{-|
Module      : Monomer.Main.Platform
Copyright   : (c) 2018 Francisco Vallarino
License     : BSD-3-Clause (see the LICENSE file)
Maintainer  : fjvallarino@gmail.com
Stability   : experimental
Portability : non-portable

Helper functions for SDL platform related operations.
-}
module Monomer.Main.Platform (
  defaultWindowSize,
  initSDLWindow,
  detroySDLWindow,
  getCurrentMousePos,
  getDrawableSize,
  getWindowSize,
  getViewportSize,
  getPlatform,
  getDisplayDPI
) where

import Control.Monad.State
import Data.Maybe
import Data.Text (Text)
import Foreign (alloca, peek)
import Foreign.C (peekCString, withCString)
import Foreign.C.Types
import SDL (($=))

import qualified Data.Text as T
import qualified Foreign.C.String as STR
import qualified SDL
import qualified SDL.Input.Mouse as Mouse
import qualified SDL.Raw as Raw
import qualified SDL.Raw.Error as SRE

import Monomer.Common
import Monomer.Core.StyleTypes
import Monomer.Main.Types
import Monomer.Event.Types
import Monomer.Widgets.Composite

foreign import ccall unsafe "initGlew" glewInit :: IO CInt
foreign import ccall unsafe "initDpiAwareness" initDpiAwareness :: IO CInt

-- | Default window size if not is specified.
defaultWindowSize :: (Int, Int)
defaultWindowSize = (800, 600)

-- | Creates and initializes a window using the provided configuration.
initSDLWindow :: AppConfig e -> IO (SDL.Window, Double, Double, SDL.GLContext)
initSDLWindow config = do
  SDL.initialize [SDL.InitVideo]
  SDL.HintRenderScaleQuality $= SDL.ScaleLinear

  do renderQuality <- SDL.get SDL.HintRenderScaleQuality
     when (renderQuality /= SDL.ScaleLinear) $
       putStrLn "Warning: Linear texture filtering not enabled!"

  platform <- getPlatform
  initDpiAwareness
  factor <- case platform of
    "Windows" -> getWindowsFactor
    "Linux" -> getLinuxFactor
    _ -> return 1 -- macOS
  let (winW, winH) = (factor * fromIntegral baseW, factor * fromIntegral baseH)

  window <-
    SDL.createWindow
      "Monomer application"
      SDL.defaultWindow {
        SDL.windowInitialSize = SDL.V2 (round winW) (round winH),
        SDL.windowHighDPI = True,
        SDL.windowResizable = windowResizable,
        SDL.windowBorder = windowBorder,
        SDL.windowGraphicsContext = SDL.OpenGLContext customOpenGL
      }

  -- Get device pixel rate
  Size dw _ <- getDrawableSize window
  Size ww _ <- getWindowSize window
  let scaleFactor = factor * userScaleFactor
  let contentRatio = dw / ww
  let (dpr, epr)
        | platform `elem` ["Windows", "Linux"] = (scaleFactor, 1 / scaleFactor)
        | otherwise = (scaleFactor * contentRatio, 1 / scaleFactor) -- macOS

  when (isJust (_apcWindowTitle config)) $
    SDL.windowTitle window $= fromJust (_apcWindowTitle config)

  when windowFullscreen $
    SDL.setWindowMode window SDL.FullscreenDesktop

  when windowMaximized $
    SDL.setWindowMode window SDL.Maximized

  err <- SRE.getError
  err <- STR.peekCString err
  putStrLn err

  ctxRender <- SDL.glCreateContext window

  when (platform == "Windows") $
    void $ SDL.glCreateContext window

  _ <- glewInit

  return (window, dpr, epr, ctxRender)
  where
    customOpenGL = SDL.OpenGLConfig {
      SDL.glColorPrecision = SDL.V4 8 8 8 0,
      SDL.glDepthPrecision = 24,
      SDL.glStencilPrecision = 8,
      --SDL.glProfile = SDL.Core SDL.Debug 3 2,
      SDL.glProfile = SDL.Core SDL.Normal 3 2,
      SDL.glMultisampleSamples = 1
    }
    userScaleFactor = fromMaybe 1 (_apcScaleFactor config)
    (baseW, baseH) = case _apcWindowState config of
      Just (MainWindowNormal size) -> size
      _ -> defaultWindowSize
    windowResizable = fromMaybe True (_apcWindowResizable config)
    windowBorder = fromMaybe True (_apcWindowBorder config)
    windowFullscreen = case _apcWindowState config of
      Just MainWindowFullScreen -> True
      _ -> False
    windowMaximized = case _apcWindowState config of
      Just MainWindowMaximized -> True
      _ -> False

-- | Destroys the provided window, shutdowns the video subsystem and SDL.
detroySDLWindow :: SDL.Window -> IO ()
detroySDLWindow window = do
  putStrLn "About to destroyWindow"
  SDL.destroyWindow window
  Raw.quitSubSystem Raw.SDL_INIT_VIDEO
  SDL.quit

-- | Returns the current mouse position.
getCurrentMousePos :: (MonadIO m) => Double -> m Point
getCurrentMousePos epr = do
  SDL.P (SDL.V2 x y) <- Mouse.getAbsoluteMouseLocation
  return $ Point (epr * fromIntegral x) (epr * fromIntegral y)

-- | Returns the drawable size of the provided window. May differ from window
--   size if HDPI is enabled.
getDrawableSize :: (MonadIO m) => SDL.Window -> m Size
getDrawableSize window = do
  SDL.V2 fbWidth fbHeight <- SDL.glGetDrawableSize window
  return $ Size (fromIntegral fbWidth) (fromIntegral fbHeight)

-- | Returns the size of the provided window.
getWindowSize :: (MonadIO m) => SDL.Window -> m Size
getWindowSize window = do
  SDL.V2 rw rh <- SDL.get (SDL.windowSize window)

  return $ Size (fromIntegral rw) (fromIntegral rh)

{-|
Returns the viewport size. This is the size of the viewport the application will
render to and, depending on the platform, may match window size or not. For
example, on Windows and Linux Wayland this size may be smaller than the window
size because of dpr scaling.
-}
getViewportSize :: (MonadIO m) => SDL.Window -> Double -> m Size
getViewportSize window dpr = do
  SDL.V2 fw fh <- SDL.glGetDrawableSize window

  return $ Size (fromIntegral fw / dpr) (fromIntegral fh / dpr)

-- | Returns the name of the host OS.
getPlatform :: (MonadIO m) => m Text
getPlatform = do
  platform <- liftIO . peekCString =<< Raw.getPlatform

  return $ T.pack platform

-- | Returns the diagonal, horizontal and vertical DPI of the main display.
getDisplayDPI :: IO (Double, Double, Double)
getDisplayDPI =
  alloca $ \pddpi ->
    alloca $ \phdpi ->
      alloca $ \pvdpi -> do
        Raw.getDisplayDPI 0 pddpi phdpi pvdpi
        ddpi <- peek pddpi
        hdpi <- peek phdpi
        vdpi <- peek pvdpi
        return (realToFrac ddpi, realToFrac hdpi, realToFrac vdpi)

-- | Returns the default resize factor for Windows
getWindowsFactor :: IO Double
getWindowsFactor = do
  (ddpi, hdpi, vdpi) <- getDisplayDPI
  return (hdpi / 96)

{-|
Returns a resizing factor to handle HiDPI on Linux. Currently only tested on
Wayland (Ubuntu 21.04).
-}
getLinuxFactor :: IO Double
getLinuxFactor =
  alloca $ \pmode -> do
    Raw.getCurrentDisplayMode 0 pmode
    mode <- peek pmode
    let width = Raw.displayModeW mode
    -- Applies scale in half steps (1, 1.5, 2, etc)
    let baseFactor = 2 * fromIntegral width / 1920

    if width <= 1920
      then return 1
      else return (fromIntegral (ceiling baseFactor) / 2)