#include "arraylist.h"
#include <stdatomic.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

struct ArrayList{
    void *data;
    size_t capacity;
    size_t len;
    size_t elem_size;
};

// Grow and shrink factor is 2, 1.5 might give different results i guess
// but i'm basing myself in that Rust implementation of array does use
// 2 as the factor so i guess is good :)
static ArrayListErr arraylist_grow(ArrayList *arr);
static ArrayListErr arraylist_shrink(ArrayList *arr);

ArrayList *arraylist_init(size_t capacity, size_t elem_size) {
    if (capacity == 0) {
        return NULL;
    }

    if (elem_size == 0) {
        return NULL;
    }

    ArrayList *arr = malloc(sizeof(ArrayList));
    if (arr == NULL) {
        return NULL;
    }
    arr->capacity = capacity;
    arr->elem_size = elem_size;
    arr->len = 0;
    arr->data = malloc(capacity * elem_size);
    if (arr->data == NULL) {
        free(arr);
        return NULL;
    }

    return arr;
}

ArrayListErr arraylist_destroy(ArrayList *arr) {
    if (arr == NULL) {
        return ARRLIST_NULL_ARG;
    }

    arr->capacity = 0;
    arr->elem_size = 0;
    arr->len = 0;
    free(arr->data);
    arr->data = NULL;
    free(arr);
    return ARRLIST_OK;
}

ArrayListErr arraylist_clear(ArrayList *arr) {
    if (arr == NULL) {
        return ARRLIST_NULL_ARG;
    }

    memset(arr->data, 0, arr->capacity * arr->elem_size);
    arr->capacity = 0;
    arr->elem_size = 0;
    arr->len = 0;
    return ARRLIST_OK;
}

size_t arraylist_size(const ArrayList *arr) {
    if (arr == NULL) {
        return 0;
    }
    return arr->len;
}

size_t arraylist_capacity(const ArrayList *arr) {
    if (arr == NULL) {
        return 0;
    }
    return arr->capacity;
}

bool arraylist_is_empty(const ArrayList *arr) {
    if (arr == NULL) {
        return true;
    }
    return arr->capacity == 0;
}

static ArrayListErr arraylist_grow(ArrayList *arr) {
    // We can asume is not null because is internal
    // and only used by funtions that already verified
    // arr is not null, same with shrink.
    size_t new_capacity = arr->capacity * 2;
    void *tmp = realloc(arr->data, new_capacity * arr->elem_size);
    if (tmp == NULL) {
        return ARRLIST_BAD_ALLOC;
    }
    arr->capacity = new_capacity;
    arr->data = tmp;
    return ARRLIST_OK;
}

static ArrayListErr arraylist_shrink(ArrayList *arr) {
    size_t new_capacity = arr->capacity / 2;
    void *tmp = realloc(arr->data, new_capacity *arr->elem_size);
    if (tmp == NULL) {
        return ARRLIST_BAD_ALLOC;
    }
    arr->capacity = new_capacity;
    arr->data = tmp;
    return ARRLIST_OK;
}