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

linked_list *get_head(linked_list *node) {
	linked_list *head;
	for (head = node; head != NULL && head->prev != NULL; head = head->prev);
	return head;
}

linked_list *get_tail(linked_list *node) {
	linked_list *tail;
	for (tail = node; tail != NULL && tail->next != NULL; tail = tail->next);
	return tail;
}

linked_list *add_node(linked_list **tail, void *data) {
	if (tail == NULL) {
		return NULL;
	} else {
		linked_list *node = calloc(1, sizeof(linked_list));
		if (node == NULL) {
			return NULL;
		} else {
			node->next = NULL;
			node->data = data;

			if (*tail == NULL) {
				node->prev = NULL;
				*tail = node;
			} else {
				(*tail)->next = node;
				node->prev = *tail;
			}

			return node;
		}
	}
}

void remove_node(linked_list *node) {
	if (node != NULL) {
		if (node->prev != NULL) {
			node->prev->next = node->next;
		}

		if (node->next != NULL) {
			node->next->prev = node->prev;
		}

		free(node);
	}
}

void cleanup_linked_list(linked_list *node) {
	if (node != NULL) {
		for (node = get_tail(node); node != NULL; node = node->prev) {
			if (node->next != NULL) {
				remove_node(node->next);
			}
		}
		remove_node(node);
	}
}

void **linked_list_to_array(linked_list *node) {
	void **arr = calloc(linked_list_size(get_tail(node))+1, sizeof(void *));
	int i = 0;

	for (linked_list *n = get_head(node); n != NULL; n = n->next, ++i) {
		arr[i] = n->data;
	}

	arr[i] = NULL;

	return arr;
}

int linked_list_size(linked_list *tail) {
	int i = 0;
	for (linked_list *node = tail; node != NULL; node = node->prev, ++i);
	return i;
}