module DependencyGenerator
  ( DepGenM
  , DepGenM'
  , evalDepGenM
  , inject
  , runFunction
  , runFunctionIO
  , mapDepGenM
  , mapDepGenM_
  , filterDepGenM

  , joinPaths
  , isImageFilename
  , convertedImageFilename
  , applyTemplate
  , listDirectory
  , readTemplate
  , convertImage
  , saveFile
  , makeDir
  , runPandoc
  ) where

import Types.Token (Token(..))
import Types.Values
import Types.Value (Valuable(..))
import Types.Function (Function(..))
import Types.FunctionIO (FunctionIO(..))
import Types.Dependency (Action(..), Dependency, makeDependency)

import Control.Monad.State (MonadState, State, runState, put, get)
import Control.Monad.Writer (MonadWriter, WriterT, execWriterT, tell)

newtype DepGenM a = DepGenM { unDepGenM :: WriterT [Dependency] (State Int) a }
  deriving (Functor, Applicative, Monad, MonadState Int, MonadWriter [Dependency])

type DepGenM' a = DepGenM (Token a)

evalDepGenM' :: Int -> DepGenM () -> ([Dependency], Int)
evalDepGenM' top m = runState (execWriterT (unDepGenM m)) top

evalDepGenM :: DepGenM () -> [Dependency]
evalDepGenM m = fst (evalDepGenM' 0 m)

tellDep :: Dependency -> DepGenM ()
tellDep dep = tell [dep]

genDependencyM :: (Token a -> DepGenM Dependency) -> DepGenM' a
genDependencyM f = do
  top <- get
  let top' = top + 1
      target = Token top'
  put top'
  result <- f target
  tellDep result
  pure target

genDependency :: (Token a -> Dependency) -> DepGenM' a
genDependency f = genDependencyM (pure . f)

inject :: Valuable a => a -> DepGenM' a
inject x = genDependency (makeDependency NoToken (Inject (toValue x)))

getListElem :: Token [a] -> DepGenM' a
getListElem outer = genDependency (makeDependency outer GetListElem)

setListElem :: Token a -> Token [a] -> DepGenM ()
setListElem a outer = do
  tellDep (makeDependency a SetListElem outer)

runFunction :: Function -> Token a -> DepGenM' b
runFunction f input = genDependency (makeDependency input (Function f))

runFunctionIO :: FunctionIO -> Token a -> DepGenM' b
runFunctionIO f input = genDependency (makeDependency input (FunctionIO f))

mapDepGenM :: (Token a -> DepGenM' b) -> Token [a] -> DepGenM' [b]
mapDepGenM f input = genDependencyM $ \target -> do
  top <- get
  let (res, top') = evalDepGenM' top $ do
        inp <- getListElem input
        outp <- f inp
        setListElem outp target
  put top'
  pure (makeDependency input (MapComp res) target)

mapDepGenM_ :: (Token a -> DepGenM ()) -> Token [a] -> DepGenM ()
mapDepGenM_ f input = do
  _ <- mapDepGenM (\x -> f x >> pure NoToken) input
  pure ()

filterDepGenM :: (Token a -> DepGenM' Bool) -> Token [a] -> DepGenM' [a]
filterDepGenM f input = do
  conds <- mapDepGenM f input
  genDependency (makeDependency (TupleToken input conds) FilterComp)


joinPaths :: Token (FilePath, FilePath) -> DepGenM' FilePath
joinPaths = runFunction JoinPaths

isImageFilename :: Token FilePath -> DepGenM' Bool
isImageFilename = runFunction IsImageFilename

convertedImageFilename :: Token FilePath -> DepGenM' FilePath
convertedImageFilename = runFunction ConvertedImageFilename

applyTemplate :: Token (Template, String) -> DepGenM' String
applyTemplate = runFunction ApplyTemplate

listDirectory :: Token FilePath -> DepGenM' [FilePath]
listDirectory = runFunctionIO ListDirectory

readTemplate :: Token FilePath -> DepGenM' Template
readTemplate = runFunctionIO ReadTemplate

convertImage :: Token ((FilePath, FilePath), ImageConversionSettings) -> DepGenM ()
convertImage input = do
  _ <- runFunctionIO ConvertImage input
  pure ()

saveFile :: Token (String, FilePath) -> DepGenM ()
saveFile input = do
  _ <- runFunctionIO SaveFile input
  pure ()

makeDir :: Token FilePath -> DepGenM ()
makeDir input = do
  _ <- runFunctionIO MakeDir input
  pure ()

runPandoc :: Token FilePath -> DepGenM' String
runPandoc = runFunctionIO RunPandoc