/* NM BTS FSM */

/* (C) 2020 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de>
 * Author: Pau Espin Pedrol <pespin@sysmocom.de>
 *
 * All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation; either version 3 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 Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <errno.h>
#include <unistd.h>
#include <inttypes.h>

#include <osmocom/core/fsm.h>
#include <osmocom/core/tdef.h>
#include <osmocom/gsm/protocol/gsm_12_21.h>

#include <osmocom/bsc/bts.h>
#include <osmocom/bsc/signal.h>
#include <osmocom/bsc/abis_nm.h>
#include <osmocom/bsc/bts_ipaccess_nanobts_omlattr.h>
#include <osmocom/bsc/nm_common_fsm.h>
#include <osmocom/bsc/debug.h>

#define X(s) (1 << (s))

#define nm_bts_fsm_state_chg(fi, NEXT_STATE) \
	osmo_fsm_inst_state_chg(fi, NEXT_STATE, 0, 0)

//////////////////////////
// FSM STATE ACTIONS
//////////////////////////

static void st_op_disabled_notinstalled_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state)
{
	struct gsm_bts *bts = (struct gsm_bts *)fi->priv;

	bts->mo.get_attr_sent = false;
	bts->mo.get_attr_rep_received = false;
	bts->mo.set_attr_sent = false;
	bts->mo.set_attr_ack_received = false;
	bts->mo.adm_unlock_sent = false;
	bts->mo.opstart_sent = false;
}

static void st_op_disabled_notinstalled(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct nm_statechg_signal_data *nsd;
	const struct gsm_nm_state *new_state;

	switch (event) {
	case NM_EV_SW_ACT_REP:
		break;
	case NM_EV_STATE_CHG_REP:
		nsd = (struct nm_statechg_signal_data *)data;
		new_state = &nsd->new_state;
		if (new_state->operational == NM_OPSTATE_ENABLED) {
			/*should not happen... */
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_ENABLED);
			return;
		}
		switch (new_state->availability) { /* operational = DISABLED */
		case NM_AVSTATE_DEPENDENCY:
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_DEPENDENCY);
			return;
		case NM_AVSTATE_OFF_LINE:
		case NM_AVSTATE_OK:
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_OFFLINE);
			return;
		default:
			return;
		}
	default:
		OSMO_ASSERT(0);
	}
}

static void configure_loop(struct gsm_bts *bts, const struct gsm_nm_state *state, bool allow_opstart)
{
	struct msgb *msgb;

	/* Request generic BTS-level attributes */
	if (!bts->mo.get_attr_sent && !bts->mo.get_attr_rep_received) {
		bts->mo.get_attr_sent = true;
		/* N. B: we rely on attribute order when parsing response in abis_nm_rx_get_attr_resp() */
		const uint8_t bts_attr[] = { NM_ATT_MANUF_ID, NM_ATT_SW_CONFIG, };
		/* we should not request more attributes than we're ready to handle */
		OSMO_ASSERT(sizeof(bts_attr) < MAX_BTS_ATTR);
		abis_nm_get_attr(bts, NM_OC_BTS, 0, 0xff, 0xff,
				 bts_attr, sizeof(bts_attr));
	}

	if (bts->mo.get_attr_rep_received &&
	    !bts->mo.set_attr_sent && !bts->mo.set_attr_ack_received) {
		bts->mo.set_attr_sent = true;
		msgb = nanobts_gen_set_bts_attr(bts);
		abis_nm_set_bts_attr(bts, msgb->data, msgb->len);
		msgb_free(msgb);
	}

	if (bts->mo.set_attr_ack_received &&
	    state->administrative != NM_STATE_UNLOCKED && !bts->mo.adm_unlock_sent) {
		bts->mo.adm_unlock_sent = true;
		abis_nm_chg_adm_state(bts, NM_OC_BTS,
				      bts->bts_nr, 0xff, 0xff,
				      NM_STATE_UNLOCKED);
		/* Message containing BTS attributes, including the interference band bounds, was ACKed by the BTS.
		 * Store the sent bounds as the ones being used for logging and comparing intereference levels. */
		bts->interf_meas_params_used = bts->interf_meas_params_cfg;
	}

	if (allow_opstart && state->administrative == NM_STATE_UNLOCKED &&
	    bts->mo.set_attr_ack_received) {
		if (!bts->mo.opstart_sent) {
		    bts->mo.opstart_sent = true;
		    abis_nm_opstart(bts, NM_OC_BTS, bts->bts_nr, 0xff, 0xff);
		}
	}
}

static void rx_get_attr_rep(struct gsm_bts *bts, bool allow_opstart)
{
	struct gsm_gprs_nsvc *nsvc;

	bts->mo.get_attr_rep_received = true;
	bts->mo.get_attr_sent = false;

	/* Announce bts_features are available to related NSVC MOs */
	nsvc = gsm_bts_sm_nsvc_num(bts->site_mgr, 0); /* we only support NSVC0 so far */
	osmo_fsm_inst_dispatch(nsvc->mo.fi, NM_EV_FEATURE_NEGOTIATED, NULL);

	/* Move FSM forward */
	configure_loop(bts, &bts->mo.nm_state, allow_opstart);
}

static void st_op_disabled_dependency_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state)
{
	struct gsm_bts *bts = (struct gsm_bts *)fi->priv;

	/* nanoBTS is broken, doesn't follow TS 12.21. Opstart MUST be sent
	   during Dependency, so we simply move to OFFLINE state here to avoid
	   duplicating code */
	if (bts->site_mgr->peer_has_no_avstate_offline) {
		nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_OFFLINE);
		return;
	}
	configure_loop(bts, &bts->mo.nm_state, false);
}

static void st_op_disabled_dependency(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct gsm_bts *bts = (struct gsm_bts *)fi->priv;
	struct nm_statechg_signal_data *nsd;
	const struct gsm_nm_state *new_state;

	switch (event) {
	case NM_EV_GET_ATTR_REP:
		rx_get_attr_rep(bts, false);
		return;
	case NM_EV_SET_ATTR_ACK:
		bts->mo.set_attr_ack_received = true;
		bts->mo.set_attr_sent = false;
		configure_loop(bts, &bts->mo.nm_state, false);
		return;
	case NM_EV_STATE_CHG_REP:
		nsd = (struct nm_statechg_signal_data *)data;
		new_state = &nsd->new_state;
		if (new_state->operational == NM_OPSTATE_ENABLED) {
			/* should not happen... */
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_ENABLED);
			return;
		}
		switch (new_state->availability) { /* operational = DISABLED */
		case NM_AVSTATE_NOT_INSTALLED:
		case NM_AVSTATE_POWER_OFF:
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_NOTINSTALLED);
			return;
		case NM_AVSTATE_OFF_LINE:
		case NM_AVSTATE_OK:
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_OFFLINE);
			return;
		case NM_AVSTATE_DEPENDENCY:
			configure_loop(bts, new_state, false);
			return;
		default:
			return;
		}
	default:
		OSMO_ASSERT(0);
	}
}

static void st_op_disabled_offline_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state)
{
	struct gsm_bts *bts = (struct gsm_bts *)fi->priv;

	configure_loop(bts, &bts->mo.nm_state, true);
}

static void st_op_disabled_offline(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct gsm_bts *bts = (struct gsm_bts *)fi->priv;
	struct nm_statechg_signal_data *nsd;
	const struct gsm_nm_state *new_state;

	switch (event) {
	case NM_EV_GET_ATTR_REP:
		rx_get_attr_rep(bts, true);
		return;
	case NM_EV_SET_ATTR_ACK:
		bts->mo.set_attr_ack_received = true;
		bts->mo.set_attr_sent = false;
		configure_loop(bts, &bts->mo.nm_state, true);
		return;
	case NM_EV_STATE_CHG_REP:
		nsd = (struct nm_statechg_signal_data *)data;
		new_state = &nsd->new_state;
		if (new_state->operational == NM_OPSTATE_ENABLED) {
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_ENABLED);
			return;
		}
		switch (new_state->availability) { /* operational = DISABLED */
		case NM_AVSTATE_NOT_INSTALLED:
		case NM_AVSTATE_POWER_OFF:
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_NOTINSTALLED);
			return;
		case NM_AVSTATE_DEPENDENCY:
			/* There's no point in moving back to Dependency, since it's broken
			   and it acts actually as if it was in Offline state */
			if (!bts->site_mgr->peer_has_no_avstate_offline) {
				nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_DEPENDENCY);
			} else {
				/* Moreover, in nanoBTS we need to check here for tx
				   Opstart since we may have gone Unlocked state
				   in this event, which means Opstart may be txed here. */
				configure_loop(bts, new_state, true);
			}
			return;
		case NM_AVSTATE_OFF_LINE:
		case NM_AVSTATE_OK:
			configure_loop(bts, new_state, true);
			return;
		default:
			return;
		}
	default:
		OSMO_ASSERT(0);
	}
}

static void st_op_enabled_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state)
{
	struct gsm_bts *bts = (struct gsm_bts *)fi->priv;

	/* Reset state, we don't need it in this state and it will need to be
	  reused as soon as we move back to Disabled */
	bts->mo.opstart_sent = false;
	bts->mo.adm_unlock_sent = false;
	bts->mo.get_attr_sent = false;
	bts->mo.get_attr_rep_received = false;
	bts->mo.set_attr_sent = false;
	bts->mo.set_attr_ack_received = false;
}

static void st_op_enabled(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct nm_statechg_signal_data *nsd;
	const struct gsm_nm_state *new_state;

	switch (event) {
	case NM_EV_STATE_CHG_REP:
		nsd = (struct nm_statechg_signal_data *)data;
		new_state = &nsd->new_state;
		if (new_state->operational == NM_OPSTATE_ENABLED)
			return;
		switch (new_state->availability) { /* operational = DISABLED */
		case NM_AVSTATE_NOT_INSTALLED:
		case NM_AVSTATE_POWER_OFF:
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_NOTINSTALLED);
			return;
		case NM_AVSTATE_DEPENDENCY:
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_DEPENDENCY);
			return;
		case NM_AVSTATE_OFF_LINE:
		case NM_AVSTATE_OK:
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_OFFLINE);
			return;
		default:
			return;
		}
	default:
		OSMO_ASSERT(0);
	}
}

static void st_op_allstate(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct gsm_bts *bts = (struct gsm_bts *)fi->priv;

	switch (event) {
	case NM_EV_OPSTART_ACK:
	case NM_EV_OPSTART_NACK:
		/* TODO: if on state OFFLINE and rx NACK, try again? */
		bts->mo.opstart_sent = false;
		break;
	case NM_EV_OML_DOWN:
		if (fi->state != NM_BTS_ST_OP_DISABLED_NOTINSTALLED)
			nm_bts_fsm_state_chg(fi, NM_BTS_ST_OP_DISABLED_NOTINSTALLED);
		break;
	default:
		OSMO_ASSERT(0);
	}
}

static struct osmo_fsm_state nm_bts_fsm_states[] = {
	[NM_BTS_ST_OP_DISABLED_NOTINSTALLED] = {
		.in_event_mask =
			X(NM_EV_SW_ACT_REP) |
			X(NM_EV_STATE_CHG_REP),
		.out_state_mask =
			X(NM_BTS_ST_OP_DISABLED_DEPENDENCY) |
			X(NM_BTS_ST_OP_DISABLED_OFFLINE) |
			X(NM_BTS_ST_OP_ENABLED),
		.name = "DISABLED_NOTINSTALLED",
		.onenter = st_op_disabled_notinstalled_on_enter,
		.action = st_op_disabled_notinstalled,
	},
	[NM_BTS_ST_OP_DISABLED_DEPENDENCY] = {
		.in_event_mask =
			X(NM_EV_STATE_CHG_REP) |
			X(NM_EV_GET_ATTR_REP) |
			X(NM_EV_SET_ATTR_ACK),
		.out_state_mask =
			X(NM_BTS_ST_OP_DISABLED_NOTINSTALLED) |
			X(NM_BTS_ST_OP_DISABLED_OFFLINE) |
			X(NM_BTS_ST_OP_ENABLED),
		.name = "DISABLED_DEPENDENCY",
		.onenter = st_op_disabled_dependency_on_enter,
		.action = st_op_disabled_dependency,
	},
	[NM_BTS_ST_OP_DISABLED_OFFLINE] = {
		.in_event_mask =
			X(NM_EV_STATE_CHG_REP) |
			X(NM_EV_GET_ATTR_REP) |
			X(NM_EV_SET_ATTR_ACK),
		.out_state_mask =
			X(NM_BTS_ST_OP_DISABLED_NOTINSTALLED) |
			X(NM_BTS_ST_OP_DISABLED_DEPENDENCY) |
			X(NM_BTS_ST_OP_ENABLED),
		.name = "DISABLED_OFFLINE",
		.onenter = st_op_disabled_offline_on_enter,
		.action = st_op_disabled_offline,
	},
	[NM_BTS_ST_OP_ENABLED] = {
		.in_event_mask =
			X(NM_EV_STATE_CHG_REP),
		.out_state_mask =
			X(NM_BTS_ST_OP_DISABLED_NOTINSTALLED) |
			X(NM_BTS_ST_OP_DISABLED_DEPENDENCY) |
			X(NM_BTS_ST_OP_DISABLED_OFFLINE),
		.name = "ENABLED",
		.onenter = st_op_enabled_on_enter,
		.action = st_op_enabled,
	},
};

struct osmo_fsm nm_bts_fsm = {
	.name = "NM_BTS_OP",
	.states = nm_bts_fsm_states,
	.num_states = ARRAY_SIZE(nm_bts_fsm_states),
	.allstate_event_mask =
		X(NM_EV_OPSTART_ACK) |
		X(NM_EV_OPSTART_NACK) |
		X(NM_EV_OML_DOWN),
	.allstate_action = st_op_allstate,
	.event_names = nm_fsm_event_names,
	.log_subsys = DNM,
};

static __attribute__((constructor)) void nm_bts_fsm_init(void)
{
	OSMO_ASSERT(osmo_fsm_register(&nm_bts_fsm) == 0);
}
