/*
 * Stopped at https://vkguide.dev/docs/new_chapter_1/vulkan_mainloop_code/
 */

#include "vk_engine.h"
#include "vk_images.h"
#include <print>

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

#include <vk_types.h>
#include <vk_initializers.h>
#include "VkBootstrap.h"

#include <chrono>
#include <thread>

constexpr bool bUseValidationLayers = false;

VulkanEngine* loadedEngine = nullptr;

VulkanEngine& VulkanEngine::Get() { 
  return *loadedEngine;
}

void VulkanEngine::init()
{
  assert(loadedEngine == nullptr);
  loadedEngine = this;

  // We initialize SDL and create a window with it. 
  SDL_Init(SDL_INIT_VIDEO);

  SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_VULKAN);

  _window = SDL_CreateWindow(
      "Vulkan Engine",
      SDL_WINDOWPOS_UNDEFINED,
      SDL_WINDOWPOS_UNDEFINED,
      int(_windowExtent.width),
      int(_windowExtent.height),
      window_flags);

  init_vulkan();
  init_swapchain();
  init_commands();
  init_sync_structures();

  //everything went fine
  _isInitialized = true;
}

void VulkanEngine::cleanup()
{  
  if (_isInitialized) {
    vkDeviceWaitIdle(_device);

    for(int i = 0; i < FRAME_OVERLAP; i++) {
      vkDestroyCommandPool(_device, _frames[i]._commandPool, nullptr);

      //destroy sync objects
      vkDestroyFence(_device, _frames[i]._renderFence, nullptr);
      vkDestroySemaphore(_device, _frames[i]._renderSemaphore, nullptr);
      vkDestroySemaphore(_device ,_frames[i]._swapchainSemaphore, nullptr);
    }

    destroy_swapchain();

    vkDestroySurfaceKHR(_instance, _surface, nullptr);
    vkDestroyDevice(_device, nullptr);
    vkb::destroy_debug_utils_messenger(_instance, _debug_messenger);
    vkDestroyInstance(_instance, nullptr);
    SDL_DestroyWindow(_window);
  }

  loadedEngine = nullptr;
}

void VulkanEngine::draw()
{
  // wait until the gpu has finished rendering the last frame. Timeout of 1 second
  VK_CHECK(vkWaitForFences(_device, 1, &get_current_frame()._renderFence, true, 1000000000));
  VK_CHECK(vkResetFences(_device, 1, &get_current_frame()._renderFence));

  uint32_t swapchainImageIndex = 0;
  VK_CHECK(vkAcquireNextImageKHR(_device, _swapchain, 1000000000, get_current_frame()._swapchainSemaphore, nullptr, &swapchainImageIndex));

  VkCommandBuffer cmd = get_current_frame()._mainCommandBuffer;
  VK_CHECK(vkResetCommandBuffer(cmd, 0));

  VkCommandBufferBeginInfo cmdBeginInfo = vkinit::command_buffer_begin_info(VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT);

  VK_CHECK(vkBeginCommandBuffer(cmd, &cmdBeginInfo));

  vkutil::transition_image(cmd, _swapchainImages[swapchainImageIndex], VK_IMAGE_LAYOUT_UNDEFINED, VK_IMAGE_LAYOUT_GENERAL);

  VkClearColorValue clearValue;
  float flash = std::abs(std::sin(_frameNumber / 120.0f));
  clearValue = { { 0.0f, 0.0f, flash, 1.0f} };

  VkImageSubresourceRange clearRange = vkinit::image_subresource_range(VK_IMAGE_ASPECT_COLOR_BIT);

  vkCmdClearColorImage(cmd, _swapchainImages[swapchainImageIndex], VK_IMAGE_LAYOUT_GENERAL, &clearValue, 1, &clearRange);

  vkutil::transition_image(cmd, _swapchainImages[swapchainImageIndex], VK_IMAGE_LAYOUT_GENERAL, VK_IMAGE_LAYOUT_PRESENT_SRC_KHR);
  VK_CHECK(vkEndCommandBuffer(cmd));

  //prepare the submission to the queue. 
  //we want to wait on the _presentSemaphore, as that semaphore is signaled when the swapchain is ready
  //we will signal the _renderSemaphore, to signal that rendering has finished

  VkCommandBufferSubmitInfo cmdinfo = vkinit::command_buffer_submit_info(cmd);	

  VkSemaphoreSubmitInfo waitInfo = vkinit::semaphore_submit_info(VK_PIPELINE_STAGE_2_COLOR_ATTACHMENT_OUTPUT_BIT_KHR,get_current_frame()._swapchainSemaphore);
  VkSemaphoreSubmitInfo signalInfo = vkinit::semaphore_submit_info(VK_PIPELINE_STAGE_2_ALL_GRAPHICS_BIT, get_current_frame()._renderSemaphore);	

  VkSubmitInfo2 submit = vkinit::submit_info(&cmdinfo,&signalInfo,&waitInfo);	

  //submit command buffer to the queue and execute it.
  // _renderFence will now block until the graphic commands finish execution
  VK_CHECK(vkQueueSubmit2(_graphicsQueue, 1, &submit, get_current_frame()._renderFence));

  //prepare present
  // this will put the image we just rendered to into the visible window.
  // we want to wait on the _renderSemaphore for that, 
  // as its necessary that drawing commands have finished before the image is displayed to the user
  VkPresentInfoKHR presentInfo = {};
  presentInfo.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
  presentInfo.pNext = nullptr;
  presentInfo.pSwapchains = &_swapchain;
  presentInfo.swapchainCount = 1;

  presentInfo.pWaitSemaphores = &get_current_frame()._renderSemaphore;
  presentInfo.waitSemaphoreCount = 1;

  presentInfo.pImageIndices = &swapchainImageIndex;

  VK_CHECK(vkQueuePresentKHR(_graphicsQueue, &presentInfo));

  //increase the number of frames drawn
  _frameNumber++;
}

void VulkanEngine::run()
{
  SDL_Event e;
  bool bQuit = false;
  bool stop_rendering = false;

  //main loop
  while(!bQuit)
  {
    //Handle events on queue
    while(SDL_PollEvent(&e) != 0)
    {
      //close the window when user alt-f4s or clicks the X button      
      if(e.type == SDL_QUIT) {
        bQuit = true;
      }

      if(e.type == SDL_WINDOWEVENT) {
        if(e.window.event == SDL_WINDOWEVENT_MINIMIZED) {
          stop_rendering = true;
        }

        if(e.window.event == SDL_WINDOWEVENT_RESTORED) {
          stop_rendering = false;
        }
      }
    }

    if(stop_rendering) {
      std::this_thread::sleep_for(std::chrono::milliseconds(100));
      continue;
    }

    draw();
  }
}

void VulkanEngine::init_vulkan() {
  vkb::InstanceBuilder builder;

  // make the vulkan instance, with basic debug features

  auto inst_ret = builder.set_app_name("Example Vulkan Application")
    .request_validation_layers(bUseValidationLayers)
    .use_default_debug_messenger()
    .require_api_version(1, 3, 0)
    .build();

  vkb::Instance vkb_inst = inst_ret.value();

  // grab the instance
  _instance = vkb_inst.instance;
  _debug_messenger = vkb_inst.debug_messenger;

  SDL_Vulkan_CreateSurface(_window, _instance, &_surface);

  //vulkan 1.3 features
  VkPhysicalDeviceVulkan13Features features{ .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_VULKAN_1_3_FEATURES };
  features.dynamicRendering = true;
  features.synchronization2 = true;

  //vulkan 1.2 features
  VkPhysicalDeviceVulkan12Features features12{ .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_VULKAN_1_2_FEATURES };
  features12.bufferDeviceAddress = true;
  features12.descriptorIndexing = true;

  // use vkbootstrap to select a gpu
  // We want a gpu that can write to the SDL surface
  vkb::PhysicalDeviceSelector selector{ vkb_inst };
  vkb::PhysicalDevice physicalDevice = selector
    .set_minimum_version(1, 4)
    .set_required_features_13(features)
    .set_required_features_12(features12)
    .set_surface(_surface)
    .select()
    .value();

  vkb::DeviceBuilder deviceBuilder{physicalDevice};
  vkb::Device vkbDevice = deviceBuilder.build().value();

  _device = vkbDevice.device;
  _chosenGPU = physicalDevice.physical_device;

  _graphicsQueue = vkbDevice.get_queue(vkb::QueueType::graphics).value();
  _graphicsQueueFamily = vkbDevice.get_queue_index(vkb::QueueType::graphics).value();
}

void VulkanEngine::create_swapchain(uint32_t width, uint32_t height) {
  vkb::SwapchainBuilder swapchainBuilder{ _chosenGPU, _device, _surface};

  _swapchainImageFormat = VK_FORMAT_B8G8R8A8_UNORM;

  vkb::Swapchain vkbSwapchain = swapchainBuilder
    //.use_default_format_selection()
    .set_desired_format(VkSurfaceFormatKHR{.format=_swapchainImageFormat})
    // use vsync present mode
    .set_desired_present_mode(VK_PRESENT_MODE_FIFO_KHR)
    .set_desired_extent(width, height)
    .add_image_usage_flags(VK_IMAGE_USAGE_TRANSFER_DST_BIT)
    .build()
    .value();

  _swapchainExtent = vkbSwapchain.extent;
  _swapchain = vkbSwapchain.swapchain;
  _swapchainImages = vkbSwapchain.get_images().value();
  _swapchainImageViews = vkbSwapchain.get_image_views().value();
}

void VulkanEngine::destroy_swapchain() {
  vkDestroySwapchainKHR(_device, _swapchain, nullptr);

  for(auto& view : _swapchainImageViews) {
    vkDestroyImageView(_device, view, nullptr);
  }
}

void VulkanEngine::init_swapchain() {
  create_swapchain(_windowExtent.width, _windowExtent.height);
}

void VulkanEngine::init_commands() {
  	//create a command pool for commands submitted to the graphics queue.
	//we also want the pool to allow for resetting of individual command buffers
	VkCommandPoolCreateInfo commandPoolInfo = vkinit::command_pool_create_info(_graphicsQueueFamily, VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT);

	for (int i = 0; i < FRAME_OVERLAP; i++) {

		VK_CHECK(vkCreateCommandPool(_device, &commandPoolInfo, nullptr, &_frames[i]._commandPool));

		// allocate the default command buffer that we will use for rendering
		VkCommandBufferAllocateInfo cmdAllocInfo = vkinit::command_buffer_allocate_info(_frames[i]._commandPool, 1);

		VK_CHECK(vkAllocateCommandBuffers(_device, &cmdAllocInfo, &_frames[i]._mainCommandBuffer));
	}
}

void VulkanEngine::init_sync_structures() {
  VkFenceCreateInfo fenceCreateInfo = vkinit::fence_create_info(VK_FENCE_CREATE_SIGNALED_BIT);
  VkSemaphoreCreateInfo semaphoreCreateInfo = vkinit::semaphore_create_info();

  for (int i = 0; i < FRAME_OVERLAP; i++) {
    VK_CHECK(vkCreateFence(_device, &fenceCreateInfo, nullptr, &_frames[i]._renderFence));

    VK_CHECK(vkCreateSemaphore(_device, &semaphoreCreateInfo, nullptr, &_frames[i]._swapchainSemaphore));
    VK_CHECK(vkCreateSemaphore(_device, &semaphoreCreateInfo, nullptr, &_frames[i]._renderSemaphore));
  }
}