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

int main ()
{
	int pid;
	char c;
	int goodfd, badfd, infd;
	int pipefds[2];

	unlink ("pipe");
	if (mkfifo ("pipe", S_IRUSR | S_IWUSR) < 0) {
		perror ("mkfifo");
		exit (1);
	}
	infd = open ("pipe", O_RDONLY);
	if (infd < 0) {
		perror ("open");
		exit (1);
	}
	/* Create good child */
	if (pipe (pipefds) < 0) {
		perror ("pipe (good)");
		exit (1);
	}
	pid = fork ();
	if (pid < 0) {
		perror ("fork (good)");
		exit (1);
	}
	if (pid == 0) {   /* Good Child, first Element in pipe (sort) */
		/* Close write end of pipe and assign read end to stdin */
		close (pipefds[1]);
		close (0);
		dup (pipefds[0]);
		/* Close duplicate file descriptior */
		close (pipefds[0]);
		/* Create a new pipe for standard output */
		if (pipe (pipefds) < 0) {
			perror ("pipe");
			exit (1);
		}
		pid = fork ();
		if (pid < 0) {
			perror ("fork");
			exit (1);
		}
		if (pid) { /* Second Child (uniq) */
			/* Close write end of pipe and assign read end to
			 * stdin */
			close (pipefds[1]);
			close (0);
			dup (pipefds[0]);
			close (pipefds[0]);
			printf ("Hier Toepfchen:\n");
			execlp ("uniq", "uniq", "-c", NULL);
			perror ("execlp");
			exit (1);
		}

		/* Close read end of pipe */
		close (pipefds[0]);
		/* Assign write end of pipe to stdin */
		close (1);
		dup (pipefds[1]);
		close (pipefds[1]);
		execlp ("sort", NULL);
		perror ("execlp");
		exit (1);
	}
	close (pipefds[0]);
	goodfd = pipefds[1];

	/* Create Bad child */
	if (pipe (pipefds) < 0) {
		perror ("pipe (bad)");
		exit (1);
	}
	pid = fork ();
	if (pid < 0) {
		perror ("fork (bad)");
		exit (1);
	}
	if (pid == 0) {   /* Bad Child */
		int ret;
		int count = 0;
		/* Close write end of pipe and assign read end to infd */
		close (pipefds[1]);
		infd = pipefds[0];
		while (1) {
			ret = read (infd, &c, 1);
			if (ret == 0)  /* End of file */
				break;
			if (ret < 0) {
				perror ("Warning: read");
			}
			count ++;
		}
		printf ("Hier Kroepfchen: %d\n", count);
		exit (0);
	}
	close (pipefds[0]);
	badfd = pipefds[1];


	/* Main Program */
	while (1) {
		int ret;
		ret = read (infd, &c, 1);
		if (ret < 0) {
			perror ("Warning:  read");
			continue;
		}
		if (ret == 0) {
			close (infd);
			break;
		}
		if (strchr ("gutGUT", c)) {
			char buf[2];
			buf[0] = c; buf[1] = '\n';
			if (write (goodfd, buf, 2) < 0) {
				perror ("write");
			}
		} else if (strchr ("schlechtSCHLECHT", c)) {
			if (write (badfd, &c, 1) < 0) {
				perror ("write");
			}
		}
	}
	/* Signal end of file to children */
	close (goodfd);
	close (badfd);
	/* Wait for termination of children */
	wait (NULL);
	wait (NULL);
	return 0;
}