#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include "assert.h"

struct list_node {
  int data;
  struct list_node *next;
};
typedef struct list_node list_node_t;

int list_length(list_node_t * list) {
  list_node_t *cur;
  int count = 0;

  cur = list;
  while (cur != NULL) {
    count++;
    cur = cur->next;
  }

  return count;
}

bool list_empty(list_node_t *list) {
  return (list == NULL);
}

void list_print(list_node_t * list) {
  list_node_t *cur;

  cur = list;
  while (cur != NULL) {
    printf("%d ", cur->data);
    cur = cur->next;
  }
  printf("\n");
}

void list_add(list_node_t *list, list_node_t *item) {
  list_node_t *cur;

  cur = list;
  assert(cur != NULL);
  while (cur->next != NULL) {
    cur = cur->next;
  }

  cur->next = item;
}

int main(int argc, char *argv[]) {
  list_node_t *emptylist = NULL;
  assert(list_length(emptylist) == 0);
  assert(list_empty(emptylist) == true);
  list_print(emptylist);
  printf("list_length = %d\n", list_length(emptylist));

  list_node_t foo = { 1, NULL };

  assert(list_length(&foo) == 1);
  assert(list_empty(&foo) == false);
  list_print(&foo);
  printf("list_length = %d\n", list_length(&foo));

  // append something to foo
  list_node_t bar = { 2, NULL };
  list_add(&foo, &bar);

  assert(list_length(&foo) == 2);
  assert(list_length(&bar) == 1);
  list_print(&foo);
  printf("list_length = %d\n", list_length(&foo));

  // append more
  const int howmany = 100;
  for(int i = 0; i < howmany; i++) {
    list_node_t *newnode = malloc(sizeof(list_node_t));
    newnode->data = i;

    list_add(&foo, newnode);
  }
  assert(list_length(&foo) == 2 + howmany);
  list_print(&foo);
  printf("list_length = %d\n", list_length(&foo));
}