/**
 * list1.c
 *   One wrapped implementation of lists.
 */

// +---------+--------------------------------------------------------
// | Headers |
// +---------+

#include <stdio.h>
#include <stdlib.h>
#include "node.h"
#include "list.h"

#ifdef UNIT_TESTS
#include "utest.h"
#endif


// +-------+----------------------------------------------------------
// | Types |
// +-------+

struct list {
  struct node *head;    // The first element
  struct node *tail;    // The last element
  int size;             // The number of elements
};


// +---------+--------------------------------------------------------
// | Globals |
// +---------+

#ifdef UNIT_TESTS
static int errors;
#endif


// +-----------------+------------------------------------------------
// | Basic Functions |
// +-----------------+

struct list *new_list ()
{
  struct list *result;
  result = malloc (sizeof (struct list));
  if (result != NULL)
    {
      result->head = NULL;
      result->tail = NULL;
    }
  return result;
} // new_list

char *
list_first (struct list *lst)
{
  if (lst->head == NULL)
    return NULL;
  else
    return lst->head->data;
} // list_first

char *
list_last (struct list *lst)
{
  if (lst->tail == NULL)
    return NULL;
  else
    return lst->tail->data;
} // list_last

int 
list_length (struct list *lst)
{
  return lst->size;
} // list_length

void
list_print (struct list *lst, FILE *fp)
{
  np_print (lst->head, fp);
} // list_print

int 
list_append (struct list *lst, char *str)
{
  struct node *newnode = cons (str, NULL);
  if (newnode == NULL)
    return 0;
  if (lst->size == 0)
    {
      lst->head = newnode;
      lst->tail = newnode;
    }
  else
    {
      set_cdr (lst->tail, newnode);
      lst->tail = newnode;
    }
  ++(lst->size);
  return 1;
} // list_append

int 
list_prepend (struct list *lst, char *str)
{
  struct node *newnode = cons (str, lst->head);
  if (newnode == NULL)
    return 0;
  lst->head = newnode;
  if (lst->size == 0)
    lst->tail = newnode;
  ++(lst->size);
  return 1;
} // list_prepend

int
list_delete (struct list *lst, char *str)
{
  lst->head = np_delete (lst->head, str);
  if (lst->head == NULL)
    lst->tail = NULL;
  return 0;
} // list_delete


// +------------+-----------------------------------------------------
// | Unit Tests |
// +------------+

#ifdef UNIT_TESTS
int
main ()
{
  struct node *np = NULL;

  CHECK_INT (is_null (np), 1);

  fprintf (stderr, "%d errors encountered.\n", errors);
  return errors;
} // main
#endif // UNIT_TESTS