#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>

#define MAXSIZE 10

int main(int argc, char *argv[])
{
    int i;
    int p2c[2];
    int child2p[2];
    int val = 0;
    int val2 = 0;
    int threecount = 0;
    int fivecount = 0;

    // create pipe descriptors
    pipe(p2c);
    pipe(child2p);

    // fork() returns 0 for child process, child-pid for parent process.
    if (fork() != 0)
    {
        // parent: writing only, so close read-descriptor.
        close(p2c[0]);
        // parent: reading only, so close write descriptor
        close(child2p[1]);
        for(i = 0; i < MAXSIZE; i++)
        {
            // send the value on the write-descriptor to the child.
            if(i % 5 == 0)
            {
                fivecount++;

            }
            else
            {
                write(p2c[1],&i, sizeof(i));
                printf("Parent(%d) send value: %d\n", getpid(), i);

            }
        }
            // read from the child



        // close the write descriptor
        close(p2c[1]);
        read(child2p[0], &threecount,sizeof(threecount));
            printf("Parent(%d) received value: %d for threecount and has %d for fivecount.\n", getpid(), threecount, fivecount);

        wait();

        // close the read descriptor from the child
        close(child2p[0]);
    }
    else
    {   // child: reading only, so close the write-descriptor
        close(p2c[1]);
        // child: writing only, so close the read descriptor
        close(child2p[0]);

        // now read the data from parent(will block)
        while (read(p2c[0], &i, sizeof(i))){
            printf("Child(%d) received value: %d\n", getpid(), i);
            if(i % 3 == 0)
            {
            threecount++;
            }
        }

        // send to the
        write(child2p[1], &threecount, sizeof(threecount));
        printf("Child(%d) sendvalue: %d\n", getpid(), threecount);


        // close the read-descriptor
        close(p2c[0]);
        // close the write-descriptor
        close(child2p[1]);
    }
    return 0;
}