// SPDX-License-Identifier: GPL-2.0-or-later
/* BGP Nexthop Group Support
 * Copyright (C) 2023 NVIDIA Corporation
 * Copyright (C) 2023 6WIND
 */

#include <zebra.h>

#include <bgpd/bgpd.h>
#include <bgpd/bgp_debug.h>
#include <bgpd/bgp_nhg.h>


/****************************************************************************
 * L3 NHGs are used for fast failover of nexthops in the dplane. These are
 * the APIs for allocating L3 NHG ids. Management of the L3 NHG itself is
 * left to the application using it.
 * PS: Currently EVPN host routes is the only app using L3 NHG for fast
 * failover of remote ES links.
 ***************************************************************************/
static bitfield_t bgp_nh_id_bitmap;
static uint32_t bgp_nhg_start;

/* XXX - currently we do nothing on the callbacks */
static void bgp_nhg_add_cb(const char *name)
{
}

static void bgp_nhg_modify_cb(const struct nexthop_group_cmd *nhgc)
{
}

static void bgp_nhg_add_nexthop_cb(const struct nexthop_group_cmd *nhgc,
				   const struct nexthop *nhop)
{
}

static void bgp_nhg_del_nexthop_cb(const struct nexthop_group_cmd *nhgc,
				   const struct nexthop *nhop)
{
}

static void bgp_nhg_del_cb(const char *name)
{
}

static void bgp_nhg_zebra_init(void)
{
	static bool bgp_nhg_zebra_inited;

	if (bgp_nhg_zebra_inited)
		return;

	bgp_nhg_zebra_inited = true;
	bgp_nhg_start = zclient_get_nhg_start(ZEBRA_ROUTE_BGP);
	nexthop_group_init(bgp_nhg_add_cb, bgp_nhg_modify_cb,
			   bgp_nhg_add_nexthop_cb, bgp_nhg_del_nexthop_cb,
			   bgp_nhg_del_cb);
}

void bgp_nhg_init(void)
{
	uint32_t id_max;

	id_max = MIN(ZEBRA_NHG_PROTO_SPACING - 1, 16 * 1024);
	bf_init(bgp_nh_id_bitmap, id_max);
	bf_assign_zero_index(bgp_nh_id_bitmap);

	if (BGP_DEBUG(nht, NHT) || BGP_DEBUG(evpn_mh, EVPN_MH_ES))
		zlog_debug("bgp nhg range %u - %u", bgp_nhg_start + 1,
			   bgp_nhg_start + id_max);
}

void bgp_nhg_finish(void)
{
	bf_free(bgp_nh_id_bitmap);
}

uint32_t bgp_nhg_id_alloc(void)
{
	uint32_t nhg_id = 0;

	bgp_nhg_zebra_init();
	bf_assign_index(bgp_nh_id_bitmap, nhg_id);
	if (nhg_id)
		nhg_id += bgp_nhg_start;

	return nhg_id;
}

void bgp_nhg_id_free(uint32_t nhg_id)
{
	if (!nhg_id || (nhg_id <= bgp_nhg_start))
		return;

	nhg_id -= bgp_nhg_start;

	bf_release_index(bgp_nh_id_bitmap, nhg_id);
}