struct FrameData {

	VkCommandPool _commandPool;
	VkCommandBuffer _mainCommandBuffer;
};

constexpr unsigned int FRAME_OVERLAP = 2;

class VulkanEngine{
public:
	FrameData _frames[FRAME_OVERLAP];

	FrameData& get_current_frame() { return _frames[_frameNumber % FRAME_OVERLAP]; };

	VkQueue _graphicsQueue;
	uint32_t _graphicsQueueFamily;
}

void VulkanEngine::init_vulkan(){

// ---- other code, initializing vulkan device ----

	// use vkbootstrap to get a Graphics queue
	_graphicsQueue = vkbDevice.get_queue(vkb::QueueType::graphics).value();
	_graphicsQueueFamily = vkbDevice.get_queue_index(vkb::QueueType::graphics).value();
}

void VulkanEngine::init_commands()
{
	//create a command pool for commands submitted to the graphics queue.
	//we also want the pool to allow for resetting of individual command buffers
	VkCommandPoolCreateInfo commandPoolInfo =  {};
	commandPoolInfo.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
	commandPoolInfo.pNext = nullptr;
	commandPoolInfo.flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT;
	commandPoolInfo.queueFamilyIndex = _graphicsQueueFamily;
	
	for (int i = 0; i < FRAME_OVERLAP; i++) {

		VK_CHECK(vkCreateCommandPool(_device, &commandPoolInfo, nullptr, &_frames[i]._commandPool));

		// allocate the default command buffer that we will use for rendering
		VkCommandBufferAllocateInfo cmdAllocInfo = {};
		cmdAllocInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
		cmdAllocInfo.pNext = nullptr;
		cmdAllocInfo.commandPool = _frames[i]._commandPool;
		cmdAllocInfo.commandBufferCount = 1;
		cmdAllocInfo.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;

		VK_CHECK(vkAllocateCommandBuffers(_device, &cmdAllocInfo, &_frames[i]._mainCommandBuffer));
	}
}

VkCommandPoolCreateInfo commandPoolInfo = {};

VkCommandPoolCreateInfo vkinit::command_pool_create_info(uint32_t queueFamilyIndex,
    VkCommandPoolCreateFlags flags /*= 0*/)
{
    VkCommandPoolCreateInfo info = {};
    info.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
    info.pNext = nullptr;
    info.queueFamilyIndex = queueFamilyIndex;
    info.flags = flags;
    return info;
}


VkCommandBufferAllocateInfo vkinit::command_buffer_allocate_info(
    VkCommandPool pool, uint32_t count /*= 1*/)
{
    VkCommandBufferAllocateInfo info = {};
    info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
    info.pNext = nullptr;

    info.commandPool = pool;
    info.commandBufferCount = count;
    info.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
    return info;
}

void VulkanEngine::init_commands()
{
	//create a command pool for commands submitted to the graphics queue.
	//we also want the pool to allow for resetting of individual command buffers
	VkCommandPoolCreateInfo commandPoolInfo = vkinit::command_pool_create_info(_graphicsQueueFamily, VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT);

	for (int i = 0; i < FRAME_OVERLAP; i++) {

		VK_CHECK(vkCreateCommandPool(_device, &commandPoolInfo, nullptr, &_frames[i]._commandPool));

		// allocate the default command buffer that we will use for rendering
		VkCommandBufferAllocateInfo cmdAllocInfo = vkinit::command_buffer_allocate_info(_frames[i]._commandPool, 1);

		VK_CHECK(vkAllocateCommandBuffers(_device, &cmdAllocInfo, &_frames[i]._mainCommandBuffer));
	}
}

void VulkanEngine::cleanup()
{
	if (_isInitialized) {
		//make sure the gpu has stopped doing its things
		vkDeviceWaitIdle(_device);

		for (int i = 0; i < FRAME_OVERLAP; i++) {
			vkDestroyCommandPool(_device, _frames[i]._commandPool, nullptr);
		}

		// --- rest of code
	}
}