#include <vulkan/vulkan.h>

#include <SDL2/SDL.h>
#include <SDL2/SDL_vulkan.h>

//#define _USE_MATH_DEFINES // Will be needed when/if I need to # include <cmath>

#define GLM_FORCE_RADIANS
#define GLM_FORCE_DEPTH_ZERO_TO_ONE
#include <glm/vec4.hpp>
#include <glm/mat4x4.hpp>

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

#include "game-gui-sdl.hpp"

using namespace std;
using namespace glm;

const int SCREEN_WIDTH = 800;
const int SCREEN_HEIGHT = 600;

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

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

struct QueueFamilyIndices {
    optional<uint32_t> graphicsFamily;
    optional<uint32_t> presentFamily;

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

static VKAPI_ATTR VkBool32 VKAPI_CALL debugCallback(
      VkDebugUtilsMessageSeverityFlagBitsEXT messageSeverity,
      VkDebugUtilsMessageTypeFlagsEXT messageType,
      const VkDebugUtilsMessengerCallbackDataEXT* pCallbackData,
      void* pUserData) {
   cerr << "validation layer: " << pCallbackData->pMessage << endl;

   return VK_FALSE;
}

VkResult CreateDebugUtilsMessengerEXT(VkInstance instance,
      const VkDebugUtilsMessengerCreateInfoEXT* pCreateInfo,
      const VkAllocationCallbacks* pAllocator,
      VkDebugUtilsMessengerEXT* pDebugMessenger) {
   auto func = (PFN_vkCreateDebugUtilsMessengerEXT) vkGetInstanceProcAddr(
      instance, "vkCreateDebugUtilsMessengerEXT");

   if (func != nullptr) {
      return func(instance, pCreateInfo, pAllocator, pDebugMessenger);
   } else {
      return VK_ERROR_EXTENSION_NOT_PRESENT;
   }
}

void DestroyDebugUtilsMessengerEXT(VkInstance instance,
      VkDebugUtilsMessengerEXT debugMessenger,
      const VkAllocationCallbacks* pAllocator) {
   auto func = (PFN_vkDestroyDebugUtilsMessengerEXT) vkGetInstanceProcAddr(
      instance, "vkDestroyDebugUtilsMessengerEXT");

   if (func != nullptr) {
      func(instance, debugMessenger, pAllocator);
   }
}

class VulkanGame {
   public:
      void run() {
         if (initWindow() == RTWO_ERROR) {
            return;
         }
         initVulkan();
         mainLoop();
         cleanup();
      }
   private:
      GameGui* gui = new GameGui_SDL();
      SDL_Window* window = nullptr;

      VkInstance instance;
      VkDebugUtilsMessengerEXT debugMessenger;
      VkSurfaceKHR surface;

      VkPhysicalDevice physicalDevice = VK_NULL_HANDLE;
      VkDevice device;

      VkQueue graphicsQueue;
      VkQueue presentQueue;

      // both SDL and GLFW create window functions return NULL on failure
      bool initWindow() {
         if (gui->Init() == RTWO_ERROR) {
            cout << "UI library could not be initialized!" << endl;
            return RTWO_ERROR;
         } else {
            // On Apple's OS X you must set the NSHighResolutionCapable Info.plist property to YES,
            // otherwise you will not receive a High DPI OpenGL canvas.

            // TODO: Move this into some generic method in game-gui-sdl
            window = SDL_CreateWindow("Vulkan Game",
               SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
               SCREEN_WIDTH, SCREEN_HEIGHT,
               SDL_WINDOW_VULKAN | SDL_WINDOW_SHOWN);

            if (window == nullptr) {
               cout << "Window could not be created!" << endl;
               return RTWO_ERROR;
            } else {
               return RTWO_SUCCESS;
            }
         }
      }

      void initVulkan() {
         createInstance();
         setupDebugMessenger();
         createSurface();
         pickPhysicalDevice();
         createLogicalDevice();
      }

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

         VkApplicationInfo appInfo = {};
         appInfo.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
         appInfo.pApplicationName = "Vulkan Game";
         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;

         vector<const char*> extensions = getRequiredExtensions();
         createInfo.enabledExtensionCount = static_cast<uint32_t>(extensions.size());
         createInfo.ppEnabledExtensionNames = extensions.data();

         cout << endl << "SDL extensions:" << endl;
         for (const char* extensionName : extensions) {
            cout << extensionName << endl;
         }
         cout << endl;

         VkDebugUtilsMessengerCreateInfoEXT debugCreateInfo;
         if (enableValidationLayers) {
            createInfo.enabledLayerCount = static_cast<uint32_t>(validationLayers.size());
            createInfo.ppEnabledLayerNames = validationLayers.data();

            populateDebugMessengerCreateInfo(debugCreateInfo);
            createInfo.pNext = &debugCreateInfo;
         } else {
            createInfo.enabledLayerCount = 0;

            createInfo.pNext = nullptr;
         }

         if (vkCreateInstance(&createInfo, nullptr, &instance) != VK_SUCCESS) {
            throw runtime_error("failed to create instance!");
         }
      }

      void setupDebugMessenger() {
         if (!enableValidationLayers) return;

         VkDebugUtilsMessengerCreateInfoEXT createInfo;
         populateDebugMessengerCreateInfo(createInfo);

         if (CreateDebugUtilsMessengerEXT(instance, &createInfo, nullptr, &debugMessenger) != VK_SUCCESS) {
            throw runtime_error("failed to setup debug messenger!");
         }
      }

      void createSurface() {
         //SDL_Surface* screenSurface = nullptr;

         if (!SDL_Vulkan_CreateSurface(window, instance, &surface)) {
            throw runtime_error("failed to create window surface!");
         }

         /*
         if (glfwCreateWindowSurface(instance, window, nullptr, &surface) != VK_SUCCESS) {
            throw runtime_error("failed to create window surface!");
         }
         */
      }

      void pickPhysicalDevice() {
         uint32_t deviceCount = 0;
         vkEnumeratePhysicalDevices(instance, &deviceCount, nullptr);

         if (deviceCount == 0) {
            throw runtime_error("failed to find GPUs with Vulkan support!");
         }

         vector<VkPhysicalDevice> devices(deviceCount);
         vkEnumeratePhysicalDevices(instance, &deviceCount, devices.data());

         cout << endl << "Graphics cards:" << endl;
         for (const VkPhysicalDevice& device : devices) {
            if (isDeviceSuitable(device)) {
               physicalDevice = device;
               break;
            }
         }
         cout << endl;

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

      bool isDeviceSuitable(VkPhysicalDevice device) {
         VkPhysicalDeviceProperties deviceProperties;
         VkPhysicalDeviceFeatures deviceFeatures;

         vkGetPhysicalDeviceProperties(device, &deviceProperties);
         vkGetPhysicalDeviceFeatures(device, &deviceFeatures);

         cout << "Device: " << deviceProperties.deviceName << endl;

         QueueFamilyIndices indices = findQueueFamilies(device);

         return indices.isComplete();
      }

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

         vector<VkDeviceQueueCreateInfo> queueCreateInfos;
         set<uint32_t> uniqueQueueFamilies = {indices.graphicsFamily.value(), indices.presentFamily.value()};

         float queuePriority = 1.0f;
         for (uint32_t queueFamily : uniqueQueueFamilies) {
            VkDeviceQueueCreateInfo queueCreateInfo = {};

            queueCreateInfo.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
            queueCreateInfo.queueFamilyIndex = queueFamily;
            queueCreateInfo.queueCount = 1;
            queueCreateInfo.pQueuePriorities = &queuePriority;

            queueCreateInfos.push_back(queueCreateInfo);
         }

         VkPhysicalDeviceFeatures deviceFeatures = {};

         VkDeviceCreateInfo createInfo = {};
         createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;

         createInfo.queueCreateInfoCount = static_cast<uint32_t>(queueCreateInfos.size());;
         createInfo.pQueueCreateInfos = queueCreateInfos.data();

         createInfo.pEnabledFeatures = &deviceFeatures;

         createInfo.enabledExtensionCount = 0;

         // These fields are ignored  by up-to-date Vulkan implementations,
         // but it's a good idea to set them for backwards compatibility
         if (enableValidationLayers) {
            createInfo.enabledLayerCount = static_cast<uint32_t>(validationLayers.size());
            createInfo.ppEnabledLayerNames = validationLayers.data();
         } else {
            createInfo.enabledLayerCount = 0;
         }

         if (vkCreateDevice(physicalDevice, &createInfo, nullptr, &device) != VK_SUCCESS) {
            throw runtime_error("failed to create logical device!");
         }

         vkGetDeviceQueue(device, indices.graphicsFamily.value(), 0, &graphicsQueue);
         vkGetDeviceQueue(device, indices.presentFamily.value(), 0, &presentQueue);
      }

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

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

         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;
      }

      QueueFamilyIndices findQueueFamilies(VkPhysicalDevice device) {
         QueueFamilyIndices indices;

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

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

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

            VkBool32 presentSupport = false;
            vkGetPhysicalDeviceSurfaceSupportKHR(device, i, surface, &presentSupport);

            if (queueFamily.queueCount > 0 && presentSupport) {
               indices.presentFamily = i;
            }

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

            i++;
         }

         return indices;
      }

      void populateDebugMessengerCreateInfo(VkDebugUtilsMessengerCreateInfoEXT& createInfo) {
         createInfo = {};
         createInfo.sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_MESSENGER_CREATE_INFO_EXT;
         createInfo.messageSeverity = VK_DEBUG_UTILS_MESSAGE_SEVERITY_VERBOSE_BIT_EXT | VK_DEBUG_UTILS_MESSAGE_SEVERITY_WARNING_BIT_EXT | VK_DEBUG_UTILS_MESSAGE_SEVERITY_ERROR_BIT_EXT;
         createInfo.messageType = VK_DEBUG_UTILS_MESSAGE_TYPE_GENERAL_BIT_EXT | VK_DEBUG_UTILS_MESSAGE_TYPE_VALIDATION_BIT_EXT | VK_DEBUG_UTILS_MESSAGE_TYPE_PERFORMANCE_BIT_EXT;
         createInfo.pfnUserCallback = debugCallback;
      }

      vector<const char*> getRequiredExtensions() {
         uint32_t extensionCount = 0;
         SDL_Vulkan_GetInstanceExtensions(window, &extensionCount, nullptr);

         vector<const char*> extensions(extensionCount);
         SDL_Vulkan_GetInstanceExtensions(window, &extensionCount, extensions.data());

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

         return extensions;
      }

      void mainLoop() {
         // TODO: Create some generic event-handling functions in game-gui-*
         SDL_Event e;
         bool quit = false;

         /*
         screenSurface = SDL_GetWindowSurface(window);
         cout << "Got here" << endl;
         cout << (screenSurface == nullptr ? "true" : "false") << endl;

         SDL_FillRect(screenSurface, nullptr, SDL_MapRGB(screenSurface->format, 0xFF, 0xFF, 0xFF));
         cout << "Filled" << endl;

         SDL_UpdateWindowSurface(window);
         cout << "Updated" << endl;
         */

         while (!quit) {
            while (SDL_PollEvent(&e)) {
               if (e.type == SDL_QUIT) {
                  quit = true;
               }
               if (e.type == SDL_KEYDOWN) {
                  quit = true;
               }
               if (e.type == SDL_MOUSEBUTTONDOWN) {
                  quit = true;
               }
            }
         }
      }

      void cleanup() {
         vkDestroyDevice(device, nullptr);

         if (enableValidationLayers) {
            DestroyDebugUtilsMessengerEXT(instance, debugMessenger, nullptr);
         }

         vkDestroySurfaceKHR(instance, surface, nullptr);
         vkDestroyInstance(instance, nullptr);

         // TODO: Move this into some generic method in game-gui-sdl
         SDL_DestroyWindow(window);

         gui->Shutdown();
         delete gui;
      }
};

int main(int argc, char* argv[]) {

#ifdef NDEBUG
   cout << "DEBUGGING IS OFF" << endl;
#else
   cout << "DEBUGGING IS ON" << endl;
#endif

   mat4 matrix;
   vec4 vec;
   vec4 test = matrix * vec;

   cout << "Starting Vulkan game..." << endl;

   VulkanGame game;

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

   cout << "Finished running the game" << endl;

   return EXIT_SUCCESS;
}