#include <vulkan/vulkan.h>

#include <iostream>
#include <stdexcept>
#include <cstdlib>
#include <vector>
#include <optional>

const std::vector<const char*> validationLayers = {
	"VK_LAYER_KHRONOS_validation"
};

#ifdef NDEBUG
const bool enableValidationLayers = false;
#else
const bool enableValidationLayers = true;
#endif

struct QueueFamilyIndices {
	std::optional<uint32_t> graphicsFamily;

	bool isComplete() {
		return graphicsFamily.has_value();
	}
};

class Engine {
public:
	void Start() {
		InitWindow();
		InitVulkan();
		BeginLoop();
		Shutdown();
	}
private:
	// Stuff
	GLFWwindow* window;
	VkInstance instance;
	VkDevice device;
	VkPhysicalDevice physicalDevice = VK_NULL_HANDLE;
private:
	// Functions
	void InitWindow() {
		glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
		glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);

		window = glfwCreateWindow(1280, 720, "Vulkan", nullptr, nullptr);
	}

	void InitVulkan() {
		CreateInstance();
		PickPhysicalDevice();
		CreateLogicalDevice();
	}

	void CreateLogicalDevice() {
		QueueFamilyIndices indices = findQueueFamilies(physicalDevice);

		VkDeviceQueueCreateInfo queueCreateInfo{};
		queueCreateInfo.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
		queueCreateInfo.queueFamilyIndex = indices.graphicsFamily.value();
		queueCreateInfo.queueCount = 1;

		float queuePriority = 1.0f;
		queueCreateInfo.pQueuePriorities = &queuePriority;
		VkPhysicalDeviceFeatures deviceFeatures{};

		VkDeviceCreateInfo createInfo{};
		createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
		createInfo.pQueueCreateInfos = &queueCreateInfo;
		createInfo.queueCreateInfoCount = 1;

		createInfo.pEnabledFeatures = &deviceFeatures;
		createInfo.enabledExtensionCount = 0;

		if (enableValidationLayers) {
			createInfo.enabledLayerCount = static_cast<uint32_t>(validationLayers.size());
			createInfo.ppEnabledLayerNames = validationLayers.data();
		}
		else {
			createInfo.enabledLayerCount = 0;
		}
	}

	QueueFamilyIndices findQueueFamilies(VkPhysicalDevice device) {
		QueueFamilyIndices indices;

		uint32_t queueFamilyCount = 0;
		vkGetPhysicalDeviceQueueFamilyProperties(device, &queueFamilyCount, nullptr);

		std::vector<VkQueueFamilyProperties> queueFamilies(queueFamilyCount);
		vkGetPhysicalDeviceQueueFamilyProperties(device, &queueFamilyCount, queueFamilies.data());

		int i = 0;
		for (const auto& queueFamily : queueFamilies) {
			if (queueFamily.queueFlags & VK_QUEUE_GRAPHICS_BIT) {
				indices.graphicsFamily = i;
			}

			if (indices.isComplete()) {
				break;
			}

			i++;
		}

		return indices;
	}

	void PickPhysicalDevice() {
		uint32_t deviceCount = 0;
		vkEnumeratePhysicalDevices(instance, &deviceCount, nullptr);
		if (deviceCount == 0) {
			throw std::runtime_error("failed to find GPUs with Vulkan support!");
		}
		std::vector<VkPhysicalDevice> devices(deviceCount);
		vkEnumeratePhysicalDevices(instance, &deviceCount, devices.data());
		for (const auto& device : devices) {
			if (isDeviceSuitable(device)) {
				physicalDevice = device;
				break;
			}
		}

		if (physicalDevice == VK_NULL_HANDLE) {
			throw std::runtime_error("failed to find a suitable GPU!");
		}
	}

	bool isDeviceSuitable(VkPhysicalDevice device) {
		return true;
	}

	bool checkValidationLayerSupport() {
		uint32_t layerCount;
		vkEnumerateInstanceLayerProperties(&layerCount, nullptr);

		std::vector<VkLayerProperties> availableLayers(layerCount);
		vkEnumerateInstanceLayerProperties(&layerCount, availableLayers.data());

		return false;
	}

	std::vector<const char*> getRequiredExtensions() {
		uint32_t glfwExtensionCount = 0;
		const char** glfwExtensions;
		glfwExtensions = glfwGetRequiredInstanceExtensions(&glfwExtensionCount);

		std::vector<const char*> extensions(glfwExtensions, glfwExtensions + glfwExtensionCount);

		if (enableValidationLayers) {
			extensions.push_back(VK_EXT_DEBUG_UTILS_EXTENSION_NAME);
		}

		return extensions;
	}

	void CreateInstance() {
		if (enableValidationLayers && !checkValidationLayerSupport()) {
			throw std::runtime_error("validation layers requested, but not available!");
		}

		VkApplicationInfo appInfo{};
		appInfo.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
		appInfo.pApplicationName = "Hello Triangle";
		appInfo.applicationVersion = VK_MAKE_VERSION(1, 0, 0);
		appInfo.pEngineName = "No Engine";
		appInfo.engineVersion = VK_MAKE_VERSION(1, 0, 0);
		appInfo.apiVersion = VK_API_VERSION_1_0;
		VkInstanceCreateInfo createInfo{};
		createInfo.sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO;
		createInfo.pApplicationInfo = &appInfo;

		uint32_t glfwExtensionCount = 0;
		const char** glfwExtensions;

		glfwExtensions = glfwGetRequiredInstanceExtensions(&glfwExtensionCount);

		createInfo.enabledExtensionCount = glfwExtensionCount;
		createInfo.ppEnabledExtensionNames = glfwExtensions;
		createInfo.enabledLayerCount = 0;

		auto extensions = getRequiredExtensions();
		createInfo.enabledExtensionCount = static_cast<uint32_t>(extensions.size());
		createInfo.ppEnabledExtensionNames = extensions.data();

		VkResult result = vkCreateInstance(&createInfo, nullptr, &instance);
	}

	void BeginLoop() {
		while (!glfwWindowShouldClose(window)) {
			glfwPollEvents();
		}
	}

	void Shutdown() {
		vkDestroyInstance(instance, nullptr);
		glfwDestroyWindow(window);
		glfwTerminate();
	}
};