/**************************************************************************
 *
 * Copyright (C) 2008 Steve Karg
 *
 * SPDX-License-Identifier: GPL-2.0-or-later WITH GCC-exception-2.0
 *
 *********************************************************************/
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#/* BACnet Stack defines - first */
#include "bacnet/bacdef.h"
/* BACnet Stack API */
#include "bacnet/basic/sys/mstimer.h"
#include "bacnet/basic/sys/bytes.h"
#include "bacnet/datalink/crc.h"
#include "bacnet/datalink/mstp.h"
#include "bacnet/datalink/dlmstp.h"
#include "bacnet/datalink/mstptext.h"
#include "bacnet/bacint.h"
/* OS specific include*/
#include "bacport.h"
/* local includes */
#include "rs485.h"

/** @file linux/mstpsnap.c  Example application testing BACnet MS/TP on Linux.
 */

#ifndef max
#define max(a, b) (((a)(b)) ? (a) : (b))
#define min(a, b) (((a) < (b)) ? (a) : (b))
#endif

/* local port data - shared with RS-485 */
static struct mstp_port_struct_t MSTP_Port;
/* buffers needed by mstp port struct */
static uint8_t RxBuffer[DLMSTP_MPDU_MAX];
static uint8_t TxBuffer[DLMSTP_MPDU_MAX];
static struct mstimer Silence_Timer;

static uint32_t Timer_Silence(void *pArg)
{
    uint32_t delta_time = 0;

    delta_time = mstimer_elapsed(&Silence_Timer);
    if (delta_time > 0xFFFF) {
        delta_time = 0xFFFF;
    }

    return delta_time;
}

static void Timer_Silence_Reset(void *pArg)
{
    mstimer_set(&Silence_Timer, 0);
}

/* functions used by the MS/TP state machine to put or get data */
uint16_t MSTP_Put_Receive(struct mstp_port_struct_t *mstp_port)
{
    (void)mstp_port;

    return 0;
}

/* for the MS/TP state machine to use for getting data to send */
/* Return: amount of PDU data */
uint16_t MSTP_Get_Send(struct mstp_port_struct_t *mstp_port, unsigned timeout)
{ /* milliseconds to wait for a packet */
    (void)mstp_port;
    (void)timeout;
    return 0;
}

/**
 * @brief Send an MSTP frame
 * @param mstp_port - port specific data
 * @param buffer - data to send
 * @param nbytes - number of bytes of data to send
 */
void MSTP_Send_Frame(
    struct mstp_port_struct_t *mstp_port,
    const uint8_t *buffer,
    uint16_t nbytes)
{
    (void)mstp_port;
    (void)buffer;
    (void)nbytes;
}

uint16_t MSTP_Get_Reply(struct mstp_port_struct_t *mstp_port, unsigned timeout)
{ /* milliseconds to wait for a packet */
    (void)mstp_port;
    (void)timeout;
    return 0;
}

static int network_init(const char *name, int protocol)
{
    /* check to see if we are being run as root */
    if (getuid() != 0) {
        fprintf(stderr, "Requires root priveleges.\n");
        return -1;
    }

    int sockfd = socket(PF_PACKET, SOCK_RAW, htons(protocol));

    if (sockfd == -1) {
        perror("Unable to create socket");
        return sockfd;
    }

    struct ifreq ifr;

    memset(&ifr, 0, sizeof(ifr));
    snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s", name);
    if (ioctl(sockfd, SIOCGIFINDEX, &ifr) == -1) {
        perror("Unable to get interface index");
        return -1;
    }

    struct sockaddr_ll sll;

    memset(&sll, 0, sizeof(sll));
    sll.sll_family = AF_PACKET;
    sll.sll_ifindex = ifr.ifr_ifindex;
    sll.sll_protocol = htons(protocol);

    if (bind(sockfd, (struct sockaddr *)&sll, sizeof(sll)) == -1) {
        perror("Unable to bind socket");
        return -1;
    }

    return sockfd;
}

static void
snap_received_packet(const struct mstp_port_struct_t *mstp_port, int sockfd)
{
    uint16_t mtu_len = 0; /* number of octets of packet saved in file */
    unsigned i = 0; /* counter */
    static uint8_t mtu[1500] = { 0 };
    uint16_t max_data = 0;

    mtu[0] = 0;
    mtu[1] = 0;
    mtu[2] = 0;
    mtu[3] = 0;
    mtu[4] = 0;
    mtu[5] = mstp_port->DestinationAddress;
    mtu[6] = 0;
    mtu[7] = 0;
    mtu[8] = 0;
    mtu[9] = 0;
    mtu[10] = 0;
    mtu[11] = mstp_port->SourceAddress;
    /* length - 12, 13 */
    mtu[14] = 0xaa; /* DSAP for SNAP */
    mtu[15] = 0xaa; /* SSAP for SNAP */
    mtu[16] = 0x03; /* Control Field for SNAP */
    mtu[17] = 0x00; /* Organization Code: Cimetrics */
    mtu[18] = 0x10; /* Organization Code: Cimetrics */
    mtu[19] = 0x90; /* Organization Code: Cimetrics */
    mtu[20] = 0x00; /* Protocol ID */
    mtu[21] = 0x01; /* Protocol ID */
    mtu[22] = 0x00; /* delta time */
    mtu[23] = 0x00; /* delta time */
    mtu[24] = 0x80; /* unknown byte */
    mtu[25] = mstp_port->FrameType;
    mtu[26] = mstp_port->DestinationAddress;
    mtu[27] = mstp_port->SourceAddress;
    mtu[28] = HI_BYTE(mstp_port->DataLength);
    mtu[29] = LO_BYTE(mstp_port->DataLength);
    mtu[30] = mstp_port->HeaderCRCActual;
    mtu_len = 31;
    if (mstp_port->DataLength) {
        max_data = min(mstp_port->InputBufferSize, mstp_port->DataLength);
        for (i = 0; i < max_data; i++) {
            mtu[31 + i] = mstp_port->InputBuffer[i];
        }
        mtu[31 + max_data] = mstp_port->DataCRCActualMSB;
        mtu[31 + max_data + 1] = mstp_port->DataCRCActualLSB;
        mtu_len += (max_data + 2);
    }
    /* Ethernet length is data only - not address or length bytes */
    encode_unsigned16(&mtu[12], mtu_len - 14);
    (void)write(sockfd, &mtu[0], mtu_len);
}

static void cleanup(void)
{
}

#if (!defined(_WIN32))
static void sig_int(int signo)
{
    (void)signo;

    cleanup();
    exit(0);
}

void signal_init(void)
{
    signal(SIGINT, sig_int);
    signal(SIGHUP, sig_int);
    signal(SIGTERM, sig_int);
}
#endif

/* simple test to packetize the data and print it */
int main(int argc, char *argv[])
{
    struct mstp_port_struct_t *mstp_port;
    long my_baud = 38400;
    uint32_t packet_count = 0;
    int sockfd = -1;
    char *my_interface = "eth0";

    /* mimic our pointer in the state machine */
    mstp_port = &MSTP_Port;
    if ((argc > 1) && (strcmp(argv[1], "--help") == 0)) {
        printf("mstsnap [serial] [baud] [network]\r\n"
               "Captures MS/TP packets from a serial interface\r\n"
               "and sends them to a network interface using SNAP \r\n"
               "protocol packets (mimics Cimetrics U+4 packet).\r\n"
               "\r\n"
               "Command line options:\r\n"
               "[serial] - serial interface.\r\n"
               "    defaults to /dev/ttyUSB0.\r\n"
               "[baud] - baud rate.  9600, 19200, 38400, 57600, 115200\r\n"
               "    defaults to 38400.\r\n"
               "[network] - network interface.\r\n"
               "    defaults to eth0.\r\n"
               "");
        return 0;
    }
    /* initialize our interface */
    if (argc > 1) {
        RS485_Set_Interface(argv[1]);
    }
    if (argc > 2) {
        my_baud = strtol(argv[2], NULL, 0);
    }
    if (argc > 3) {
        my_interface = argv[3];
    }
    sockfd = network_init(my_interface, ETH_P_ALL);
    if (sockfd == -1) {
        return 1;
    }
    RS485_Set_Baud_Rate(my_baud);
    RS485_Initialize();
    MSTP_Port.InputBuffer = &RxBuffer[0];
    MSTP_Port.InputBufferSize = sizeof(RxBuffer);
    MSTP_Port.OutputBuffer = &TxBuffer[0];
    MSTP_Port.OutputBufferSize = sizeof(TxBuffer);
    MSTP_Port.This_Station = 127;
    MSTP_Port.Nmax_info_frames = 1;
    MSTP_Port.Nmax_master = 127;
    MSTP_Port.SilenceTimer = Timer_Silence;
    MSTP_Port.SilenceTimerReset = Timer_Silence_Reset;
    MSTP_Init(mstp_port);
    fprintf(
        stdout, "mstpcap: Using %s for capture at %ld bps.\n",
        RS485_Interface(), (long)RS485_Get_Baud_Rate());
    atexit(cleanup);
#if defined(_WIN32)
    SetConsoleMode(GetStdHandle(STD_INPUT_HANDLE), ENABLE_PROCESSED_INPUT);
    SetConsoleCtrlHandler((PHANDLER_ROUTINE)CtrlCHandler, TRUE);
#else
    signal_init();
#endif
    /* run forever */
    for (;;) {
        RS485_Check_UART_Data(mstp_port);
        MSTP_Receive_Frame_FSM(mstp_port);
        /* process the data portion of the frame */
        if (mstp_port->ReceivedValidFrame) {
            mstp_port->ReceivedValidFrame = false;
            snap_received_packet(mstp_port, sockfd);
            packet_count++;
        } else if (mstp_port->ReceivedInvalidFrame) {
            mstp_port->ReceivedInvalidFrame = false;
            fprintf(stderr, "ReceivedInvalidFrame\n");
            snap_received_packet(mstp_port, sockfd);
            packet_count++;
        }
        if (!(packet_count % 100)) {
            fprintf(stdout, "\r%hu packets", packet_count);
        }
    }

    return 0;
}