/*
 * definition of functions in sorted-int-list.h
 *
 * implemented using recursion (for fun?)
 */
#include "sorted-int-list.h"

static sorted_int_list_node_t * insert_helper(
		sorted_int_list_node_t * lst, 
		sorted_int_list_node_t * newnode)
{
	if (lst == NULL) {
		return newnode;
	}
	else if (newnode->data < lst->data) {
		newnode->next = lst;
		return newnode;
	}
	else {
		lst->next = insert_helper(lst->next, newnode);
		return lst;
	}
}

/*
 * insert n into list and return updated list 
 */
sorted_int_list_node_t * sorted_int_list_insert(
		sorted_int_list_node_t * lst, int n) 
{
	sorted_int_list_node_t * newnode = malloc(sizeof *newnode);
	if (newnode == NULL) {
		puts("could not get memory");
		exit(1);
	}
	newnode->data = n;
	newnode->next = NULL;
	return insert_helper(lst, newnode);
}

/* 
 * count occurrences of n in list
 */
int sorted_int_list_count(sorted_int_list_node_t * lst, int n) {
	if (lst == NULL) {
		return 0;
	}
	else if (n < lst->data) {
		return 0;
	}
	else if (n == lst->data) {
		return 1 + sorted_int_list_count(lst->next, n);
	}
	else {
		return sorted_int_list_count(lst->next, n);
	}
}

/* 
 * remove all occurrences of n from list and return updated list
 */
sorted_int_list_node_t * sorted_int_list_remove(
		sorted_int_list_node_t * lst, int n)
{
	if (lst == NULL) {
		return NULL;
	}
	else if (n < lst->data) {
		return lst;
	}
	else if (n == lst->data) {
		sorted_int_list_node_t * newlist =
			sorted_int_list_remove(lst->next, n);
		free(lst);
		return newlist;
	}
	else {
		lst->next = sorted_int_list_remove(lst->next, n);
		return lst;
	}
}

/*
 * remove all nodes from list and return NULL
 */
sorted_int_list_node_t * sorted_int_list_remove_all(
		sorted_int_list_node_t * lst) 
{
	if (lst != NULL) {
		sorted_int_list_remove_all(lst->next);
		free(lst);
	}
	return NULL;
}

/*
 * print all elements of lst to output stream f using format fmt
 * ("fmt" is the kind of string expected by fprintf, e.g., "%d " or "%d\n")
 *
 * the FILE * parameter lets the caller decide whether to print
 *   to stdout or a file (already open) or what
 * the fmt parameter lets the caller decide whether to print all on 
 *   one line or each on a separate line or what
 */
void sorted_int_list_print(sorted_int_list_node_t * lst, FILE * f, char * fmt)
{
	if (lst != NULL) {
		/* print this item */
		fprintf(f, fmt, lst->data);
		/* print rest */
		sorted_int_list_print(lst->next , f, fmt);
	}
}