combine.html.hamlet

$with scripts <- ["Prelude", "Config", "KV"]
  ^{combineScripts "app" scripts}

renderCombinedJS.hs

renderHamlet ∷ Bool → (Text → Text → Sh FilePath) → Text
renderHamlet isDebug hasher =
    let hashedFile fp = toTextIgnore $
          if isDebug then fp else unsafePerformIO $ shelly $ do
            contents ← readfile fp
            hasher (LT.fromStrict $ fromJust $ extension fp) contents
    in renderHtml $(hamletFile "combine.html.hamlet")
  where 
   combineScripts path = (mkScripts ∘ map encodeString) ∘
         (if isDebug then id else unsafePerformIO ∘ combine "js") ∘ map (λfp → path </> fp <.> "js")
      where
        mkScripts scripts  = [hamletN|$forall script <- scripts
        <script type=text/javascript src=#{script}>
        |]

        combine ∷ Text → [FilePath] → IO [FilePath]
        combine ext files = shelly $ do
            contents ← mapM readfile files
            let content = LT.concat contents
            fmap (:[]) $ hasher ext content

      hashedFile ∷ Text → Text → Sh FilePath
      hashedFile ext orig = shelly $ do
        (hashedName, content) ← hashedFileWithContents ext orig
        let newName = (if ext ≡ "js" then "scripts" else "resources/css") </> hashedName
        writefile (deploy_dir </> newName) content
        return newName

hashedFileWithContents ∷ Text → Text → Sh (FilePath, Text)
hashedFileWithContents ext orig = do
  contents ← if ext ≡ "js" then uglify orig else return orig
  let hashed = hashContents contents
  return (hashed `addExtension` LT.toStrict ext, contents)

uglify :: Text -> Sh Text
uglify contents = do
  setStdin contents
  print_stdout False $ cmd "../vendor/node_modules/uglify-js/bin/uglifyjs" ""

-- from yesod-static
hashContents ∷ Text → FilePath
hashContents = decodeString ∘ base64 ∘ hash ∘ TE.encodeUtf8 ∘ LT.toStrict
  where
    base64 ∷ ByteString → String
    base64 = map tr
           ∘ take 8
           ∘ S8.unpack
           ∘ Data.ByteString.Base64.encode
      where
        tr '+' = '-' 
        tr '/' = '_' 
        tr c   = c 

-- use: 
renderHamlet True undefined -- development
renderHamlet False hashedFile -- production