module Main (main) where

import qualified Data.Text.Lazy              as LT
import qualified Data.Text.Lazy.IO           as IO
import           Data.Time.Clock             as Time (diffUTCTime,
                                                      getCurrentTime,
                                                      nominalDiffTimeToSeconds)
import qualified Language.GLSL.AST           as GLSL
import qualified Language.GLSL.Optimizer     as Opt
import qualified Language.GLSL.Optimizer.DFG as DFG
import qualified Language.GLSL.Parser        as GLSL
import qualified Language.GLSL.PrettyPrint   as GLSL
import qualified System.Environment          as Env

main :: IO ()
main = Env.getArgs >>= mapM_ process

parseShader :: LT.Text -> Either String (GLSL.GLSL ())
parseShader = GLSL.parseShader

process :: FilePath -> IO ()
process inFile = do
  putStrLn "Loading file..."
  inText <- IO.readFile inFile
  putStrLn "Parsing file..."
  case parseShader inText of
    Left err -> fail err
    Right ok -> do
      putStrLn "Generating data flow graph (opt.dot)..."
      let dfg = DFG.genDFG ok
      DFG.toDot "opt.dot" dfg
      -- DFG.toSvg dfg "../opt.svg"
      putStrLn "Optimizing shader (opt.glsl)..."
      s <- Time.getCurrentTime
      let outText = GLSL.printShader $ Opt.optimize ok
      IO.writeFile "opt.glsl" outText
      e <- Time.getCurrentTime
      let elapsed = Time.nominalDiffTimeToSeconds $ Time.diffUTCTime e s
      putStrLn $ "Optimizer took " <> show elapsed <> "s"
      let inLen = LT.length inText
          outLen = LT.length outText
          factor :: Float
          factor = fromIntegral inLen / fromIntegral outLen
      putStrLn $ "Size: " <> showKB inLen <> " -> "
                  <> showKB outLen <> ", " <> show factor <> "x reduction"


showKB :: (Show a, Integral a) => a -> String
showKB x | x > 1024 * 1024 = show (x `div` (1024 * 1024)) <> "MiB"
showKB x | x > 1024 = show (x `div` 1024) <> "KiB"
showKB x = show x <> "B"