/*
 * testll.c	Matt Bishop	November 20, 1996
 *
 * This program reads commands and integers from the standard input
 * and manipulates the linked list accordingly.
 *
 * Modification history:
 *	11/20/96	Matt Bishop	original
 */
#include <stdio.h>
#include "llist.h"

/*
 * macro
 */
#define SZ_BUF 1024		/* size of the input buffer */

/*
 * function prototypes
 */
int insert(LLIST **, int);		/* insertion function */
int delete(LLIST **, int);		/* deletion function */
void prforw(LLIST *);			/* print function */
void prback(LLIST *);			/* print in reverse function */

/*
 * This does the obvious -- read commands and add to or delete from
 * the list using the linked list functions
 */
void main(void)
{
	LLIST *head = L_NULL;		/* head of linked list */
	char buf[SZ_BUF];		/* input buffer */
	int sv;				/* number of parts of comand read */
	int i;				/* number to operate on */
	char c;				/* the command */

	/*
	 * loop as long as the user throws input at us
	 */
	while(printf("> "), fgets(buf, SZ_BUF, stdin) != NULL){
		/*
		 * read command
		 */
		sv = sscanf(buf, "%c %d\n", &c, &i);
		/*
		 * process the command
		 */
		switch(c){
		case 'i':			/* insert an element */
			if (sv != 2)
				printf("need an integer; type 'h' for help\n");
			else if (insert(&head, i) == 0)
				printf("insertion failed!\n");
			break;
		case 'd':			/* delete an element */
			if (sv != 2)
				printf("need an integer; type 'h' for help\n");
			else if (delete(&head, i) == 0)
				printf("%d not in list!\n", i);
			break;
		case 'h':			/* help */
			printf("Commands are:\n");
			printf("\td <integer> delete <integer> from list\n");
			printf("\th           print help message\n");
			printf("\ti <integer> insert <integer> into list\n");
			printf("\tp           print list in order\n");
			printf("\tr           print list in reverseorder\n");
			printf("Command must be first char of input line\n");
			break;
		case 'p':			/* print */
			(void) prforw(head);
			break;
		case 'r':			/* print backwards */
			(void) prback(head);
			break;
		default:			/* ??? */
			printf("unknown command '%c'\n", c);
			printf("for help type 'h'\n");
			break;
		}
	}
	/*
	 * say goodbye gracefully
	 */
	exit(0);
}