/*
  Copyright (c) 2013-2014, Matthias Schiffer <mschiffer@universe-factory.net>
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice,
       this list of conditions and the following disclaimer in the documentation
       and/or other materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/


#ifndef _GMRF_PROTO_BABEL_BABEL_H_
#define _GMRF_PROTO_BABEL_BABEL_H_

#include "types.h"


#define GP_BABEL_INFINITY 0xffff

#define GP_BABEL_PACKET_MAX 1000

#define GP_BABEL_HELLO_INTERVAL 400
#define GP_BABEL_IHU_INTERVAL (3*GP_BABEL_HELLO_INTERVAL)

#define GP_BABEL_UPDATE_INTERVAL 3000

#define GP_BABEL_HELLO_TIMEOUT(interval) (16*(interval))
#define GP_BABEL_IHU_TIMEOUT(interval) ((interval)*7/2)
#define GP_BABEL_UPDATE_TIMEOUT(interval) ((interval)*7/2) /* 3.5 intervals */
#define GP_BABEL_UPDATE_REQUEST_TIMEOUT(interval) ((interval)*13/4) /* 3.25 intervals */

#define GP_BABEL_MAINTENANCE_INTERVAL GP_BABEL_HELLO_INTERVAL
#define GP_BABEL_PURGE_TIMEOUT GP_BABEL_UPDATE_TIMEOUT(GP_BABEL_UPDATE_INTERVAL)
#define GP_BABEL_NEIGH_PACKET_TIMEOUT 6000


#define GP_BABEL_SEQNO_REQ_HOP_LIMIT 127


struct gmrf_context {
	gmrf_t *gmrf;

	gp_babel_node_id_t self;
	uint16_t hello_seqno;

	gmrf_iface_state_t *interfaces;
	gp_babel_neigh_t *neighbours;

	gp_babel_route_t *routes;
};

struct gmrf_iface_state {
	gmrf_iface_state_t *next;

	gmrf_iface_t *gmrf_iface;

	gp_babel_neigh_t *neighbours;
};

struct gp_babel_neigh {
	gp_babel_neigh_t *next;

	unsigned ref;
	gmrf_time_t last_packet;

	gmrf_iface_state_t *iface;
	gmrf_addr_t addr;

	uint16_t hello_log;
	uint16_t hello_interval;
	uint16_t last_seqno;
	gmrf_time_t last_hello;

	uint16_t ihu_interval;
	gmrf_time_t last_ihu;

	uint16_t txcost;
};

struct gp_babel_route {
	gp_babel_route_t *next;

	gp_babel_node_id_t node;

	gp_babel_metric_seqno_t metric;
	uint16_t last_metric;
	gp_babel_metric_seqno_t feasibility_distance;

	gp_babel_nexthop_t *selected;
	gp_babel_nexthop_t *nexthops;

	gmrf_time_t last_nexthop;
};

struct gp_babel_nexthop {
	gp_babel_nexthop_t *next;

	gp_babel_neigh_t *neigh;
	gp_babel_metric_seqno_t metric_seqno;

	gmrf_time_t last_update;
	uint16_t interval;
	bool requested_update;
};


void gp_babel_handle_packet(gmrf_context_t *ctx, gmrf_iface_state_t *iface, const gmrf_addr_t *source, const gp_babel_packet_t *packet);

void gp_babel_send_ack(gmrf_context_t *ctx, gp_babel_neigh_t *neigh, uint16_t nonce);
void gp_babel_send_hellos(gmrf_context_t *ctx);

void gp_babel_send_update(gmrf_context_t *ctx, gmrf_iface_state_t *iface, gp_babel_neigh_t *neigh);
void gp_babel_send_update_for_route(gmrf_context_t *ctx, gmrf_iface_state_t *iface, gp_babel_neigh_t *neigh, gp_babel_route_t *route);
void gp_babel_send_retract(gmrf_context_t *ctx, gmrf_iface_state_t *iface, gp_babel_neigh_t *neigh, const gp_babel_node_id_t *node);

void gp_babel_send_route_request(gmrf_context_t *ctx, gmrf_iface_state_t *iface, gp_babel_neigh_t *neigh, const gp_babel_node_id_t *node);
void gp_babel_send_seqno_request(gmrf_context_t *ctx, gp_babel_neigh_t *neigh, gp_babel_route_t *route, uint16_t seqno, uint8_t hop_count);

gp_babel_route_t* gp_babel_route_new(gmrf_context_t *ctx);
gp_babel_route_t* gp_babel_route_find(gmrf_context_t *ctx, const gp_babel_node_id_t *node);
gp_babel_route_t* gp_babel_route_get(gmrf_context_t *ctx, const gp_babel_node_id_t *node);
void gp_babel_route_maintain(gmrf_context_t *ctx, gp_babel_route_t *route);
void gp_babel_route_free(gmrf_context_t *ctx, gp_babel_route_t *route);

gp_babel_nexthop_t* gp_babel_route_nexthop_new(gp_babel_route_t *route, gp_babel_neigh_t *neigh);
gp_babel_nexthop_t* gp_babel_route_nexthop_find(const gp_babel_route_t *route, gp_babel_neigh_t *neigh);
void gp_babel_route_nexthop_delete(gmrf_context_t *ctx, gp_babel_route_t *route, gp_babel_nexthop_t *nexthop);
void gp_babel_route_update_nexthop(gmrf_context_t *ctx, gp_babel_route_t *route, gp_babel_nexthop_t *nexthop, gp_babel_metric_seqno_t ms, uint16_t interval);


static inline bool gp_babel_node_id_equal(const gp_babel_node_id_t *id1, const gp_babel_node_id_t *id2) {
	return (memcmp(id1->id, id2->id, GP_BABEL_NODE_ID_LENGTH) == 0);
}

static inline bool gp_babel_node_id_is_unspec(const gp_babel_node_id_t *id) {
	return gp_babel_node_id_equal(id, &gp_babel_node_id_unspec);
};

static inline bool gp_babel_less(uint16_t a, uint16_t b) {
	int16_t diff = a - b;

	return (diff < 0);
}

static inline int64_t gp_babel_since(gmrf_context_t *ctx, gmrf_time_t t) {
	if (t == gmrf_time_unspec)
		return INT64_MAX;

	return (gmrf_now(ctx->gmrf) - t)/10;
}

static inline bool gp_babel_is_metric_better(gp_babel_metric_seqno_t ms1, gp_babel_metric_seqno_t ms2) {
	if (ms1.metric == GP_BABEL_INFINITY)
		return false;

	if (ms2.metric == GP_BABEL_INFINITY)
		return true;

	int16_t seqno_diff = ms2.seqno - ms1.seqno;

	if (seqno_diff < 0)
		return true;
	if (seqno_diff == 0 && ms1.metric < ms2.metric)
		return true;

	return false;
}

static inline bool gp_babel_route_is_reachable(const gp_babel_route_t *route) {
	return (route->metric.metric != GP_BABEL_INFINITY);
}

static inline bool gp_babel_is_feasible(const gp_babel_route_t *route, gp_babel_metric_seqno_t ms) {
	if (ms.metric == GP_BABEL_INFINITY)
		return true;

	return gp_babel_is_metric_better(ms, route->feasibility_distance);
}

static inline void gp_babel_send_seqno_request_for(gmrf_context_t *ctx, gp_babel_neigh_t *neigh, gp_babel_route_t *route) {
	if (route->feasibility_distance.metric == GP_BABEL_INFINITY)
		return;

	gp_babel_send_seqno_request(ctx, neigh, route, route->feasibility_distance.seqno+1, GP_BABEL_SEQNO_REQ_HOP_LIMIT);
}

#endif /* _GMRF_PROTO_BABEL_BABEL_H_ */