#include "LinkedList.h"
#include <stdlib.h>

LinkedList *linkedlist_new(void) {
    LinkedList *ll = malloc(sizeof(LinkedList));
    if (!ll) return NULL;

    ll->head = NULL;
    ll->tail = NULL;
    ll->size = 0;

    return ll;
}

void linkedlist_delete(LinkedList *ll) {
    LinkedListNode *node = ll->head;
    LinkedListNode *next;

    while (node) {
        next = node->next;
        free(node);
        node = next;
    }

    free(ll);
}

LinkedListNode *linkedlist_append(LinkedList *ll, void *elem) {
    LinkedListNode *new_node = malloc(sizeof(LinkedListNode));
    if (!new_node) return NULL;

    new_node->data = elem;
    new_node->next = NULL;
    if (!ll->head) {
        new_node->prev = NULL;
        ll->head = new_node;
        ll->tail = new_node;
    } else {
        ll->tail->next = new_node;
        new_node->prev = ll->tail;
        ll->tail = new_node;
    }

    ll->size++;
    return new_node;
}

void *linkedlist_popfront(LinkedList *ll) {
    if (!ll->head) return NULL;

    void *elem = ll->head->data;
    LinkedListNode *node = ll->head;
    ll->head = ll->head->next;

    ll->size--;
    free(node);
    return elem;
}

LinkedListNode *linkedlist_find(LinkedList *ll, void *elem) {
    if (!ll->head) return NULL;

    LinkedListNode *node = ll->head;
    while (node) {
        /* !NOTE should use a given comparator function
         * instead of '==' operator */
        if (node->data == elem) return node;
        node = node->next;
    }

    return NULL; // Couldn't find the element
}

void *linkedlist_remove(LinkedList *ll, LinkedListNode *node) {
    void *elem = node->data;

    if (node->prev) node->prev->next = node->next;
    else ll->head = node->next;

    if (node->next) node->next->prev = node->prev;
    else ll->tail = node->prev;

    free(node);
    ll->size--;
    return elem;
}