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/*
 * (C) 2016 by Holger Hans Peter Freyther
 *
 * 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 "sip.h"
#include "app.h"
#include "call.h"
#include "logging.h"
#include "sdp.h"

#include <osmocom/core/utils.h>

#include <sofia-sip/sip_status.h>

#include <talloc.h>

#include <string.h>

extern void *tall_mncc_ctx;

static void sip_release_call(struct call_leg *_leg);
static void sip_ring_call(struct call_leg *_leg);
static void sip_connect_call(struct call_leg *_leg);
static void sip_dtmf_call(struct call_leg *_leg, int keypad);

static void call_progress(struct sip_call_leg *leg, const sip_t *sip)
{
	struct call_leg *other = call_leg_other(&leg->base);

	if (!other)
		return;

	LOGP(DSIP, LOGL_NOTICE, "leg(%p) is now rining.\n", leg);
	other->ring_call(other);
}

static void call_connect(struct sip_call_leg *leg, const sip_t *sip)
{
	/* extract SDP file and if compatible continue */
	struct call_leg *other = call_leg_other(&leg->base);

	if (!other) {
		LOGP(DSIP, LOGL_ERROR, "leg(%p) connected but leg gone\n", leg);
		nua_cancel(leg->nua_handle, TAG_END());
		return;
	}

	if (!sdp_extract_sdp(leg, sip, false)) {
		LOGP(DSIP, LOGL_ERROR, "leg(%p) incompatible audio, releasing\n", leg);
		nua_cancel(leg->nua_handle, TAG_END());
		other->release_call(other);
		return;
	}

	LOGP(DSIP, LOGL_NOTICE, "leg(%p) is now connected.\n", leg);
	leg->state = SIP_CC_CONNECTED;
	other->connect_call(other);
	nua_ack(leg->nua_handle, TAG_END());
}

static void new_call(struct sip_agent *agent, nua_handle_t *nh,
			const sip_t *sip)
{
	struct call *call;
	struct sip_call_leg *leg;
	const char *from = NULL, *to = NULL;

	LOGP(DSIP, LOGL_DEBUG, "Incoming call handle(%p)\n", nh);

	if (!sdp_screen_sdp(sip)) {
		LOGP(DSIP, LOGL_ERROR, "No supported codec.\n");
		nua_respond(nh, SIP_406_NOT_ACCEPTABLE, TAG_END());
		nua_handle_destroy(nh);
		return;
	}

	call = call_sip_create();
	if (!call) {
		LOGP(DSIP, LOGL_ERROR, "No supported codec.\n");
		nua_respond(nh, SIP_500_INTERNAL_SERVER_ERROR, TAG_END());
		nua_handle_destroy(nh);
		return;
	}

	if (sip->sip_to)
		to = sip->sip_to->a_url->url_user;
	if (sip->sip_from)
		from = sip->sip_from->a_url->url_user;

	if (!to || !from) {
		LOGP(DSIP, LOGL_ERROR, "Unknown from/to for invite.\n");
		nua_respond(nh, SIP_406_NOT_ACCEPTABLE, TAG_END());
		nua_handle_destroy(nh);
		return;
	}

	leg = (struct sip_call_leg *) call->initial;
	leg->state = SIP_CC_DLG_CNFD;
	leg->dir = SIP_DIR_MO;

	/*
	 * FIXME/TODO.. we need to select the codec at some point. But it is
	 * not this place. It starts with the TCH/F vs. TCH/H selection based
	 * on the offered codecs, and then RTP_CREATE should have it. So both
	 * are GSM related... and do not belong here. Just pick the first codec
	 * so the IP addresss port and payload type is set.
	 */
	if (!sdp_extract_sdp(leg, sip, true)) {
		LOGP(DSIP, LOGL_ERROR, "leg(%p) no audio, releasing\n", leg);
		nua_respond(nh, SIP_406_NOT_ACCEPTABLE, TAG_END());
		nua_handle_destroy(nh);
		call_leg_release(&leg->base);
		return;
	}

	leg->base.release_call = sip_release_call;
	leg->base.ring_call = sip_ring_call;
	leg->base.connect_call = sip_connect_call;
	leg->base.dtmf = sip_dtmf_call;
	leg->agent = agent;
	leg->nua_handle = nh;
	nua_handle_bind(nh, leg);
	leg->sdp_payload = talloc_strdup(leg, sip->sip_payload->pl_data);

	app_route_call(call,
			talloc_strdup(leg, from),
			talloc_strdup(leg, to));
}

void nua_callback(nua_event_t event, int status, char const *phrase, nua_t *nua, nua_magic_t *magic, nua_handle_t *nh, nua_hmagic_t *hmagic, sip_t const *sip, tagi_t tags[])
{
	LOGP(DSIP, LOGL_DEBUG, "SIP event(%u) status(%d) phrase(%s) %p\n",
		event, status, phrase, hmagic);

	if (event == nua_r_invite) {
		struct sip_call_leg *leg;
		leg = (struct sip_call_leg *) hmagic;

		/* MT call is moving forward */

		/* The dialogue is now confirmed */
		if (leg->state == SIP_CC_INITIAL)
			leg->state = SIP_CC_DLG_CNFD;

		if (status == 180 || status == 183)
			call_progress(leg, sip);
		else if (status == 200)
			call_connect(leg, sip);
		else if (status >= 300) {
			struct call_leg *other = call_leg_other(&leg->base);

			LOGP(DSIP, LOGL_ERROR, "leg(%p) unknown err, releasing.\n", leg);
			nua_cancel(leg->nua_handle, TAG_END());
			nua_handle_destroy(leg->nua_handle);
			call_leg_release(&leg->base);

			if (other)
				other->release_call(other);
		}
	} else if (event == nua_r_bye || event == nua_r_cancel) {
		/* our bye or hang up is answered */
		struct sip_call_leg *leg = (struct sip_call_leg *) hmagic;
		LOGP(DSIP, LOGL_NOTICE, "leg(%p) got resp to %s\n",
			leg, event == nua_r_bye ? "bye" : "cancel");
		nua_handle_destroy(leg->nua_handle);
		call_leg_release(&leg->base);
	} else if (event == nua_i_bye) {
		/* our remote has hung up */
		struct sip_call_leg *leg = (struct sip_call_leg *) hmagic;
		struct call_leg *other = call_leg_other(&leg->base);

		LOGP(DSIP, LOGL_ERROR, "leg(%p) got bye, releasing.\n", leg);
		nua_handle_destroy(leg->nua_handle);
		call_leg_release(&leg->base);

		if (other)
			other->release_call(other);
	} else if (event == nua_i_invite) {
		/* new incoming leg */

		if (status == 100)
			new_call((struct sip_agent *) magic, nh, sip);
	} else if (event == nua_i_cancel) {
		struct sip_call_leg *leg;
		struct call_leg *other;

		LOGP(DSIP, LOGL_ERROR, "Canceled on leg(%p)\n", hmagic);

		leg = (struct sip_call_leg *) hmagic;
		other = call_leg_other(&leg->base);

		nua_handle_destroy(leg->nua_handle);
		call_leg_release(&leg->base);
		if (other)
			other->release_call(other);
	}
}


static void sip_release_call(struct call_leg *_leg)
{
	struct sip_call_leg *leg;

	OSMO_ASSERT(_leg->type == CALL_TYPE_SIP);
	leg = (struct sip_call_leg *) _leg;

	/*
	 * If a dialogue is not confirmed yet, we can probably not do much
	 * but wait for the timeout. For a confirmed one we can send cancel
	 * and for a connected one bye. I don't see how sofia-sip is going
	 * to help us here.
	 */
	switch (leg->state) {
	case SIP_CC_INITIAL:
		LOGP(DSIP, LOGL_NOTICE, "Canceling leg(%p) in int state\n", leg);
		nua_handle_destroy(leg->nua_handle);
		call_leg_release(&leg->base);
		break;
	case SIP_CC_DLG_CNFD:
		LOGP(DSIP, LOGL_NOTICE, "Canceling leg(%p) in cnfd state\n", leg);
		if (leg->dir == SIP_DIR_MT)
			nua_cancel(leg->nua_handle, TAG_END());
		else {
			nua_respond(leg->nua_handle, SIP_486_BUSY_HERE,
					TAG_END());
			nua_handle_destroy(leg->nua_handle);
			call_leg_release(&leg->base);
		}
		break;
	case SIP_CC_CONNECTED:
		LOGP(DSIP, LOGL_NOTICE, "Ending leg(%p) in con\n", leg);
		nua_bye(leg->nua_handle, TAG_END());
		break;
	}
}

static void sip_ring_call(struct call_leg *_leg)
{
	struct sip_call_leg *leg;

	OSMO_ASSERT(_leg->type == CALL_TYPE_SIP);
	leg = (struct sip_call_leg *) _leg;

	nua_respond(leg->nua_handle, SIP_180_RINGING, TAG_END());
}

static void sip_connect_call(struct call_leg *_leg)
{
	struct call_leg *other;
	struct sip_call_leg *leg;
	char *sdp;

	OSMO_ASSERT(_leg->type == CALL_TYPE_SIP);
	leg = (struct sip_call_leg *) _leg;

	/*
	 * TODO/FIXME: check if resulting codec is compatible..
	 */

	other = call_leg_other(&leg->base);
	if (!other) {
		sip_release_call(&leg->base);
		return;
	}

	sdp = sdp_create_file(leg, other);

	leg->state = SIP_CC_CONNECTED;
	nua_respond(leg->nua_handle, SIP_200_OK,
			NUTAG_MEDIA_ENABLE(0),
			SIPTAG_CONTENT_TYPE_STR("application/sdp"),
			SIPTAG_PAYLOAD_STR(sdp),
			TAG_END());
	talloc_free(sdp);
}

static void sip_dtmf_call(struct call_leg *_leg, int keypad)
{
	struct sip_call_leg *leg;
	char *buf;

	OSMO_ASSERT(_leg->type == CALL_TYPE_SIP);
	leg = (struct sip_call_leg *) _leg;

	buf = talloc_asprintf(leg, "Signal=%c\nDuration=160\n", keypad);
	nua_info(leg->nua_handle,
		NUTAG_MEDIA_ENABLE(0),
		SIPTAG_CONTENT_TYPE_STR("application/dtmf-relay"),
		SIPTAG_PAYLOAD_STR(buf), TAG_END());
	talloc_free(buf);
}

static int send_invite(struct sip_agent *agent, struct sip_call_leg *leg,
			const char *calling_num, const char *called_num)
{
	struct call_leg *other = leg->base.call->initial;

	char *from = talloc_asprintf(leg, "sip:%s@%s:%d",
				calling_num,
				agent->app->sip.local_addr,
				agent->app->sip.local_port);
	char *to = talloc_asprintf(leg, "sip:%s@%s:%d",
				called_num,
				agent->app->sip.remote_addr,
				agent->app->sip.remote_port);
	char *sdp = sdp_create_file(leg, other);

	leg->state = SIP_CC_INITIAL;
	leg->dir = SIP_DIR_MT;
	nua_invite(leg->nua_handle,
			SIPTAG_FROM_STR(from),
			SIPTAG_TO_STR(to),
			NUTAG_MEDIA_ENABLE(0),
			SIPTAG_CONTENT_TYPE_STR("application/sdp"),
			SIPTAG_PAYLOAD_STR(sdp),
			TAG_END());

	leg->base.call->remote = &leg->base;
	talloc_free(from);
	talloc_free(to);
	talloc_free(sdp);
	return 0;
}

int sip_create_remote_leg(struct sip_agent *agent, struct call *call)
{
	struct sip_call_leg *leg;

	leg = talloc_zero(call, struct sip_call_leg);
	if (!leg) {
		LOGP(DSIP, LOGL_ERROR, "Failed to allocate leg for call(%u)\n",
			call->id);
		return -1;
	}

	leg->base.type = CALL_TYPE_SIP;
	leg->base.call = call;
	leg->base.release_call = sip_release_call;
	leg->base.dtmf = sip_dtmf_call;
	leg->agent = agent;

	leg->nua_handle = nua_handle(agent->nua, leg, TAG_END());
	if (!leg->nua_handle) {
		LOGP(DSIP, LOGL_ERROR, "Failed to allocate nua for call(%u)\n",
			call->id);
		talloc_free(leg);
		return -2;
	}

	return send_invite(agent, leg, call->source, call->dest);
}

char *make_sip_uri(struct sip_agent *agent)
{
	const char *hostname = agent->app->sip.local_addr;

	/* We need to map 0.0.0.0 to '*' to bind everywhere */
	if (strcmp(hostname, "0.0.0.0") == 0)
		hostname = "*";

	return talloc_asprintf(tall_mncc_ctx, "sip:%s:%d",
				agent->app->sip.local_addr,
				agent->app->sip.local_port);
}

void sip_agent_init(struct sip_agent *agent, struct app_config *app)
{
	agent->app = app;

	su_init();
	su_home_init(&agent->home);
	agent->root = su_glib_root_create(NULL);
	su_root_threading(agent->root, 0);
}

int sip_agent_start(struct sip_agent *agent)
{
	char *sip_uri = make_sip_uri(agent);

	agent->nua = nua_create(agent->root,
				nua_callback, agent,
				NUTAG_URL(sip_uri),
				NUTAG_AUTOACK(0),
				NUTAG_AUTOALERT(0),
				NUTAG_AUTOANSWER(0),
				TAG_END());
	talloc_free(sip_uri);
	return agent->nua ? 0 : -1;
}