#include "llist.h"
#include <stdlib.h>
#include <string.h>

/* create new linked list
 * use llistFree after use
 * retturns NULL on failure
 * otherwise newNode with data as content and cmpFN to compare data
 * only use to initialize
 * To insert into list use llistAppend
 */
llist *llistNew(void *data, int (*cmpFN)(const void *a, const void *b)) {
  llist *r = (llist *)malloc(sizeof(llist));
  if (r != NULL) {
    r->cmpFn = cmpFN;
    r->data = data;
    r->prev = NULL;
    r->next = NULL;
    r->tail = r;
  }
  return r;
}

/*return  last node of linked list;
 */
llist *llistTail(llist *head) {
  // llist *tail = head;
  // while (tail->next != NULL) {
  //   tail = tail->next;
  // }
  return head->tail;
}

/* creates new node from data and appends it to tail
 *
 */
llist *llistAppend(llist *head, void *data) {
  llist *new = llistNew(data, head->cmpFn);
  if (new != NULL) {
    llist *tail = llistTail(head);
    new->data = data;
    new->next = NULL;
    new->prev = tail;
    tail->next = new;
    head->tail = new;
  }
  return new;
}

/*
 * return Node containing key or NULL
 */
llist *llistGet(llist *head, void *key) {
  llist *c = head;
  while (c != NULL) {
    if (head->cmpFn(c->data, key) == 0) {

      return c;
    }
    c = c->next;
  }
  return NULL;
}

bool llistContains(llist *head, void *key) {
  return llistGet(head, key) != NULL;
}
void llistFree(llist *head) {
  while (head != NULL) {
    llist *tmp = head->next;
    free(head);
    head = tmp;
  }
}
/*
 * get linked list length
 */
int llistLen(llist *head) {
  int len = 0;
  llist *c = head;
  while (c != NULL) {
    len += 1;
    c = c->next;
  }
  return len;
}