// Vulkan backend for the mock game. Brings up a real Vulkan instance/device/swap chain via volk
// (which dlopens vulkan-1.dll -- the loader-bypass case the capture hook must handle) and renders
// the same pattern as the other backends -- an animated background, a moving vertical bar, and the
// top-left frame-counter block -- so a dropped/duplicated/stale frame is detectable by the capture
// test just like the D3D/GL paths. The per-rect draw uses a render pass whose load clears the
// background and vkCmdClearAttachments for the bar + block, so it still needs no pipeline / shaders.
#include "render_backend.hpp"

#include <vector>

#include <volk.h>

namespace coop::mock {
namespace {
class VkBackend : public RenderBackend {
  public:
	bool init(HWND hwnd, std::uint32_t width, std::uint32_t height) override
	{
		width_ = width;
		height_ = height;
		if (volkInitialize() != VK_SUCCESS) {
			return false; // no Vulkan loader on this machine
		}

		VkApplicationInfo app{VK_STRUCTURE_TYPE_APPLICATION_INFO};
		app.pApplicationName = "coop_mock_game";
		app.apiVersion = VK_API_VERSION_1_1;
		const char* inst_ext[] = {VK_KHR_SURFACE_EXTENSION_NAME, VK_KHR_WIN32_SURFACE_EXTENSION_NAME};
		VkInstanceCreateInfo ici{VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO};
		ici.pApplicationInfo = &app;
		ici.enabledExtensionCount = 2;
		ici.ppEnabledExtensionNames = inst_ext;
		if (vkCreateInstance(&ici, nullptr, &instance_) != VK_SUCCESS) {
			return false;
		}
		volkLoadInstance(instance_);

		VkWin32SurfaceCreateInfoKHR sci{VK_STRUCTURE_TYPE_WIN32_SURFACE_CREATE_INFO_KHR};
		sci.hinstance = GetModuleHandleW(nullptr);
		sci.hwnd = hwnd;
		if (vkCreateWin32SurfaceKHR(instance_, &sci, nullptr, &surface_) != VK_SUCCESS) {
			return false;
		}

		return pick_device() && create_device() && create_swapchain() && create_render_pass() && create_framebuffers()
		       && create_commands();
	}

	void render_and_present(std::uint32_t frame) override
	{
		if (device_ == VK_NULL_HANDLE || swapchain_ == VK_NULL_HANDLE) {
			return;
		}
		vkWaitForFences(device_, 1, &in_flight_, VK_TRUE, UINT64_MAX);

		std::uint32_t idx = 0;
		VkResult acq = vkAcquireNextImageKHR(device_, swapchain_, UINT64_MAX, acquire_sem_, VK_NULL_HANDLE, &idx);
		if (acq != VK_SUCCESS) {
			return; // OUT_OF_DATE / SUBOPTIMAL / error: skip (the mock window isn't resized in practice)
		}
		vkResetFences(device_, 1, &in_flight_);

		const FramePattern pat = frame_pattern(frame, extent_.width);

		VkCommandBuffer cb = cmd_;
		vkResetCommandBuffer(cb, 0);
		VkCommandBufferBeginInfo bi{VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO};
		bi.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
		vkBeginCommandBuffer(cb, &bi);

		// The render pass's load op clears the whole attachment to the animated background; the
		// pass's final layout is PRESENT_SRC_KHR, so no manual image barriers are needed.
		VkClearValue clear{};
		clear.color = {{pat.bg_r / 255.0f, pat.bg_g / 255.0f, pat.bg_b / 255.0f, 1.0f}};
		VkRenderPassBeginInfo rpbi{VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO};
		rpbi.renderPass = render_pass_;
		rpbi.framebuffer = framebuffers_[idx];
		rpbi.renderArea = {{0, 0}, extent_};
		rpbi.clearValueCount = 1;
		rpbi.pClearValues = &clear;
		vkCmdBeginRenderPass(cb, &rpbi, VK_SUBPASS_CONTENTS_INLINE);

		// Moving vertical bar (full height) then the top-left frame-counter block, cleared as
		// rectangular regions of the bound attachment (no pipeline needed).
		clear_rect(cb, {{static_cast<std::int32_t>(pat.bar_x), 0}, {kBarWidth, extent_.height}},
		           {{1.0f, 1.0f, 1.0f, 1.0f}});
		clear_rect(cb, {{0, 0}, {kFrameBlock, kFrameBlock}},
		           {{pat.code_r / 255.0f, pat.code_g / 255.0f, pat.code_b / 255.0f, 1.0f}});

		vkCmdEndRenderPass(cb);
		vkEndCommandBuffer(cb);

		VkPipelineStageFlags wait_stage = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
		VkSubmitInfo si{VK_STRUCTURE_TYPE_SUBMIT_INFO};
		si.waitSemaphoreCount = 1;
		si.pWaitSemaphores = &acquire_sem_;
		si.pWaitDstStageMask = &wait_stage;
		si.commandBufferCount = 1;
		si.pCommandBuffers = &cb;
		si.signalSemaphoreCount = 1;
		si.pSignalSemaphores = &submit_sem_;
		vkQueueSubmit(queue_, 1, &si, in_flight_);

		VkPresentInfoKHR pi{VK_STRUCTURE_TYPE_PRESENT_INFO_KHR};
		pi.waitSemaphoreCount = 1;
		pi.pWaitSemaphores = &submit_sem_;
		pi.swapchainCount = 1;
		pi.pSwapchains = &swapchain_;
		pi.pImageIndices = &idx;
		vkQueuePresentKHR(queue_, &pi);
	}

	[[nodiscard]] const char* name() const override { return "vk"; }

	~VkBackend() override
	{
		if (device_ != VK_NULL_HANDLE) {
			vkDeviceWaitIdle(device_);
			for (VkFramebuffer fb : framebuffers_)
				if (fb != VK_NULL_HANDLE)
					vkDestroyFramebuffer(device_, fb, nullptr);
			for (VkImageView v : views_)
				if (v != VK_NULL_HANDLE)
					vkDestroyImageView(device_, v, nullptr);
			if (render_pass_ != VK_NULL_HANDLE)
				vkDestroyRenderPass(device_, render_pass_, nullptr);
			if (in_flight_ != VK_NULL_HANDLE)
				vkDestroyFence(device_, in_flight_, nullptr);
			if (acquire_sem_ != VK_NULL_HANDLE)
				vkDestroySemaphore(device_, acquire_sem_, nullptr);
			if (submit_sem_ != VK_NULL_HANDLE)
				vkDestroySemaphore(device_, submit_sem_, nullptr);
			if (pool_ != VK_NULL_HANDLE)
				vkDestroyCommandPool(device_, pool_, nullptr);
			if (swapchain_ != VK_NULL_HANDLE)
				vkDestroySwapchainKHR(device_, swapchain_, nullptr);
			vkDestroyDevice(device_, nullptr);
		}
		if (surface_ != VK_NULL_HANDLE)
			vkDestroySurfaceKHR(instance_, surface_, nullptr);
		if (instance_ != VK_NULL_HANDLE)
			vkDestroyInstance(instance_, nullptr);
	}

  private:
	// Clear one rectangular region of the bound color attachment to `color`.
	void clear_rect(VkCommandBuffer cb, VkRect2D rect, VkClearColorValue color)
	{
		VkClearAttachment att{};
		att.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
		att.colorAttachment = 0;
		att.clearValue.color = color;
		VkClearRect cr{};
		cr.rect = rect;
		cr.baseArrayLayer = 0;
		cr.layerCount = 1;
		vkCmdClearAttachments(cb, 1, &att, 1, &cr);
	}

	bool pick_device()
	{
		std::uint32_t n = 0;
		vkEnumeratePhysicalDevices(instance_, &n, nullptr);
		std::vector<VkPhysicalDevice> devs(n);
		vkEnumeratePhysicalDevices(instance_, &n, devs.data());
		for (VkPhysicalDevice pd : devs) {
			std::uint32_t qn = 0;
			vkGetPhysicalDeviceQueueFamilyProperties(pd, &qn, nullptr);
			std::vector<VkQueueFamilyProperties> qf(qn);
			vkGetPhysicalDeviceQueueFamilyProperties(pd, &qn, qf.data());
			for (std::uint32_t i = 0; i < qn; ++i) {
				VkBool32 present = VK_FALSE;
				vkGetPhysicalDeviceSurfaceSupportKHR(pd, i, surface_, &present);
				if ((qf[i].queueFlags & VK_QUEUE_GRAPHICS_BIT) && present) {
					phys_ = pd;
					qfam_ = i;
					return true;
				}
			}
		}
		return false;
	}

	bool create_device()
	{
		float prio = 1.0f;
		VkDeviceQueueCreateInfo qci{VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO};
		qci.queueFamilyIndex = qfam_;
		qci.queueCount = 1;
		qci.pQueuePriorities = &prio;
		const char* dev_ext[] = {VK_KHR_SWAPCHAIN_EXTENSION_NAME};
		VkDeviceCreateInfo dci{VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO};
		dci.queueCreateInfoCount = 1;
		dci.pQueueCreateInfos = &qci;
		dci.enabledExtensionCount = 1;
		dci.ppEnabledExtensionNames = dev_ext;
		if (vkCreateDevice(phys_, &dci, nullptr, &device_) != VK_SUCCESS) {
			return false;
		}
		volkLoadDevice(device_);
		vkGetDeviceQueue(device_, qfam_, 0, &queue_);
		return true;
	}

	bool create_swapchain()
	{
		VkSurfaceCapabilitiesKHR caps{};
		vkGetPhysicalDeviceSurfaceCapabilitiesKHR(phys_, surface_, &caps);

		std::uint32_t fn = 0;
		vkGetPhysicalDeviceSurfaceFormatsKHR(phys_, surface_, &fn, nullptr);
		std::vector<VkSurfaceFormatKHR> formats(fn);
		vkGetPhysicalDeviceSurfaceFormatsKHR(phys_, surface_, &fn, formats.data());
		VkSurfaceFormatKHR chosen =
		    formats.empty() ? VkSurfaceFormatKHR{VK_FORMAT_B8G8R8A8_UNORM, VK_COLOR_SPACE_SRGB_NONLINEAR_KHR}
		                    : formats[0];
		for (const VkSurfaceFormatKHR& f : formats) {
			if (f.format == VK_FORMAT_B8G8R8A8_UNORM || f.format == VK_FORMAT_R8G8B8A8_UNORM) {
				chosen = f;
				break;
			}
		}
		format_ = chosen.format;
		extent_ = caps.currentExtent.width != 0xFFFFFFFFu ? caps.currentExtent : VkExtent2D{width_, height_};

		std::uint32_t want = caps.minImageCount + 1;
		if (caps.maxImageCount > 0 && want > caps.maxImageCount) {
			want = caps.maxImageCount;
		}
		VkSwapchainCreateInfoKHR sc{VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR};
		sc.surface = surface_;
		sc.minImageCount = want;
		sc.imageFormat = chosen.format;
		sc.imageColorSpace = chosen.colorSpace;
		sc.imageExtent = extent_;
		sc.imageArrayLayers = 1;
		// COLOR_ATTACHMENT so the render pass can draw into it; TRANSFER_SRC so the capture hook can
		// copy it out.
		sc.imageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
		sc.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;
		sc.preTransform = caps.currentTransform;
		sc.compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
		// The mock is a perf fixture and must run UNCAPPED: prefer IMMEDIATE (no vsync) > MAILBOX >
		// FIFO. FIFO (vsync) would cap it at the refresh, hiding capture-induced slowdowns.
		std::uint32_t pmn = 0;
		vkGetPhysicalDeviceSurfacePresentModesKHR(phys_, surface_, &pmn, nullptr);
		std::vector<VkPresentModeKHR> pmodes(pmn);
		vkGetPhysicalDeviceSurfacePresentModesKHR(phys_, surface_, &pmn, pmodes.data());
		auto has_mode = [&](VkPresentModeKHR m) {
			for (VkPresentModeKHR p : pmodes)
				if (p == m)
					return true;
			return false;
		};
		sc.presentMode = has_mode(VK_PRESENT_MODE_IMMEDIATE_KHR) ? VK_PRESENT_MODE_IMMEDIATE_KHR
		                 : has_mode(VK_PRESENT_MODE_MAILBOX_KHR) ? VK_PRESENT_MODE_MAILBOX_KHR
		                                                         : VK_PRESENT_MODE_FIFO_KHR;
		sc.clipped = VK_TRUE;
		if (vkCreateSwapchainKHR(device_, &sc, nullptr, &swapchain_) != VK_SUCCESS) {
			return false;
		}
		std::uint32_t in = 0;
		vkGetSwapchainImagesKHR(device_, swapchain_, &in, nullptr);
		images_.resize(in);
		vkGetSwapchainImagesKHR(device_, swapchain_, &in, images_.data());
		return true;
	}

	bool create_render_pass()
	{
		VkAttachmentDescription color{};
		color.format = format_;
		color.samples = VK_SAMPLE_COUNT_1_BIT;
		color.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR; // clears to the animated background each frame
		color.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
		color.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
		color.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
		color.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
		color.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR; // ready to present, no manual barrier

		VkAttachmentReference ref{0, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL};
		VkSubpassDescription sub{};
		sub.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
		sub.colorAttachmentCount = 1;
		sub.pColorAttachments = &ref;

		// Order the acquire against the attachment's first write.
		VkSubpassDependency dep{};
		dep.srcSubpass = VK_SUBPASS_EXTERNAL;
		dep.dstSubpass = 0;
		dep.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
		dep.dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
		dep.srcAccessMask = 0;
		dep.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;

		VkRenderPassCreateInfo rpci{VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO};
		rpci.attachmentCount = 1;
		rpci.pAttachments = &color;
		rpci.subpassCount = 1;
		rpci.pSubpasses = &sub;
		rpci.dependencyCount = 1;
		rpci.pDependencies = &dep;
		return vkCreateRenderPass(device_, &rpci, nullptr, &render_pass_) == VK_SUCCESS;
	}

	bool create_framebuffers()
	{
		views_.resize(images_.size(), VK_NULL_HANDLE);
		framebuffers_.resize(images_.size(), VK_NULL_HANDLE);
		for (std::size_t i = 0; i < images_.size(); ++i) {
			VkImageViewCreateInfo ivci{VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO};
			ivci.image = images_[i];
			ivci.viewType = VK_IMAGE_VIEW_TYPE_2D;
			ivci.format = format_;
			ivci.subresourceRange = {VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1};
			if (vkCreateImageView(device_, &ivci, nullptr, &views_[i]) != VK_SUCCESS) {
				return false;
			}
			VkFramebufferCreateInfo fbci{VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO};
			fbci.renderPass = render_pass_;
			fbci.attachmentCount = 1;
			fbci.pAttachments = &views_[i];
			fbci.width = extent_.width;
			fbci.height = extent_.height;
			fbci.layers = 1;
			if (vkCreateFramebuffer(device_, &fbci, nullptr, &framebuffers_[i]) != VK_SUCCESS) {
				return false;
			}
		}
		return true;
	}

	bool create_commands()
	{
		VkCommandPoolCreateInfo pci{VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO};
		pci.flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT;
		pci.queueFamilyIndex = qfam_;
		if (vkCreateCommandPool(device_, &pci, nullptr, &pool_) != VK_SUCCESS) {
			return false;
		}
		VkCommandBufferAllocateInfo ai{VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO};
		ai.commandPool = pool_;
		ai.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
		ai.commandBufferCount = 1;
		if (vkAllocateCommandBuffers(device_, &ai, &cmd_) != VK_SUCCESS) {
			return false;
		}
		VkSemaphoreCreateInfo si{VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO};
		VkFenceCreateInfo fi{VK_STRUCTURE_TYPE_FENCE_CREATE_INFO};
		fi.flags = VK_FENCE_CREATE_SIGNALED_BIT;
		return vkCreateSemaphore(device_, &si, nullptr, &acquire_sem_) == VK_SUCCESS
		       && vkCreateSemaphore(device_, &si, nullptr, &submit_sem_) == VK_SUCCESS
		       && vkCreateFence(device_, &fi, nullptr, &in_flight_) == VK_SUCCESS;
	}

	std::uint32_t width_ = 0;
	std::uint32_t height_ = 0;
	VkInstance instance_ = VK_NULL_HANDLE;
	VkSurfaceKHR surface_ = VK_NULL_HANDLE;
	VkPhysicalDevice phys_ = VK_NULL_HANDLE;
	std::uint32_t qfam_ = 0;
	VkDevice device_ = VK_NULL_HANDLE;
	VkQueue queue_ = VK_NULL_HANDLE;
	VkSwapchainKHR swapchain_ = VK_NULL_HANDLE;
	VkFormat format_ = VK_FORMAT_UNDEFINED;
	VkExtent2D extent_ = {0, 0};
	std::vector<VkImage> images_;
	std::vector<VkImageView> views_;
	std::vector<VkFramebuffer> framebuffers_;
	VkRenderPass render_pass_ = VK_NULL_HANDLE;
	VkCommandPool pool_ = VK_NULL_HANDLE;
	VkCommandBuffer cmd_ = VK_NULL_HANDLE;
	VkSemaphore acquire_sem_ = VK_NULL_HANDLE;
	VkSemaphore submit_sem_ = VK_NULL_HANDLE;
	VkFence in_flight_ = VK_NULL_HANDLE;
};
} // namespace

std::unique_ptr<RenderBackend> create_vk_backend()
{
	return std::make_unique<VkBackend>();
}

} // namespace coop::mock