#include "Vector.h"
#include "Types.h"
#include <string.h>

/** Metadata **/

struct VectorMeta {
    MemoryManager *mm;
    usize element_size;
    usize count;
    usize length;
};

static inline struct VectorMeta*
V_metadata(void *arr) {
    return arr - sizeof(struct VectorMeta);
}

/* Create */

Vector
V_new(MemoryManager *mm, usize element_size, usize length) {
    if (NULL == mm)
        return NULL;

    struct VectorMeta vm = {
        .mm = mm,
        .element_size = element_size,
        .count = 0,
        .length = length,
    };

    void* start = NULL;
    if (R_Ok != mm->alloc(*mm, &start, sizeof(vm) + element_size * length) ||
        NULL == start)
    {
        return NULL;
    }

    memcpy(start, &vm, sizeof(vm));
    return start + sizeof(vm);
}

/* Free */

Result
V_free(Vector *arr) {
    if (NULL == arr || NULL == *arr)
        return R_NullArgument;

    struct VectorMeta *vm = V_metadata(*arr);
    *arr = vm;
    return vm->mm->free(*vm->mm, arr);
}

/* Modify */

Result
V_push(Vector *arr, void *pvalue) {
    if (NULL == arr || NULL == *arr)
        return R_Uninitialized;

    struct VectorMeta *vm = V_metadata(*arr);

    if (vm->count >= vm->length) {
        void *start = vm;
        RETURN_NOTOK(
            vm->mm->realloc(*vm->mm, &start, sizeof(*vm) + vm->element_size * (vm->length << 1)));

        vm = start;
        *arr = start + sizeof(*vm);
        vm->length <<= 1;
    }

    memcpy(*arr + vm->count++ * vm->element_size, pvalue, vm->element_size);

    return R_Ok;
}

Result
V_pushp(Vector* *arr, void *value) {
    void *temp = value;
    return V_push((void**)arr, &temp);
}

Result
V_pop(Vector *arr) {
    if (NULL == arr || NULL == *arr)
        return R_NullArgument;

    struct VectorMeta *vm = V_metadata(arr);

    if (vm->count == 0)
        return R_OutOfBounds;

    --vm->count;
    return R_Ok;
}

/* Get */

usize
V_length(Vector arr) {
    if (NULL == arr)
        return 0;
    return V_metadata(arr)->length;
}

usize
V_count(Vector arr) {
    if (NULL == arr)
        return 0;
    return V_metadata(arr)->count;
}

void*
V_top(Vector arr) {
    if (NULL == arr)
        return NULL;

    struct VectorMeta *vm = V_metadata(arr);

    if (0 == vm->count)
        return NULL;

    return arr + (vm->count - 1) * vm->element_size;
}