{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FlexibleContexts #-}
module Init where

import qualified Control.Concurrent.STM as STM
import Control.Monad
import Control.Monad.IO.Class
import Control.Monad.Reader
import Control.Monad.Trans.Resource
import qualified Data.Vector as V
import qualified SDL hiding (V2)
import qualified SDL.Video.Vulkan as SDL
import Foreign.Ptr
import Linear as L
import qualified Vulkan.Core10 as Vk
import qualified Vulkan.Extensions.VK_KHR_swapchain as Khr
import qualified Vulkan.Extensions.VK_KHR_surface as Khr

-- internal imports

import Instance
import Devices
import GraphicsPipeline
import Framebuffers
import CommandBuffer
import Memory
import Types
import Mesh

initEngine
  :: Render EngineData
initEngine = do
  -- initialize SDL2 with all subsystems
  void $ allocate_
    SDL.initializeAll
    (do
      putStrLn "This is the end!"
      SDL.quit
      )

  -- create a window configuration
  let windowConfig = SDL.defaultWindow
        { SDL.windowGraphicsContext = SDL.VulkanContext -- enable Vulkan support
        }

  -- load vulkan library
  SDL.vkLoadLibrary Nothing

  -- create the window
  (_, window) <-
    allocate
      (SDL.createWindow "Haskell ❤️ Vulkan" windowConfig)
      (\window -> do
        liftIO $ putStrLn "destroying window"
        SDL.destroyWindow window
        )

  -- initialize vúlkan data structures
  initVulkan window


initVulkan
  :: SDL.Window
  -> Render EngineData
initVulkan window = do

  vulkanInstance <- createInstance window

  (_, vulkanSurface) <- allocate
    (Khr.SurfaceKHR <$>
      SDL.vkCreateSurface window (castPtr (Vk.instanceHandle vulkanInstance))
      )
    (\vulkanSurface -> do
      putStrLn "destroying surface"
      Khr.destroySurfaceKHR vulkanInstance vulkanSurface Nothing
      )

  vulkanPhysicalDevice <- pickPhysicalDevice vulkanInstance
  (vulkanLogicalDevice, surfaceFormats) <- createLogicalDevice vulkanPhysicalDevice vulkanSurface

  allocator <- initAllocator vulkanPhysicalDevice vulkanLogicalDevice vulkanInstance

  dimensions <- liftIO $ SDL.windowInitialSize <$> SDL.getWindowConfig window
  (swapchain, surfaceFormat, depthImageView, depthAllocatedImage) <-
    createSwapchain vulkanSurface surfaceFormats dimensions vulkanLogicalDevice allocator
  imageViews <- getImageViewHandles swapchain surfaceFormat vulkanLogicalDevice
  meshVertexShader <- loadShader vulkanLogicalDevice "shadersrc/mesh.vert" "vert"
  meshFragmentShader <- loadShader vulkanLogicalDevice "shadersrc/rainbow.frag" "frag"
  renderPass <- createRenderPass vulkanLogicalDevice (Khr.format surfaceFormat) Vk.FORMAT_D32_SFLOAT
  meshLayout <- createMeshPipelineLayout vulkanLogicalDevice
  let meshContainer = ShaderContainer (Just meshVertexShader) (Just meshFragmentShader)
  createGraphicsPipelines
    vulkanLogicalDevice
    renderPass
    meshContainer
    dimensions
    meshLayout
    (Just (createDepthStencilStateCreateInfo True True Vk.COMPARE_OP_LESS_OR_EQUAL))

  frameBuffers <- createFramebuffer vulkanLogicalDevice renderPass imageViews depthImageView dimensions

  (commandPool, graphicsQueue) <- createCommandPool vulkanPhysicalDevice vulkanLogicalDevice
  commandBuffer <- createCommandBuffer vulkanLogicalDevice commandPool (length frameBuffers)

  (imageAvailableSemaphore, renderFinishedSemaphore, inFlightFence) <-
    createSyncObjects vulkanLogicalDevice

  loadMeshes allocator

  initScene

  return $ EngineData
    window
    dimensions
    vulkanPhysicalDevice
    vulkanLogicalDevice
    vulkanInstance
    swapchain
    graphicsQueue
    commandBuffer
    frameBuffers
    meshLayout
    renderPass
    inFlightFence
    imageAvailableSemaphore
    renderFinishedSemaphore
    allocator
    depthImageView
    depthAllocatedImage
    Vk.FORMAT_D32_SFLOAT

initScene :: (MonadReader ReadState m, MonadIO m) => m ()
initScene = do
  let mask = RenderObject
        { objectMesh     = "mask"
        , objectMaterial = "defaultMesh"
        , objectMatrix   = identity
        }

  renderableContainer <- asks renderables
  renderableVector <- liftIO $ STM.atomically $ STM.readTMVar renderableContainer

  void $ liftIO $ STM.atomically $ STM.swapTMVar renderableContainer $
    renderableVector `V.snoc` mask