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

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

    newList->length = length;
    memcpy(newList->elements, elements, length * sizeof(list_element_t));

    return newList;
}

list_t *append_list(list_t *list1, list_t *list2) {
    if (list1 == NULL || list2 == NULL) {
        return NULL;
    }

    list_t *combinedList = (list_t *)malloc(sizeof(list_t) + (list1->length + list2->length) * sizeof(list_element_t));
    if (combinedList == NULL) {
        return NULL;
    }

    combinedList->length = list1->length + list2->length;

    memcpy(combinedList->elements, list1->elements, list1->length * sizeof(list_element_t));
    memcpy(combinedList->elements + list1->length, list2->elements, list2->length * sizeof(list_element_t));

    return combinedList;
}

list_t *filter_list(list_t *list, bool (*filter)(list_element_t)) {
    if (list == NULL || filter == NULL) {
        return NULL;
    }

    list_t *filteredList = (list_t *)malloc(sizeof(list_t));
    if (filteredList == NULL) {
        return NULL;
    }

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

    filteredList->length = count;

    filteredList->elements = (list_element_t *)malloc(count * sizeof(list_element_t));
    if (filteredList->elements == NULL) {
        free(filteredList);
        return NULL;
    }

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

    return filteredList;
}

size_t length_list(list_t *list) {
    if (list == NULL) {
        return 0;
    }
    return list->length;
}

list_t *map_list(list_t *list, list_element_t (*map)(list_element_t)) {
    if (list == NULL || map == NULL) {
        return NULL;
    }

    list_t *mappedList = (list_t *)malloc(sizeof(list_t) + list->length * sizeof(list_element_t));
    if (mappedList == NULL) {
        return NULL;
    }

    mappedList->length = list->length;

    mappedList->elements = (list_element_t *)malloc(list->length * sizeof(list_element_t));
    if (mappedList->elements == NULL) {
        free(mappedList);
        return NULL;
    }

    for (size_t i = 0; i < list->length; ++i) {
        mappedList->elements[i] = map(list->elements[i]);
    }

    return mappedList;
}

list_element_t foldl_list(list_t *list, list_element_t initial, list_element_t (*foldl)(list_element_t, list_element_t)) {
    if (list == NULL) {
        return initial;
    }

    list_element_t result = initial;

    for (size_t i = 0; i < list->length; ++i) {
        result = foldl(result, list->elements[i]);
    }

    return result;
}

list_element_t foldr_list(list_t *list, list_element_t initial, list_element_t (*foldr)(list_element_t, list_element_t)) {
    if (list == NULL) {
        return initial;
    }

    list_element_t result = initial;

    for (size_t i = list->length; i > 0; --i) {
        result = foldr(list->elements[i - 1], result);
    }

    return result;
}

list_t *reverse_list(list_t *list) {
    if (list == NULL) {
        return NULL;
    }

    list_t *reversedList = (list_t *)malloc(sizeof(list_t) + list->length * sizeof(list_element_t));
    if (reversedList == NULL) {
        return NULL;
    }

    reversedList->length = list->length;

    reversedList->elements = (list_element_t *)malloc(list->length * sizeof(list_element_t));
    if (reversedList->elements == NULL) {
        free(reversedList);
        return NULL;
    }

    for (size_t i = 0; i < list->length; ++i) {
        reversedList->elements[i] = list->elements[list->length - i - 1];
    }

    return reversedList;
}

void delete_list(list_t *list) {
    if (list != NULL) {
        free(list->elements);
        free(list);
    }
}