/*****************************************************************************
* File:	     	linklist.c
* Programmer: 	Dorian Winterfeld
* 		Anne Raugh
* Institution:  PDS/Small Bodies Node
*               University of Maryland
* Abstract: 	implementation of a linked list
*****************************************************************************/

#include <stdlib.h>
#include <string.h>
#include "linklist.h"
#include "pdserror.h"

list_type *list_create(){
  list_type *l;

  l = (list_type *)malloc(sizeof(list_type));

  if (l == NULL)
    return NULL;
  else {
    l->rear = NULL;
    l->head = NULL;
  }
  return l;
} /* end list_create */

void list_destroy(list_type *l){
/*  loop thru list, freeing all nodes */
	list_node *curr;
	list_node *tmp;

	curr = l->rear;
	while (curr != NULL) {
		tmp = curr->prev;  /* loop thru list, freeing nodes */
		free(curr->data);
		free(curr);
		curr = tmp;
	}
}

int list_empty(list_type *l){
/* is list empty ? */
	if (l->rear == NULL)
		return 1;
	else
		return 0;
}

/*
int remove(list_type *l, list_node *node){

	list_node *tmp1;
	list_node *tmp2;


	if ( l == NULL || l->rear == NULL || l->rear->data == NULL )
		return ERROR;

	if (node->next == NULL) l->rear = node->prev;
	tmp1 = node->prev;
	tmp2 = node->next;
	if (tmp1 != NULL) tmp1->next = tmp2;
	if (tmp2 != NULL) tmp2->prev = tmp1;
	free(node);

	return 1;
}
*/

int insert(list_type *l, char *item){
/* inserts at rear of list */
	list_node *tmp;
	int        len;

	tmp = l->rear;
	if (l->rear == NULL){  /* new list */
		l->rear = (list_node *)
			malloc(sizeof(list_node));
		if (l->rear == NULL)
			return MALLOC_ERROR;
		l->head = l->rear;
	}
	else {        /* add node to rear of list */
		l->rear->next = (list_node *)
			malloc(sizeof(list_node));
		if (l->rear->next == NULL)
			return MALLOC_ERROR;

		l->rear = l->rear->next;  /* update rear pntr */
	}
	l->rear->next = NULL;
	l->rear->prev = tmp;
	len = strlen(item);
	l->rear->data = (char *) malloc(len+1);
	if (l->rear->data == NULL)
		return MALLOC_ERROR;
	else
		strcpy(l->rear->data,item);

	return 1;
}