/*
 * PDU Decode
 *
 * Copyright (C) 2010 by James Maki
 *
 * Author: James Maki <jmaki@multitech.com>
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

#define _GNU_SOURCE

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <ctype.h>

#include "config.h"
#include "log.h"
#include "utils.h"
#include "pdu_decode.h"

#define DECODE_FAIL(cond, name, ret) \
do { \
	if (cond) { \
		log_error("decode failed at %s", name); \
		return ret; \
	} \
} while (0)

int pdu_decode_timestamp(const char *pdu_str, struct tm *tm)
{
	char buf[PDU_TIMESTAMP_SIZE + 3];
	char *cp;
	int off_upper;
	int off_lower;
	int off;

	STRLEN_CHECK(pdu_str, PDU_TIMESTAMP_LEN, -1);

	memset(tm, 0, sizeof(*tm));
	memset(buf, 0, sizeof(buf));

	strncpy(buf, pdu_str, PDU_TIMESTAMP_LEN);
	nibble_swap(buf, PDU_TIMESTAMP_LEN);
	strunpad(buf, 'F');

	off_upper = hex_nibble_scan(buf + GMT_OFFSET_IDX, 1);
	off_lower = hex_nibble_scan(buf + GMT_OFFSET_IDX + 1, 1);

	if (off_upper & BIT(3)) {
		off_upper &= ~BIT(3);
		buf[GMT_OFFSET_IDX] = '-';
	} else {
		buf[GMT_OFFSET_IDX] = '+';
	}

	off = (off_upper * 10 + off_lower) * 15;

	snprintf(buf + GMT_OFFSET_IDX + 1, 5, "%02d%02d", off / 60, off % 60);

	cp = (char *) strptime(buf, "%y%m%d%H%M%S%z", tm);
	if (!cp || *cp) {
		log_error("timestamp could not be converted to tm");
		return -1;
	}

	return PDU_TIMESTAMP_LEN;
}

int pdu_decode_addr(const char *pdu_str, struct sms_addr *addr, int smsc)
{
	const char *begin = pdu_str;
	int addr_len;
	int tmp;

	memset(addr, 0, sizeof(*addr));

	STRLEN_CHECK(pdu_str, HEX_BYTE_LEN, -1);

	tmp = hex_byte_decode(pdu_str);
	DECODE_FAIL(tmp < 0, "addr-len", -1);
	pdu_str += HEX_BYTE_LEN;
	addr->len = tmp;

	addr_len = addr->len;
	if (smsc) {
		if (!addr_len) {
			goto done;
		}
		addr_len = addr_len * HEX_BYTE_LEN - HEX_BYTE_LEN;
	} else {
		if (addr_len & 1) {
			addr_len++;
		}
	}

	STRLEN_CHECK(pdu_str, HEX_BYTE_LEN, -1);

	tmp = hex_byte_decode(pdu_str);
	DECODE_FAIL(tmp < 0, "addr-type", -1);
	pdu_str += HEX_BYTE_LEN;
	addr->type = tmp;

	if (addr_len < 0 || addr_len >= sizeof(addr->addr)) {
		log_error("invalid length: 0x%02X", addr_len);
		return -1;
	}

	log_debug("addr-len [transformed]: 0x%02X", addr_len);
	log_debug("addr-type: 0x%02X", addr->type);

	STRLEN_CHECK(pdu_str, addr_len, -1);

	strncpy(addr->addr, pdu_str, addr_len);

	nibble_swap(addr->addr, addr_len);
	strunpad(addr->addr, 'F');
	pdu_str += addr_len;

done:

	log_debug("addr: %s", addr->addr);
	log_debug("addr-len: 0x%02X", addr->len);

	return pdu_str - begin;
}

#define octet_idx(n)		octet_align(n)

#define decode_septet(buf, n) \
shiftl(bit_maskr(cycledown(n, 8)) & buf[octet_idx(n)], cycleup(n, 8)) | \
shiftr(bit_maskl(cycleup(n, 8), 8) & buf[octet_idx(n - 1)], cycledown(n - 1, 8))

int pdu_decode_user_data(const char *pdu_str, struct pdu_info *pdu)
{
	const char *begin = pdu_str;
	int tmp;
	uint8_t octets[PDU_OCTETS_MAX + 1];
	int nr_octets;
	int i;

	STRLEN_CHECK(pdu_str, HEX_BYTE_LEN, -1);

	tmp = hex_byte_decode(pdu_str);
	DECODE_FAIL(tmp < 0, "user-data-len", -1);
	pdu_str += HEX_BYTE_LEN;
	pdu->user_data_len = tmp;

	if (pdu->data_coding.general.unused) {
		log_error("data coding group 0x%02X not implemented",
				pdu->data_coding.data_coding & 0xF0);
		return -1;
	}

	if (pdu->data_coding.general.alphabet == PDU_ALPHABET_DEFAULT) {
		log_debug("data coding alphabet is default");

		if (pdu->user_data_len > PDU_UD_7BIT_MAX) {
			log_warning("pdu contains invalid user-data-len: 0x%02X",
					pdu->user_data_len);
			pdu->user_data_len = PDU_UD_7BIT_MAX;
		}

		nr_octets = octet_align(pdu->user_data_len);
	} else if (pdu->data_coding.general.alphabet == PDU_ALPHABET_EIGHT) {
		log_debug("data coding alphabet is eight");

		if (pdu->user_data_len > PDU_UD_8BIT_MAX) {
			log_warning("pdu contains invalid user-data-len: 0x%02X",
					pdu->user_data_len);
			pdu->user_data_len = PDU_UD_8BIT_MAX;
		}

		nr_octets = pdu->user_data_len;
	} else {
		log_debug("data coding alphabet 0x%02X not implemented",
				pdu->data_coding.general.alphabet);
		return -1;
	}

	STRLEN_CHECK(pdu_str, nr_octets * 2, -1);

	log_debug("user-data-len: 0x%02X", pdu->user_data_len);
	log_debug("nr_octets: 0x%02X", nr_octets);

	for (i = 0; i < nr_octets; i++) {
		octets[i] = hex_byte_decode(pdu_str);
		pdu_str += HEX_BYTE_LEN;
	}

	if (pdu->data_coding.general.alphabet == PDU_ALPHABET_DEFAULT) {
		for (i = 0; i < pdu->user_data_len; i++) {
			pdu->user_data[i] = decode_septet(octets, i);
		}
		pdu->user_data[i] = '\0';
	} else {
		for (i = 0; i < pdu->user_data_len; i++) {
			pdu->user_data[i] = octets[i];
		}
		pdu->user_data[i] = '\0';
	}

	return pdu_str - begin;
}

int pdu_decode(const char *pdu_str, struct pdu_info *pdu)
{
	const char *begin = pdu_str;
	const char *msg_begin;
	int tmp;

	memset(pdu, 0, sizeof(*pdu));

	tmp = pdu_decode_addr(pdu_str, &pdu->smsc_addr, 1);
	DECODE_FAIL(tmp < 0, "smsc-addr", -1);
	pdu_str += tmp;

	msg_begin = pdu_str;

	log_debug("smsc-addr: %s", pdu->smsc_addr.addr);
	log_debug("smsc-addr-type: 0x%02X", pdu->smsc_addr.type);
	log_debug("smsc-addr-len: 0x%02X", pdu->smsc_addr.len);

	STRLEN_CHECK(pdu_str, HEX_BYTE_LEN, -1);

	tmp = hex_byte_decode(pdu_str);
	DECODE_FAIL(tmp < 0, "type", -1);
	pdu_str += HEX_BYTE_LEN;
	pdu->type.type = tmp;

	log_debug("type: 0x%02X", pdu->type.type);

	if (pdu->type.msg_type == PDU_MTI_SUBMIT ||
	    pdu->type.msg_type == PDU_MTI_REPORT) {
		STRLEN_CHECK(pdu_str, HEX_BYTE_LEN, -1);

		tmp = hex_byte_decode(pdu_str);
		DECODE_FAIL(tmp < 0, "msg-reference", -1);
		pdu_str += HEX_BYTE_LEN;
		pdu->msg_reference = tmp;

		log_debug("msg-reference: 0x%02X", pdu->msg_reference);
	}

	tmp = pdu_decode_addr(pdu_str, &pdu->addr, 0);
	DECODE_FAIL(tmp < 0, "addr", -1);
	pdu_str += tmp;

	log_debug("addr: %s", pdu->addr.addr);
	log_debug("addr-type: 0x%02X", pdu->addr.type);
	log_debug("addr-len: 0x%02X", pdu->addr.len);

	switch (pdu->type.msg_type) {
	case PDU_MTI_REPORT:
		tmp = pdu_decode_timestamp(pdu_str, &pdu->timestamp);
		DECODE_FAIL(tmp < 0, "report-timestamp", -1);
		pdu_str += tmp;

		break;
	case PDU_MTI_DELIVER:
	case PDU_MTI_SUBMIT:
		STRLEN_CHECK(pdu_str, HEX_BYTE_LEN, -1);

		tmp = hex_byte_decode(pdu_str);
		DECODE_FAIL(tmp < 0, "protocol-id", -1);
		pdu_str += HEX_BYTE_LEN;
		pdu->protocol_id = tmp;

		log_debug("protocol-id: 0x%02X", pdu->protocol_id);

		STRLEN_CHECK(pdu_str, HEX_BYTE_LEN, -1);

		tmp = hex_byte_decode(pdu_str);
		DECODE_FAIL(tmp < 0, "data-coding-scheme", -1);
		pdu_str += HEX_BYTE_LEN;
		pdu->data_coding.data_coding = tmp;

		log_debug("data-coding-scheme: 0x%02X", pdu->data_coding.data_coding);

		if (pdu->type.msg_type == PDU_MTI_SUBMIT) {
			log_debug("validity-period-format: 0x%02X",
					pdu->type.validity_period_format);
			switch (pdu->type.validity_period_format) {
			case PDU_VPF_RELATIVE:
				STRLEN_CHECK(pdu_str, HEX_BYTE_LEN, -1);

				tmp = hex_byte_decode(pdu_str);
				DECODE_FAIL(tmp < 0, "validity-period", -1);
				pdu_str += HEX_BYTE_LEN;
				pdu->validity_period = tmp;

				log_debug("validity-period: 0x%02X", pdu->validity_period);

				break;

			case PDU_VPF_ENHANCED:
				log_warning("PDU_VPF_ENHANCED? Falling through to absolute");
			case PDU_VPF_ABSOUTE:
				tmp = pdu_decode_timestamp(pdu_str, &pdu->timestamp);
				DECODE_FAIL(tmp < 0, "validity-period-timestamp", -1);
				pdu_str += tmp;

				return -1;

			case PDU_VPF_NOT_PRESENT:
			default:
				break;
			}
		} else if (pdu->type.msg_type == PDU_MTI_DELIVER) {
			tmp = pdu_decode_timestamp(pdu_str, &pdu->timestamp);
			DECODE_FAIL(tmp < 0, "delivery-timestamp", -1);
			pdu_str += tmp;
		}

		tmp = pdu_decode_user_data(pdu_str, pdu);
		DECODE_FAIL(tmp < 0, "user-data", -1);
		pdu_str += tmp;
	}

	pdu->msg_len = (pdu_str - msg_begin) / 2;

	log_debug("msg_len: %d", pdu->msg_len);

	return pdu_str - begin;
}