struct FrameData {
	VkSemaphore _swapchainSemaphore, _renderSemaphore;
	VkFence _renderFence;
};

VkFenceCreateInfo vkinit::fence_create_info(VkFenceCreateFlags flags /*= 0*/)
{
    VkFenceCreateInfo info = {};
    info.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO;
    info.pNext = nullptr;

    info.flags = flags;

    return info;
}

VkSemaphoreCreateInfo vkinit::semaphore_create_info(VkSemaphoreCreateFlags flags /*= 0*/)
{
    VkSemaphoreCreateInfo info = {};
    info.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;
    info.pNext = nullptr;
    info.flags = flags;
    return info;
}

void VulkanEngine::init_sync_structures()
{
	//create syncronization structures
	//one fence to control when the gpu has finished rendering the frame,
	//and 2 semaphores to syncronize rendering with swapchain
	//we want the fence to start signalled so we can wait on it on the first frame
	VkFenceCreateInfo fenceCreateInfo = vkinit::fence_create_info(VK_FENCE_CREATE_SIGNALED_BIT);
	VkSemaphoreCreateInfo semaphoreCreateInfo = vkinit::semaphore_create_info();

	for (int i = 0; i < FRAME_OVERLAP; i++) {
		VK_CHECK(vkCreateFence(_device, &fenceCreateInfo, nullptr, &_frames[i]._renderFence));

		VK_CHECK(vkCreateSemaphore(_device, &semaphoreCreateInfo, nullptr, &_frames[i]._swapchainSemaphore));
		VK_CHECK(vkCreateSemaphore(_device, &semaphoreCreateInfo, nullptr, &_frames[i]._renderSemaphore));
	}
}

void VulkanEngine::draw()
{
	// wait until the gpu has finished rendering the last frame. Timeout of 1
	// second
	VK_CHECK(vkWaitForFences(_device, 1, &get_current_frame()._renderFence, true, 1000000000));
	VK_CHECK(vkResetFences(_device, 1, &get_current_frame()._renderFence));
}

	//request image from the swapchain
	uint32_t swapchainImageIndex;
	VK_CHECK(vkAcquireNextImageKHR(_device, _swapchain, 1000000000, get_current_frame()._swapchainSemaphore, nullptr, &swapchainImageIndex));

VkCommandBufferBeginInfo vkinit::command_buffer_begin_info(VkCommandBufferUsageFlags flags /*= 0*/)
{
    VkCommandBufferBeginInfo info = {};
    info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
    info.pNext = nullptr;

    info.pInheritanceInfo = nullptr;
    info.flags = flags;
    return info;
}

	//naming it cmd for shorter writing
	VkCommandBuffer cmd = get_current_frame()._mainCommandBuffer;

	// now that we are sure that the commands finished executing, we can safely
	// reset the command buffer to begin recording again.
	VK_CHECK(vkResetCommandBuffer(cmd, 0));

	//begin the command buffer recording. We will use this command buffer exactly once, so we want to let vulkan know that
	VkCommandBufferBeginInfo cmdBeginInfo = vkinit::command_buffer_begin_info(VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT);

	//start the command buffer recording
	VK_CHECK(vkBeginCommandBuffer(cmd, &cmdBeginInfo));

#pragma once 

#include <vulkan/vulkan.h>

namespace vkutil {

void transition_image(VkCommandBuffer cmd, VkImage image, VkImageLayout currentLayout, VkImageLayout newLayout);
}

#include <vk_initializers.h>

void vkutil::transition_image(VkCommandBuffer cmd, VkImage image, VkImageLayout currentLayout, VkImageLayout newLayout)
{
    VkImageMemoryBarrier2 imageBarrier {.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER_2};
    imageBarrier.pNext = nullptr;

    imageBarrier.srcStageMask = VK_PIPELINE_STAGE_2_ALL_COMMANDS_BIT;
    imageBarrier.srcAccessMask = VK_ACCESS_2_MEMORY_WRITE_BIT;
    imageBarrier.dstStageMask = VK_PIPELINE_STAGE_2_ALL_COMMANDS_BIT;
    imageBarrier.dstAccessMask = VK_ACCESS_2_MEMORY_WRITE_BIT | VK_ACCESS_2_MEMORY_READ_BIT;

    imageBarrier.oldLayout = currentLayout;
    imageBarrier.newLayout = newLayout;

    VkImageAspectFlags aspectMask = (newLayout == VK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_OPTIMAL) ? VK_IMAGE_ASPECT_DEPTH_BIT : VK_IMAGE_ASPECT_COLOR_BIT;
    imageBarrier.subresourceRange = vkinit::image_subresource_range(aspectMask);
    imageBarrier.image = image;

    VkDependencyInfo depInfo {};
    depInfo.sType = VK_STRUCTURE_TYPE_DEPENDENCY_INFO;
    depInfo.pNext = nullptr;

    depInfo.imageMemoryBarrierCount = 1;
    depInfo.pImageMemoryBarriers = &imageBarrier;

    vkCmdPipelineBarrier2(cmd, &depInfo);
}

VkImageSubresourceRange vkinit::image_subresource_range(VkImageAspectFlags aspectMask)
{
    VkImageSubresourceRange subImage {};
    subImage.aspectMask = aspectMask;
    subImage.baseMipLevel = 0;
    subImage.levelCount = VK_REMAINING_MIP_LEVELS;
    subImage.baseArrayLayer = 0;
    subImage.layerCount = VK_REMAINING_ARRAY_LAYERS;

    return subImage;
}

	//make the swapchain image into writeable mode before rendering
	vkutil::transition_image(cmd, _swapchainImages[swapchainImageIndex], VK_IMAGE_LAYOUT_UNDEFINED, VK_IMAGE_LAYOUT_GENERAL);

	//make a clear-color from frame number. This will flash with a 120 frame period.
	VkClearColorValue clearValue;
	float flash = std::abs(std::sin(_frameNumber / 120.f));
	clearValue = { { 0.0f, 0.0f, flash, 1.0f } };

	VkImageSubresourceRange clearRange = vkinit::image_subresource_range(VK_IMAGE_ASPECT_COLOR_BIT);

	//clear image
	vkCmdClearColorImage(cmd, _swapchainImages[swapchainImageIndex], VK_IMAGE_LAYOUT_GENERAL, &clearValue, 1, &clearRange);

	//make the swapchain image into presentable mode
	vkutil::transition_image(cmd, _swapchainImages[swapchainImageIndex],VK_IMAGE_LAYOUT_GENERAL, VK_IMAGE_LAYOUT_PRESENT_SRC_KHR);

	//finalize the command buffer (we can no longer add commands, but it can now be executed)
	VK_CHECK(vkEndCommandBuffer(cmd));

VkSemaphoreSubmitInfo vkinit::semaphore_submit_info(VkPipelineStageFlags2 stageMask, VkSemaphore semaphore)
{
	VkSemaphoreSubmitInfo submitInfo{};
	submitInfo.sType = VK_STRUCTURE_TYPE_SEMAPHORE_SUBMIT_INFO;
	submitInfo.pNext = nullptr;
	submitInfo.semaphore = semaphore;
	submitInfo.stageMask = stageMask;
	submitInfo.deviceIndex = 0;
	submitInfo.value = 1;

	return submitInfo;
}

VkCommandBufferSubmitInfo vkinit::command_buffer_submit_info(VkCommandBuffer cmd)
{
	VkCommandBufferSubmitInfo info{};
	info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_SUBMIT_INFO;
	info.pNext = nullptr;
	info.commandBuffer = cmd;
	info.deviceMask = 0;

	return info;
}

VkSubmitInfo2 vkinit::submit_info(VkCommandBufferSubmitInfo* cmd, VkSemaphoreSubmitInfo* signalSemaphoreInfo,
    VkSemaphoreSubmitInfo* waitSemaphoreInfo)
{
    VkSubmitInfo2 info = {};
    info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO_2;
    info.pNext = nullptr;

    info.waitSemaphoreInfoCount = waitSemaphoreInfo == nullptr ? 0 : 1;
    info.pWaitSemaphoreInfos = waitSemaphoreInfo;

    info.signalSemaphoreInfoCount = signalSemaphoreInfo == nullptr ? 0 : 1;
    info.pSignalSemaphoreInfos = signalSemaphoreInfo;

    info.commandBufferInfoCount = 1;
    info.pCommandBufferInfos = cmd;

    return info;
}

	//prepare the submission to the queue. 
	//we want to wait on the _presentSemaphore, as that semaphore is signaled when the swapchain is ready
	//we will signal the _renderSemaphore, to signal that rendering has finished

	VkCommandBufferSubmitInfo cmdinfo = vkinit::command_buffer_submit_info(cmd);	
	
	VkSemaphoreSubmitInfo waitInfo = vkinit::semaphore_submit_info(VK_PIPELINE_STAGE_2_COLOR_ATTACHMENT_OUTPUT_BIT_KHR,get_current_frame()._swapchainSemaphore);
	VkSemaphoreSubmitInfo signalInfo = vkinit::semaphore_submit_info(VK_PIPELINE_STAGE_2_ALL_GRAPHICS_BIT, get_current_frame()._renderSemaphore);	
	
	VkSubmitInfo2 submit = vkinit::submit_info(&cmdinfo,&signalInfo,&waitInfo);	

	//submit command buffer to the queue and execute it.
	// _renderFence will now block until the graphic commands finish execution
	VK_CHECK(vkQueueSubmit2(_graphicsQueue, 1, &submit, get_current_frame()._renderFence));

	//prepare present
	// this will put the image we just rendered to into the visible window.
	// we want to wait on the _renderSemaphore for that, 
	// as its necessary that drawing commands have finished before the image is displayed to the user
	VkPresentInfoKHR presentInfo = {};
	presentInfo.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
	presentInfo.pNext = nullptr;
	presentInfo.pSwapchains = &_swapchain;
	presentInfo.swapchainCount = 1;

	presentInfo.pWaitSemaphores = &get_current_frame()._renderSemaphore;
	presentInfo.waitSemaphoreCount = 1;

	presentInfo.pImageIndices = &swapchainImageIndex;

	VK_CHECK(vkQueuePresentKHR(_graphicsQueue, &presentInfo));

	//increase the number of frames drawn
	_frameNumber++;

	for (int i = 0; i < FRAME_OVERLAP; i++) {
	
		//already written from before
		vkDestroyCommandPool(_device, _frames[i]._commandPool, nullptr);

		//destroy sync objects
		vkDestroyFence(_device, _frames[i]._renderFence, nullptr);
		vkDestroySemaphore(_device, _frames[i]._renderSemaphore, nullptr);
		vkDestroySemaphore(_device ,_frames[i]._swapchainSemaphore, nullptr);
	}