{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedStrings #-}
module Yesod.Dispatch
    ( -- * Quasi-quoted routing
      parseRoutes
    , parseRoutesFile
    , mkYesod
    , mkYesodSub
      -- ** More fine-grained
    , mkYesodData
    , mkYesodSubData
    , mkYesodDispatch
    , mkYesodSubDispatch
      -- ** Path pieces
    , SinglePiece (..)
    , MultiPiece (..)
    , Texts
      -- * Convert to WAI
    , toWaiApp
    , toWaiAppPlain
    ) where

import Data.Functor   ((<$>))
import Data.Either    (partitionEithers)
import Prelude hiding (exp)
import Yesod.Internal.Core
import Yesod.Handler
import Yesod.Internal.Dispatch
import Yesod.Widget (GWidget)

import Web.PathPieces (SinglePiece (..), MultiPiece (..))
import Yesod.Internal.RouteParsing (THResource, Pieces (..), createRoutes, createRender, Resource (..), parseRoutes, parseRoutesFile)
import Language.Haskell.TH.Syntax

import qualified Network.Wai as W
import Network.Wai.Middleware.Jsonp
import Network.Wai.Middleware.Gzip
import Network.Wai.Middleware.Autohead

import Data.ByteString.Lazy.Char8 ()

import Web.ClientSession
import Data.Char (isUpper)
import Data.Text (Text)

type Texts = [Text]

-- | Generates URL datatype and site function for the given 'Resource's. This
-- is used for creating sites, /not/ subsites. See 'mkYesodSub' for the latter.
-- Use 'parseRoutes' to create the 'Resource's.
mkYesod :: String -- ^ name of the argument datatype
        -> [Resource]
        -> Q [Dec]
mkYesod name = fmap (uncurry (++)) . mkYesodGeneral name [] [] False

-- | Generates URL datatype and site function for the given 'Resource's. This
-- is used for creating subsites, /not/ sites. See 'mkYesod' for the latter.
-- Use 'parseRoutes' to create the 'Resource's. In general, a subsite is not
-- executable by itself, but instead provides functionality to
-- be embedded in other sites.
mkYesodSub :: String -- ^ name of the argument datatype
           -> Cxt
           -> [Resource]
           -> Q [Dec]
mkYesodSub name clazzes =
    fmap (uncurry (++)) . mkYesodGeneral name' rest clazzes True
  where
    (name':rest) = words name

-- | Sometimes, you will want to declare your routes in one file and define
-- your handlers elsewhere. For example, this is the only way to break up a
-- monolithic file into smaller parts. Use this function, paired with
-- 'mkYesodDispatch', to do just that.
mkYesodData :: String -> [Resource] -> Q [Dec]
mkYesodData name res = mkYesodDataGeneral name [] False res

mkYesodSubData :: String -> Cxt -> [Resource] -> Q [Dec]
mkYesodSubData name clazzes res = mkYesodDataGeneral name clazzes True res

mkYesodDataGeneral :: String -> Cxt -> Bool -> [Resource] -> Q [Dec]
mkYesodDataGeneral name clazzes isSub res = do
    let (name':rest) = words name
    (x, _) <- mkYesodGeneral name' rest clazzes isSub res
    let rname = mkName $ "resources" ++ name
    eres <- lift res
    let y = [ SigD rname $ ListT `AppT` ConT ''Resource
            , FunD rname [Clause [] (NormalB eres) []]
            ]
    return $ x ++ y

-- | See 'mkYesodData'.
mkYesodDispatch :: String -> [Resource] -> Q [Dec]
mkYesodDispatch name = fmap snd . mkYesodGeneral name [] [] False

mkYesodSubDispatch :: String -> Cxt -> [Resource] -> Q [Dec]
mkYesodSubDispatch name clazzes = fmap snd . mkYesodGeneral name' rest clazzes True 
  where (name':rest) = words name

mkYesodGeneral :: String -- ^ foundation name
               -> [String] -- ^ parameters for foundation
               -> Cxt -- ^ classes
               -> Bool -- ^ is subsite?
               -> [Resource]
               -> Q ([Dec], [Dec])
mkYesodGeneral name args clazzes isSub res = do
    let args' = map mkName args
        arg = foldl AppT (ConT name') $ map VarT args'
    th' <- mapM thResourceFromResource res
    let th = map fst th'
    w' <- createRoutes th
    let routesName = mkName $ name ++ "Route"
    let w = DataD [] routesName [] w' [''Show, ''Read, ''Eq]
    let x = TySynInstD ''Route [arg] $ ConT routesName

    render <- createRender th
    let x' = InstanceD [] (ConT ''RenderRoute `AppT` ConT routesName)
                [ FunD (mkName "renderRoute") render
                ]

    let splitter :: (THResource, Maybe String)
                 -> Either
                        (THResource, Maybe String)
                        (THResource, Maybe String)
        splitter a@((_, SubSite{}), _) = Left a
        splitter a = Right a
    let (resSub, resLoc) = partitionEithers $ map splitter th'
    yd <- mkYesodDispatch' resSub resLoc
    let master = mkName "master"
    let ctx = if isSub
                then ClassP (mkName "Yesod") [VarT master] : clazzes
                else []
    let ytyp = if isSub
                then ConT ''YesodDispatch `AppT` arg `AppT` VarT master
                else ConT ''YesodDispatch `AppT` arg `AppT` arg
    let y = InstanceD ctx ytyp [FunD (mkName "yesodDispatch") [yd]]
    return ([w, x, x'] ++ masterTypSyns, [y])
  where
    name' = mkName name
    masterTypSyns
        | isSub = []
        | otherwise =
            [ TySynD
                (mkName "Handler")
                []
                (ConT ''GHandler `AppT` ConT name' `AppT` ConT name')
            , TySynD
                (mkName "Widget")
                []
                (ConT ''GWidget `AppT` ConT name' `AppT` ConT name' `AppT` TupleT 0)
            ]

thResourceFromResource :: Resource -> Q (THResource, Maybe String)
thResourceFromResource (Resource n ps atts)
    | all (all isUpper) atts = return ((n, Simple ps atts), Nothing)
thResourceFromResource (Resource n ps [stype, toSubArg]) = do
    let stype' = ConT $ mkName stype
    parse <- [|error "ssParse"|]
    dispatch <- [|error "ssDispatch"|]
    render <- [|renderRoute|]
    tmg <- [|error "ssToMasterArg"|]
    return ((n, SubSite
        { ssType = ConT ''Route `AppT` stype'
        , ssParse = parse
        , ssRender = render
        , ssDispatch = dispatch
        , ssToMasterArg = tmg
        , ssPieces = ps
        }), Just toSubArg)

thResourceFromResource (Resource n _ _) =
    error $ "Invalid attributes for resource: " ++ n

-- | Convert the given argument into a WAI application, executable with any WAI
-- handler. This is the same as 'toWaiAppPlain', except it includes three
-- middlewares: GZIP compression, JSON-P and path cleaning. This is the
-- recommended approach for most users.
toWaiApp :: (Yesod y, YesodDispatch y y) => y -> IO W.Application
toWaiApp y = gzip False . jsonp . autohead <$> toWaiAppPlain y

-- | Convert the given argument into a WAI application, executable with any WAI
-- handler. This differs from 'toWaiApp' in that it uses no middlewares.
toWaiAppPlain :: (Yesod y, YesodDispatch y y) => y -> IO W.Application
toWaiAppPlain a = toWaiApp' a <$> encryptKey a


toWaiApp' :: (Yesod y, YesodDispatch y y)
          => y
          -> Maybe Key
          -> W.Application
toWaiApp' y key' env =
    case yesodDispatch y key' (W.pathInfo env) y id of
        Just app -> app env
        Nothing -> yesodRunner y y id key' Nothing notFound env