#include "c_ArrayStack.h"
#include <c_Memory.h>

#define DEFAULT_INITIAL_CAPACITY 4

c_err_t c_ArrayStack_Init(c_ArrayStack_t* self, int obj_size, c_size_t capacity) {
    if (!self || obj_size <= 0) return C_ERR_PARAM;

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

    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_ArrayStack_Destroy(c_ArrayStack_t* self) {
    if (!self) return;

    C_FREE(self->array);
    self->capacity = 0;
    self->size = 0;
    self->obj_size = 0;
}

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

    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;
    }

    // 計算頂端目標記憶體地址並寫入資料
    char* target = (char*)self->array + (self->size * self->obj_size);
    memcpy(target, obj, self->obj_size);
    self->size++;

    return C_ERR_SUCCESS;
}

c_err_t c_ArrayStack_Pop(c_ArrayStack_t* self, void* obj) {
    if (!self || !self->array || !obj) return C_ERR_PARAM;
    if (self->size == 0) return C_ERR_EMPTY; // 堆疊已空

    // 取得位於 size - 1 的堆疊頂端元素地址
    const char* pop_src = (char*)self->array + ((self->size - 1) * self->obj_size);

    // 直接複製到呼叫端提供的記憶體中
    memcpy(obj, pop_src, self->obj_size);

    self->size--;
    return C_ERR_SUCCESS;
}

void* c_ArrayStack_Peek(c_ArrayStack_t* self) {
    if (!self || !self->array || self->size == 0) return NULL;
    return (char*)self->array + ((self->size - 1) * self->obj_size);
}

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

    // 如果刪除的不是頂端元素，則後續元素需向前平移一個單位
    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;
        memmove(dest, src, num_elements_to_move * self->obj_size);
    }

    self->size--;
    return C_ERR_SUCCESS;
}