#include "unp.h"


int main(int argc, char *argv[])
{
    int     listenfd, confd, sockfd, maxfd, maxi, i;
    int     nready, client[FD_SETSIZE];
    ssize_t n;
    fd_set  rset, allset;
    char    buf[MAXLINE];
    socklen_t clilen;
    struct sockaddr_in cliaddr, servaddr;

    listenfd = Socket(AF_INET, SOCK_STREAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(SERV_PORT);

    Bind(listenfd, (SA *)&servaddr, sizeof(servaddr));

    Listen(listenfd, LISTENQ);

    maxfd = listenfd; // initalize
    maxi = -1;        // index into client[] array
    for(i = 0; i<FD_SETSIZE; i++)
        client[i] = -1; // -1 indicates available entry
    FD_ZERO(&allset);
    FD_SET(listenfd, &allset);

    for(;;) {
        rset = allset; // structure assignment 
        nready = Select(maxfd+1, &rset, NULL, NULL, NULL);

        if(FD_ISSET(listenfd, &rset)) { // new client connection 
            clilen = sizeof(cliaddr);
            confd = Accept(listenfd, (SA *) &cliaddr, &clilen);
        
            for ( i = 0; i < FD_SETSIZE; i++)
                if(client[i] < 0) {
                    client[i] = confd; // save descriptor
                    break;
                }
            if( i == FD_SETSIZE)
                err_quit("too many clients");

            FD_SET(confd, &allset); // add  new descriptor to set
            if(confd > maxfd)
                maxfd = confd; // for select
            if( i > maxi) 
                maxi = i;       // max index in client[] array

            if(--nready <= 0)
                continue;       // no more readable descriptor
        }

        for(i = 0; i <= maxi; i++) { // check all clients for data 
            if((sockfd = client[i]) < 0)
                continue;
            if(FD_ISSET(sockfd, &rset)) {
                if( (n = Read(sockfd, buf, MAXLINE)) == 0) { 
                    // connection closed by client
                    Close(sockfd);
                    FD_CLR(sockfd, &allset);
                    client[i] = -1;

                } else {
                    Writen(sockfd, buf, n);
                }

                if(--nready <= 0) 
                    break; // no more readable descriptors
            }
        }
    }

}