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/*
 * (C) 2010-2013 by Holger Hans Peter Freyther <zecke@selfish.org>
 * (C) 2010-2013 by On-Waves
 * 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 Affero 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 <osmocom/bsc/osmo_bsc_grace.h>
#include <osmocom/bsc/osmo_bsc_rf.h>
#include <osmocom/bsc/bsc_msc_data.h>
#include <osmocom/bsc/gsm_04_80.h>
#include <osmocom/bsc/bsc_subscriber.h>
#include <osmocom/bsc/paging.h>
#include <osmocom/bsc/signal.h>
#include <osmocom/bsc/lchan_fsm.h>

int bsc_grace_allow_new_connection(struct gsm_network *network, struct gsm_bts *bts)
{
	if (bts->excl_from_rf_lock)
		return 1;
	return network->bsc_data->rf_ctrl->policy == S_RF_ON;
}


/* Return value is like paging_request_bts():
 * returns 1 on success (one BTS was paged); 0 in case of error (e.g. TRX down) */
static int locked_paging_bts(struct gsm_bts *bts,
			     struct bsc_subscr *subscr,
			     int chan_needed,
			     struct bsc_msc_data *msc)
{
	/* Return error if the BTS is not excluded from the lock. */
	if (!bts->excl_from_rf_lock)
		return 0;

	/* in case of no lac patching is in place, check the BTS */
	if (msc->core_lac == -1 && subscr->lac != bts->location_area_code)
		return 0;

	return paging_request_bts(bts, subscr, chan_needed, msc);
}

/**
 * Page a subscriber in an MSC.
 * \param[in] rf_policy if not S_RF_ON, page only BTSs which are not excluded from the RF lock
 * \param[in] subscr subscriber we want to page
 * \param[in] chan_needed value of the GSM0808_IE_CHANNEL_NEEDED IE
 * \param[in] msc MSC which has issued this paging
 * \param[in] bts The BTS to issue the paging on
 * \returns 1 if paging was issued to the BTS, 0 if not
 */
int bsc_grace_paging_request(enum signal_rf rf_policy,
			     struct bsc_subscr *subscr,
			     int chan_needed,
			     struct bsc_msc_data *msc,
			     struct gsm_bts *bts)
{
	if (rf_policy == S_RF_ON)
		return paging_request_bts(bts, subscr, chan_needed, msc);
	return locked_paging_bts(bts, subscr, chan_needed, msc);
}

static int handle_sub(struct gsm_lchan *lchan, const char *text)
{
	struct gsm_subscriber_connection *conn;

	/* only send it to TCH */
	if (lchan->type != GSM_LCHAN_TCH_H && lchan->type != GSM_LCHAN_TCH_F)
		return -1;

	/* only send on the primary channel */
	conn = lchan->conn;
	if (!conn)
		return -1;

	if (conn->lchan != lchan)
		return -1;

	/* only when active */
	if (lchan->fi->state != LCHAN_ST_ACTIVE)
		return -1;

	bsc_send_ussd_notify(conn, 0, text);
	bsc_send_ussd_release_complete(conn);

	return 0;
}

/*
 * The place to handle the grace mode. Right now we will send
 * USSD messages to the subscriber, in the future we might start
 * a timer to have different modes for the grace period.
 */
static int handle_grace(struct gsm_network *network)
{
	int ts_nr, lchan_nr;
	struct gsm_bts *bts;
	struct gsm_bts_trx *trx;

	if (!network->bsc_data->mid_call_txt)
		return 0;

	llist_for_each_entry(bts, &network->bts_list, list) {
		llist_for_each_entry(trx, &bts->trx_list, list) {
			for (ts_nr = 0; ts_nr < TRX_NR_TS; ++ts_nr) {
				struct gsm_bts_trx_ts *ts = &trx->ts[ts_nr];
				for (lchan_nr = 0; lchan_nr < TS_MAX_LCHAN; ++lchan_nr) {
					handle_sub(&ts->lchan[lchan_nr],
						   network->bsc_data->mid_call_txt);
				}
			}
		}
	}
	return 0;
}

static int handle_rf_signal(unsigned int subsys, unsigned int signal,
			    void *handler_data, void *signal_data)
{
	struct rf_signal_data *sig;

	if (subsys != SS_RF)
		return -1;

	sig = signal_data;

	if (signal == S_RF_GRACE)
		handle_grace(sig->net);

	return 0;
}

static __attribute__((constructor)) void on_dso_load_grace(void)
{
	osmo_signal_register_handler(SS_RF, handle_rf_signal, NULL);
}