/* common process
 *
 * (C) 2020 by Andreas Eversberg <jolly@eversberg.eu>
 * All Rights Reserved
 *
 * This program 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 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 General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <sys/types.h>
#include "../libdebug/debug.h"
#include "../libtimer/timer.h"
#include "../libselect/select.h"
#include "../libosmocc/endpoint.h"
#include "../libosmocc/helper.h"
#include "common.h"

/*
 * generate messages towards CC
 */

void reject_call(osmo_cc_endpoint_t *cc_ep, uint32_t callref, uint8_t isdn_cause)

{
	osmo_cc_msg_t *new_msg;

	/* create osmo-cc message */
	new_msg = osmo_cc_new_msg(OSMO_CC_MSG_REJ_IND);
	/* cause */
	osmo_cc_add_ie_cause(new_msg, OSMO_CC_LOCATION_BEYOND_INTERWORKING, isdn_cause, 0, 0);
	/* send message to osmo-cc */
	osmo_cc_ll_msg(cc_ep, callref, new_msg);
}

void release_call(osmo_cc_endpoint_t *cc_ep, uint32_t callref, uint8_t isdn_cause)
{
	osmo_cc_msg_t *new_msg;

	/* create osmo-cc message */
	new_msg = osmo_cc_new_msg(OSMO_CC_MSG_REL_IND);
	/* cause */
	osmo_cc_add_ie_cause(new_msg, OSMO_CC_LOCATION_BEYOND_INTERWORKING, isdn_cause, 0, 0);
	/* send message to osmo-cc */
	osmo_cc_ll_msg(cc_ep, callref, new_msg);
}

void disconnect_call(osmo_cc_endpoint_t *cc_ep, uint32_t callref, uint8_t isdn_cause)
{
	osmo_cc_msg_t *new_msg;

	/* create osmo-cc message */
	new_msg = osmo_cc_new_msg(OSMO_CC_MSG_DISC_IND);
	/* progress */
	osmo_cc_add_ie_progress(new_msg, OSMO_CC_CODING_ITU_T, OSMO_CC_LOCATION_BEYOND_INTERWORKING, OSMO_CC_PROGRESS_INBAND_INFO_AVAILABLE);
	/* cause */
	osmo_cc_add_ie_cause(new_msg, OSMO_CC_LOCATION_BEYOND_INTERWORKING, isdn_cause, 0, 0);
	/* send message to osmo-cc */
	osmo_cc_ll_msg(cc_ep, callref, new_msg);
}

void proceed_call(osmo_cc_endpoint_t *cc_ep, uint32_t callref, const char *sdp)
{
	osmo_cc_msg_t *new_msg;

	/* create osmo-cc message */
	new_msg = osmo_cc_new_msg(OSMO_CC_MSG_PROC_IND);
	/* progress */
	osmo_cc_add_ie_progress(new_msg, OSMO_CC_CODING_ITU_T, OSMO_CC_LOCATION_BEYOND_INTERWORKING, OSMO_CC_PROGRESS_INBAND_INFO_AVAILABLE);
	/* sdp */
	osmo_cc_add_ie_sdp(new_msg, sdp);
	/* send message to osmo-cc */
	osmo_cc_ll_msg(cc_ep, callref, new_msg);
}

void alert_call(osmo_cc_endpoint_t *cc_ep, uint32_t callref)
{
	osmo_cc_msg_t *new_msg;

	/* create osmo-cc message */
	new_msg = osmo_cc_new_msg(OSMO_CC_MSG_ALERT_IND);
	/* send message to osmo-cc */
	osmo_cc_ll_msg(cc_ep, callref, new_msg);
}

void answer_call(osmo_cc_endpoint_t *cc_ep, uint32_t callref)
{
	osmo_cc_msg_t *new_msg;

	/* create osmo-cc message */
	new_msg = osmo_cc_new_msg(OSMO_CC_MSG_SETUP_CNF);
	/* send message to osmo-cc */
	osmo_cc_ll_msg(cc_ep, callref, new_msg);
}

void setup_comp_call(osmo_cc_endpoint_t *cc_ep, uint32_t callref)
{
	osmo_cc_msg_t *new_msg;

	/* create osmo-cc message */
	new_msg = osmo_cc_new_msg(OSMO_CC_MSG_SETUP_COMP_IND);
	/* send message to osmo-cc */
	osmo_cc_ll_msg(cc_ep, callref, new_msg);
}

/*
 * dial string generation and parsing
 */

static char *prefix_1_digit[] = { "1", "7", NULL };
static char *prefix_2_digit[] = {
	"20", "27", "28", "30", "31", "32", "33", "34", "36", "39", "40", "41",
	"43", "44", "45", "46", "47", "48", "49", "51", "52", "53", "54", "55",
	"56", "57", "58", "60", "61", "62", "63", "64", "65", "66", "81", "82",
	"83", "84", "86", "89", "90", "91", "92", "93", "94", "95", "98",
	NULL };

/* use number and number type to generate an SS5 dial string
 * the digits are checked if they can be dialed
 * if the number is already in SS5 format, only digits are checked
 */
int generate_dial_string(uint8_t type, const char *dialing, char *string, int string_size)
{
	int full_string_given = 0;
	int i, ii;

	if ((int)strlen(dialing) + 4 > string_size) {
		PDEBUG(DSS5, DEBUG_NOTICE, "Dial string is too long for our digit register, call is rejected!\n");
		return -EINVAL;
	}

	/* check for correct digits */
	for (i = 0, ii = strlen(dialing); i < ii; i++) {
		/* string may start with 'a' or 'b', but then 'c' must be the last digit */
		if (dialing[i] == 'a' || dialing[i] == 'b') {
			full_string_given = 1;
			if (dialing[ii - 1] != 'c') {
				PDEBUG(DSS5, DEBUG_NOTICE, "Number starts with 'a' (KP1) or 'b' (KP2) but missing 'c' (ST) at the end, call is rejected!\n");
				return -EINVAL;
			}
			/* remove check of last digit 'c' */
			--ii;
			continue;
		}
		/* string must only consist of numerical digits and '*' (code 11) and '#' (code 12) */
		if (!strchr("0123456789*#", dialing[i])) {
			PDEBUG(DSS5, DEBUG_NOTICE, "Number has invalid digits, call is rejected!\n");
			return -EINVAL;
		}
	}

	/* if full string with 'a'/'b' and 'c' is given, we have complete dial string */
	if (full_string_given) {
		strcpy(string, dialing);
		return 0;
	}

	/* if number is not of international type, create national dial string */
	if (type != OSMO_CC_TYPE_INTERNATIONAL) {
		// make GCC happy
		strcpy(string, "a0");
		strcat(string, dialing);
		strcat(string, "c");
		return 0;
	}

	/* check international prefix with length of 1 digit */
	if ((int)strlen(dialing) < 1) {
		PDEBUG(DSS5, DEBUG_NOTICE, "International number too short to get country code from, call is rejected!\n");
		return -EINVAL;
	}
	for (i = 0; prefix_1_digit[i]; i++) {
		if (prefix_1_digit[i][0] == dialing[0])
			break;
	}
	/* if number is of international type, create international dial string */
	if (prefix_1_digit[i]) {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-overflow"
		sprintf(string, "b%c0%sc", dialing[0], dialing + 1);
#pragma GCC diagnostic pop
		return 0;
	}

	/* check international prefix with length of 2 digits */
	if ((int)strlen(dialing) < 2) {
		PDEBUG(DSS5, DEBUG_NOTICE, "International number too short to get country code from, call is rejected!\n");
		return -EINVAL;
	}
	for (i = 0; prefix_2_digit[i]; i++) {
		if (prefix_2_digit[i][0] == dialing[0]
		 && prefix_2_digit[i][1] == dialing[1])
			break;
	}
	/* if number is of international type, create international dial string */
	if (prefix_2_digit[i]) {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-overflow"
		sprintf(string, "b%c%c0%sc", dialing[0], dialing[1], dialing + 2);
#pragma GCC diagnostic pop
		return 0;
	}

	/* check international prefix with length of 3 digits */
	if ((int)strlen(dialing) < 3) {
		PDEBUG(DSS5, DEBUG_NOTICE, "International number too short to get country code from, call is rejected!\n");
		return -EINVAL;
	}
	/* if number is of international type, create international dial string */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-overflow"
	sprintf(string, "b%c%c%c0%sc", dialing[0], dialing[1], dialing[2], dialing + 3);
#pragma GCC diagnostic pop
	return 0;
}

/* parse received SS5 dial string and convert it into a national or international number */
int parse_dial_string(uint8_t *type, char *dialing, int dialing_size, const char *string)
{
	char kp_digit;
	const char *prefix;
	int length;
	int i;

	/* remove start and stop digits, set string after start digit and set length to digits between start and stop */
	if (string[0] != 'a' && string[0] != 'b') {
		PDEBUG(DSS5, DEBUG_NOTICE, "Received digits do not start with 'a' (KP1) nor 'b' (KP2), call is rejected!\n");
		return -EINVAL;
	}
	length = strlen(string) - 1;
	if (string[length] != 'c') {
		PDEBUG(DSS5, DEBUG_NOTICE, "Received digits do end with 'c' (ST), call is rejected!\n");
		return -EINVAL;
	}
	kp_digit = *string++;
	length--;
	if (length > dialing_size - 1) {
		PDEBUG(DSS5, DEBUG_NOTICE, "Received dial string is too long, call is rejected!\n");
		return -EINVAL;
	}
	if (!length) {
		PDEBUG(DSS5, DEBUG_NOTICE, "Nothing dialed between KP and ST, call is rejected!\n");
		return -EINVAL;
	}

	/* received local or national call */
	if (kp_digit == 'a') {
		/* remove discriminaing digit */
		if (string[0] == '0') {
			string++;
			length--;
			*type = OSMO_CC_TYPE_NATIONAL;
		} else
			*type = OSMO_CC_TYPE_UNKNOWN;
		strncpy(dialing, string, length);
		dialing[length] = '\0';
		return 0;
	}

	/* check international prefix with length of 1 digit */
	if (length < 2) {
		PDEBUG(DSS5, DEBUG_NOTICE, "International number too short to get country code from, call is rejected!\n");
		return -EINVAL;
	}
	for (i = 0; prefix_1_digit[i]; i++) {
		if (prefix_1_digit[i][0] == string[0])
			break;
	}
	/* if number is of international type, create international dial string */
	if (prefix_1_digit[i]) {
		prefix = string;
		string += 1;
		length -= 1;
		/* remove discriminaing digit */
		string++;
		--length;
		*type = OSMO_CC_TYPE_INTERNATIONAL;
		dialing[0] = prefix[0];
		strncpy(dialing + 1, string, length);
		dialing[1 + length] = '\0';
		return 0;
	}

	/* check international prefix with length of 2 digits */
	if (length < 3) {
		PDEBUG(DSS5, DEBUG_NOTICE, "International number too short to get country code from, call is rejected!\n");
		return -EINVAL;
	}
	for (i = 0; prefix_2_digit[i]; i++) {
		if (prefix_2_digit[i][0] == string[0]
		 && prefix_2_digit[i][1] == string[1])
			break;
	}
	/* if number is of international type, create international dial string */
	if (prefix_2_digit[i]) {
		prefix = string;
		string += 2;
		length -= 2;
		/* remove discriminaing digit */
		string++;
		--length;
		*type = OSMO_CC_TYPE_INTERNATIONAL;
		dialing[0] = prefix[0];
		dialing[1] = prefix[1];
		strncpy(dialing + 2, string, length);
		dialing[2 + length] = '\0';
		return 0;
	}

	/* check international prefix with length of 3 digits */
	if (length < 4) {
		PDEBUG(DSS5, DEBUG_NOTICE, "International number too short to get country code from, call is rejected!\n");
		return -EINVAL;
	}
	/* if number is of international type, create international dial string */
	prefix = string;
	string += 3;
	length -= 3;
	/* remove discriminaing digit */
	string++;
	--length;
	*type = OSMO_CC_TYPE_INTERNATIONAL;
	dialing[0] = prefix[0];
	dialing[1] = prefix[1];
	dialing[2] = prefix[2];
	strncpy(dialing + 3, string, length);
	dialing[3 + length] = '\0';
	return 0;
}