#include <event2/listener.h>
#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/thread.h>

#include <arpa/inet.h>

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>

#include <pthread.h>

/* g++ Test_libevent.cpp -o Test_libevent -levent_core -levent_pthreads && ./Test_libevent  */

static void
echo_read_cb(struct bufferevent *bev, void *ctx)
{
        struct evbuffer *input = bufferevent_get_input(bev);
        struct evbuffer *output = bufferevent_get_output(bev);
        evbuffer_add_buffer(output, input);
}

static void
echo_event_cb(struct bufferevent *bev, short events, void *ctx)
{
        fprintf( stderr, "An event from one of the clients...\n" );
        if (events & BEV_EVENT_ERROR)
                perror("Error from bufferevent");
        if (events & (BEV_EVENT_EOF | BEV_EVENT_ERROR)) {
                bufferevent_free(bev);
        }
}

static void
client_event_cb(struct bufferevent *bev, short events, void *ctx)
{
        if (events & BEV_EVENT_ERROR)
                perror("Error from bufferevent");
        if (events & (BEV_EVENT_EOF | BEV_EVENT_ERROR)) {
                bufferevent_free(bev);
        }
}

static void
accept_conn_cb(struct evconnlistener *listener,
                evutil_socket_t fd, struct sockaddr *address, int socklen,
                void *ctx)
{
        struct event_base *base = evconnlistener_get_base(listener);
        struct bufferevent *bev = bufferevent_socket_new(
                        base, fd, BEV_OPT_CLOSE_ON_FREE);

        bufferevent_setcb(bev, echo_read_cb, NULL, echo_event_cb, NULL);

        bufferevent_enable(bev, EV_READ|EV_WRITE);
}

static void
client_incoming_socket_cb( struct bufferevent *bev, void *ctx )
{
        char recv_msg[256];
        memset(recv_msg, 0, 256);
        bufferevent_read( bev, recv_msg, sizeof(recv_msg));

        fprintf( stderr, "Incoming message from Server to Client = '%s'\n", recv_msg );

        fprintf( stderr, "Simulating Client CUTOFF\n" );
        struct event_base *base = (struct event_base*) ctx;
        event_base_loopexit( base, NULL );
}

static void
accept_error_cb(struct evconnlistener *listener, void *ctx)
{
        struct event_base *base = evconnlistener_get_base(listener);
        int err = EVUTIL_SOCKET_ERROR();
        fprintf(stderr, "Got an error %d (%s) on the listener. "
                        "Shutting down.\n", err, evutil_socket_error_to_string(err));

        event_base_loopexit(base, NULL);
}

static void* startServer( void* userData )
{
        struct event_base *base;
        struct evconnlistener *listener;
        struct sockaddr_in sin;

        int port = 7777;

        base = event_base_new();
        if (!base) {
                puts("Couldn't open event base");
                return NULL;
        }

        memset(&sin, 0, sizeof(sin));
        sin.sin_family = AF_INET;
        sin.sin_addr.s_addr = htonl(0);
        sin.sin_port = htons(port);

        listener = evconnlistener_new_bind(base, accept_conn_cb, NULL,
                        LEV_OPT_CLOSE_ON_FREE|LEV_OPT_REUSEABLE, -1,
                        (struct sockaddr*)&sin, sizeof(sin));
        if (!listener) {
                perror("Couldn't create listener");
                return NULL;
        }
        evconnlistener_set_error_cb(listener, accept_error_cb);

        event_base_dispatch(base);
        return NULL;
}

static void* startClient( void* userData )
{
        int port = 7777;
        struct sockaddr_in sin;
        int sockfd;

        bzero( &sin, sizeof( sin ));
        sin.sin_family      = AF_INET;
        sin.sin_addr.s_addr = inet_addr( "127.0.0.1" );
        sin.sin_port        = htons( port );
        if ( (sockfd=socket( PF_INET, SOCK_STREAM, IPPROTO_TCP )) < 0 )      // AF_INET also seems to work
        {
                perror( "socket() failed: " );
                exit( -1 );
        }
        if ( (connect( sockfd, (struct sockaddr *) &sin, sizeof(sin))) < 0 )
        {
                perror( "connect() failed: " );
                exit( -1 );
        }

        struct event_base*  base = event_base_new();
        struct bufferevent* bev = bufferevent_socket_new( base, sockfd, BEV_OPT_CLOSE_ON_FREE|BEV_OPT_THREADSAFE );
        bufferevent_enable( bev, EV_READ|EV_WRITE );
        bufferevent_setcb(  bev, client_incoming_socket_cb, NULL, client_event_cb, base );

        const char* str = "Hello World!";
        evbuffer_add( bufferevent_get_output( bev ), str, strlen( str ));

        event_base_dispatch(base);
        return NULL;
}

int
main(int argc, char **argv)
{
        evthread_use_pthreads();

        pthread_t a, b;

        pthread_create( &a, NULL, startServer, NULL );
        usleep( 5000 );  // wait a bit for the server to come up
        pthread_create( &b, NULL, startClient, NULL );

        pthread_join( a, NULL );
        pthread_join( b, NULL );
}