module Hakyll.Util
    (
    -- * Route utils
      dropParentRoute
    , modifyDirRoute
    , modifyDirRoute_
    -- * Context utils
    , transformContext
    , transformContext_
    ) where

import Prolog
import Hakyll
import System.FilePath

-- | Drop some number of parent directories
dropParentRoute :: Int -> Routes
dropParentRoute n = modifyDirRoute_ $ drop n

modifyDirRoute :: ([FilePath] -> FilePath) -> Routes
modifyDirRoute f = customRoute $ f . splitDirectories . toFilePath

modifyDirRoute_ :: ([FilePath] -> [FilePath]) -> Routes
modifyDirRoute_ f = modifyDirRoute $ joinPath . f

-- | General contramap
transformContext :: (Item b -> Compiler (Item a)) -> Context a -> Context b
transformContext f (Context c) = Context $ \n args itm -> c n args =<< f itm

-- | Slightly more general contramap
transformContext_ :: (b -> Compiler a) -> Context a -> Context b
transformContext_ = transformContext . traverse