{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
---------------------------------------------------------
--
-- Module        : Yesod.Helpers.Static
-- Copyright     : Michael Snoyman
-- License       : BSD3
--
-- Maintainer    : Michael Snoyman <michael@snoyman.com>
-- Stability     : Unstable
-- Portability   : portable
--

-- | Serve static files from a Yesod app.
--
-- This is most useful for standalone testing. When running on a production
-- server (like Apache), just let the server do the static serving.
--
-- In fact, in an ideal setup you'll serve your static files from a separate
-- domain name to save time on transmitting cookies. In that case, you may wish
-- to use 'urlRenderOverride' to redirect requests to this subsite to a
-- separate domain name.
module Yesod.Helpers.Static
    ( -- * Subsite
      Static (..)
    , StaticRoute (..)
      -- * Smart constructor
    , static
      -- * Template Haskell helpers
    , staticFiles
    {-
      -- * Embed files
    , getStaticHandler
    -}
      -- * Hashing
    , base64md5
#if TEST
    , testSuite
#endif
    ) where

import System.Directory
import Control.Monad

import Yesod.Handler
import Yesod.Core

import Data.List (intercalate)
import Language.Haskell.TH
import Language.Haskell.TH.Syntax

import Data.Char
import qualified Data.ByteString.Lazy as L
import Data.Digest.Pure.MD5
import qualified Data.ByteString.Base64
import qualified Data.ByteString.Char8 as S8
import qualified Data.Serialize

import Network.Wai.Application.Static
    ( defaultMimeTypeByExt, StaticSettings (..), staticAppPieces
    , defaultListing
    )

#if TEST
import Test.Framework (testGroup, Test)
import Test.Framework.Providers.HUnit
import Test.HUnit hiding (Test)
#endif

newtype Static = Static StaticSettings

-- | Default value of 'Static' for a given file folder.
--
-- Does not have index files, uses default directory listings and default mime
-- type list.
static :: FilePath -> Static
static fp = Static $ StaticSettings fp [] (Just defaultListing)
                     (return . defaultMimeTypeByExt)

-- | Manually construct a static route.
-- The first argument is a sub-path to the file being served whereas the second argument is the key value pairs in the query string.
-- For example,
-- > StaticRoute $ StaticR ["thumb001.jpg"] [("foo", "5"), ("bar", "choc")]
-- would generate a url such as 'http://site.com/static/thumb001.jpg?foo=5&bar=choc'
-- The StaticRoute constructor can be used when url's cannot be statically generated at compile-time.
-- E.g. When generating image galleries.
data StaticRoute = StaticRoute [String] [(String, String)]
    deriving (Eq, Show, Read)

type instance Route Static = StaticRoute

instance RenderRoute StaticRoute where
    renderRoute (StaticRoute x y) = (x, y)

instance Yesod master => YesodDispatch Static master where
    yesodDispatch (Static set) _ pieces  _ _ =
        Just $ staticAppPieces set pieces

{- FIXME
-- | Dispatch static route for a subsite
--
-- Subsites with static routes can't (yet) define Static routes the same way "master" sites can.
-- Instead of a subsite route:
-- /static StaticR Static getStatic
-- Use a normal route:
-- /static/*Strings StaticR GET
--
-- Then, define getStaticR something like:
-- getStaticR = getStaticHandler ($(mkEmbedFiles "static") typeByExt) StaticR
-- */ end CPP comment
getStaticHandler :: Static -> (StaticRoute -> Route sub) -> [String] -> GHandler sub y ChooseRep
getStaticHandler static toSubR pieces = do
  toMasterR <- getRouteToMaster   
  toMasterHandler (toMasterR . toSubR) toSub route handler
  where route = StaticRoute pieces []
        toSub _ = static
        staticSite = getSubSite :: Site (Route Static) (String -> Maybe (GHandler Static y ChooseRep))
        handler = fromMaybe notFound $ handleSite staticSite undefined route "GET"
-}

notHidden :: FilePath -> Bool
notHidden ('.':_) = False
notHidden "tmp" = False
notHidden _ = True

getFileList :: FilePath -> IO [[String]]
getFileList = flip go id
  where
    go :: String -> ([String] -> [String]) -> IO [[String]]
    go fp front = do
        allContents <- filter notHidden `fmap` getDirectoryContents fp
        let fullPath :: String -> String
            fullPath f = fp ++ '/' : f
        files <- filterM (doesFileExist . fullPath) allContents
        let files' = map (front . return) files
        dirs <- filterM (doesDirectoryExist . fullPath) allContents
        dirs' <- mapM (\f -> go (fullPath f) (front . (:) f)) dirs
        return $ concat $ files' : dirs'

-- | This piece of Template Haskell will find all of the files in the given directory and create Haskell identifiers for them. For example, if you have the files \"static\/style.css\" and \"static\/js\/script.js\", it will essentailly create:
--
-- > style_css = StaticRoute ["style.css"] []
-- > js_script_js = StaticRoute ["js/script.js"] []
staticFiles :: FilePath -> Q [Dec]
staticFiles fp = do
    fs <- qRunIO $ getFileList fp
    concat `fmap` mapM go fs
  where
    replace' c
        | 'A' <= c && c <= 'Z' = c
        | 'a' <= c && c <= 'z' = c
        | '0' <= c && c <= '9' = c
        | otherwise = '_'
    go f = do
        let adjust [] = ""
            adjust str@(x:xs) | isDigit x = '_' : x : xs
                              | isUpper x = toLower x : xs
                              | otherwise = str
        let name = mkName $ intercalate "_" $ map (adjust . map replace') f
        f' <- lift f
        let sr = ConE $ mkName "StaticRoute"
        hash <- qRunIO $ fmap base64md5 $ L.readFile $ fp ++ '/' : intercalate "/" f
        let qs = ListE [TupE [LitE $ StringL hash, ListE []]]
        return
            [ SigD name $ ConT ''Route `AppT` ConT ''Static
            , FunD name
                [ Clause [] (NormalB $ sr `AppE` f' `AppE` qs) []
                ]
            ]

#if TEST

testSuite :: Test
testSuite = testGroup "Yesod.Helpers.Static"
    [ testCase "get file list" caseGetFileList
    ]

caseGetFileList :: Assertion
caseGetFileList = do
    x <- getFileList "test"
    x @?= [["foo"], ["bar", "baz"]]

#endif

-- | md5-hashes the given lazy bytestring and returns the hash as
-- base64url-encoded string.
--
-- This function returns the first 8 characters of the hash.
base64md5 :: L.ByteString -> String
base64md5 = map go
          . take 8
          . S8.unpack
          . Data.ByteString.Base64.encode
          . Data.Serialize.encode
          . md5
  where
    go '+' = '-'
    go '/' = '_'
    go c   = c