#include <fmt/format.h>
#include <fstream>
#include <iostream>
#include <set>

#define VK_ENABLE_BETA_EXTENSIONS
#define VULKAN_HPP_NO_CONSTRUCTORS
#include <vulkan/vulkan.hpp>

#include "util/types.h"
#include "vkfw.hpp"

namespace vk {
  using DebugUtilsMessengerUnique = vk::UniqueHandle<vk::DebugUtilsMessengerEXT, vk::DispatchLoaderDynamic>;
}

constexpr i32 WIDTH  = 800;
constexpr i32 HEIGHT = 600;

constexpr std::array<const char*, 1> validationLayers = { "VK_LAYER_KHRONOS_validation" };

#ifdef __APPLE__
constexpr std::array<const char*, 2> deviceExtensions = { vk::KHRSwapchainExtensionName,
                                                          vk::KHRPortabilitySubsetExtensionName };
#else
constexpr std::array<const char*, 1> deviceExtensions = { vk::KHRSwapchainExtensionName };
#endif

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

class VulkanApp {
 public:
  fn run() -> void {
    initWindow();
    initVulkan();
    mainLoop();
  }

 private:
  vkfw::UniqueInstance mGLFWInstance;
  vkfw::UniqueWindow   mWindow;

  vk::UniqueInstance mInstance;

  vk::DebugUtilsMessengerUnique mDebugMessenger;
  vk::DispatchLoaderDynamic     mLoader;
  vk::UniqueSurfaceKHR          mSurface;

  vk::PhysicalDevice mPhysicalDevice;
  vk::UniqueDevice   mDevice;

  vk::Queue mGraphicsQueue;
  vk::Queue mPresentQueue;

  vk::UniqueSwapchainKHR           mSwapChain;
  std::vector<vk::Image>           mSwapChainImages;
  vk::Format                       mSwapChainImageFormat;
  vk::Extent2D                     mSwapChainExtent;
  std::vector<vk::UniqueImageView> mSwapChainImageViews;

  vk::UniqueRenderPass     mRenderPass;
  vk::UniquePipelineLayout mPipelineLayout;
  vk::UniquePipeline       mGraphicsPipeline;

  std::vector<vk::UniqueFramebuffer> mSwapChainFramebuffers;

  struct QueueFamilyIndices {
    std::optional<u32> graphics_family;
    std::optional<u32> present_family;

    fn isComplete() -> bool { return graphics_family.has_value() && present_family.has_value(); }
  };

  struct SwapChainSupportDetails {
    vk::SurfaceCapabilitiesKHR        capabilities;
    std::vector<vk::SurfaceFormatKHR> formats;
    std::vector<vk::PresentModeKHR>   present_modes;
  };

  static fn readFile(const std::string& filename) -> std::vector<char> {
    std::ifstream file(filename, std::ios::ate | std::ios::binary);

    if (!file.is_open())
      throw std::runtime_error("Failed to open file! " + filename);

    usize             fileSize = static_cast<usize>(file.tellg());
    std::vector<char> buffer(fileSize);

    file.seekg(0);
    file.read(buffer.data(), static_cast<std::streamsize>(fileSize));

    file.close();

    return buffer;
  }

  fn initWindow() -> void {
    mGLFWInstance = vkfw::initUnique();

    vkfw::WindowHints hints;

    hints.clientAPI = vkfw::ClientAPI::eNone;
    hints.resizable = vkfw::eFalse;

    mWindow = vkfw::createWindowUnique(WIDTH, HEIGHT, "Vulkan", hints);
  }

  fn initVulkan() -> void {
    createInstance();
    setupDebugMessenger();
    createSurface();
    pickPhysicalDevice();
    createLogicalDevice();
    createSwapChain();
    createImageViews();
    createRenderPass();
    createGraphicsPipeline();
    createFramebuffers();
  }

  fn mainLoop() -> void {
    while (!mWindow->shouldClose()) { vkfw::waitEvents(); }
  }

  fn createInstance() -> void {
    if (enableValidationLayers && !checkValidationLayerSupport())
      throw std::runtime_error("Validation layers requested, but not available!");

    vk::ApplicationInfo appInfo { .pApplicationName   = "Hello Triangle",
                                  .applicationVersion = 1,
                                  .pEngineName        = "No Engine",
                                  .engineVersion      = 1,
                                  .apiVersion         = vk::ApiVersion10 };

    // Retrieve extensions using custom function
    std::vector<const char*> extensions = getRequiredExtensions();

#ifdef __APPLE__
    // Enable the portability extension and set flags
    extensions.emplace_back(vk::KHRPortabilityEnumerationExtensionName);
    // Technically deprecated but vulkan complains if I don't include it for macOS
    // So instead of using the vk::KHRPortabilitySubsetExtensionName, I just use
    // the direct string.
    extensions.emplace_back("VK_KHR_get_physical_device_properties2");
#endif

    vk::InstanceCreateInfo createInfo {
#ifdef __APPLE__
      .flags = vk::InstanceCreateFlagBits::eEnumeratePortabilityKHR,
#endif
      .pApplicationInfo        = &appInfo,
      .enabledLayerCount       = enableValidationLayers ? static_cast<u32>(validationLayers.size()) : 0,
      .ppEnabledLayerNames     = enableValidationLayers ? validationLayers.data() : nullptr,
      .enabledExtensionCount   = static_cast<u32>(extensions.size()),
      .ppEnabledExtensionNames = extensions.data()
    };

#ifndef NDEBUG
    fmt::println("Available extensions:");

    for (const char* extension : extensions) fmt::println("\t{}", extension);
#endif

    try {
      mInstance = vk::createInstanceUnique(createInfo);
      mLoader   = vk::DispatchLoaderDynamic(mInstance.get(), vkGetInstanceProcAddr);
    } catch (const vk::SystemError& err) {
      throw std::runtime_error("Failed to create instance: " + std::string(err.what()));
    }
  }

  fn setupDebugMessenger() -> void {
    if (!enableValidationLayers)
      return;

    vk::DebugUtilsMessengerCreateInfoEXT messengerCreateInfo {
      .messageSeverity = vk::DebugUtilsMessageSeverityFlagBitsEXT::eVerbose |
                         vk::DebugUtilsMessageSeverityFlagBitsEXT::eWarning |
                         vk::DebugUtilsMessageSeverityFlagBitsEXT::eError,
      .messageType = vk::DebugUtilsMessageTypeFlagBitsEXT::eGeneral |
                     vk::DebugUtilsMessageTypeFlagBitsEXT::eValidation |
                     vk::DebugUtilsMessageTypeFlagBitsEXT::ePerformance,
      .pfnUserCallback = debugCallback,
    };

    mDebugMessenger = mInstance->createDebugUtilsMessengerEXTUnique(messengerCreateInfo, nullptr, mLoader);
  }

  fn createSurface() -> void { mSurface = vkfw::createWindowSurfaceUnique(mInstance.get(), mWindow.get()); }

  fn pickPhysicalDevice() -> void {
    std::vector<vk::PhysicalDevice> devices = mInstance->enumeratePhysicalDevices();

    if (devices.empty())
      throw std::runtime_error("Failed to find GPUs with Vulkan support!");

#ifndef NDEBUG
    fmt::println("Available devices:");
#endif

    for (const auto& device : devices) {
#ifndef NDEBUG
      vk::PhysicalDeviceProperties properties = device.getProperties();
      fmt::println("\t{}", properties.deviceName.data());
#endif

      if (isDeviceSuitable(device)) {
        mPhysicalDevice = device;
        break;
      }
    }

    if (!mPhysicalDevice)
      throw std::runtime_error("Failed to find a suitable GPU!");
  }

  fn createLogicalDevice() -> void {
    QueueFamilyIndices indices = findQueueFamilies(mPhysicalDevice);

    std::vector<vk::DeviceQueueCreateInfo> queueCreateInfos;
    std::set<u32> uniqueQueueFamilies = { indices.graphics_family.value(), indices.present_family.value() };

    f32 queuePriority = 1.0F;

    for (u32 queueFamily : uniqueQueueFamilies) {
      vk::DeviceQueueCreateInfo queueCreateInfo { .queueFamilyIndex = queueFamily,
                                                  .queueCount       = 1,
                                                  .pQueuePriorities = &queuePriority };

      queueCreateInfos.emplace_back(queueCreateInfo);
    }

    vk::PhysicalDeviceFeatures deviceFeatures;

    vk::DeviceCreateInfo createInfo { .queueCreateInfoCount    = static_cast<u32>(queueCreateInfos.size()),
                                      .pQueueCreateInfos       = queueCreateInfos.data(),
                                      .enabledExtensionCount   = static_cast<u32>(deviceExtensions.size()),
                                      .ppEnabledExtensionNames = deviceExtensions.data(),
                                      .pEnabledFeatures        = &deviceFeatures };

    mDevice = mPhysicalDevice.createDeviceUnique(createInfo);

    mGraphicsQueue = mDevice->getQueue(indices.graphics_family.value(), 0);
    mPresentQueue  = mDevice->getQueue(indices.present_family.value(), 0);
  }

  fn createSwapChain() -> void {
    SwapChainSupportDetails swapChainSupport = querySwapChainSupport(mPhysicalDevice);

    vk::SurfaceFormatKHR surfaceFormat = chooseSwapSurfaceFormat(swapChainSupport.formats);
    vk::PresentModeKHR   presentMode   = chooseSwapPresentMode(swapChainSupport.present_modes);
    vk::Extent2D         extent        = chooseSwapExtent(swapChainSupport.capabilities);

    u32 imageCount = swapChainSupport.capabilities.minImageCount + 1;

    if (swapChainSupport.capabilities.maxImageCount > 0 &&
        imageCount > swapChainSupport.capabilities.maxImageCount)
      imageCount = swapChainSupport.capabilities.maxImageCount;

    QueueFamilyIndices indices            = findQueueFamilies(mPhysicalDevice);
    std::array<u32, 2> queueFamilyIndices = { indices.graphics_family.value(),
                                              indices.present_family.value() };

    vk::SwapchainCreateInfoKHR createInfo {
      .surface          = mSurface.get(),
      .minImageCount    = imageCount,
      .imageFormat      = surfaceFormat.format,
      .imageColorSpace  = surfaceFormat.colorSpace,
      .imageExtent      = extent,
      .imageArrayLayers = 1,
      .imageUsage       = vk::ImageUsageFlagBits::eColorAttachment,
      .imageSharingMode = indices.graphics_family != indices.present_family ? vk::SharingMode::eConcurrent
                                                                            : vk::SharingMode::eExclusive,
      .queueFamilyIndexCount = static_cast<u32>(indices.graphics_family != indices.present_family ? 2 : 0),
      .pQueueFamilyIndices =
        indices.graphics_family != indices.present_family ? queueFamilyIndices.data() : nullptr,
      .preTransform   = swapChainSupport.capabilities.currentTransform,
      .compositeAlpha = vk::CompositeAlphaFlagBitsKHR::eOpaque,
      .presentMode    = presentMode,
      .clipped        = vk::True,
      .oldSwapchain   = nullptr,
    };

    mSwapChain = mDevice->createSwapchainKHRUnique(createInfo);

    mSwapChainImages      = mDevice->getSwapchainImagesKHR(mSwapChain.get());
    mSwapChainImageFormat = surfaceFormat.format;
    mSwapChainExtent      = extent;
  }

  fn createImageViews() -> void {
    mSwapChainImageViews.resize(mSwapChainImages.size());

    for (u32 i = 0; i < mSwapChainImages.size(); i++) {
      vk::ImageViewCreateInfo createInfo {
        .image            = mSwapChainImages[i],
        .viewType         = vk::ImageViewType::e2D,
        .format           = mSwapChainImageFormat,
        .components       = { .r = vk::ComponentSwizzle::eIdentity,
                             .g = vk::ComponentSwizzle::eIdentity,
                             .b = vk::ComponentSwizzle::eIdentity,
                             .a = vk::ComponentSwizzle::eIdentity },
        .subresourceRange = { .aspectMask     = vk::ImageAspectFlagBits::eColor,
                             .baseMipLevel   = 0,
                             .levelCount     = 1,
                             .baseArrayLayer = 0,
                             .layerCount     = 1 },
      };

      mSwapChainImageViews[i] = mDevice->createImageViewUnique(createInfo);
    }
  }

  fn createRenderPass() -> void {
    vk::AttachmentDescription colorAttachment {
      .format         = mSwapChainImageFormat,
      .samples        = vk::SampleCountFlagBits::e1,
      .loadOp         = vk::AttachmentLoadOp::eClear,
      .storeOp        = vk::AttachmentStoreOp::eStore,
      .stencilLoadOp  = vk::AttachmentLoadOp::eDontCare,
      .stencilStoreOp = vk::AttachmentStoreOp::eDontCare,
      .initialLayout  = vk::ImageLayout::eUndefined,
      .finalLayout    = vk::ImageLayout::ePresentSrcKHR,
    };

    vk::AttachmentReference colorAttachmentRef {
      .attachment = 0,
      .layout     = vk::ImageLayout::eColorAttachmentOptimal,
    };

    vk::SubpassDescription subpass {
      .pipelineBindPoint    = vk::PipelineBindPoint::eGraphics,
      .colorAttachmentCount = 1,
      .pColorAttachments    = &colorAttachmentRef,
    };

    vk::RenderPassCreateInfo renderPassInfo {
      .attachmentCount = 1,
      .pAttachments    = &colorAttachment,
      .subpassCount    = 1,
      .pSubpasses      = &subpass,
    };

    mRenderPass = mDevice->createRenderPassUnique(renderPassInfo);
  }

  fn createGraphicsPipeline() -> void {
    std::vector<char> vertShaderCode = readFile("src/shaders/vert.spv");
    std::vector<char> fragShaderCode = readFile("src/shaders/frag.spv");

    vk::UniqueShaderModule vertShaderModule = createShaderModule(vertShaderCode);
    vk::UniqueShaderModule fragShaderModule = createShaderModule(fragShaderCode);

    vk::PipelineShaderStageCreateInfo vertShaderStageInfo {
      .stage  = vk::ShaderStageFlagBits::eVertex,
      .module = vertShaderModule.get(),
      .pName  = "main",
    };

    vk::PipelineShaderStageCreateInfo fragShaderStageInfo {
      .stage  = vk::ShaderStageFlagBits::eFragment,
      .module = fragShaderModule.get(),
      .pName  = "main",
    };

    std::array<vk::PipelineShaderStageCreateInfo, 2> shaderStages = { vertShaderStageInfo,
                                                                      fragShaderStageInfo };

    vk::PipelineVertexInputStateCreateInfo vertexInputInfo {
      .vertexBindingDescriptionCount   = 0,
      .pVertexBindingDescriptions      = nullptr,
      .vertexAttributeDescriptionCount = 0,
      .pVertexAttributeDescriptions    = nullptr,
    };

    vk::PipelineInputAssemblyStateCreateInfo inputAssembly {
      .topology               = vk::PrimitiveTopology::eTriangleList,
      .primitiveRestartEnable = vk::False,
    };

    vk::PipelineViewportStateCreateInfo viewportState {
      .viewportCount = 1,
      .scissorCount  = 1,
    };

    vk::PipelineRasterizationStateCreateInfo rasterizer {
      .depthClampEnable        = vk::False,
      .rasterizerDiscardEnable = vk::False,
      .polygonMode             = vk::PolygonMode::eFill,
      .cullMode                = vk::CullModeFlagBits::eBack,
      .frontFace               = vk::FrontFace::eClockwise,
      .depthBiasEnable         = vk::False,
      .lineWidth               = 1.0F,
    };

    vk::PipelineMultisampleStateCreateInfo multisampling {
      .rasterizationSamples = vk::SampleCountFlagBits::e1,
      .sampleShadingEnable  = vk::False,
    };

    vk::PipelineColorBlendAttachmentState colorBlendAttachment {
      .blendEnable    = vk::False,
      .colorWriteMask = vk::ColorComponentFlagBits::eR | vk::ColorComponentFlagBits::eG |
                        vk::ColorComponentFlagBits::eB | vk::ColorComponentFlagBits::eA,
    };

    vk::PipelineColorBlendStateCreateInfo colorBlending {
      .logicOpEnable   = vk::False,
      .logicOp         = vk::LogicOp::eCopy,
      .attachmentCount = 1,
      .pAttachments    = &colorBlendAttachment,
      .blendConstants  = std::array<float, 4> { 0.0F, 0.0F, 0.0F, 0.0F },
    };
    std::vector<vk::DynamicState> dynamicStates = { vk::DynamicState::eViewport, vk::DynamicState::eScissor };

    vk::PipelineDynamicStateCreateInfo dynamicState {
      .dynamicStateCount = static_cast<u32>(dynamicStates.size()),
      .pDynamicStates    = dynamicStates.data(),
    };

    vk::PipelineLayoutCreateInfo pipelineLayoutInfo {
      .setLayoutCount         = 0,
      .pushConstantRangeCount = 0,
    };

    mPipelineLayout = mDevice->createPipelineLayoutUnique(pipelineLayoutInfo);

    vk::GraphicsPipelineCreateInfo pipelineInfo {
      .stageCount          = static_cast<u32>(shaderStages.size()),
      .pStages             = shaderStages.data(),
      .pVertexInputState   = &vertexInputInfo,
      .pInputAssemblyState = &inputAssembly,
      .pViewportState      = &viewportState,
      .pRasterizationState = &rasterizer,
      .pMultisampleState   = &multisampling,
      .pColorBlendState    = &colorBlending,
      .pDynamicState       = &dynamicState,
      .layout              = mPipelineLayout.get(),
      .renderPass          = mRenderPass.get(),
      .subpass             = 0,
    };

    mGraphicsPipeline = mDevice->createGraphicsPipelineUnique(nullptr, pipelineInfo).value;
  }

  fn createFramebuffers() -> void {
    mSwapChainFramebuffers.resize(mSwapChainImageViews.size());

    for (usize i = 0; i < mSwapChainImageViews.size(); i++) {
      vk::FramebufferCreateInfo framebufferInfo {
        .renderPass      = mRenderPass.get(),
        .attachmentCount = 1,
        .pAttachments    = &mSwapChainImageViews[i].get(),
        .width           = mSwapChainExtent.width,
        .height          = mSwapChainExtent.height,
        .layers          = 1,
      };

      mSwapChainFramebuffers[i] = mDevice->createFramebufferUnique(framebufferInfo);
    }
  }

  fn createShaderModule(const std::vector<char>& code) -> vk::UniqueShaderModule {
    vk::ShaderModuleCreateInfo createInfo { .codeSize = code.size(),
                                            .pCode    = std::bit_cast<const u32*>(code.data()) };

    return mDevice->createShaderModuleUnique(createInfo);
  }

  static fn chooseSwapSurfaceFormat(const std::vector<vk::SurfaceFormatKHR>& availableFormats
  ) -> vk::SurfaceFormatKHR {
    for (const auto& availableFormat : availableFormats)
      if (availableFormat.format == vk::Format::eB8G8R8A8Srgb &&
          availableFormat.colorSpace == vk::ColorSpaceKHR::eSrgbNonlinear)
        return availableFormat;

    return availableFormats[0];
  }

  static fn chooseSwapPresentMode(const std::vector<vk::PresentModeKHR>& availablePresentModes
  ) -> vk::PresentModeKHR {
    for (const auto& availablePresentMode : availablePresentModes)
      if (availablePresentMode == vk::PresentModeKHR::eMailbox)
        return availablePresentMode;

    return vk::PresentModeKHR::eFifo;
  }

  fn chooseSwapExtent(const vk::SurfaceCapabilitiesKHR capabilities) -> vk::Extent2D {
    if (capabilities.currentExtent.width != UINT32_MAX)
      return capabilities.currentExtent;

    u32 width = 0, height = 0;
    std::tie(width, height) = mWindow->getFramebufferSize();

    vk::Extent2D actualExtent = { width, height };

    actualExtent.width =
      std::clamp(actualExtent.width, capabilities.minImageExtent.width, capabilities.maxImageExtent.width);
    actualExtent.height =
      std::clamp(actualExtent.height, capabilities.minImageExtent.height, capabilities.maxImageExtent.height);

    return actualExtent;
  }

  fn querySwapChainSupport(vk::PhysicalDevice device) -> SwapChainSupportDetails {
    SwapChainSupportDetails details;

    details.capabilities  = device.getSurfaceCapabilitiesKHR(mSurface.get());
    details.formats       = device.getSurfaceFormatsKHR(mSurface.get());
    details.present_modes = device.getSurfacePresentModesKHR(mSurface.get());

    return details;
  }

  fn isDeviceSuitable(vk::PhysicalDevice device) -> bool {
    QueueFamilyIndices indices = findQueueFamilies(device);

    bool extensionsSupported = checkDeviceExtensionSupport(device);

    bool swapChainAdequate = false;

    if (extensionsSupported) {
      SwapChainSupportDetails swapChainSupport = querySwapChainSupport(device);
      swapChainAdequate = !swapChainSupport.formats.empty() && !swapChainSupport.present_modes.empty();
    }

    return indices.isComplete() && extensionsSupported && swapChainAdequate;
  }

  static fn checkDeviceExtensionSupport(vk::PhysicalDevice device) -> bool {
    std::vector<vk::ExtensionProperties> availableExtensions = device.enumerateDeviceExtensionProperties();

    std::set<string> requiredExtensions(deviceExtensions.begin(), deviceExtensions.end());

    for (const auto& extension : availableExtensions) requiredExtensions.erase(extension.extensionName);

    return requiredExtensions.empty();
  }

  fn findQueueFamilies(vk::PhysicalDevice device) -> QueueFamilyIndices {
    QueueFamilyIndices indices;

    std::vector<vk::QueueFamilyProperties> queueFamilies = device.getQueueFamilyProperties();

    for (u32 i = 0; i < queueFamilies.size(); i++) {
      if (queueFamilies[i].queueFlags & vk::QueueFlagBits::eGraphics)
        indices.graphics_family = i;

      vk::Bool32 presentSupport = device.getSurfaceSupportKHR(i, mSurface.get());

      if (presentSupport)
        indices.present_family = i;

      if (indices.isComplete())
        break;
    }

    return indices;
  }

  static fn getRequiredExtensions() -> std::vector<const char*> {
    std::span<const char*> extensionsSpan = vkfw::getRequiredInstanceExtensions();

    std::vector extensions(extensionsSpan.begin(), extensionsSpan.end());

    if (enableValidationLayers)
      extensions.emplace_back(vk::EXTDebugUtilsExtensionName);

    return extensions;
  }

  static fn checkValidationLayerSupport() -> bool {
    std::vector<vk::LayerProperties> availableLayers = vk::enumerateInstanceLayerProperties();

    for (const char* layerName : validationLayers) {
      bool layerFound = false;

      for (const auto& layerProperties : availableLayers)
        if (strcmp(layerName, layerProperties.layerName) == 0) {
          layerFound = true;
          break;
        }

      if (!layerFound)
        return false;
    }

    return true;
  }

  static VKAPI_ATTR fn VKAPI_CALL debugCallback(
    VkDebugUtilsMessageSeverityFlagBitsEXT /*messageSeverity*/,
    VkDebugUtilsMessageTypeFlagsEXT /*messageType*/,
    const VkDebugUtilsMessengerCallbackDataEXT* pCallbackData,
    void* /*pUserData*/
  ) -> vk::Bool32 {
    fmt::println("Validation layer: {}", pCallbackData->pMessage);

    return vk::False;
  }
};

fn main() -> i32 {
  VulkanApp app;

  try {
    app.run();
  } catch (const std::exception& e) {
    std::cerr << e.what() << std::endl;
    return EXIT_FAILURE;
  }

  return EXIT_SUCCESS;
}