#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/socket.h> 
#include<netdb.h>
#include "sockets.h"

/*Input: accepts port number to use as a command line arguement when
* program is first run
* Output: NONE
* Return: NONE
* Notes: Main method to use socket and file descriptor i/o library to
* start a very simple to client chat server
*/
int main ( int argc, char ** argv )
{
    /*initializes all variables*/
    int listen_sd;
    int io_sd1;
    int io_sd2;
    struct protoent * p_ptr;
    struct sockaddr_in  serv;
    struct sockaddr_in  client1;
    struct sockaddr_in  client2;
    socklen_t cli_length1 = sizeof( struct sockaddr_in );
    socklen_t cli_length2 = sizeof( struct sockaddr_in );
    int port_num = 17835;
    int rc;
    int tmp;
    char buf1[80];
    char buf2[80];
    int check = 0;

    /*if port was specified at command line, this block sets it to
    * port_num
    */
    if ( argc > 1 )
    {
        port_num = atoi( argv[1] );
    }

    p_ptr = getprotobyname( "tcp" );

    /* calls _socket function*/
    listen_sd = _socket( p_ptr , &listen_sd);

    /*checks if call to socket failed, and exits if it did fail*/
    if ( -1 == listen_sd )
    {
        fprintf ( stderr, "socket failed\n" );
        exit(1);
    }

    /*sets up sockaddr for server*/
    serv.sin_family = PF_INET;
    serv.sin_port = htons( port_num );
    serv.sin_addr.s_addr = htonl( INADDR_ANY );

    /* calls to _bind function*/
    rc = _bind( serv , &rc , &listen_sd);

    
    /*checks if call to bind failed, and exits if it did fail*/
    if ( -1 == rc )
    {
        fprintf ( stderr, "bind failed\n" );
        exit(2);
    }

    /* calls to _listen function */
    rc = _listen( &listen_sd , &rc );

    /*checks if call to listen failed, and exits if it did fail*/
    if ( -1 == rc )
    {
        fprintf ( stderr, "listen failed\n" );
        exit(4);
    }

    /* accept once per connection */ 
    io_sd1 = _accept ( &listen_sd, &io_sd1, client1, cli_length1 );
    io_sd2 = _accept ( &listen_sd, &io_sd2, client2, cli_length2 );

    /*checks if call to accept failed, and exits if it did fail*/
    if ( -1 == io_sd1 || -1 == io_sd2 )
    {
        fprintf ( stderr, "accept failed\n" );
        exit(8);
    }

    /*do/while loop to handle communication back and forth between
    * clients
    */
    do
    {
        /*calls read from client1*/
        tmp = _read ( &io_sd1 , buf1 );

        /*checks if call to read failed, and exits if it did fail*/
        if ( tmp == -1 )
        {
            fprintf ( stderr, "read failed\n" );
            exit(16);
        }

        /*finds length of input read*/
        tmp = strlen( buf1 );

        /*checks if client entered 'quit' and informs other client, and
        * sets condition to end loop if 'quit' was entered
        */
        if (((buf1[0]=='Q' || buf1[0]=='q') && (buf1[1]=='U' || buf1[1]=='u') &&
            (buf1[2]=='I' || buf1[2]=='i') && (buf1[3]=='T' ||
                buf1[3]=='t')))
        {
            check = 1;
            sprintf(buf1, "connection closed\n");
        }
        
        /*writes to client2's display*/
        _write( &io_sd2 , buf1 , &tmp );


        /*if client1 entered 'quit', nothing is read from client2*/
        if ( check == 1 )
        {

        }
        else
        {
            /*calls read from client2*/
            tmp = _read ( &io_sd2 , buf2 );

            /*checks if call to read failed, and exits if it did fail*/
            if ( tmp == -1 )
            {
                fprintf ( stderr, "read failed\n" );
                exit(16);
            }
    
            /*finds length of input read*/
            tmp = strlen( buf2 );

            /*checks if client entered 'quit' and informs other client, and
            * sets condition to end loop if 'quit' was entered
            */
            if (((buf2[0]=='Q' || buf2[0]=='q') && (buf2[1]=='U' || 
                            buf2[1]=='u') && (buf2[2]=='I' || buf2[2]=='i') && 
                            (buf2[3]=='T' || buf2[3]=='t')))
            {
                check = 1;
                sprintf(buf1, "connection closed\n");
            }
        
            /*writes to client2's display*/
            _write( &io_sd1 , buf2 , &tmp );

        }
    } while ( check != 1 );

    /* close the file descriptors */
    close( io_sd1 );
    close( io_sd2 );
    close( listen_sd );

    return 0;
}