---

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

struct node *init(struct door door) {
    struct node *new_node = (struct node *)malloc(sizeof(struct node));

    if (new_node != NULL) {
        new_node->door = door;
        new_node->next = NULL;
    }

    return new_node;
}

struct node *add_door(struct node *elem, struct door door) {
    struct node *new_node = NULL;

    if (elem != NULL) {
        new_node = (struct node *)malloc(sizeof(struct node));
        if (new_node != NULL) {
            new_node->door = door;
            new_node->next = elem->next;
            elem->next = new_node;
        }
    }

    return new_node;
}

struct node *find_door(int door_id, struct node *root) {
    struct node *current = root;
    struct node *result = NULL;
    int found = 0;

    while (current != NULL && found == 0) {
        if (current->door.id == door_id) {
            result = current;
            found = 1;
        } else {
            current = current->next;
        }
    }

    return result;
}

struct node *remove_door(struct node *elem, struct node *root) {
    struct node *current = root;
    struct node *prev = NULL;
    struct node *new_root = root;
    int found = 0;

    if (elem == NULL || root == NULL) {
        new_root = root;
    } else if (elem == root) {
        new_root = root->next;
        free(root);
    } else {
        while (current != NULL && found == 0) {
            if (current == elem) {
                prev->next = current->next;
                free(current);
                found = 1;
            } else {
                prev = current;
                current = current->next;
            }
        }
    }

    return new_root;
}

void destroy(struct node *root) {
    struct node *current = root;
    struct node *next_node;

    while (current != NULL) {
        next_node = current->next;
        free(current);
        current = next_node;
    }
}