/*********************************************************************************
 *      Copyright:  (C) 2020 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  tlv_server.c
 *    Description:  This is a socket server program to receive RPi's temperature 
 *                  from socket client and save it in sqlite database.
 *                 
 *        Version:  1.0.0(2020年04月14日)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "2020年04月14日 00时52分56秒"
 *                 
 ********************************************************************************/
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <getopt.h>
#include <libgen.h>

#include "logger.h"
#include "proc.h"
#include "socket.h"
#include "tlv_pack.h"
#include "crc-itu-t.h"

#define PROG_VERSION     "1.0.0"

#define DEF_LOG_FILE     "tlv_server.log"
#define DEF_LISTEN_IP    "0.0.0.0"
#define DEF_LISTEN_PORT  10086

#define MAX_EVENTS       512


/* Every client need get a stand alone buffer to save TLV packet data */
typedef struct cli_buf_s 
{
    int                  fd;         /* client fd  */
    char                 buf[512];   /* client receive buffer */
    int                  bytes;      /* left bytes in buffer  */
    struct list_head     list;       /* all client buffer saved in a list */
} cli_buf_t;  

static int  parser_tlvpack(cli_buf_t *cli_buf);
static void term_socket_client(int epollfd, int fd, struct list_head *buf_list);

static void banner(void)
{
    printf("Version %s build on %s %s\n", PROG_VERSION, __DATE__, __TIME__); 
    printf("Copyright (C) 2020 LingYun IoT System Studio.\n\n");

    return ;
}

static void program_usage(const char *progname)
{
    printf("Usage: %s [OPTION]...\n", progname);
    printf("This program receive RPi's temperature from socket client and save it in sqlite database.\n");

    printf("\nMandatory arguments to long options are mandatory for short options too:\n");
    printf(" -d[debug   ]  Running in debug mode\n");
    printf(" -l[level   ]  Set the log level as [0..%d]\n", LOG_LEVEL_MAX-1); 
    printf(" -h[help    ]  Display this help information\n"); 
    printf(" -v[version ]  Display the program version\n");
    printf("\n");

    banner();
    return ;
}

int main (int argc, char *argv[])
{ 
    int                   opt; 
    int                   i = 0; 
    int                   rv = 0; 
    int                   debug = 0;
    int                   port = DEF_LISTEN_PORT;

    char                  pid_file[64] = { 0 }; /* The file used to record the PID */
    const char           *progname=NULL;

    int                   log_level = LOG_LEVEL_NRML;
    char                 *log_file = DEF_LOG_FILE;
    logger_t              logger;

    socket_t              sock;
    int                   epollfd;
    int                   connfd;
    int                   fd;
    int                   nfds;
    struct epoll_event    event_array[MAX_EVENTS];

    cli_buf_t            *cli_buf;
    cli_buf_t            *node;
    struct list_head      buf_list; /* every client get a stand alone buffer saved in the list */

    struct option long_options[] = { 
        {"port", required_argument, NULL, 'p'}, 
        {"debug", no_argument, NULL, 'd'}, 
        {"level", required_argument, NULL, 'l'}, 
        {"version", no_argument, NULL, 'v'}, 
        {"help", no_argument, NULL, 'h'}, 
        {NULL, 0, NULL, 0}
    };

    memset(&logger, 0, sizeof(logger));
    memset(&sock, 0, sizeof(sock));
    INIT_LIST_HEAD(&buf_list);

    progname = basename(argv[0]); /* get program name */

    /* parser the command line parameters */ 
    while ((opt = getopt_long(argc, argv, "p:dl:vh", long_options, NULL)) != -1) 
    { 
        switch (opt) 
        {
            case 'p': /* listen port  */
                port = atoi(optarg); 
                break;

            case 'd': /* set debug running */
                debug = 1;
                log_level= LOG_LEVEL_DEBUG;
                log_file = NULL;  /* use standard output */
                break;

            case 'l': /* set the log level */
                i = atoi(optarg); 
                log_level = i>LOG_LEVEL_MAX ? LOG_LEVEL_MAX-1 : i; 
                logger.flag |= FLAG_LOGGER_LEVEL_OPT; 
                break; 

            case 'v':  /* print software version */
                banner();
                return EXIT_SUCCESS; 

            case 'h':  /* print help information */
                program_usage(progname);
                return 0; 

            default: 
                break; 
        } 
    }

    if( port <= 0 )
    {
        printf("ERROR: no listen port specified, refer to program usage\n\n");
        program_usage(progname);
    }

    /* check program already running or not, if already running then exit, or set running as daemon */
    snprintf(pid_file, sizeof(pid_file), "/var/run/%s.pid", progname);
    if( !debug )
    {
        if( check_daemon_running(pid_file) )
        {
            printf("Programe already running, exit now.\n");
            return -1;
        }

        set_daemon_running(pid_file);
    }

    /* initial and open logger system */
    if( logger_init(&logger, log_file, log_level, 512)<0 || logger_open()<0 )
    {
        printf("ERROR: Initialise logger system failure\n");
        return -1;
    }

    /* install signal proc handler */
    install_proc_signal();

    log_nrml("TLV server program start running\n");

    /* set open file description number to max */
    set_socket_rlimit();

    /* initial listen socket  */
    if( socket_listen(&sock, DEF_LISTEN_IP, port) < 0 )
    {
        log_err("create listen socket failure\n");
        return -2;
    }

    /* create epoll and put listen socket into it  */
    if( (epollfd=epoll_init(MAX_EVENTS, sock.fd)) < 0 )
    {
        log_err("initial epoll for listen socket failure\n");
        return -2;
    }

    /* g_signal.stop defined in proc.c, and will be set when catch stop signal */
    while( !g_signal.stop )
    {
        /* epoll wailt and program will blocked here */ 
        nfds = epoll_wait(epollfd, event_array, MAX_EVENTS, -1 /* never timeout */);
        if( nfds <= 0 )
        {
            log_err("epoll_wait failure or timeout: %s\n", strerror(errno));
            continue;
        }

        /* nfds>0 is the active events count */ 
        for(i=0; i<nfds; i++)
        {
            fd = event_array[i].data.fd;

            /* epoll get error  */
            if ( (event_array[i].events&EPOLLERR) || (event_array[i].events&EPOLLHUP) )
            {
                log_err("epoll_wait get error on fd[%d]: %s\n", fd, strerror(errno)); 
                if( fd != sock.fd )
                    term_socket_client(epollfd, event_array[i].data.fd, &buf_list);

                continue;
            }

            /* listen socket get event means new client start connect now */ 
            if( fd == sock.fd )
            {
                /* accept new client socket  */
                if( (connfd=accept(sock.fd, (struct sockaddr *)NULL, NULL)) < 0)
                {
                    log_nrml("accept new client failure: %s\n", strerror(errno));
                    continue;
                }

                /* add new client socket into epoll  */
                if( epoll_add(epollfd, connfd) < 0 )
                {
                    close(connfd);
                    log_err("epoll add client socket failure, rv=%d\n", rv);
                }

                /* malloc client buffer and add it into list */
                if( NULL != (cli_buf=(cli_buf_t *)malloc(sizeof(*cli_buf))) )
                {
                    memset(cli_buf, 0, sizeof(cli_buf));
                    cli_buf->fd = connfd;
                    list_add_tail(&cli_buf->list, &buf_list);
                    log_info("alloc and add socket[%d] buffer[%p] into list\n", cli_buf->fd, cli_buf);
                }

                log_nrml("accept and add new client socket[%d] ok.\n", connfd); 
            }
            /* already connected client socket get data arrive  */
            else 
            {
                cli_buf = NULL; 

                /* Use list_for_each_entry to find the client buf in  buf list */
                list_for_each_entry(node, &buf_list, list)
                {
                    if( node->fd == fd )
                    {
                        log_info("found socket[%d] buffer[%p] in list\n", fd, node);
                        cli_buf = node;
                    }
                }

                if( !cli_buf )
                {
                    log_err("can not find socket[%d] buffer and close it now\n", fd);
                    term_socket_client(epollfd, fd, NULL);
                }

                rv=read(fd, &cli_buf->buf[cli_buf->bytes], sizeof(cli_buf->buf)-cli_buf->bytes); 
                if( rv <= 0 )
                {
                    log_warn("socket[%d] read failure [%s] or disconncet, terminate it now.\n", 
                            fd, strerror(errno));

                    term_socket_client(epollfd, fd, &buf_list);
                    continue;
                }
                else
                {
                    cli_buf->bytes += rv;
                    log_dbg("socket[%d] receive %d bytes data\n", fd, rv); 
                }

                parser_tlvpack(cli_buf);
            }
        }

        sleep(1);
    }

    logger_term();

    return 0;
} 

static int parser_tlvpack(cli_buf_t *cli_buf)
{
    int                     i;
    int                     left_bytes;
    unsigned short          crc16;
    tlv_pack_t             *tlv_pack;

    if( !cli_buf )
    {
        log_err("Invalid input arguments\n");
        return -1;
    }

    log_info("start to parser client buffer %d bytes data:\n", cli_buf->bytes);
    logger_dump(LOG_LEVEL_INFO, cli_buf->buf, cli_buf->bytes);

    if( cli_buf->bytes < TLV_MIN_SIZE )
    {
        log_warn("TLV packet bytes less than min. size\n");
        return -2;
    }

PARSER_AGAIN:
    for(i=0; i<cli_buf->bytes; i++)
    {
        if( PACK_HEADER == (unsigned char )cli_buf->buf[i] )
        {
            log_dbg("found TLV packet header on [%d]\n", i);
            left_bytes = cli_buf->bytes - i;

            if(left_bytes < TLV_MIN_SIZE)
            {
                log_warn("TLV packet bytes less than min. size\n");
                memmove(cli_buf->buf, &cli_buf->buf[i], left_bytes);
                cli_buf->bytes = left_bytes;
                break;
            }

            tlv_pack = (tlv_pack_t *) &cli_buf->buf[i];
            log_info("header: 0x%02x tag: 0x%02x len: 0x%02x\n", tlv_pack->header, tlv_pack->tag, tlv_pack->len);

            if(tlv_pack->len > left_bytes )
            {
                log_err("TLV packet not integrated, continue to receive left data\n");
                memmove(cli_buf->buf, &cli_buf->buf[i], left_bytes);
                cli_buf->bytes = left_bytes;
                break;
            }

            if( tlv_pack->len > TLV_MAX_SIZE )
            {
                log_err("TLV packet length more than max. length, maybe found wrong header?\n");

                /* skip current header */
                left_bytes -= 1;
                memmove(cli_buf->buf, &cli_buf->buf[i+1], left_bytes); 
                cli_buf->bytes = left_bytes;
                goto PARSER_AGAIN;
            }

            crc16 = crc_itu_t(MAGIC_CRC, (unsigned char *)&cli_buf->buf[i], tlv_pack->len-2);
            if( crc16 != bytes_to_ushort((unsigned char *)&cli_buf->buf[i+tlv_pack->len-2], 2) )
            {
                log_err("TLV packet CRC check error, maybe found wrong header?\n");

                /* skip current header */
                left_bytes -= 1;
                memmove(cli_buf->buf, &cli_buf->buf[i+1], left_bytes); 
                cli_buf->bytes = left_bytes;

                goto PARSER_AGAIN;
            }

            if( tlv_pack->tag == TAG_SN )
            {
                log_nrml("Found SN TLV data:\n"); 
                dump_buf(tlv_pack->data, tlv_pack->len-TLV_FIXED_SIZE);
            }
            else if( tlv_pack->tag == TAG_TEMP )
            {
                log_nrml("Found temperature TLV data:\n");
                dump_buf(tlv_pack->data, tlv_pack->len-TLV_FIXED_SIZE);
            }
            else if( tlv_pack->tag == TAG_TIME )
            {
                log_nrml("Found date time TLV data:\n");
                dump_buf(tlv_pack->data, tlv_pack->len-TLV_FIXED_SIZE);
            }

            left_bytes -= tlv_pack->len;
            memmove(cli_buf->buf, &cli_buf->buf[i+tlv_pack->len], left_bytes); 
            cli_buf->bytes = left_bytes;

            log_info("left %d bytes data:\n", cli_buf->bytes);
            logger_dump(LOG_LEVEL_INFO, cli_buf->buf, cli_buf->bytes);
            goto PARSER_AGAIN;
        }
    }

    return 0;
}

static void term_socket_client(int epollfd, int fd, struct list_head *buf_list)
{
    cli_buf_t          *buf, *tmp;

    log_warn("start terminatl client socket[%d]\n", fd);

    /* if get buf_list, then remove buf from list */
    if( buf_list )
    {
        /* Use list_for_each_entry_safe to travel the socket list and destroy the buffer */
        list_for_each_entry_safe(buf, tmp, buf_list, list)
        {
            if( buf->fd == fd )
            {
                list_del(&buf->list);
                free(buf);
                log_info("free socket[%d] buffer[%p]\n", fd, buf);
                break;
            }
        }
    }

    epoll_del(epollfd, fd); 
    close( fd );
}