/* linked_list.c -- singly linked list implementation. */
#include "linked_list.h"

#include <stdio.h>
#include <stdlib.h>

void ll_init(LinkedList *list) {
    if (!list) return;
    list->head = NULL;
    list->size = 0;
}

void ll_destroy(LinkedList *list) {
    if (!list) return;
    LLNode *cur = list->head;
    while (cur) {
        LLNode *next = cur->next;
        free(cur);
        cur = next;
    }
    list->head = NULL;
    list->size = 0;
}

int ll_push_front(LinkedList *list, int value) {
    if (!list) return -1;
    LLNode *node = malloc(sizeof(*node));
    if (!node) return -1;
    node->data = value;
    node->next = list->head;
    list->head = node;
    list->size++;
    return 0;
}

int ll_push_back(LinkedList *list, int value) {
    if (!list) return -1;
    LLNode *node = malloc(sizeof(*node));
    if (!node) return -1;
    node->data = value;
    node->next = NULL;
    if (!list->head) {
        list->head = node;
    } else {
        LLNode *cur = list->head;
        while (cur->next) cur = cur->next;
        cur->next = node;
    }
    list->size++;
    return 0;
}

int ll_pop_front(LinkedList *list, int *out) {
    if (!list || !list->head) return -1;
    LLNode *node = list->head;
    if (out) *out = node->data;
    list->head = node->next;
    free(node);
    list->size--;
    return 0;
}

int ll_get(const LinkedList *list, size_t index, int *out) {
    if (!list || !out || index >= list->size) return -1;
    LLNode *cur = list->head;
    for (size_t i = 0; i < index; i++) cur = cur->next;
    *out = cur->data;
    return 0;
}

int ll_remove(LinkedList *list, size_t index) {
    if (!list || index >= list->size) return -1;
    LLNode *to_free;
    if (index == 0) {
        to_free = list->head;
        list->head = to_free->next;
    } else {
        LLNode *prev = list->head;
        for (size_t i = 0; i < index - 1; i++) prev = prev->next;
        to_free = prev->next;
        prev->next = to_free->next;
    }
    free(to_free);
    list->size--;
    return 0;
}

int ll_find(const LinkedList *list, int value) {
    if (!list) return -1;
    LLNode *cur = list->head;
    int index = 0;
    while (cur) {
        if (cur->data == value) return index;
        cur = cur->next;
        index++;
    }
    return -1;
}

size_t ll_size(const LinkedList *list) {
    return list ? list->size : 0;
}

void ll_print(const LinkedList *list) {
    if (!list) return;
    printf("[");
    LLNode *cur = list->head;
    while (cur) {
        printf("%d", cur->data);
        if (cur->next) printf(", ");
        cur = cur->next;
    }
    printf("]\n");
}