#include <stdio.h>
#include <time.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/tcp.h>
#include <errno.h>
#include <assert.h>
#include <signal.h>

#include <vcl/vppcom.h>

#define MAX_EVENTS 512

struct epoll_event ev;
struct epoll_event events[MAX_EVENTS];

static int message_size = 4096;
static char *buf = NULL;

static int epfd = -1;
static int sockfd = -1;
static int is_client = 0;

/* Echo server */
int loop(void *arg)
{
    /* Wait for events to happen */
    int nevents = vppcom_epoll_wait(epfd, events, MAX_EVENTS, 0);
    if (nevents < 0)
    {
        return 0;
    }

    int i;

    for (i = 0; i < nevents; ++i)
    {
        /* Handle new connection */
        if (events[i].data.fd == sockfd)
        {
            while (1)
            {
                int nclientfd = vppcom_session_accept(sockfd, NULL, 0);
                if (nclientfd < 0)
                {
                    break;
                }
                /* Add to event list */
                ev.data.fd = nclientfd;
                ev.events = EPOLLIN;
                int rv = vppcom_epoll_ctl(epfd, EPOLL_CTL_ADD, nclientfd, &ev);
                if (rv)
                {
                    printf("vppcom_epoll_ctl failed: %d\n", rv);
                    break;
                }
            }
        }
        else
        {
            if (events[i].events & (EPOLLERR|EPOLLHUP))
            {
                /* Simply close socket */
                vppcom_epoll_ctl(epfd, EPOLL_CTL_DEL, events[i].data.fd, NULL);
                vppcom_session_close(events[i].data.fd);
            }
            else if (events[i].events & EPOLLIN)
            {
                vppcom_data_segment_t seg[8];
                size_t readlen = vppcom_session_read_segments(
                    events[i].data.fd, seg, sizeof(seg)/sizeof(seg[0]), message_size
                );
                if (readlen > 0)
                {
                    size_t left = readlen;
                    for (int i = 0; left > 0; i++)
                    {
                        vppcom_session_write(events[i].data.fd, seg[i].data, seg[i].len);
                        left -= seg[i].len;
                    }
                    // FIXME: I'm not sure if I can do that. Maybe the buffer can't be freed until it's really sent
                    vppcom_session_free_segments(events[i].data.fd, readlen);
                }
                else
                {
                    vppcom_epoll_ctl(epfd, EPOLL_CTL_DEL, events[i].data.fd, NULL);
                    vppcom_session_close(events[i].data.fd);
                }
            }
            else
            {
                printf("unknown event: %8.8X\n", events[i].events);
            }
        }
    }

    return 0;
}

static uint64_t sum_us = 0, count_us = 0;
static int to_write = 0;
static int to_read = 0;
static int connected = 0;
static struct timespec connect_time;
static struct timespec start, end;

void sigint_handler(int signum)
{
    if (sockfd >= 0)
    {
        vppcom_session_close(sockfd);
        sockfd = 0;
    }
    if (is_client)
    {
        struct timespec stop_time;
        clock_gettime(CLOCK_REALTIME, &stop_time);
        double duration_sec = ((stop_time.tv_nsec - connect_time.tv_nsec)/1000000000.0 + 1.0*(stop_time.tv_sec - connect_time.tv_sec));
        uint64_t mps = count_us/duration_sec;
        printf(
            "%lu messages in %.2f seconds (%lu messages per second), %lu us avg ping-pong\n", count_us,
            duration_sec, mps, sum_us/(count_us == 0 ? 1 : count_us)
        );
    }
    exit(0);
}

int loop_client(void *arg)
{
    ssize_t len = 0;
    int nevents = vppcom_epoll_wait(epfd, events, MAX_EVENTS, 0);
    int i;
    for (i = 0; i < nevents; ++i)
    {
        if (events[i].events & (EPOLLHUP|EPOLLERR))
        {
            /* Simply close socket */
            printf("Error event\n");
            vppcom_epoll_ctl(epfd, EPOLL_CTL_DEL, events[i].data.fd, NULL);
            vppcom_session_close(events[i].data.fd);
            sigint_handler(SIGINT);
            exit(0);
        }
        else if (events[i].events & EPOLLIN)
        {
            /* Read everything back */
            if (to_read > 0)
            {
                vppcom_data_segment_t seg[8];
                len = vppcom_session_read_segments(
                    events[i].data.fd, seg, sizeof(seg)/sizeof(seg[0]), to_read
                );
                if (len > 0)
                    to_read = to_read > len ? to_read-len : 0;
                // FIXME: I'm not sure if I can do that. Maybe the buffer can't be freed until it's really sent
                vppcom_session_free_segments(events[i].data.fd, len);
                if (to_read == 0)
                {
                    /* Calculate latency */
                    clock_gettime(CLOCK_REALTIME, &end);
                    sum_us += (end.tv_nsec - start.tv_nsec)/1000 + (end.tv_sec - start.tv_sec)*1000000;
                    count_us++;
                    /* Send next request */
                    start = end;
                    memset(buf, 0xab, message_size);
                    to_write = message_size;
                    len = vppcom_session_write(events[i].data.fd, buf, to_write);
                    if (len > 0)
                        to_write -= len;
                    if (to_write == 0)
                        to_read = message_size;
                }
            }
        }
        else if (events[i].events & EPOLLOUT)
        {
            /* Connected or buffer available */
            if (!connected)
            {
                connected = 1;
                printf("Connected, starting ping-pong, press Ctrl-C to interrupt\n");
                clock_gettime(CLOCK_REALTIME, &connect_time);
                start = connect_time;
                memset(buf, 0xab, message_size);
                to_write = message_size;
            }
            if (to_write > 0)
            {
                len = vppcom_session_write(events[i].data.fd, buf, to_write);
                if (len > 0)
                    to_write -= len;
                if (to_write == 0)
                    to_read = message_size;
            }
        }
        else
        {
            printf("unknown event: %8.8X\n", events[i].events);
        }
    }
    return 0;
}

int main(int argc, char *argv[])
{
    char *server = NULL;
    char **f_argv = malloc(sizeof(char*) * (argc+1));
    int f_argidx = 1;
    int rv;
    f_argv[0] = argv[0];
    for (int i = 1; i < argc; i++)
    {
        if (!strcmp(argv[i], "--size"))
        {
            if (i < argc-1)
                message_size = atoi(argv[++i]);
            if (message_size < 4)
            {
                printf("invalid argument for --size\n");
                exit(1);
            }
        }
        else if (argv[i][0] == '-')
        {
            f_argv[f_argidx++] = argv[i++];
            f_argv[f_argidx++] = argv[i];
        }
        else
        {
            server = argv[i];
            break;
        }
    }
    f_argv[f_argidx] = NULL;

    buf = malloc(message_size);
    if (!buf)
    {
        printf("failed to allocate buffer\n");
        exit(1);
    }

    rv = vppcom_app_create("pingpong");
    if (rv)
    {
        printf("vppcom_app_create() failed: %d\n", rv);
        exit(1);
    }

    sockfd = vppcom_session_create(VPPCOM_PROTO_TCP, 1/* is_nonblocking */);
    if (sockfd < 0)
    {
        printf("vppcom_session_create failed: %d\n", sockfd);
        exit(1);
    }

    if (server)
    {
        printf("Client mode, message size %d, connecting to %s port 7777\n", message_size, server);
        is_client = 1;

        struct sockaddr_in my_addr;
        bzero(&my_addr, sizeof(my_addr));
        my_addr.sin_family = AF_INET;
        my_addr.sin_port = htons(7777);
        my_addr.sin_addr.s_addr = inet_addr(server);

        vppcom_endpt_t endpt;
        endpt.is_ip4 = 1;
        endpt.ip = (uint8_t *)&my_addr.sin_addr;
        endpt.port = (uint16_t)my_addr.sin_port;

        rv = vppcom_session_connect(sockfd, &endpt);
        if (rv < 0 && rv != VPPCOM_EINPROGRESS)
        {
            printf("vppcom_session_connect failed: %d\n", rv);
            exit(1);
        }
    }
    else
    {
        printf("Server mode, listening on port 7777 and echoing everything back\n");

        struct sockaddr_in my_addr;
        bzero(&my_addr, sizeof(my_addr));
        my_addr.sin_family = AF_INET;
        my_addr.sin_port = htons(7777);
        my_addr.sin_addr.s_addr = htonl(INADDR_ANY);

        vppcom_endpt_t endpt;
        endpt.is_ip4 = 1;
        endpt.ip = (uint8_t *)&my_addr.sin_addr;
        endpt.port = (uint16_t)my_addr.sin_port;

        rv = vppcom_session_bind(sockfd, &endpt);
        if (rv < 0)
        {
            printf("vppcom_session_bind() failed: %d", rv);
            exit(1);
        }

        rv = vppcom_session_listen(sockfd, MAX_EVENTS);
        if (rv < 0)
        {
            printf("vppcom_session_listen() failed: %d", rv);
            exit(1);
        }
    }

    assert((epfd = vppcom_epoll_create()) > 0);
    ev.data.fd = sockfd;
    ev.events = (server ? EPOLLOUT : 0) | EPOLLIN|EPOLLHUP|EPOLLET;
    rv = vppcom_epoll_ctl(epfd, EPOLL_CTL_ADD, sockfd, &ev);
    if (rv < 0)
    {
        printf("vppcom_epoll_ctl() failed: %d", rv);
        exit(1);
    }
    signal(SIGINT, sigint_handler);

    if (server)
        while (1)
            loop_client(NULL);
    else
        while (1)
            loop(NULL);

    vppcom_app_destroy();

    return 0;
}