#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <iostream>

using namespace std;

#include <event2/event.h>

#include <event2/bufferevent.h>

void accept_cb(int fd, short events, void* arg);

void socket_read_cb(bufferevent* bev, void* arg);

void event_cb(struct bufferevent *bev, short event, void *arg);

int tcp_server_init(int port, int listen_num);

int main(int argc, char** argv)

{

#ifdef WIN32

    WSADATA wsa_data;

    WSAStartup(0x0201, &wsa_data);

#endif

    int listener = tcp_server_init(9999, 10);

    if( listener == -1 )

    {

        perror(" tcp_server_init error ");

        return -1;

    }

    struct event_base* base = event_base_new();

    //添加监听客户端请求连接事件

    struct event* ev_listen = event_new(base, listener, EV_READ | EV_PERSIST,

        accept_cb, base);

    event_add(ev_listen, NULL);

    event_base_dispatch(base);

    event_base_free(base);

#ifdef WIN32

    WSACleanup();

#endif

    return 0;

}

void accept_cb(int fd, short events, void* arg)

{

    evutil_socket_t sockfd;

    struct sockaddr_in client;

    int len = sizeof(client);

    sockfd = ::accept(fd, (struct sockaddr*)&client, &len );

    evutil_make_socket_nonblocking(sockfd);

    cout << "accept a client " << sockfd << endl;

    struct event_base* base = (event_base*)arg;

    bufferevent* bev = bufferevent_socket_new(base, sockfd, BEV_OPT_CLOSE_ON_FREE);

    bufferevent_setcb(bev, socket_read_cb, NULL, event_cb, arg);

    bufferevent_enable(bev, EV_READ | EV_PERSIST);

}

void socket_read_cb(bufferevent* bev, void* arg)

{

    char msg[4096] = {0};

    size_t len = bufferevent_read(bev, msg, sizeof(msg));

    cout << "recv the client msg: " << msg << endl;

    // msg[len] = '\r';

    // msg[len+1] = '\n'; 

    char reply_msg[4096] = "I have recvieced the msg: ";

    strcat(reply_msg + strlen(reply_msg), msg);

    bufferevent_write(bev, reply_msg, strlen(reply_msg));

}

void event_cb(struct bufferevent *bev, short event, void *arg)

{

    if (event & BEV_EVENT_EOF)

    {

        cout << "connection closed" << endl;

    }

    else if (event & BEV_EVENT_ERROR)

    {

        cout << "some other error" << endl;

    }

    //这将自动close套接字和free读写缓冲区

    bufferevent_free(bev);

}

typedef struct sockaddr SA;

int tcp_server_init(int port, int listen_num)

{

    evutil_socket_t listener;

    listener = ::socket(AF_INET, SOCK_STREAM, 0);

    if( listener == -1 )

        return -1;

    //允许多次绑定同一个地址。要用在socket和bind之间

    evutil_make_listen_socket_reuseable(listener);

    do

    {

        struct sockaddr_in sin;

        sin.sin_family = AF_INET;

        sin.sin_addr.s_addr = 0;

        sin.sin_port = htons(port);

        if( ::bind(listener, (SA*)&sin, sizeof(sin)) < 0 )

            break;

        if( ::listen(listener, listen_num) < 0)

            break;

        //跨平台统一接口，将套接字设置为非阻塞状态

        evutil_make_socket_nonblocking(listener);

        return listener;

    } while (0);

    int errno_save;

    errno_save = errno;

    evutil_closesocket(listener);

    errno = errno_save;

    return -1;

}