/* Prosty interpreter polece
 */
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include <sys/wait.h>
#include <sys/resource.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <fcntl.h>
          
#define INPUTSIZ        256
#define MAXPAR	20

int outfd = -1;
int readfd,dupfd,stderrfd;
char *filename;
pthread_mutex_t outfd_mutex = PTHREAD_MUTEX_INITIALIZER;

#define BUFSIZE 1024

void *checkth(void *arg){
//    fd_set fs;
    char buf[BUFSIZE];
    
    while (1) {
	
/*        FD_ZERO(&fs);
	FD_SET(readfd,&fs);
	if (select(readfd+1,&fs,0,0,0)!=1) 
	    continue;
*/	
	ssize_t ret = read(readfd,buf,BUFSIZE);
	if (ret > 0) {
	    write(0,buf,ret);
	    
	    pthread_mutex_lock(&outfd_mutex);
	    if (outfd !=-1)
		write(outfd,buf,ret);
	    pthread_mutex_unlock(&outfd_mutex);	
	}
    }
};

void doshell(char *cmd) {
	char *argv[MAXPAR+1];
	int argc=0, status;
        pid_t pid;
	struct rusage ru;
/* Dzielenie linii polecen na "wyrazy" */
	if((argv[argc]=strtok(cmd," \t\n"))==NULL) return;
	while(argv[argc] && argc<MAXPAR-1){
		argv[++argc]=strtok(NULL," \t\n");
	}
	
	if ((strcmp(argv[0],"kopia")==0)&& (argc == 2)) {
	    pthread_mutex_lock(&outfd_mutex);
	    
	    if (outfd!=-1) {
		close(outfd);
		free(filename);    
		outfd = -1;
	    }
	    
	    if (strcmp(argv[1],"NULL")==0)  {
	        pthread_mutex_unlock(&outfd_mutex);
		return;	
	    }
	
	    outfd = open(argv[1],O_WRONLY|O_CREAT|O_APPEND,S_IRUSR|S_IWUSR);
	    if (outfd == -1) 
		perror("kopia::open");
	    
	    filename = (char *)malloc(strlen(argv[1])+1);
	    if (!filename) {
		perror("malloc");
		exit (-1);
	    }
	    strcpy(filename,argv[1]);
	    
	    pthread_mutex_unlock(&outfd_mutex);

	    return;
	} else if (strcmp(argv[0],"kopia")==0) {
	    if (outfd==-1)
		fprintf(stderr,"kopiowane nie jest w uzyciu\n");
	    else
		fprintf(stderr,"kopiowane jest w uzyciu, nazwa pliku %s\n",filename);
	    
	    return;
	}
	
        if ( (pid = fork()) < 0) { 
		perror("Blad wywolania fork"); exit(2);
        }
        if (pid == 0) {
		
		if (dup2(dupfd,1)==-1) {
		    perror("child::stdout_dup2");
		    exit(-1);
		} else
		    close(dupfd);
	
		if (dup2(stderrfd,2)==-1) {
		    perror("child::stderr_dup2");
		    exit(-1);
		} else
		    close(stderrfd);
		    
                execvp(argv[0],argv);
                perror("Blad wywolania execvp"); exit(1);
        }
        while( (pid=wait3(&status,0,&ru))>0 ){
		if(WIFEXITED(status)){
			printf("Proces nr %d zakonczony z kodem wyjscia %d\n",
				pid,WEXITSTATUS(status));
		}
		if(WIFSIGNALED(status)){
			printf("Proces nr %d dostal sygnal nr %d\n",
				pid,WTERMSIG(status));
		}
		if(WIFSTOPPED(status)){
			printf("Proces nr %d zatrzymany przez sygnal nr %d\n",
				pid, WSTOPSIG(status));
		}
/* Tu mona doda kod wykorzystujcy informacje zawarte w strukturze ru
 * Opis pl struktury w: man getrusage
 */
	}
}
int main() {
        char buf[INPUTSIZ];
	int pipes[2];
	pthread_t tid;
	
	if (pipe(pipes)!=0) {
	    perror("pipe");
	    exit (-1);
	}
	
	readfd = pipes[0];
	dupfd = pipes[1];
	
	stderrfd = open("stderr.txt",O_WRONLY|O_CREAT|O_APPEND,S_IRUSR|S_IWUSR);
	if (stderrfd == -1) {
	    perror("stderr::open");
	    exit(-1);
	}
	
	
	if (pthread_create(&tid,0,checkth,0)!=0){
	    perror("pthread_create");
	    exit(-1);
	}
	
        printf("\n> ");
        while (fgets(buf, INPUTSIZ, stdin) != NULL) {
                doshell(buf);
                printf("\n> ");
        }
        exit(0);
}