#include "list_ops.h"
#include <string.h> 

list_t *new_list(size_t length, list_element_t elements[]) {
    list_t *list = malloc(sizeof(list_t) + sizeof(list_element_t) * length);
    if (!list) return NULL;

    list->length = length;
    if (elements && length > 0) {
        memcpy(list->elements, elements, sizeof(list_element_t) * length);
    }
    return list;
}
list_t *append_list(list_t *list1, list_t *list2) {
    size_t len1 = list1 ? list1->length : 0;
    size_t len2 = list2 ? list2->length : 0;

    list_t *result = malloc(sizeof(list_t) + sizeof(list_element_t) * (len1 + len2));
    if (!result) return NULL;

    result->length = len1 + len2;
    if (len1 > 0)
        memcpy(result->elements, list1->elements, sizeof(list_element_t) * len1);
    if (len2 > 0)
        memcpy(result->elements + len1, list2->elements, sizeof(list_element_t) * len2);

    return result;
}
list_t *filter_list(list_t *list, bool (*filter)(list_element_t)) {
    if (!list || list->length == 0) return new_list(0, NULL);

    list_element_t *temp = malloc(sizeof(list_element_t) * list->length);
    if (!temp) return NULL;

    size_t count = 0;
    for (size_t i = 0; i < list->length; ++i) {
        if (filter(list->elements[i])) {
            temp[count++] = list->elements[i];
        }
    }

    list_t *result = new_list(count, temp);
    free(temp);
    return result;
}

size_t length_list(list_t *list) {
    return list ? list->length : 0;
}