module Kit.Repository (
    extractKit,
    readKitSpec,
    KitRepository(KitRepository)
  ) where

  import Kit.Spec
  import Kit.Util

  import Control.Monad.Error
  import qualified Data.List as L
  import qualified Data.Traversable as T
  import qualified Data.ByteString as BS

  data KitRepository = KitRepository { repositoryBase :: FilePath } deriving (Eq, Show)

  extractKit :: KitRepository -> Kit -> FilePath -> IO ()
  extractKit repo kit destPath = copyFile (repositoryBase repo </> kitPackagePath kit) destPath

  readKitSpec :: KitRepository -> Kit -> KitIO KitSpec
  readKitSpec repo kit = do
    mbKitStuff <- liftIO $ doRead repo (kitSpecPath kit)
    maybe (throwError $ "Missing " ++ packageFileName kit) f mbKitStuff
    where f contents = maybeToKitIO ("Invalid KitSpec file for " ++ packageFileName kit) $ decodeSpec contents

  doRead :: KitRepository -> String -> IO (Maybe BS.ByteString) 
  doRead (KitRepository baseDir) fp = let file = (baseDir </> fp) in do
    exists <- doesFileExist file
    T.sequenceA $ justTrue exists $ BS.readFile file

  baseKitPath :: Kit -> String
  baseKitPath k = joinS ["kits", kitName k, kitVersion k] "/"
    where joinS xs x = foldl1 (++) $ L.intersperse x xs

  kitPackagePath, kitSpecPath :: Kit -> String
  kitPackagePath k = baseKitPath k ++ "/" ++ packageFileName k ++ ".tar.gz"
  kitSpecPath k = baseKitPath k ++ "/" ++ "KitSpec"