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

struct ArrayList{
    uint8_t *buffer;
    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->buffer = malloc(capacity * elem_size);
    if (arr->buffer == 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->buffer);
    arr->buffer = NULL;
    free(arr);
    return ARRLIST_OK;
}

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

    memset(arr->buffer, 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->buffer, new_capacity * arr->elem_size);
    if (tmp == NULL) {
        return ARRLIST_BAD_ALLOC;
    }
    arr->capacity = new_capacity;
    arr->buffer = tmp;
    return ARRLIST_OK;
}

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

ArrayListErr arraylist_push_back(ArrayList *arr, void *data) {
    if (arr == NULL || data == NULL) {
        return ARRLIST_NULL_ARG;
    }

    if (arr->len >= arr->capacity) {
        ArrayListErr err = arraylist_grow(arr);

        if (err != ARRLIST_OK) {
            return err;
        }
    }

    memcpy(arr->buffer, data, arr->elem_size);
    arr->len++;
    return ARRLIST_OK;
}

ArrayListErr arraylist_push_front(ArrayList *arr, void *data) {
    if (arr == NULL || data == NULL) {
        return ARRLIST_NULL_ARG;
    }

    if (arr->len >= arr->capacity) {
        ArrayListErr err = arraylist_grow(arr);

        if (err != ARRLIST_OK) {
            return err;
        }
    }

    // No problem if array is full because  it grows if it's full
    for (size_t i = arr->len - 1; i >= 0; i--) {
        memcpy(
            arr->buffer + ((i + 1) * arr->elem_size),
            arr->buffer + (i * arr->elem_size),
            arr->elem_size);
    }

    memcpy(arr->buffer, data, arr->elem_size);
    arr->len++;

    return ARRLIST_OK;
}

ArrayListErr arraylist_insert(ArrayList *arr, size_t index, void *data) {
    if (arr == NULL || data == NULL) {
        return ARRLIST_NULL_ARG;
    }

    if (index >= arr->len) {
        return ARRLIST_OUT_OF_BOUNDS;
    }

    if (arr->len >= arr->capacity) {
        ArrayListErr err = arraylist_grow(arr);
        if (err != ARRLIST_OK) {
            return err;
        }
    }

    for (size_t i = arr->len - 1; i >= index; i--) {
        memcpy(
            arr->buffer + ((i + 1) * arr->elem_size),
            arr->buffer + (i * arr->elem_size),
            arr->elem_size);
    }

    memcpy(arr->buffer + (index * arr->elem_size), data, arr->elem_size);
    arr->len++;

    return ARRLIST_OK;
}