{- |
 Handlers for serving static resources
-}
module WebGear.Core.Handler.Static (
  serveDir,
  serveFile,
) where

import Control.Arrow ((<<<))
import qualified Data.Text as Text
import qualified Network.Mime as Mime
import System.FilePath (joinPath, takeFileName, (</>))
import WebGear.Core.Handler (Handler (..), RoutePath (..), unwitnessA, (>->))
import WebGear.Core.Request (Request (..))
import WebGear.Core.Response (Response, ResponseBody (..))
import WebGear.Core.Trait (Sets, With)
import WebGear.Core.Trait.Body (UnknownContentBody, setBodyWithoutContentType)
import WebGear.Core.Trait.Header (RequiredResponseHeader, setHeader)
import WebGear.Core.Trait.Status (Status, notFound404, ok200)
import Prelude hiding (readFile)

-- | Serve files under the specified directory.
serveDir ::
  ( Handler h m
  , Sets
      h
      [ Status
      , RequiredResponseHeader "Content-Type" Mime.MimeType
      , UnknownContentBody
      ]
      Response
  ) =>
  -- | The directory to serve
  FilePath ->
  -- | Optional index filename for the root directory. A 404 Not Found
  -- response will be returned for requests to the root path if this
  -- is set to @Nothing@.
  Maybe FilePath ->
  h (Request `With` ts) Response
serveDir root index = proc _request -> consumeRoute go -< ()
  where
    go = proc path -> do
      case (path, index) of
        (RoutePath [], Nothing) -> unwitnessA <<< notFound404 -< ()
        (RoutePath [], Just f) -> serveFile -< root </> f
        (RoutePath ps, _) -> serveFile -< root </> joinPath (Text.unpack <$> ps)

-- | Serve a file specified by the input filepath.
serveFile ::
  ( Handler h m
  , Sets
      h
      [ Status
      , RequiredResponseHeader "Content-Type" Mime.MimeType
      , UnknownContentBody
      ]
      Response
  ) =>
  h FilePath Response
serveFile = proc file -> do
  let contents = ResponseBodyFile file Nothing
      contentType = Mime.defaultMimeLookup $ Text.pack $ takeFileName file
  (ok200 -< ())
    >-> (\resp -> setBodyWithoutContentType -< (resp, contents))
    >-> (\resp -> setHeader @"Content-Type" -< (resp, contentType))
    >-> (\resp -> unwitnessA -< resp)