/*
 * IMS IPSEC PCSCF module
 *
 * Copyright (C) 2018 Tsvetomir Dimitrov
 *
 * This file is part of Kamailio, a free SIP server.
 *
 * Kamailio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version
 *
 * Kamailio 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 General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include "spi_gen.h"
#include "spi_list.h"
#include <pthread.h>
#include "../../core/mem/shm_mem.h"

#define MAX_HASH_SPI 10000

typedef struct spi_generator
{
	pthread_mutex_t spis_mut;
	spi_list_t used_spis[MAX_HASH_SPI];
	spi_list_t free_spi;
	uint32_t spi_val;
	uint32_t min_spi;
	uint32_t max_spi;
	uint32_t sport_start_val;
	uint32_t cport_start_val;
	uint32_t port_range;
} spi_generator_t;

spi_generator_t *spi_data = NULL;

static int init_free_spi()
{
	uint32_t sport_start_val, cport_start_val, port_range, sport, cport, j;

	if(!spi_data) {
		return 1;
	}

	sport_start_val = spi_data->sport_start_val;
	cport_start_val = spi_data->cport_start_val;
	port_range = spi_data->port_range;
	//save the initial value for the highly unlikely case where there are no free SPIs
	sport = sport_start_val;
	cport = cport_start_val;

	spi_data->free_spi = create_list();
	for(j = spi_data->min_spi; j < spi_data->max_spi; j += 2) {
		spi_add(&spi_data->free_spi, j, j + 1, cport, sport);
		cport++;
		sport++;

		if(cport >= cport_start_val + port_range) {
			cport = cport_start_val;
		}

		if(sport >= sport_start_val + port_range) {
			sport = sport_start_val;
		}
	}

	return 0;
}

int init_spi_gen(uint32_t spi_start_val, uint32_t spi_range,
		uint32_t sport_start_val, uint32_t cport_start_val, uint32_t port_range)
{
	uint32_t j;

	if(spi_start_val < 1) {
		return 1;
	}

	if(UINT32_MAX - spi_range < spi_start_val) {
		return 2;
	}

	if(spi_data) {
		return 3;
	}

	spi_data = shm_malloc(sizeof(spi_generator_t));
	if(spi_data == NULL) {
		return 4;
	}

	if(pthread_mutex_init(&spi_data->spis_mut, NULL)) {
		shm_free(spi_data);
		return 5;
	}

	if(pthread_mutex_lock(&spi_data->spis_mut) != 0) {
		return 6;
	}

	for(j = 0; j < MAX_HASH_SPI; j++) {
		spi_data->used_spis[j] = create_list();
	}

	spi_data->spi_val = spi_data->min_spi = spi_start_val;
	spi_data->max_spi = spi_start_val + spi_range;
	spi_data->sport_start_val = sport_start_val;
	spi_data->cport_start_val = cport_start_val;
	spi_data->port_range = port_range;

	if(init_free_spi() != 0) {
		return 7;
	}

	pthread_mutex_unlock(&spi_data->spis_mut);

	return 0;
}

uint32_t acquire_spi(
		uint32_t *spi_cid, uint32_t *spi_sid, uint16_t *cport, uint16_t *sport)
{
	if(!spi_data) {
		LM_ERR("spi_data is NULL\n");
		return 0;
	}

	if(pthread_mutex_lock(&spi_data->spis_mut) != 0) {
		LM_ERR("spi_data failed to lock\n");
		return 0;
	}

	if(!spi_data->free_spi.head) {
		LM_ERR("spi_data:%p spi_data->free_spi.head %p\n", spi_data,
				spi_data->free_spi.head);
		pthread_mutex_unlock(&spi_data->spis_mut);
		return 0;
	}

	*spi_cid = spi_data->free_spi.head->spi_cid;
	*spi_sid = spi_data->free_spi.head->spi_sid;
	*sport = spi_data->free_spi.head->sport;
	*cport = spi_data->free_spi.head->cport;
	spi_remove_head(&spi_data->free_spi);
	spi_add(&spi_data->used_spis[*spi_cid % MAX_HASH_SPI], *spi_cid, *spi_sid,
			*cport, *sport);
	pthread_mutex_unlock(&spi_data->spis_mut);

	LM_DBG("spi acquired spi_cid:%u spi_sid:%u sport:%u cport:%u \n", *spi_cid,
			*spi_sid, *sport, *cport);

	return 1;
}

int release_spi(
		uint32_t spi_cid, uint32_t spi_sid, uint16_t cport, uint16_t sport)
{
	LM_DBG("releasing spi spi_data:%p spi_cid:%u spi_sid:%u cport:%u "
		   "sport:%u\n",
			spi_data, spi_cid, spi_sid, cport, sport);
	if(!spi_data) {
		return 1;
	}

	if(pthread_mutex_lock(&spi_data->spis_mut) != 0) {
		return 1;
	}

	// if we successfully remove from used spi we will insert into free spi
	if(spi_remove(&spi_data->used_spis[spi_cid % MAX_HASH_SPI], spi_cid,
			   spi_sid)) {
		spi_add(&spi_data->free_spi, spi_cid, spi_sid, cport, sport);
	}

	pthread_mutex_unlock(&spi_data->spis_mut);

	return 0;
}

int clean_spi_list()
{
	uint32_t j;

	if(!spi_data) {
		return 1;
	}

	if(pthread_mutex_lock(&spi_data->spis_mut) != 0) {
		return 1;
	}

	for(j = 0; j < MAX_HASH_SPI; j++) {
		destroy_list(&spi_data->used_spis[j]);
	}

	destroy_list(&spi_data->free_spi);
	init_free_spi();

	spi_data->spi_val = spi_data->min_spi;

	pthread_mutex_unlock(&spi_data->spis_mut);

	return 0;
}

int destroy_spi_gen()
{
	if(!spi_data) {
		return 1;
	}

	clean_spi_list();

	int ret = pthread_mutex_destroy(&spi_data->spis_mut);
	shm_free(spi_data);
	return ret;
}
