/*
 * (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 <osmocom/core/utils.h>

#include <sofia-sip/sdp.h>
#include <sofia-sip/sip_status.h>

#include <talloc.h>

#include <string.h>

extern void *tall_mncc_ctx;

/*
 * We want to decide on the audio codec later but we need to see
 * if it is even including some of the supported ones.
 */
static bool screen_sdp(const sip_t *sip)
{
	const char *sdp_data;
	sdp_parser_t *parser;
	sdp_session_t *sdp;
	sdp_media_t *media;

	if (!sip->sip_payload || !sip->sip_payload->pl_data) {
		LOGP(DSIP, LOGL_ERROR, "No SDP file\n");
		return false;
	}

	sdp_data = sip->sip_payload->pl_data;
	parser = sdp_parse(NULL, sdp_data, strlen(sdp_data), 0);
	if (!parser) {
		LOGP(DSIP, LOGL_ERROR, "Failed to parse SDP\n");
		return false;
	}

	sdp = sdp_session(parser);
	if (!sdp) {
		LOGP(DSIP, LOGL_ERROR, "No sdp session\n");
		sdp_parser_free(parser);
		return false;
	}

	for (media = sdp->sdp_media; media; media = media->m_next) {
		sdp_rtpmap_t *map;

		if (media->m_proto != sdp_proto_rtp)
			continue;
		if (media->m_type != sdp_media_audio)
			continue;

		for (map = media->m_rtpmaps; map; map = map->rm_next) {
			if (strcasecmp(map->rm_encoding, "GSM") == 0)
				goto success;
			if (strcasecmp(map->rm_encoding, "GSM-EFR") == 0)
				goto success;
			if (strcasecmp(map->rm_encoding, "GSM-HR-08") == 0)
				goto success;
			if (strcasecmp(map->rm_encoding, "AMR") == 0)
				goto success;
		}
	}

	sdp_parser_free(parser);
	return false;

success:
	sdp_parser_free(parser);
	return true;
}

static bool extract_sdp(struct sip_call_leg *leg, const sip_t *sip)
{
	sdp_connection_t *conn;
	sdp_session_t *sdp;
	sdp_parser_t *parser;
	sdp_media_t *media;
	const char *sdp_data;
	bool found_conn = false, found_map = false;

	if (!sip->sip_payload || !sip->sip_payload->pl_data) {
		LOGP(DSIP, LOGL_ERROR, "leg(%p) but no SDP file\n", leg);
		return false;
	}

	sdp_data = sip->sip_payload->pl_data;
	parser = sdp_parse(NULL, sdp_data, strlen(sdp_data), 0);
	if (!parser) {
		LOGP(DSIP, LOGL_ERROR, "leg(%p) failed to parse SDP\n",
			leg);
		return false;
	}

	sdp = sdp_session(parser);
	if (!sdp) {
		LOGP(DSIP, LOGL_ERROR, "leg(%p) no sdp session\n", leg);
		sdp_parser_free(parser);
		return false;
	}

	for (conn = sdp->sdp_connection; conn; conn = conn->c_next) {
		struct in_addr addr;

		if (conn->c_addrtype != sdp_addr_ip4)
			continue;
		inet_aton(conn->c_address, &addr);
		leg->base.ip = addr.s_addr;
		found_conn = true;
		break;
	}

	for (media = sdp->sdp_media; media; media = media->m_next) {
		sdp_rtpmap_t *map;

		if (media->m_proto != sdp_proto_rtp)
			continue;
		if (media->m_type != sdp_media_audio)
			continue;

		for (map = media->m_rtpmaps; map; map = map->rm_next) {
			if (strcasecmp(map->rm_encoding, leg->wanted_codec) != 0)
				continue;

			leg->base.port = media->m_port;
			leg->base.payload_type = map->rm_pt;
			found_map = true;
			break;
		}

		if (found_map)
			break;
	}

	if (!found_conn || !found_map) {
		LOGP(DSIP, LOGL_ERROR, "leg(%p) did not find %d/%d\n",
			leg, found_conn, found_map);
		sdp_parser_free(parser);
		return false;
	}

	sdp_parser_free(parser);
	return true;
}

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 (!extract_sdp(leg, sip)) {
		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)
{
	LOGP(DSIP, LOGL_DEBUG, "Incoming call handle(%p)\n", nh);

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

	nua_respond(nh, SIP_501_NOT_IMPLEMENTED, TAG_END());
	nua_handle_destroy(nh);
}

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)
			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 */
		struct sip_call_leg *leg = (struct sip_call_leg *) hmagic;

		if (status == 100)
			new_call((struct sip_agent *) magic, nh, sip);
	} else if (event == nua_i_cancel) {
		LOGP(DSIP, LOGL_ERROR, "Canceled but not implemented.\n");
	}
}


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);
		nua_cancel(leg->nua_handle, TAG_END());
		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 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;
	struct in_addr net = { .s_addr = ntohl(other->ip) };

	leg->wanted_codec = app_media_name(other->payload_msg_type);

	char *from = talloc_asprintf(leg, "sip:%s@%s",
				calling_num,
				agent->app->sip.local_addr);
	char *to = talloc_asprintf(leg, "sip:%s@%s",
				called_num,
				agent->app->sip.remote_addr);
	char *sdp = talloc_asprintf(leg,
				"v=0\r\n"
				"o=Osmocom 0 0 IN IP4 %s\r\n"
				"s=GSM Call\r\n"
				"c=IN IP4 %s\r\n"
				"t=0 0\r\n"
				"m=audio %d RTP/AVP %d\r\n"
				"a=rtpmap:%d %s/8000\r\n",
				inet_ntoa(net), inet_ntoa(net), /* never use diff. addr! */
				other->port, other->payload_type,
				other->payload_type,
				leg->wanted_codec);

	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,
				const char *source, const char *dest)
{
	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->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, source, 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;
}