#include "instance.h"

constexpr const char* validationLayerName("VK_LAYER_KHRONOS_validation");

Engine::Instance::Instance() :
    initialized(false),
    validationLayersEnabledAndSupported(false),
    layerNames(),
    extensionNames(),
    layers(),
    extensions(),
    vk(),
    debugMessenger()
{}

Engine::Instance::~Instance() {
    deinitialize();
}

void Engine::Instance::initialize(const std::vector<const char*>& requiredExtensions) {
    if (initialized)
        return;

    VkApplicationInfo appInfo {};
    appInfo.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
    appInfo.pApplicationName = "Hello Triangle";
    appInfo.applicationVersion = VK_MAKE_VERSION(0, 0, 1);
    appInfo.pEngineName = "Stories";
    appInfo.engineVersion = VK_MAKE_VERSION(0, 0, 1);
    appInfo.apiVersion = VK_API_VERSION_1_0;
    appInfo.pNext = nullptr;

    //TODO handle exception
    Support exts = getVulkanExtensions(extensionNames, requiredExtensions);
    if (exts.unsupportedCritical.size() > 0) {
        std::string error("Unable to create Vulkan instance, following critical extensions are unsupported:\n");
        for (const char* ext : exts.unsupportedCritical)
            error += "\t" + std::string(ext) + "\n";

        throw std::runtime_error(error);
    }
    //TODO log unsupported;
    exts.logSupported("Applying extensions:");

    //TODO handle exception
    Support layers = getVulkanLayers(layerNames);
    //TODO log unsupported
    layers.logSupported("Applying layers:");

    VkInstanceCreateInfo createInfo {};
    createInfo.sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO;
    createInfo.pApplicationInfo = &appInfo;
    createInfo.flags = 0;
    createInfo.enabledExtensionCount = static_cast<uint32_t>(exts.supported.size());
    createInfo.ppEnabledExtensionNames = exts.supported.data();
    createInfo.enabledLayerCount = static_cast<uint32_t>(layers.supported.size());
    createInfo.ppEnabledLayerNames = layers.supported.data();

    VkDebugUtilsMessengerCreateInfoEXT debugCreateInfo {};
    if (hasValidationLayers()) {
        validationLayersEnabledAndSupported = true; //TODO make sure it's actually supported, this shows that they are just enabled;
        populateDebugMessengerCreateInfo(debugCreateInfo, debugCallback);
        createInfo.pNext = (VkDebugUtilsMessengerCreateInfoEXT*) &debugCreateInfo;
    }

    VkResult res = vkCreateInstance(&createInfo, nullptr, &vk);
    switch (res) {
        case VK_SUCCESS:
            break;
        case VK_ERROR_INCOMPATIBLE_DRIVER:
            throw std::runtime_error("unable to create vulkan instance, cannot find a compatible Vulkan ICD");
        case VK_ERROR_OUT_OF_HOST_MEMORY:
            throw std::runtime_error("unable to create vulkan instance, out of host memory");
        case VK_ERROR_OUT_OF_DEVICE_MEMORY:
            throw std::runtime_error("unable to create vulkan instance, out of device memory");
        case VK_ERROR_INITIALIZATION_FAILED:
            throw std::runtime_error("unable to create vulkan instance, initialization failed");
        case VK_ERROR_LAYER_NOT_PRESENT:
            throw std::runtime_error("unable to create vulkan instance, layer not present");
        case VK_ERROR_EXTENSION_NOT_PRESENT:
            throw std::runtime_error("unable to create vulkan instance, extension not present");
        default:
            throw std::runtime_error("unable to create Vulkan instance: unknown error");
    }

    if (validationLayersEnabledAndSupported)
        setupDebugMessenger();

    initialized = true;
}

void Engine::Instance::deinitialize() {
    if (!initialized)
        return;

    if (validationLayersEnabledAndSupported)
        destroyDebugUtilsMessengerEXT(vk, debugMessenger, nullptr);

    vkDestroyInstance(vk, nullptr);
    initialized = false;
}

void Engine::Instance::addExtension(const std::string& extensionName) {
    if (initialized)
        throw std::runtime_error("Adding extension to an initialized engine is not supported yet");

    std::pair<std::set<std::string>::const_iterator, bool> pair = extensionNames.insert(extensionName);
    if (pair.second)
        extensions.push_back(pair.first->c_str());
}

void Engine::Instance::addLayer(const std::string& layerName) {
    if (initialized)
        throw std::runtime_error("Adding layers to an initialized engine is not supported yet");

    std::pair<std::set<std::string>::const_iterator, bool> pair = layerNames.insert(layerName);
    if (pair.second)
        layers.push_back(pair.first->c_str());
}

bool Engine::Instance::hasValidationLayers() {
    return  extensionNames.count(VK_EXT_DEBUG_REPORT_EXTENSION_NAME) > 0 &&
            extensionNames.count(VK_EXT_DEBUG_UTILS_EXTENSION_NAME) > 0 &&
            layerNames.count(validationLayerName) > 0;
}

void Engine::Instance::enableDebug() {
    addLayer(validationLayerName);
    addExtension(VK_EXT_DEBUG_REPORT_EXTENSION_NAME);
    addExtension(VK_EXT_DEBUG_UTILS_EXTENSION_NAME);
}

void Engine::Instance::setupDebugMessenger() {
    VkDebugUtilsMessengerCreateInfoEXT createInfo{};
    populateDebugMessengerCreateInfo(createInfo, debugCallback);

    VkResult res = createDebugUtilsMessengerEXT(vk, &createInfo, nullptr, &debugMessenger);
    switch (res) {
        case VK_SUCCESS:
            break;
        case VK_ERROR_EXTENSION_NOT_PRESENT:
            throw std::runtime_error("failed to set up debug messenger: extension not present");
            break;
        default:
            throw std::runtime_error("failed to set up debug messenger");
    }
}

std::vector<VkPhysicalDevice> Engine::Instance::enumeratePhysicalDevices() const {
    uint32_t deviceCount = 0;
    vkEnumeratePhysicalDevices(vk, &deviceCount, nullptr);

    std::vector<VkPhysicalDevice> devices(deviceCount);
    if (deviceCount > 0)
        vkEnumeratePhysicalDevices(vk, &deviceCount, devices.data());

    return devices;
}

std::vector<const char *> Engine::Instance::getLayers() const {
    return layers;
}