTER;

	if (a->quality.clockAccuracy > b->quality.clockAccuracy)

		return B_BETTER;

	if (a->quality.offsetScaledLogVariance <

	    b->quality.offsetScaledLogVariance)

		return A_BETTER;

	if (a->quality.offsetScaledLogVariance >

	    b->quality.offsetScaledLogVariance)

		return B_BETTER;

	if (a->priority2 < b->priority2)

		return A_BETTER;

	if (a->priority2 > b->priority2)

		return B_BETTER;

	return diff < 0 ? A_BETTER : B_BETTER;

}

enum port_state bmc_state_decision(struct clock *c, struct port *r,

				   int (*compare)(struct dataset *a, struct dataset *b))

{

	struct dataset *clock_ds, *clock_best, *port_best;

	enum port_state ps;

	clock_ds = clock_default_ds(c);

	clock_best = clock_best_foreign(c);

	port_best = port_best_foreign(r);

	ps = port_state(r);

	if (!port_best && PS_LISTENING == ps)

		return ps;

	if (clock_class(c) <= 127) {

		if (compare(clock_ds, port_best) > 0) {

			return PS_GRAND_MASTER; /*M1*/

		} else {

			return PS_PASSIVE; /*P1*/

		}

	}

	if (compare(clock_ds, clock_best) > 0) {

		return PS_GRAND_MASTER; /*M2*/

	}

	if (clock_best_port(c) == r) {

		return PS_SLAVE; /*S1*/

	}

	if (compare(clock_best, port_best) == A_BETTER_TOPO) {

		return PS_PASSIVE; /*P2*/

	} else {

		return PS_MASTER; /*M3*/

	}

}