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

list_t *new_list(size_t length, list_element_t default_value) {
    list_t *list = malloc(sizeof(list_t));
    list->length = length;
    list->elements = malloc(sizeof(list_element_t) * length);
    for (size_t i = 0; i < length; ++i) {
        list->elements[i] = default_value;
    }
    return list;
}

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

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

list_t *append_list(list_t *list1, list_t *list2) {
    size_t total_length = list1->length + list2->length;
    list_t *new_list = malloc(sizeof(list_t));
    new_list->length = total_length;
    new_list->elements = malloc(sizeof(list_element_t) * total_length);

    for (size_t i = 0; i < list1->length; ++i) {
        new_list->elements[i] = list1->elements[i];
    }
    for (size_t i = 0; i < list2->length; ++i) {
        new_list->elements[list1->length + i] = list2->elements[i];
    }

    return new_list;
}

list_t *filter_list(list_t *list, bool (*filter_fn)(list_element_t)) {
    size_t count = 0;
    for (size_t i = 0; i < list->length; ++i) {
        if (filter_fn(list->elements[i])) {
            count++;
        }
    }

    list_element_t *buffer = malloc(sizeof(list_element_t) * count);
    size_t index = 0;
    for (size_t i = 0; i < list->length; ++i) {
        if (filter_fn(list->elements[i])) {
            buffer[index++] = list->elements[i];
        }
    }

    list_t *new_list = malloc(sizeof(list_t));
    new_list->length = count;
    new_list->elements = buffer;
    return new_list;
}

list_t *map_list(list_t *list, list_element_t (*map_fn)(list_element_t)) {
    list_t *new_list = malloc(sizeof(list_t));
    new_list->length = list->length;
    new_list->elements = malloc(sizeof(list_element_t) * list->length);

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

    return new_list;
}

list_element_t foldl_list(list_t *list, list_element_t init, list_element_t (*fn)(list_element_t, list_element_t)) {
    list_element_t acc = init;
    for (size_t i = 0; i < list->length; ++i) {
        acc = fn(acc, list->elements[i]);
    }
    return acc;
}

list_element_t foldr_list(list_t *list, list_element_t init, list_element_t (*fn)(list_element_t, list_element_t)) {
    list_element_t acc = init;
    for (size_t i = list->length; i > 0; --i) {
        acc = fn(list->elements[i - 1], acc);
    }
    return acc;
}

list_t *reverse_list(list_t *list) {
    list_t *new_list = malloc(sizeof(list_t));
    new_list->length = list->length;
    new_list->elements = malloc(sizeof(list_element_t) * list->length);

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

    return new_list;
}