#include <stdio.h>
#include <stdlib.h>

#include "dlist.h"

struct dlist *dlist_init(void)
{
    struct dlist *res = malloc(sizeof(struct dlist));
    if (res == NULL)
        return NULL;

    res->size = 0;
    res->head = NULL;
    res->tail = NULL;
    return res;
}

int dlist_push_front(struct dlist *list, int element)
{
    if (element < 0)
        return 0;
    struct dlist_item *new = malloc(sizeof(struct dlist_item));
    if (new == NULL)
        return 0;

    new->data = element;
    new->next = list->head;
    new->prev = NULL;

    if (list->size == 0)
        list->tail = new;
    else
        list->head->prev = new;

    list->head = new;
    list->size++;

    return 1;
}

void dlist_print(const struct dlist *list)
{
    if (list->size == 0)
        return;

    for (struct dlist_item *i = list->head; i != list->tail; i = i->next)
    {
        printf("%d\n", i->data);
    }
    printf("%d\n", list->tail->data);
}

int dlist_push_back(struct dlist *list, int element)
{
    if (element < 0)
        return 0;
    struct dlist_item *new = malloc(sizeof(struct dlist_item));
    if (new == NULL)
        return 0;

    new->data = element;
    new->prev = list->tail;
    new->next = NULL;

    if (list->size == 0)
        list->head = new;
    else
        list->tail->next = new;
    list->tail = new;
    list->size++;

    return 1;
}

size_t dlist_size(const struct dlist *list)
{
    return list->size;
}