/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * Mark Michelson <mmichelson@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

#include "asterisk.h"

#include <pjsip.h>

#include "asterisk/res_sip.h"

static int distribute(void *data);
static pj_bool_t distributor(pjsip_rx_data *rdata);

static pjsip_module distributor_mod = {
	.name = {"Request Distributor", 19},
	.priority = PJSIP_MOD_PRIORITY_TSX_LAYER - 6,
	.on_rx_request = distributor,
	.on_rx_response = distributor,
};

/*! Dialog-specific information the distributor uses */
struct distributor_dialog_data {
	/* Serializer to distribute tasks to for this dialog */
	struct ast_taskprocessor *serializer;
	/* Endpoint associated with this dialog */
	struct ast_sip_endpoint *endpoint;
};

/*!
 * \internal
 *
 * \note Call this with the dialog locked
 */
static struct distributor_dialog_data *distributor_dialog_data_alloc(pjsip_dialog *dlg)
{
	struct distributor_dialog_data *dist;

	dist = PJ_POOL_ZALLOC_T(dlg->pool, struct distributor_dialog_data);
	pjsip_dlg_set_mod_data(dlg, distributor_mod.id, dist);

	return dist;
}

void ast_sip_dialog_set_serializer(pjsip_dialog *dlg, struct ast_taskprocessor *serializer)
{
	struct distributor_dialog_data *dist;
	SCOPED_LOCK(lock, dlg, pjsip_dlg_inc_lock, pjsip_dlg_dec_lock);
	
	dist = pjsip_dlg_get_mod_data(dlg, distributor_mod.id);
	if (!dist) {
		dist = distributor_dialog_data_alloc(dlg);
	}
	dist->serializer = serializer;
}

void ast_sip_dialog_set_endpoint(pjsip_dialog *dlg, struct ast_sip_endpoint *endpoint)
{
	struct distributor_dialog_data *dist;
	SCOPED_LOCK(lock, dlg, pjsip_dlg_inc_lock, pjsip_dlg_dec_lock);
	
	dist = pjsip_dlg_get_mod_data(dlg, distributor_mod.id);
	if (!dist) {
		dist = distributor_dialog_data_alloc(dlg);
	}
	dist->endpoint = endpoint;
}

struct ast_sip_endpoint *ast_sip_dialog_get_endpoint(pjsip_dialog *dlg)
{
	struct distributor_dialog_data *dist;
	SCOPED_LOCK(lock, dlg, pjsip_dlg_inc_lock, pjsip_dlg_dec_lock);

	dist = pjsip_dlg_get_mod_data(dlg, distributor_mod.id);
	if (!dist || !dist->endpoint) {
		return NULL;
	}
	ao2_ref(dist->endpoint, +1);
	return dist->endpoint;
}

static pj_bool_t distributor(pjsip_rx_data *rdata)
{
	pjsip_dialog *dlg = pjsip_ua_find_dialog(&rdata->msg_info.cid->id, &rdata->msg_info.to->tag, &rdata->msg_info.from->tag, PJ_TRUE);
	struct distributor_dialog_data *dist = NULL;
	struct ast_taskprocessor *serializer = NULL;
	pjsip_rx_data *clone;

	pjsip_rx_data_clone(rdata, 0, &clone);
	if (dlg) {
		dist = pjsip_dlg_get_mod_data(dlg, distributor_mod.id);
		if (dist) {
			serializer = dist->serializer;
			clone->endpt_info.mod_data[distributor_mod.id] = dist->endpoint;
		}
	}

	ast_sip_push_task(serializer, distribute, clone);

	if (dlg) {
		pjsip_dlg_dec_lock(dlg);
	}

	return PJ_TRUE;
}

static pj_bool_t endpoint_lookup(pjsip_rx_data *rdata);

static pjsip_module endpoint_mod = {
	.name = {"Endpoint Identifier", 19},
	.priority = PJSIP_MOD_PRIORITY_TSX_LAYER - 3,
	.on_rx_request = endpoint_lookup,
};

static pj_bool_t endpoint_lookup(pjsip_rx_data *rdata)
{
	struct ast_sip_endpoint *endpoint;
	int is_ack = rdata->msg_info.msg->line.req.method.id == PJSIP_ACK_METHOD;

	endpoint = rdata->endpt_info.mod_data[distributor_mod.id];
	if (endpoint) {
		/* Bumping the refcount makes refcounting consistent whether an endpoint
		 * is looked up or not */
		ao2_ref(endpoint, +1);
	} else {
		endpoint = ast_sip_identify_endpoint(rdata);
	}

	if (!endpoint && !is_ack) {
		/* XXX When we do an alwaysauthreject-like option, we'll need to take that into account
		 * for this response. Either that, or have a pseudo-endpoint to pass along so that authentication
		 * will fail
		 */
		pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 403, NULL, NULL, NULL);
		return PJ_TRUE;
	}
	rdata->endpt_info.mod_data[endpoint_mod.id] = endpoint;
	return PJ_FALSE;
}

static pj_bool_t authenticate(pjsip_rx_data *rdata)
{
	RAII_VAR(struct ast_sip_endpoint *, endpoint, ast_pjsip_rdata_get_endpoint(rdata), ao2_cleanup);
	int is_ack = rdata->msg_info.msg->line.req.method.id == PJSIP_ACK_METHOD;

	ast_assert(endpoint != NULL);

	if (!is_ack && ast_sip_requires_authentication(endpoint, rdata)) {
		pjsip_tx_data *tdata;
		pjsip_endpt_create_response(ast_sip_get_pjsip_endpoint(), rdata, 401, NULL, &tdata);
		switch (ast_sip_check_authentication(endpoint, rdata, tdata)) {
		case AST_SIP_AUTHENTICATION_CHALLENGE:
			/* Send the 401 we created for them */
			pjsip_endpt_send_response2(ast_sip_get_pjsip_endpoint(), rdata, tdata, NULL, NULL);
			return PJ_TRUE;
		case AST_SIP_AUTHENTICATION_SUCCESS:
			pjsip_tx_data_dec_ref(tdata);
			return PJ_FALSE;
		case AST_SIP_AUTHENTICATION_FAILED:
			pjsip_tx_data_dec_ref(tdata);
			pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 403, NULL, NULL, NULL);
			return PJ_TRUE;
		case AST_SIP_AUTHENTICATION_ERROR:
			pjsip_tx_data_dec_ref(tdata);
			pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 500, NULL, NULL, NULL);
			return PJ_TRUE;
		}
	}

	return PJ_FALSE;
}

static pjsip_module auth_mod = {
	.name = {"Request Authenticator", 21},
	.priority = PJSIP_MOD_PRIORITY_APPLICATION - 1,
	.on_rx_request = authenticate,
};

static int distribute(void *data)
{
	static pjsip_process_rdata_param param = {
		.start_mod = &distributor_mod,
		.idx_after_start = 1,
	};
	pj_bool_t handled;
	pjsip_rx_data *rdata = data;
	int is_request = rdata->msg_info.msg->type == PJSIP_REQUEST_MSG;
	int is_ack = is_request ? rdata->msg_info.msg->line.req.method.id == PJSIP_ACK_METHOD : 0;
	struct ast_sip_endpoint *endpoint;

	pjsip_endpt_process_rx_data(ast_sip_get_pjsip_endpoint(), rdata, &param, &handled);
	if (!handled && is_request && !is_ack) {
		pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 501, NULL, NULL, NULL);
	}

	/* The endpoint_mod stores an endpoint reference in the mod_data of rdata. This
	 * is the only appropriate spot to actually decrement the reference.
	 */
	endpoint = rdata->endpt_info.mod_data[endpoint_mod.id];
	ao2_cleanup(endpoint);
	pjsip_rx_data_free_cloned(rdata);
	return 0;
}

struct ast_sip_endpoint *ast_pjsip_rdata_get_endpoint(pjsip_rx_data *rdata)
{
	struct ast_sip_endpoint *endpoint = rdata->endpt_info.mod_data[endpoint_mod.id];
	if (endpoint) {
		ao2_ref(endpoint, +1);
	}
	return endpoint;
}

int ast_sip_initialize_distributor(void)
{
	if (ast_sip_register_service(&distributor_mod)) {
		return -1;
	}
	if (ast_sip_register_service(&endpoint_mod)) {
		return -1;
	}
	if (ast_sip_register_service(&auth_mod)) {
		return -1;
	}
	return 0;
}