/* MASTERMIND by Ernst Schwartz, 0004444*/




#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <string.h>
#include <ctype.h>


#define MAXCHAR 5


const char *szCommand = "<not yet set>";
static int pipe_father2son[2];
static int pipe_son2father[2];
static FILE *stream_father2son = (FILE *) 0;
static FILE *stream_son2father = (FILE *) 0;
int status;
pid_t pid;
pid_t wpid;




void BailOut(const char *szMessage);
void FreeRessources(void);


/* GENERATES RANDOM 4-DIGIT NUMBER & STORES IT IN AN CHAR-ARRAY */


char *GenerateRandom(void)
{
    static char random_number[MAXCHAR];


    srand(time(NULL)*rand());
    (void) sprintf(random_number, "%04d\0", rand()%10000);


    return random_number;

}


/* COMPARES 2 NUMBERS AND RETURNS THE POINTS & X */


char *CompareNumbers(char *number1, char *number2)
{
    int i;
    int j;
    int anzahl_X;	/* Ziffern vorhanden, aber an der falschen Stelle */
    int anzahl_Punkte; 	/* Ziffern an der richtigen Stelle */


    char *result = "\0";


    i = j = anzahl_X = anzahl_Punkte = 0;


    /* printf("%s vs. %s\n", number1, number2); */




    while(i<(MAXCHAR-1))
    {
	while(j<(MAXCHAR-1))
	{


	    if(number1[i] == number2[j])
	    {
	    	if(i==j)
	    	{
	    	    anzahl_X++;
		    /* printf("%d - %d, %c - %c: X: %d\n", i, j, number1[i], number2[j], anzahl_X); */
	    	} else
	    	{
	    	    anzahl_Punkte++;
		    /* printf("%d - %d, %c - %c: Punkte: %d\n", i, j, number1[i], number2[j], anzahl_Punkte); */
	    	}

		number2[j] = 'X';


		/* printf("number1: %s, number2: %s\n", number1, number2); */


		break;


	    }
	    j++;
	}    	
 	i++;   
	j=0;   	
    }


    if (anzahl_X == 4)
	(void) sprintf(result, "Du hast meine Zahl erraten!\n");
    else    	
        (void) sprintf(result, "X = %d, Punkte = %d\n", anzahl_X, anzahl_Punkte);


    return(result);


}


/* CHECKS IF INPUT IS CORRECT (only digits, not too short) */


int CheckInput(char *text)
{
    int i = 0;


    do 
    {
	if(!isdigit(text[i]) && text[i] != '\0')
    	    return 1;


    } while (text[i++] != '\0');


    return 0;


}


/* HOW TO USE THIS PROGRAM */


void Usage(void)
{
 	(void) fprintf(stderr, "USAGE: %s\n", szCommand);

 	BailOut((const char *) 0);
}


/* PRINTS ERROR-MESSAGES */


void BailOut(const char *szMessage)
{
    if (szMessage != (const char *) 0)
	(void) fprintf(stderr, "%s", szMessage);


    exit(EXIT_FAILURE);


}


/* THE CHILD PROCESS; GENERATES RANDOM NUMBER & COMPARES IT TO WHAT IT GETS FROM THE FATHER */
/* RETURNS THE RESULT TO THE FATHER */


void ChildProcess(void)
{
    char *number, *number_tmp = "\0";
    char buffer[MAXCHAR];
    char *result;
    number = GenerateRandom();


    (void) printf("CHILD: created number %s\n", number);


    if (close(pipe_father2son[1]) == -1)
    {
	BailOut("Error closing the write descriptor father -> son!");
    }


    /* printf("CHILD (134): CLOSED WRITE DESCRIPTOR father -> son.\n"); */

    if ((stream_father2son = fdopen(pipe_father2son[0], "r")) == (FILE *) NULL)
    {
	BailOut("Cannot open pipe father -> son for reading!");
    }


    /* printf("CHILD (141): OPENED PIPE father -> son FOR READING.\n"); */


    if (close(pipe_son2father[0]) == -1)
    {
	BailOut("Error closing the read descriptor son -> father!");
    }


    /* printf("CHILD (169): CLOSED READ DESCRIPTOR son -> father.\n"); */


	
    if ((stream_son2father = fdopen(pipe_son2father[1], "w")) == (FILE *) NULL)
    {
	BailOut("Cannot open pipe son -> father for writing!");
    }


    /* printf("CHILD (177): OPENED PIPE son -> father FOR WRITING.\n"); */


/* NOW READING FROM FATHER ! */


do {


    (void) strncpy(number_tmp, number, sizeof(number));
 
    /* printf("ANFANG: %s\n", number); */




    if (fgets(buffer, MAXCHAR, stream_father2son) == NULL)
    {
	BailOut("Can't read from stream father -> son!");
    }


    /* printf("CHILD (148): READ FROM PIPE father -> son.\n"); */


    /* printf("VOR COMPARE: %s vs. %s\n", number, buffer); */


    result = CompareNumbers(number_tmp, buffer);


    /* printf("NACH COMPARE: %s vs. %s\n", number, buffer); */


    /* printf("CHILD: FUNCTION RETURNED: %s\n", result); */


    /* printf("CHILD (158): CHECKED RESULT.\n"); */






/* NOW WRITING TO FATHER ! */




    if (fprintf(stream_son2father, result) < 0)
    {
	BailOut("Cannot write to pipe son -> father!");
    }


    /* printf("CHILD (185): WROTE TO PIPE son -> father.\n"); */


			
    if (fflush(stream_son2father) == EOF)
    {
	BailOut("Cannot flush pipe son -> father!");
    }


    /* printf("CHILD (193): FLUSHED PIPE son -> father.\n"); */


    if(result[0] == 'D')
    	break;


    /* printf("ENDE: %s\n", number); */




} while (1);


    FreeRessources();


    /* printf("CHILD (205): FREE'D RESSOURCES.\n"); */


    exit(EXIT_SUCCESS);


}


/* FATHER PROCESS; GETS USER INPUT, SENDS IT TO CHILD, RECEIVES RESULTS FROM CHILD */
/* AND PRINTS THEM ON stdout */


void FatherProcess(void)
{
    char input[MAXCHAR];
    char result[1024];
    result[0] = '\0';


    if (close(pipe_father2son[0]) == -1)
    {
	BailOut("Error closing the read descriptor father -> son!");
    }


    /* printf("PARENT (227): CLOSED READ DESCRIPTOR father -> son.\n"); */


    if ((stream_father2son = fdopen(pipe_father2son[1], "w")) == (FILE *) NULL)
    {
	BailOut("Cannot open pipe father -> son for writing!");
    }


    /* printf("PARENT (235): OPENED PIPE father -> son FOR WRITING.\n"); */

    if (close(pipe_son2father[1]) == -1)
    {
	BailOut("Error closing the write descriptor son -> father!");
    }


    /* printf("PARENT (261): CLOSED WRITE DESCRIPTOR son -> father.\n"); */


		
    if ((stream_son2father = fdopen(pipe_son2father[0], "r")) == (FILE *) NULL)
    {
	BailOut("Cannot open pipe son -> father for reading!");
    }


    /* printf("PARENT (269): OPENED PIPE son -> father FOR READING.\n"); */


while (result[0] != 'D')
{


    result[0] = '\0';


    do 
    {
    	input[0] = '\0';



    	(void) printf("PARENT: Write something: "); 


    	if (fgets(input, MAXCHAR, stdin) == NULL)
    	{
    	    BailOut("Couldn't read from stdin!");
    	}

    	if (fflush(stdin) == EOF)
    	{
    	    BailOut("Couldn't flush stdin!");	
    	}


    	if(CheckInput(input) == 1)
    	{
    	    (void) printf("%s: Bad bad input!\n", input);
	    continue;
    	}


	break;


    } while(1);




/* NOW WRITING TO SON ! */


	
    if (fprintf(stream_father2son, input) < 0)
    {
	BailOut("Can't write to pipe father -> son!");	
    }


    /* printf("PARENT (243): WROTE TO PIPE father -> son.\n"); */




    if(fflush(stream_father2son) == EOF)
    {
    	BailOut("Can't flush stream father -> son");
    }


    /* printf("PARENT (251): FLUSHED STREAM father -> son.\n"); */




/* NOW READING FROM SON ! */




    if (fgets(result, 1024, stream_son2father) == NULL)
    {
	BailOut("Can't read from stream son -> father!");
    }


    /* printf("PARENT (277): READ FROM PIPE son -> father.\n"); */


    (void) printf("%s", result);


}


    FreeRessources();


    /* printf("PARENT (282): FREE'D RESSOURCES.\n"); */

}


/* MAKES THE PIPES */


void AllocateRessources(void)
{
    if (pipe(pipe_father2son) == -1)
	BailOut("Cannot create pipe father -> son!");		
    if (pipe(pipe_son2father) == -1)
	BailOut("Cannot create pipe son -> father!");		
}


/* CLOSES THE STREAMS */


void FreeRessources(void)
{
	if (stream_father2son != (FILE *) 0)
	{
		if (fclose((FILE *) stream_father2son) == EOF)
		{
			stream_father2son = (FILE *) 0;
			BailOut("Cannot close pipestream!");
		}	
		stream_father2son = (FILE *) 0;	
	}

	if (stream_son2father != (FILE *) 0)
	{
		if (fclose((FILE *) stream_son2father) == EOF)
		{
			stream_son2father = (FILE *) 0;
			BailOut("Cannot close pipestream!");
		}	
		stream_son2father = (FILE *) 0;	
	}

}


/* MAIN METHOD; FORKS CHILD, PLAYS GAME, WAITS FOR CHILD TO EXIT, THEN EXITS */


int main(int argc, char *argv[])
{


    szCommand = argv[0];

    if (argc != 1)
    {
	Usage();
    }


    AllocateRessources();


    switch(pid=fork()) 
    {
        case -1:
            perror("fork");  /* something went wrong */
            exit(1);         /* parent exits */


        case 0:
	    ChildProcess();


        default:
	    (void) printf("%s\n", "== MASTERMIND ==");


	    FatherProcess();


	    while ((wpid = wait(&status)) != pid)
	    {
		if (wpid != -1)
		{
		    continue;
		}

		if (errno == EINTR)
		{
		    continue;
		}

		BailOut("Error waiting for child process!"); 	

    	    }


    }


	exit(EXIT_SUCCESS);




}