#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/epoll.h>
#include <pthread.h>


#define MYPORT 4894    // the port users will be connecting to
#define BACKLOG 32     // how many pending connections queue will hold
#define BUF_SIZE 1024


class CSelectServer
{
public:
    CSelectServer()
    {
    }

    ~CSelectServer()
    {
        stop();
    }    

    struct SHORT_SESSION 
    {
        int m_uClientSockfd;
        int m_uTimestamp;
    };
    
    bool start(int nPort)
    {
        int ret=0;

        do 
        {
            m_uListenPort=nPort;
            m_hListenSockfd= socket( PF_INET, SOCK_STREAM, 0 );
            if (m_hListenSockfd < 0)
            {
                break;
            }

            struct sockaddr_in address;
            bzero( &address, sizeof( address ) );
            address.sin_family = AF_INET;
            address.sin_port = htons( m_uListenPort );

            ret = bind( m_hListenSockfd, ( struct sockaddr* )&address, sizeof( address ) );
            if (ret < 0)
            {
                break;
            }

            ret = listen( m_hListenSockfd, BACKLOG );
            if (ret < 0)
            {
                break;
            }    

            m_hMaxSockfd=m_hListenSockfd;
            m_uConnAmount=0;
            for (int i=0;i<BACKLOG;++i)
            {
                m_nClientConns[i].m_uClientSockfd=-1;
                m_nClientConns[i].m_uTimestamp=0;
            }
            
            // timeout setting
            m_tvSelectDelay.tv_sec = 1;
            m_tvSelectDelay.tv_usec = 0;

            
            return true;
        } while (0);

        stop();
        return false;
    }

    void stop()
    {
        if (-1 != m_hListenSockfd)
        {
            close(m_hListenSockfd);
            m_hListenSockfd=-1;
        }
    }

    void serve_once()
    {    
        int ret,i;    
        int now=(int)time(NULL);

        FD_ZERO(&m_hReadfds);
        FD_SET(m_hListenSockfd, &m_hReadfds);

        for ( i = 0; i < BACKLOG; i++)
        {
            if (m_nClientConns[i].m_uClientSockfd<=2)
                continue;

            if (now>=m_nClientConns[i].m_uTimestamp+5) 
            {
                printf("kickoutDeadConnection sock:%d conn_amount:%d\n",m_nClientConns[i].m_uClientSockfd,m_uConnAmount);
                FD_CLR(m_nClientConns[i].m_uClientSockfd, &m_hReadfds);
                close(m_nClientConns[i].m_uClientSockfd);
                m_nClientConns[i].m_uClientSockfd=-1;
                m_uConnAmount--;
                continue;
            }

            FD_SET(m_nClientConns[i].m_uClientSockfd, &m_hReadfds);
        }

        ret = select(m_hMaxSockfd + 1, &m_hReadfds, NULL, NULL, &m_tvSelectDelay);
        if (ret < 0)
        {
            perror("select error\n");
            return;
        }
        
        if (ret == 0)
        {
            printf("select maxsock:%d timeout\n",m_hMaxSockfd);
            return;
        }

        // check whether a new connection comes
        if (FD_ISSET(m_hListenSockfd, &m_hReadfds))
        {
            printf("will accept\n");
            struct sockaddr_in client_address;
            socklen_t client_addrlength = sizeof( client_address );
            int new_fd = accept( m_hListenSockfd, ( struct sockaddr* )&client_address, &client_addrlength );
            if (new_fd <= 0)
            {
                perror("accept");
            }
            else
            {
                printf("accept sock:%d\n",new_fd);
                addConnection(new_fd);
            }
        }

        // check every fd in the set
        for ( i = 0; i < BACKLOG; i++)
        {
            if (-1==m_nClientConns[i].m_uClientSockfd)
                continue;

            if (FD_ISSET(m_nClientConns[i].m_uClientSockfd, &m_hReadfds)) 
            {
                printf("client[%d] will recv\n", m_nClientConns[i].m_uClientSockfd);

                ret = recv(m_nClientConns[i].m_uClientSockfd, m_szReadBuffer, sizeof(m_szReadBuffer), 0);
                if (ret <= 0) 
                {        
                    printf("delConnection sock:%d conn_amount:%d\n",m_nClientConns[i].m_uClientSockfd,m_uConnAmount);
                    FD_CLR(m_nClientConns[i].m_uClientSockfd, &m_hReadfds);
                    close(m_nClientConns[i].m_uClientSockfd);
                    m_nClientConns[i].m_uClientSockfd=-1;
                    m_uConnAmount--;
                } 
                else 
                { 
                    printf("client[%d] send:%s\n", m_nClientConns[i].m_uClientSockfd, m_szReadBuffer);
                    send(m_nClientConns[i].m_uClientSockfd,m_szReadBuffer,ret,0);
                }
            }
        }

    }
protected:
    bool addConnection(int client_fd)
    {
        do 
        {
            if (m_uConnAmount>=BACKLOG)
            {
                printf("addConnection over the limit \n");
                break;
            }

            int i;
            for ( i = 0; i < BACKLOG; i++) 
            {
                if (-1==m_nClientConns[i].m_uClientSockfd) 
                {
                    m_nClientConns[i].m_uClientSockfd=client_fd;
                    m_nClientConns[i].m_uTimestamp=(int)time(NULL);
                    m_uConnAmount++;
                    printf("addConnection  sock:%d conn_amount:%d \n",client_fd,m_uConnAmount);
                    if (client_fd>m_hMaxSockfd)
                    {
                        m_hMaxSockfd=client_fd;
                    }
                    return true;
                }
            }
            
            printf("addConnection system error\n");
        } while (0);

        return false;        
    }

    void delConnection(int client_fd)
    {
        int i;
        for ( i = 0; i < BACKLOG; i++) 
        {
            if (client_fd==m_nClientConns[i].m_uClientSockfd) 
            {
                FD_CLR(m_nClientConns[i].m_uClientSockfd, &m_hReadfds);
                close(m_nClientConns[i].m_uClientSockfd);
                m_nClientConns[i].m_uClientSockfd=-1;
                m_uConnAmount--;
                //printf("delConnection sock:%d conn_amount:%d\n",client_fd,m_uConnAmount);
                return ;
            }
        }
        //printf("delConnection system error\n");

    }

    void kickoutDeadConnection()
    {
        int now=(int)time(NULL);
        int i;
        for ( i = 0; i < BACKLOG; i++) 
        {
            if (-1==m_nClientConns[i].m_uClientSockfd) 
            {
                continue;
            }

            if (now>=m_nClientConns[i].m_uTimestamp+5) 
            {
                //printf("kickoutDeadConnection sock:%d conn_amount:%d\n",m_nClientConns[i].m_uClientSockfd,m_uConnAmount);
                FD_CLR(m_nClientConns[i].m_uClientSockfd, &m_hReadfds);
                close(m_nClientConns[i].m_uClientSockfd);
                m_nClientConns[i].m_uClientSockfd=-1;
                m_uConnAmount--;
            }

        }
    }

private:
    SHORT_SESSION    m_nClientConns[BACKLOG];
    char             m_szReadBuffer[BUF_SIZE];
    int                 m_uListenPort;
    int                 m_hListenSockfd;
    int                 m_uConnAmount;
    int                 m_hMaxSockfd;
    fd_set             m_hReadfds;
    struct timeval   m_tvSelectDelay;
    
};













int main( int argc, char* argv[] )
{
    if( argc <= 2 )
    {
        printf( "usage: %s ip_address port_number\n", basename( argv[0] ) );
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi( argv[2] );

    //CSimpleEpollServer  s;
    CSelectServer s;
    s.start(port);

    while (1)
    {
        s.serve_once();
        usleep(1000*1000);
    }
    

   
    return 0;
}