#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <libgen.h>
#include <stdlib.h>

#define FIFO_FILE1      ".fifo_chat1"
#define FIFO_FILE2      ".fifo_chat2"

int g_stop = 0;

void sig_pipe(int signum)
{
    if(SIGPIPE == signum)
    {
        printf("get pipe broken signal and let programe exit\n");
        g_stop = 1;
    }
}

int main(int argc, char **argv)
{
    int            fdr_fifo;
    int            fdw_fifo;
    int            rv;
    fd_set         rdset;
    char           buf[1024];
    int            mode = 0;
    char          *rd_fifo = NULL;
    char          *wr_fifo = NULL;

    if( argc != 2 )
    {
        printf("Usage: %s [0/1]\n", basename(argv[0]));
        printf("This chat program need run twice, 1st time run with [0] and 2nd time with [1]\n");
        return -1;
    }

    mode = atoi(argv[1]);

    if( 0 == mode )
    {
        rd_fifo = FIFO_FILE1;
        wr_fifo = FIFO_FILE2;
    }
    else
    {
        rd_fifo = FIFO_FILE2;
        wr_fifo = FIFO_FILE1;
    }

    if( access(FIFO_FILE1 , F_OK) )
    {
        printf("FIFO file \"%s\" not exist and create it now\n", FIFO_FILE1);
        mkfifo(FIFO_FILE1, 0666);
    }

    if( access(FIFO_FILE2 , F_OK) )
    {
        printf("FIFO file \"%s\" not exist and create it now\n", FIFO_FILE2);
        mkfifo(FIFO_FILE2, 0666);
    }

    signal(SIGPIPE, sig_pipe);

    if( 0 == mode )
    {
        printf("start open '%s' for read and it will blocked untill write endpoint opened...\n", rd_fifo);
        if( (fdr_fifo=open(rd_fifo, O_RDONLY)) < 0 )
        {
            printf("Open fifo[%s] for chat read endpoint failure: %s\n", rd_fifo, strerror(errno));
            return -1;
        } 
        
        printf("start open '%s' for write...\n", wr_fifo);
        if( (fdw_fifo=open(wr_fifo, O_WRONLY)) < 0 )
        {
            printf("Open fifo[%s] for chat write endpoint failure: %s\n", wr_fifo, strerror(errno));
            return -1;
        }
    }
    else
    {
        printf("start open '%s' for write and it will blocked untill read endpoint opened...\n", wr_fifo);
        if( (fdw_fifo=open(wr_fifo, O_WRONLY)) < 0 )
        {
            printf("Open fifo[%s] for chat write endpoint failure: %s\n", wr_fifo, strerror(errno));
            return -1;
        }

        printf("start open '%s' for read...\n", rd_fifo);
        if( (fdr_fifo=open(rd_fifo, O_RDONLY)) < 0 )
        {
            printf("Open fifo[%s] for chat read endpoint failure: %s\n", rd_fifo, strerror(errno));
            return -1;
        } 
    }

    printf("start chating with another program now, please input message now: \n");
    while( !g_stop )
    {
        FD_ZERO(&rdset);
        FD_SET(STDIN_FILENO, &rdset);
        FD_SET(fdr_fifo, &rdset);

        rv = select(fdr_fifo+1, &rdset, NULL, NULL, NULL); 
        if(  rv <= 0 )
        {
            printf("Select get timeout or error: %s\n", strerror(errno));
            continue;
        }

        /* get data arrive from FIFO */
        if( FD_ISSET(fdr_fifo, &rdset) )
        {
            memset(buf, 0, sizeof(buf));
            rv=read(fdr_fifo, buf, sizeof(buf));
            if( rv < 0)
            {
                printf("read data from FIFO get errorr: %s\n", strerror(errno));
                break;
            }
            else if( 0==rv )
            {
                printf("Another side of FIFO get closed and program will exit now\n");
                break;
            }

            printf("<-- %s", buf);
        }

        if( FD_ISSET(STDIN_FILENO, &rdset) )
        {
            memset(buf, 0, sizeof(buf));
            fgets(buf, sizeof(buf), stdin);
            write(fdw_fifo, buf, strlen(buf));
        }
    }
}