#include <c_ArrayList.h>
#include <c_Memory.h>

#define DEFAULT_INITIAL_CAPACITY 4

/* ------------------------------------------------------------------------------------------------------------------ */
/*  */

c_err_t c_ArrayList_Init(c_ArrayList_t* self, c_size_t obj_size, c_size_t capacity) {
    if (!self || obj_size == 0) return C_ERR_PARAM;

    self->obj_size = (int)obj_size;
    self->capacity = (capacity > 0) ? capacity : DEFAULT_INITIAL_CAPACITY;
    self->size = 0;

    // 分配連續記憶體空間：容量 * 單個物件大小
    self->array = C_ALLOC(self->capacity * self->obj_size);
    if (!self->array) {
        self->capacity = 0;
        return C_ERR_NOMEM;
    }

    return C_ERR_SUCCESS;
}

void c_ArrayList_Destroy(c_ArrayList_t* self) {
    if (!self) return;
    C_FREE(self->array);
    self->capacity = 0;
    self->size = 0;
    self->obj_size=0;
}

c_err_t c_ArrayList_Add(c_ArrayList_t* self, void* obj) {
    if (!self || !self->array || !obj) return C_ERR_PARAM;

    // 動態擴容邏輯
    if (self->size >= self->capacity) {
        const c_size_t new_capacity = self->capacity<<1;
        void* new_array = C_REALLOC(self->array, new_capacity * self->obj_size);
        if (!new_array) {
            return C_ERR_NOMEM;
        }
        self->array = new_array;
        self->capacity = new_capacity;
    }

    // 計算目標記憶體地址並將物件內容複製進去
    char* target_addr = (char*)self->array + (self->size * self->obj_size);
    memcpy(target_addr, obj, self->obj_size);

    self->size++;
    return C_ERR_SUCCESS;
}

void* c_ArrayList_Get(c_ArrayList_t* self, c_size_t index) {
    if (!self || !self->array || index >= self->size) {
        return NULL;
    }
    // 回傳內部記憶體塊中該元素的實際起始地址
    return (char*)self->array + (index * self->obj_size);
}

c_err_t c_ArrayList_Remove(c_ArrayList_t* self, c_size_t index) {
    if (!self || !self->array) return C_ERR_PARAM;
    if (index >= self->size) return C_ERR_INDEX;

    // 如果刪除的不是最後一個元素，需要將後方所有物件往前平移一個單位
    if (index < self->size - 1) {
        char* dest = (char*)self->array + (index * self->obj_size);
        const char* src = dest + self->obj_size;
        const c_size_t num_elements_to_move = self->size - index - 1;

        // 使用 memmove 處理重疊記憶體區塊的複製
        memmove(dest, src, num_elements_to_move * self->obj_size);
    }

    self->size--;
    return C_ERR_SUCCESS;
}