/*********************************************************************************
 *      Copyright:  (C) 2019 LingYun IoT studio
 *                  All rights reserved.
 *
 *       Filename:  tlv_sample.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(03/27/2019)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "03/27/2019 09:20:25 PM"
 *                 
 ********************************************************************************/

#include <stdio.h>
#include <string.h>
#include "crc-itu-t.h"

#define OFF                0
#define ON                 1

#define BUFSIZE            128

/* TLV Packet format: 
 *
 *+------------+---------+------------+-----------+-----------+
 *| Header(1B) | Tag(1B) | Length(1B) | Value(1B) | CRC16(2B) |
 *+------------+---------+------------+-----------+-----------+
 */

#define PACK_HEADER        0xFD

/* Tag definition */
enum
{
	TAG_LOGON=1,
	TAG_CAMERA,
	TAG_LED,
};

/* TLV packet fixed segement size, 1B Head, 1B Tag, 1B length, 2B CRC16, total 5B. */
#define TLV_FIXED_SIZE     5

/* TLV packet Minimum size is fixed bytes + 1 byte data */
#define TLV_MIN_SIZE       (TLV_FIXED_SIZE+1)

int packtlv_logon(char *buf, int size, char *pwd);
int packtlv_led(char *buf, int size, int cmd);
void dump_buf(char *data, int len);

int main(int argc, char **argv)
{
	char          buf[BUFSIZE];
	int           bytes;

	bytes = packtlv_led(buf, sizeof(buf), ON);

       	/* print every byte in the buffer as HEX and corresponding charactor, 
	  which is not printable charactor will be instead as '?' */
	dump_buf(buf, bytes);

	bytes = packtlv_logon(buf, sizeof(buf), "iot@yun");

	dump_buf(buf, bytes);

	return 0;
}


int packtlv_logon(char *buf, int size, char *pwd)
{
	unsigned short      crc16 = 0;
	int                 pack_len = 0;
	int                 data_len = 0;
	int                 ofset = 0; /* index position for the buf */

	if(!buf || !pwd || size<TLV_MIN_SIZE )
	{
		printf("Invalid input arguments\n");
		return 0;
	}

	/* Packet head */
	buf[ofset] = PACK_HEADER;
	ofset += 1;

	/* Tag */
	buf[ofset] = TAG_LOGON;
	ofset += 1;

	/* $pwd too long maybe result buffer overflow, so we need check the buffer 
	 * is large enuf or not. If buf size is not enuf we will truncate $pwd string */
	if( strlen(pwd) <= size-TLV_FIXED_SIZE )
		data_len = strlen(pwd);
	else
		data_len = size-TLV_FIXED_SIZE;

	/* Length, this packet is passwd length+5Byte () */
	pack_len = data_len + TLV_FIXED_SIZE;

	buf[ofset] = pack_len;
	ofset += 1;

	memcpy(&buf[ofset], pwd, data_len);
	ofset += data_len;

	/* Calc CRC16 checksum value from Packet Head(buf[0])~ Value(buf[ofset]) */
	crc16 = crc_itu_t(MAGIC_CRC, buf, ofset);

	/* Append the 2 Bytes CRC16 checksum value into the last two bytes in packet buffer */
	ushort_to_bytes(&buf[ofset], crc16);
	ofset += 2;

	return ofset;
}



int packtlv_led(char *buf, int size, int cmd)
{
	unsigned short      crc16;
	int                 pack_len = TLV_FIXED_SIZE+1; /* Only 1 byte data */

	if(!buf || size<TLV_MIN_SIZE )
	{
		printf("Invalid input arguments\n");
		return 0;
	}

	/* Packet head */
	buf[0] = PACK_HEADER;

	/* Tag */
	buf[1] = TAG_LED;

	/* Length, this packet total 6 bytes */
	buf[2] = pack_len;

	/* Value */
	buf[3] = (OFF==cmd) ? 0x00 : 0x01;

	/* Calc CRC16 checksum value from Packet Head(buf[0])~ Packet Value(buf[3]) */
	crc16 = crc_itu_t(MAGIC_CRC, buf, 4);

	/* Append the 2 Bytes CRC16 checksum value into the last two bytes in packet buffer */
	ushort_to_bytes(&buf[4], crc16);

	return pack_len;
}


/*+------------------------------+
 *|  dump_buf() implement code   |
 *+------------------------------+*/

#define LINELEN 81
#define CHARS_PER_LINE 16

static char *print_char =
    "                "
    "                "
    " !\"#$%&'()*+,-./"
    "0123456789:;<=>?"
    "@ABCDEFGHIJKLMNO"
    "PQRSTUVWXYZ[\\]^_"
    "`abcdefghijklmno"
    "pqrstuvwxyz{|}~ "
    "                "
    "                "
    " ???????????????"
    "????????????????"
    "????????????????"
    "????????????????"
    "????????????????"
    "????????????????";

/* print every byte in the buffer as HEX and corresponding charactor, which is not printable charactor will be instead as '?' */
void dump_buf(char *data, int len)
{
    int rc;
    int idx;
    char prn[LINELEN];
    char lit[CHARS_PER_LINE + 1];
    char hc[4];
    short line_done = 1;

    rc = len;
    idx = 0;
    lit[CHARS_PER_LINE] = '\0';

    while (rc > 0)
    {
        if (line_done)
            snprintf(prn, LINELEN, "%08X: ", idx);
        do
        {
            unsigned char c = data[idx];
            snprintf(hc, 4, "%02X ", c);
            strncat(prn, hc, 4);
            lit[idx % CHARS_PER_LINE] = print_char[c];
            ++idx;
        } while (--rc > 0 && (idx % CHARS_PER_LINE != 0));

        line_done = (idx % CHARS_PER_LINE) == 0;

        if (line_done)
            printf("%s  %s\n", prn, lit);
        else if (rc == 0)
            strncat(prn, "   ", LINELEN);
    }

    if (!line_done)
    {
        lit[(idx % CHARS_PER_LINE)] = '\0';

        while ((++idx % CHARS_PER_LINE) != 0)
            strncat(prn, "   ", LINELEN);

        printf("%s  %s\n", prn, lit);

    }
}